Sample records for martian meteorites studied

  1. Hydrogen in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.; Hervig, R.; Irving, T.

    2017-01-01

    Most volatile studies of Mars have targeted its surface via spacecraft and rover data, and have evidenced surficial water in polar caps and the atmosphere, in the presence of river channels, and in the detection of water bearing minerals. The other focus of Martian volatile studies has been on Martian meteorites which are all from its crust. Most of these studies are on hydrous phases like apatite, a late-stage phase, i.e. crystallizing near the end of the differentiation sequence of Martian basalts and cumulates. Moreover, calculating the water content of the magma a phosphate crystallized from is not always possible, and yet is an essential step to estimate how much water was present in a parent magma and its source. Water, however, is primarily dissolved in the interiors of differentiated planets as hydrogen in lattice defects of nominally anhydrous minerals (olivine, pyroxene, feldspar) of the crust and mantle. This hydrogen has tremendous influence, even in trace quantities, on a planet's formation, geodynamics, cooling history and the origin of its volcanism and atmosphere as well as its potential for life. Studies of hydrogen in nominally anhydrous phases of Martian meteorites are rare. Measuring water contents and hydrogen isotopes in well-characterized nominally anhydrous minerals of Martian meteorites is the goal of our study. Our work aims at deciphering what influences the distribution and origin of hydrogen in Martian minerals, such as source, differentiation, degassing and shock.

  2. Antarctic Martian Meteorites at Johnson Space Center

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Satterwhite, C. E.; Righter, K.; Harrington, R.

    2018-01-01

    This past year marked the 40th anniversary of the first Martian meteorite found in Antarctica by the ANSMET Antarctic Search for Meteorites) program, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET program making for a total of 15 Martian meteorites in the U. S. Antarctic meteorite collection at Johnson Space Center (JSC). Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate samples. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottite in 1982. This meteorite has been allocated to 137 scientists for research and there are 180.934 g remaining at JSC. Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain noble gas and nitrogen compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to 205 scientists for research and 5,298.435 g of sample is available.

  3. 40 Years of Collecting Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Sattershite, C. E.; Righter, K.; Harrington, R.

    2017-01-01

    This year marks the 40th anniversary of the first Martian meteorite found in Antarctica by ANSMET, ALH 77005. Since then, an additional 14 Martian meteorites have been found by the ANSMET team making for a total of 15 Martian meteorites in the Antarctic collection at Johnson Space Center. Of the 15 meteorites, some have been paired so the 15 meteorites actually represent a total of approximately 9 separate meteorites. The first Martian meteorite found by ANSMET was ALH 77005 (482.500 g), a lherzolitic shergottite. When collected, this meteorite was split as a part of the joint expedition with the National Institute of Polar Research (NIPR) Japan. Originally classified as an "achondrite-unique", it was re-classified as a Martian lherzolitic shergottites in 1982 [1]. This meteorite has been allocated to 125 scientists for research and there are 181.964 g remaining at Johnson Space Center (JSC). Two years later, one of the most significant Martian meteorites of the collection at JSC was found at Elephant Moraine, EET 79001 (7942.000 g), a shergottite. This meteorite is the largest in the Martian collection at JSC and was the largest stony meteorite sample collected during the 1979 season. In addition to its size, this meteorite is of particular interest because it contains a linear contact separating two different igneous lithologies, basaltic and olivine-phyric. EET 79001 has glass inclusions that contain chemical compositions that are proportionally identical to the Martian atmosphere, as measured by the Viking spacecraft [2]. This discovery helped scientists to identify where the "SNC" meteorite suite had originated, and that we actually possessed Martian samples. This meteorite has been allocated to 195 scientists for research and there are 5304.770 g of sample is available. Five years later, ANSMET found ALH 84001 (1930.900 g), the only Martian orthopyroxenite. This meteorite was initially classified as a diogenite but was reclassified as being a Martian

  4. Chlorine Abundances in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D.D.; Garrison, D.H.; Park, J.

    2009-01-01

    Chlorine measurements made in martian surface rocks by robotic spacecraft typically give Chlorine (Cl) abundances of approximately 0.1-0.8%. In contrast, Cl abundances in martian meteorites appear lower, although data is limited, and martian nakhlites were also subjected to Cl contamination by Mars surface brines. Chlorine abundances reported by one lab for whole rock (WR) samples of Shergotty, ALH77005, and EET79001 range 108-14 ppm, whereas Cl in nakhlites range 73-1900 ppm. Measurements of Cl in various martian weathering phases of nakhlites varied 0.04-4.7% and reveal significant concentration of Cl by martian brines Martian meteorites contain much lower Chlorine than those measured in martian surface rocks and give further confirmation that Cl in these surface rocks was introduced by brines and weathering. It has been argued that Cl is twice as effective as water in lowering the melting point and promoting melting at shallower martian depths, and that significant Cl in the shergottite source region would negate any need for significant water. However, this conclusion was based on experiments that utilized Cl concentrations more analogous to martian surface rocks than to shergottite meteorites, and may not be applicable to shergottites.

  5. Life on Mars: Evidence from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Thomas-Keptra, Katie L.; Clemett, Simon J.; Gibson, Everett K., Jr.; Spencer, Lauren; Wentworth, Susan J.

    2009-01-01

    New data on martian meteorite 84001 as well as new experimental studies show that thermal or shock decomposition of carbonate, the leading alternative non-biologic explanation for the unusual nanophase magnetite found in this meteorite, cannot explain the chemistry of the actual martian magnetites. This leaves the biogenic explanation as the only remaining viable hypothesis for the origin of these unique magnetites. Additional data from two other martian meteorites show a suite of biomorphs which are nearly identical between meteorites recovered from two widely different terrestrial environments (Egyptian Nile bottomlands and Antarctic ice sheets). This similarity argues against terrestrial processes as the cause of these biomorphs and supports an origin on Mars for these features.

  6. Cleaning a Martian Meteoritean Meteorite

    NASA Image and Video Library

    2018-02-13

    A slice of a meteorite scientists have determined came from Mars placed inside an oxygen plasma cleaner, which removes organics from the outside of surfaces. This slice will likely be used here on Earth for testing a laser instrument for NASA's Mars 2020 rover; a separate slice will go to Mars on the rover. Martian meteorites are believed to be the result of impacts to the Red Planet's surface, resulting in rock being blasted into the atmosphere. After traveling through space for eons, some of these rocks entered Earth's atmosphere. Scientists determine whether they are true Martian meteorites based on their rock and noble gas chemistry and mineralogy. The gases trapped in these meteorites bear the unique fingerprint of the Martian atmosphere, as recorded by NASA's Viking mission in 1976. The rock types also show clear signs of igneous processing not possible on smaller bodies, such as asteroids. https://photojournal.jpl.nasa.gov/catalog/PIA22247

  7. Curation of US Martian Meteorites Collected in Antarctica

    NASA Technical Reports Server (NTRS)

    Lindstrom, M.; Satterwhite, C.; Allton, J.; Stansbury, E.

    1998-01-01

    To date the ANSMET field team has collected five martian meteorites (see below) in Antarctica and returned them for curation at the Johnson Space Center (JSC) Meteorite Processing Laboratory (MPL). ne meteorites were collected with the clean procedures used by ANSMET in collecting all meteorites: They were handled with JSC-cleaned tools, packaged in clean bags, and shipped frozen to JSC. The five martian meteorites vary significantly in size (12-7942 g) and rock type (basalts, lherzolites, and orthopyroxenite). Detailed descriptions are provided in the Mars Meteorite compendium, which describes classification, curation and research results. A table gives the names, classifications and original and curatorial masses of the martian meteorites. The MPL and measures for contamination control are described.

  8. The Germanium Dichotomy in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.

    2016-01-01

    Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while shergottites contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 shergottites by LAICP- MS using a method optimized for precise germanium analysis.

  9. A Martian Meteorite for Mars 2020

    NASA Image and Video Library

    2018-02-13

    Rohit Bhartia of NASA's Mars 2020 mission holds a slice of a meteorite scientists have determined came from Mars. This slice will likely be used here on Earth for testing a laser instrument for NASA's Mars 2020 rover; a separate slice will go to Mars on the rover. Martian meteorites are believed to be the result of impacts to the Red Planet's surface, resulting in rock being blasted into the atmosphere. After traveling through space for eons, some of these rocks entered Earth's atmosphere. Scientists determine whether they are true Martian meteorites based on their rock and noble gas chemistry and mineralogy. The gases trapped in these meteorites bear the unique fingerprint of the Martian atmosphere, as recorded by NASA's Viking mission in 1976. The rock types also show clear signs of igneous processing not possible on smaller bodies, such as asteroids. https://photojournal.jpl.nasa.gov/catalog/PIA22245

  10. Martian meteorites and Martian magnetic anomalies: a new perspective from NWA 7034 (Invited)

    NASA Astrophysics Data System (ADS)

    Gattacceca, J.; Rochette, P.; Scozelli, R. B.; Munayco, P.; Agee, C. B.; Quesnel, Y.; Cournede, C.; Geissman, J. W.

    2013-12-01

    The magnetic anomalies observed above the Martian Noachian crust [1] require strong crustal remanent magnetization in the 15-60 A/m range over a thickness of 20-50 km [2,3]. The Martian rocks available for study in the form of meteorites do contain magnetic minerals (magnetite and/or pyrrhotite) but in too small amount to account for such strong remanent magnetizations [4]. Even though this contradiction was easily explained by the fact that Martian meteorites (mostly nakhlites and shergottites) are not representative of the Noachian Martian crust, we were left with no satisfactory candidate lithology to account for the Martian magnetic anomalies. The discovery in the Sahara of a new type of Martian meteorite (NWA 7034 [5] and subsequent paired stones which are hydrothermalized volcanic breccia) shed a new light on this question as it contains a much larger amount of ferromagnetic minerals than any other Martian meteorite. We present here a study of the magnetic properties of NWA 7034, together with a review of the magnetic properties of thirty other Martian meteorites. Magnetic measurements (including high and low temperature behavior and Mössbauer spectroscopy) show that NWA 7034 contains about 15 wt.% of magnetite with various degrees of substitution and maghemitization up to pure maghemite, in the pseudo-single domain size range. Pyrrhotite, a common mineral in other Martian meteorites is not detected. Although it is superparamagnetic and cannot carry remanent magnetization, nanophase goethite is present in significant amounts confirming that NWA 7034 is the most oxidized Martian meteorite studied so far, as already indicated by the presence of maghemite (this study) and pyrite [5]. These magnetic properties show that a kilometric layer of a lithology similar to NWA 7034 magnetized in a dynamo field would be enough to account for the strongest Martian magnetic anomalies. Although the petrogenesis of NWA 7034 is still debated, as the brecciation could be either

  11. Peology and Geochemistry of New Paired Martian Meteorites 12095 and LAR 12240

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Brandon, A. D.; Peslier, A.

    2015-01-01

    The meteorites LAR 12095 and LAR 12240 are believed to be paired Martian meteorites and were discovered during the Antarctic Search for Meteorites (ANSMET) 2012-2013 Season at Larkman Nunatak. The purpose of this study is to characterize these olivine-phyric shergottites by analyzing all mineral phases for major, minor and trace elements and examining their textural relationships. The goal is to constrain their crystallization history and place these shergottites among other Martian meteorites in order to better understand Martian geological history.

  12. Amino Acids in the Antarctic Martian Meteorite MIL03346

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Aubrey, A.; Dworkin, J. P.; Botta, O.; Bada, J. L.

    2005-01-01

    The report by McKay et al. that the Martian meteorite ALH84001 contains evidence for life on Mars remains controversial. Of central importance is whether ALH84001 and other Antarctic Martian meteorites contain endogenous organic compounds. In any investigation of organic compounds possibly derived from Mars it is important to focus on compounds that play an essential role in biochemistry as we know it and that have properties such as chirality which can be used to distinguish between biotic versus abiotic origins. Amino acids are one of the few compounds that fulfill these requirements. Previous analyses of the Antarctic Martian meteorites ALH84001 and EETA79001 have shown that these meteorites contain low levels of terrestrial amino acid contamination derived from Antarctic ice meltwater. Here we report preliminary amino acid investigations of a third Antarctic Martian meteorite MIL03346 which was discovered in Antarctica during the 2003-04 ANSMET season. Additional information is included in the original extended abstract

  13. The provenance and formation of reduced carbon phases on Mars from the study of Martian meteorites.

    NASA Astrophysics Data System (ADS)

    Steele, A.; McCubbin, F. M.; Fries, M.

    2015-12-01

    Organic carbon compounds are essential building blocks of terrestrial life, so the occurrence and origin (biotic or abiotic) of organic compounds on Mars is of great significance. Indeed, the question of Martian organic matter is among the highest priority targets for robotic spacecraft missions in the next decade includ- ing the Mars Science Laboratory and Mars 2020. Sev- eral Martian meteorites contain organic carbon (i.e., macromolecular reduced carbon-rich material, not nec- essarily related to biota), but there is little agreement on its origins. Initial hypotheses for the origin of this organic carbon included: terrestrial contamination; chondritic meteoritic input; thermal decomposition of Martian carbonate minerals; direct precipitation from cooling aqueous fluids; and the remains of ancient Martian biota. We report on results from the analysis of 14 martian meteorites and show the distribution of organic phases throughout the samples analyzed. We will present formation scearios for each of the types of organic matter discovered. These studies when combined show 4 possible pools of reduced carbon on Mars. 1) impact generated graphite in the Tissint meteorite, 2) secondary hydrothermal generated graphite in ALH 84001, 3) primary igneous reduced carbon in 12 Martian meteorites associated with spinel inclusions in olivine and pyroxene 4) and potentially primary hydrothermally formed organic carbon / nitrogen containing organic species in the maskelynite phases of the Tissint meteorite. These studies show that Mars has produced reduced carbon / organic carbon via several mechanisms and reveal that the building blocks of life, if not life itself, are present on Mars.

  14. Magnetism of Tissint Martian meteorite

    NASA Astrophysics Data System (ADS)

    Rochette, P.; Gattacceca, J.; Hewins, R.; Lagroix, F.; Uehara, M.; Cournede, C.; Chennaoui Aoudjehane, H.; Zanda, B.; Bernstein Scorzelli, R.

    2012-12-01

    The Tissint meteorite, an olivine-phyric shergottite that fell in July 2010 in Morocco, is only the fifth Martian meteorite fall. It offers the opportunity to study the magnetic mineralogy and the paleomagnetic signal of a pristine sample from Mars. We have performed such a magnetic study of 35 samples from the Tissint meteorite, with mass ranging from 30 mg to 30 g. We have measured a variety of magnetic properties (natural remanence an its behaviour upon thermal and alternating field demagnetization, hysteresis parameters at room and low temperatures, anisotropy of magnetic susceptibility, unblocking temperature spectrum etc). Less conventional experiments include magneto-optical imaging (coupled with electron microprobe analyses) and Mössbauer spectroscopy. The magnetic mineralogy of Tissint consists of 0.6 wt.% of metastable hexagonal ferrimagnetic pyrrhotite, and 0.1 wt.% of low Ti titanomagnetite formed by oxidation/exsolution of ulvöspinel grains. The magnetic mineralogy of Tissint consists of 0.6 wt.% of metastable hexagonal ferrimagnetic pyrrhotite, and 0.1 wt.% of low Ti titanomagnetite formed by oxidation/exsolution of ulvöspinel grains, for those minerals that are ferromagnetic at temperatures encountered at the Martian surface. Chromite (with a Curie temperature of 70K) is present with an abundance of 0.5 wt.%. Overall, these properties are in broad agreement with the other pyrrhotite-bearing basaltic shergottites, but the presence of magnetite exsolution in ulvöspinel has rarely been documented in other shergottites. We show for the first time that the magnetic fabric is homogeneous in direction in the meteorite, and may well be a proxy to the Martian paleohorizontal at the time of crystallization. The natural remanent magnetization of Tissint was acquired during post-impact cooling in a stable ambient field of about 1 μT of crustal origin. It is noteworthy that the oxides in Tissint are not magnetized, indicating that they were formed at low

  15. Nature of the Martian Uplands and Martian Meteorite Age Distribution

    NASA Astrophysics Data System (ADS)

    Hartmann, W. K.; Barlow, N. G.

    2005-12-01

    Martian meteorites have been launched from some 4 to 8 sites on Mars within the last 20 My. Some 75% to 88% of the sites ejected igneous rocks < 1.3 Gy old. Thus 75% to 88% of the rock-launching sites represent only 29% of Martian time. We hypothesize this imbalance arises not merely from poor statistics, but because much of the older Martian surface is inefficient in launching rocks during impacts. There are three lines of evidence. First, intense Noachian cratering must have produced surface layers with > 100 m of regolith, which reduces launch efficiency due to dominance of fines and possible effects of ice in the regolith. Second, both Mars Exploration Rovers in 2004, found that some older coherent strata are weak sediments, 1-2 orders of magnitude weaker than Martian igneous rocks. Low strength favors low launch efficiency, and even if launched, such rocks may produce recognizable meteorites on Earth. Third, the smaller fresh impact craters in Martian upland sites are rarely surrounded by secondary impact crater fields (cf. Barlow and Block, 2004). In a survey of 200 craters, the smallest Noachian, Hesperian, and Amazonian craters with fields of secondaries are ˜ 45 km, ˜ 24 km, and ˜ 10 km, respectively. With 40% of Mars being Noachian, and 74% being either Noachian or Hesperian, these effects could play an important role in the statistics of recognized Martian meteorites and production rates of secondary crater populations. Reference: Barlow N.G., Block, K.M. (2004), DPS abstract 47.04.

  16. Mapping the Iron Oxidation State in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Treimann, A. H.; Righter, K.

    2017-01-01

    Several types of Martian igneous meteorites have been identified: clinopyroxenites (nakhlites), basaltic shergottites, peridotitic shergottites, dunites (chassignites) and orthopyroxenites [1,2]. In order to constrain the heterogeneity of the Martian mantle and crust, and their evolution through time, numerous studies have been performed on the iron oxidation state of these meteorites [3,4,5,6,7,8,9]. The calculated fO2 values all lie within the FMQ-5 to FMQ+0.5 range (FMQ representing the Fayalite = Magnetite + Quartz buffer); however, discrepancies appear between the various studies, which are either attributed to the choice of the minerals/melts used, or to the precision of the analytical/calculation method. The redox record in volcanic samples is primarily related to the oxidation state in the mantle source(s). However, it is also influenced by several deep processes: melting, crystallization, magma mixing [10], assimilation and degassing [11]. In addition, the oxidation state in Martian meteorites is potentially affected by several surface processes: assimilation of sediment/ crust during lava flowing at Mars' surface, low temperature micro-crystallization [10], weathering at the surface of Mars and low temperature reequilibration, impact processes (i.e. high pressure phase transitions, mechanical mixing, shock degassing and melting), space weathering, and weathering on Earth (at atmospheric conditions different from Mars). Decoding the redox record of Martian meteorites, therefore, requires large-scale quantitative analysis methods, as well as a perfect understanding of oxidation processes.

  17. LU-HF Age of Martian Meteorite Larkman Nunatek 06319

    NASA Technical Reports Server (NTRS)

    Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Beard, B.; Peslier, A. H.

    2009-01-01

    Lu-Hf isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 197+/- 29 Ma. Sm-Nd isotopic data and in-situ LA-ICP-MS data from a thin section of LAR 06319 are currently being collected and will be presented at the 2009 LPSC. These new data for LAR 06319 extend the existing data set for the enriched shergottite group. Martian meteorites represent the only opportunity for ground truth investigation of the geochemistry of Mars [1]. At present, approximately 80 meteorites have been classified as Martian based on young ages and distinctive isotopic signatures [2]. LAR 06319 is a newly discovered (as part of the 2006 ANSMET field season) martian meteorite that represents an important opportunity to further our understanding of the geochemical and petrological constraints on the origin of Martian magmas. Martian meteorites are traditionally categorized into the shergottite, nakhlite, and chassignite groups. The shergottites are further classified into three distinct isotopic groups designated depleted, intermediate, and enriched [3,4] based on the isotope systematics and compositions of their source(s).

  18. Did Martian Meteorites Come From These Sources?

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2007-01-01

    Large rayed craters on Mars, not immediately obvious in visible light, have been identified in thermal infrared data obtained from the Thermal Emission Imaging System (THEMIS) onboard Mars Odyssey. Livio Tornabene (previously at the University of Tennessee, Knoxville and now at the University of Arizona, Tucson) and colleagues have mapped rayed craters primarily within young (Amazonian) volcanic plains in or near Elysium Planitia. They found that rays consist of numerous chains of secondary craters, their overlapping ejecta, and possibly primary ejecta from the source crater. Their work also suggests rayed craters may have formed preferentially in volatile-rich targets by oblique impacts. The physical details of the rayed craters and the target surfaces combined with current models of Martian meteorite delivery and cosmochemical analyses of Martian meteorites lead Tornabene and coauthors to conclude that these large rayed craters are plausible source regions for Martian meteorites.

  19. Nature of Reduced Carbon in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.

    2012-01-01

    Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. Shergottites demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, Yamato 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures

  20. Candidates source regions of martian meteorites as identified by OMEGA/MEx

    NASA Astrophysics Data System (ADS)

    Ody, A.; Poulet, F.; Quantin, C.; Bibring, J.-P.; Bishop, J. L.; Dyar, M. D.

    2015-09-01

    The objective of this study is to identify and map spectral analogues of some key martian meteorites (basaltic shergottites Los Angeles, Shergotty, QUE 94201, lherzolitic shergottite ALH A77005, Nakhla, Chassigny and the orthopyroxenite ALH 84001) in order to localize terrain candidates for their source regions. We develop a best fit procedure to reproduce the near-infrared (NIR) spectral properties of the martian surface as seen by the hyperspectral imaging spectrometer OMEGA/MEx from the NIR spectra of the martian meteorites. The fitting process is tested and validated, and Root Mean Square (RMS) global maps for each meteorite are obtained. It is found that basaltic shergottites have NIR spectral properties the most representative of the martian surface with the best spectral analogues found in early Hesperian volcanic provinces. Sites with spectral properties similar to those of ALH A77005 are scarce. They are mainly localized in olivine-bearing regions such as Nili Fossae and small Noachian/early Hesperian terrains. The only plausible source region candidate for Chassigny is the Nili Patera caldera dated to 1.6 Ga. Widespread spectral analogues for the ALH 84001 meteorite are found northeast of Syrtis Major and northwest of the Hellas basin. While this distribution is in agreement with the low-calcium-pyroxene-rich composition and old age (4.1 Ga) of this meteorite, the modal mineralogy of these candidates is not consistent with that of this meteorite. No convincing spectral analogue is found for the Amazonian-aged Nakhla meteorite suggesting that its olivine/high-calcium-pyroxene-rich composition could be representative of the Amazonian terrains buried under dust. Finally, some young rayed craters are proposed as possible candidates for source craters of the studied martian meteorites.

  1. SNC meteorites and their implications for reservoirs of Martian volatiles

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1993-01-01

    The SNC meteorites and the measurements of the Viking landers provide our only direct information about the abundance and isotopic composition of Martian volatiles. Indirect measurements include spectroscopic determinations of the D/H ratio of the Martian atmosphere. A personal view of volatile element reservoirs on Mars is presented, largely as inferred from the meteoritic evidence. This view is that the Martian mantle has had several opportunities for dehydration and is most likely dry, although not completely degassed. Consequently, the water contained in SNC meteorites was most likely incorporated during ascent through the crust. Thus, it is possible that water can be decoupled from other volatile/incompatible elements, making the SNC meteorites suspect as indicators of water inventories on Mars.

  2. Ne-20/Ne-22 in the Martian Atmosphere: New Evidence from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Park, J.; Nyquist, L. E.; Herzog, G. F.; Nagao, K.; Mikouchi, T.; Kusakabe, M.

    2017-01-01

    Analyses of Ne trapped in "pods" of impact melt in the Elephant Moraine 79001 (EET 79001) Martian meteorite led to suggest (Ne-20/Ne-22) approx.10 in the Martian atmosphere (MA). In contrast, obtained trapped (Ne-20/Ne-22)Tr approx.7 from an impact melt vein in Yamato 793605 (Y-793605) and concluded that the isotopic composition of Martian Ne remained poorly defined. A "pyroxene-rich" separate from Dhofar 378 (Dho 378) analyzed gave a comparatively high trapped Ne concentration and (Ne-20/Ne-22) = 7.3+/-0.2 in agreement with the Y-793605 value. We explore the hypothesis that Martian Ne was trapped in the Dho 378 meteorite in a manner similar to entrapment of terrestrial Ne in tektites strengthening the "Martian atmosphere" interpretation. We also report new data for Northwest Africa 7034 (NWA 7034) that are consistent with the Ne data for Dho 378.

  3. Determining the source locations of martian meteorites: Hapke mixture models applied to CRISM simulated data of igneous mineral mixtures and martian meteorites

    NASA Astrophysics Data System (ADS)

    Harris, Jennifer; Grindrod, Peter

    2017-04-01

    At present, martian meteorites represent the only samples of Mars available for study in terrestrial laboratories. However, these samples have never been definitively tied to source locations on Mars, meaning that the fundamental geological context is missing. The goal of this work is to link the bulk mineralogical analyses of martian meteorites to the surface geology of Mars through spectral mixture analysis of hyperspectral imagery. Hapke radiation transfer modelling has been shown to provide accurate (within 5 - 10% absolute error) mineral abundance values from laboratory derived hyperspectral measurements of binary [1] and ternary [2] mixtures of plagioclase, pyroxene and olivine. These three minerals form the vast bulk of the SNC meteorites [3] and the bedrock of the Amazonian provinces on Mars that are inferred to be the source regions for these meteorites based on isotopic aging. Spectral unmixing through the Hapke model could be used to quantitatively analyse the Martian surface and pinpoint the exact craters from which the SNC meteorites originated. However the Hapke model is complex with numerous variables, many of which are determinable in laboratory conditions but not from remote measurements of a planetary surface. Using binary and tertiary spectral mixtures and martian meteorite spectra from the RELAB spectral library, the accuracy of Hapke abundance estimation is investigated in the face of increasing constraints and simplifications to simulate CRISM data. Constraints and simplifications include reduced spectral resolution, additional noise, unknown endmembers and unknown particle physical characteristics. CRISM operates in two spectral resolutions, the Full Resolution Targeted (FRT) with which it has imaged approximately 2% of the martian surface, and the lower spectral resolution MultiSpectral Survey mode (MSP) with which it has covered the vast majority of the surface. On resampling the RELAB spectral mixtures to these two wavelength ranges it was

  4. Geochemistry of Martian Meteorites and the Petrologic Evolution of Mars

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.

    2002-01-01

    Mafic igneous rocks serve as probes of the interiors of their parent bodies - the compositions of the magmas contain an imprint of the source region composition and mineralogy, the melting and crystallization processes, and mixing and assimilation. Although complicated by their multifarious history, it is possible to constrain the petrologic evolution of an igneous province through compositional study of the rocks. Incompatible trace elements provide one means of doing this. I will use incompatible element ratios of martian meteorites to constrain the early petrologic evolution of Mars. Incompatible elements are strongly partitioned into the melt phase during igneous processes. The degree of incompatibility will differ depending on the mineral phases in equilibrium with the melt. Most martian meteorites contain some cumulus grains, but nevertheless, incompatible element ratios of bulk meteorites will be close to those of their parent magmas. ALH 84001 is an exception, and it will not be discussed. The martian meteorites will be considered in two groups; a 1.3 Ga group composed of the clinopyroxenites and dunite, and a younger group composed of all others.

  5. Amino acids in the Martian meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Bada, J. L.; Brinton, K. L.; McDonald, G. D.

    1999-01-01

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, beta-alanine, and gamma-amino-n-butyric acid (gamma-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

  6. Amino acids in the Martian meteorite Nakhla.

    PubMed

    Glavin, D P; Bada, J L; Brinton, K L; McDonald, G D

    1999-08-03

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, beta-alanine, and gamma-amino-n-butyric acid (gamma-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

  7. Amino acids in the Martian meteorite Nakhla

    PubMed Central

    Glavin, Daniel P.; Bada, Jeffrey L.; Brinton, Karen L. F.; McDonald, Gene D.

    1999-01-01

    A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, β-alanine, and γ-amino-n-butyric acid (γ-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract. The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the d/l ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth. PMID:10430856

  8. The Tissint Martian meteorite as evidence for the largest impact excavation.

    PubMed

    Baziotis, Ioannis P; Liu, Yang; DeCarli, Paul S; Melosh, H Jay; McSween, Harry Y; Bodnar, Robert J; Taylor, Lawrence A

    2013-01-01

    High-pressure minerals in meteorites provide clues for the impact processes that excavated, launched and delivered these samples to Earth. Most Martian meteorites are suggested to have been excavated from 3 to 7 km diameter impact craters. Here we show that the Tissint meteorite, a 2011 meteorite fall, contains virtually all the high-pressure phases (seven minerals and two mineral glasses) that have been reported in isolated occurrences in other Martian meteorites. Particularly, one ringwoodite (75 × 140 μm(2)) represents the largest grain observed in all Martian samples. Collectively, the ubiquitous high-pressure minerals of unusually large sizes in Tissint indicate that shock metamorphism was widely dispersed in this sample (~25 GPa and ~2,000 °C). Using the size and growth kinetics of the ringwoodite grains, we infer an initial impact crater with ~90 km diameter, with a factor of 2 uncertainty. These energetic conditions imply alteration of any possible low-T minerals in Tissint.

  9. No Martian soil component in shergottite meteorites

    NASA Astrophysics Data System (ADS)

    Barrat, J. A.; Jambon, A.; Ferrière, L.; Bollinger, C.; Langlade, J. A.; Liorzou, C.; Boudouma, O.; Fialin, M.

    2014-01-01

    We report on the major and trace element geochemistry of the impact melts contained in some shergottite meteorites. It has been previously proposed that some of these impact melts formed from a mixture of the host rock and a Martian soil component (e.g., Rao et al., 1999) or from partially weathered portions of the host rock (Chennaoui Aoudjehane et al., 2012). Our results contradict both of these theories. Trace element abundances of a glass pod from the EETA 79001A meteorite are identical to those of the host lithology, and indicate that no additional component is required in this case. The impact melts in Tissint share the same trace element features as the host rock, and no secondary phases produced by Martian secondary processes are involved. The light rare earth enrichments displayed by two small samples of Tissint (Chennaoui Aoudjehane et al., 2012) are possibly the result of some contamination of small stones on desert soil before the recovery of the meteorites.

  10. Tissint martian meteorite: a fresh look at the interior, surface, and atmosphere of Mars.

    PubMed

    Aoudjehane, H Chennaoui; Avice, G; Barrat, J-A; Boudouma, O; Chen, G; Duke, M J M; Franchi, I A; Gattacceca, J; Grady, M M; Greenwood, R C; Herd, C D K; Hewins, R; Jambon, A; Marty, B; Rochette, P; Smith, C L; Sautter, V; Verchovsky, A; Weber, P; Zanda, B

    2012-11-09

    Tissint (Morocco) is the fifth martian meteorite collected after it was witnessed falling to Earth. Our integrated mineralogical, petrological, and geochemical study shows that it is a depleted picritic shergottite similar to EETA79001A. Highly magnesian olivine and abundant glass containing martian atmosphere are present in Tissint. Refractory trace element, sulfur, and fluorine data for the matrix and glass veins in the meteorite indicate the presence of a martian surface component. Thus, the influence of in situ martian weathering can be unambiguously distinguished from terrestrial contamination in this meteorite. Martian weathering features in Tissint are compatible with the results of spacecraft observations of Mars. Tissint has a cosmic-ray exposure age of 0.7 ± 0.3 million years, consistent with those of many other shergottites, notably EETA79001, suggesting that they were ejected from Mars during the same event.

  11. Soil Components in Heterogeneous Impact Glass in Martian Meteorite EETA79001

    NASA Technical Reports Server (NTRS)

    Schrader, C. M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.

    2010-01-01

    Martian soil composition can illuminate past and ongoing near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Though the Mars Exploration Rovers (MER) have analyzed the major-element composition of Martian soils, no soil samples have been returned to Earth for detailed chemical analysis. Rao et al. [1] suggested that Martian meteorite EETA79001 contains melted Martian soil in its impact glass (Lithology C) based on sulfur enrichment of Lithology C relative to the meteorite s basaltic lithologies (A and B) [1,2]. If true, it may be possible to extract detailed soil chemical analyses using this meteoritic sample. We conducted high-resolution (0.3 m/pixel) element mapping of Lithology C in thin section EETA79001,18 by energy dispersive spectrometry (EDS). We use these data for principal component analysis (PCA).

  12. Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

    1998-01-01

    A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

  13. Water in Pyroxene and Olivine from Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.

    2012-01-01

    Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

  14. New Martian Meteorite Is One of the Most Oxidized Found to Date

    NASA Technical Reports Server (NTRS)

    Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Shafer, John T.; Brandon, Alan D.; Irving, Anthony J.

    2014-01-01

    As of 2013, about 60 meteorites from the planet Mars have been found and are being studied. Each time a new Martian meteorite is found, a wealth of new information comes forward about the red planet. The most abundant type of Martian meteorite is a shergottite; its lithologies are broadly similar to those of Earth basalts and gabbros; i.e., crustal igneous rocks. The entire suite of shergottites is characterized by a range of trace element, isotopic ratio, and oxygen fugacity values that mainly reflect compositional variations of the Martian mantle from which these magmas came. A newly found shergottite, NWA 5298, was the focus of a study performed by scientists within the Astromaterials Research and Exploration Science (ARES) Directorate at the Johnson Space Center (JSC) in 2012. This sample was found in Morocco in 2008. Major element analyses were performed in the electron microprobe (EMP) laboratory of ARES at JSC, while the trace elements were measured at the University of Houston by laser inductively coupled plasma mass spectrometry (ICPMS). A detailed analysis of this stone revealed that this meteorite is a crystallized magma that comes from the enriched end of the shergottite spectrum; i.e., trace element enriched and oxidized. Its oxidation comes in part from its mantle source and from oxidation during the magma ascent. It represents a pristine magma that did not mix with any other magma or see crystal accumulation or crustal contamination on its way up to the Martian surface. NWA 5298 is therefore a direct, albeit evolved, melt from the Martian mantle and, for its lithology (basaltic shergottite), it represents the oxidized end of the shergottite suite. It is thus a unique sample that has provided an end-member composition for Martian magmas.

  15. Workshop on the Issue Martian Meteorites: Where do we Stand and Where are we Going?

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The presentations in this workshop discuss the composition of Martian meteorites. Many of the talks were on a specific meteorite, i.e., Allan Hills 84001 (ALH84001). The discovery earlier of carbonates in ALH84001 lead some researchers to suggest that there was evidence of martian life. Other possible explanations for this phenomena are given. Other papers discuss methods to sterilize martian samples, the existence of water on Mars, the facilities of the Meteorite Processing Laboratory at Johnson Space Center, comparative analyses of geologic processes and the gathering of meteorites.

  16. The Chlorine Isotope Composition of Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Shearer, C. K.; Agee, C.; Burger, P. V.; McKeegan, K. D.

    2014-11-01

    The Cl isotope composition of martian meteorites range from -3.8 to +8.6 per mil. Ol-phyric shergottites are lightest; crustally contaminated samples are heaviest, basaltic shergottites are in-between. The system is explained as two component mixing.

  17. Alteration of Sedimentary Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; Tartese, R.; Santos, A. R.; Domokos, G.; Muttik, N.; Szabo, T.; Vazquez, J.; Boyce, J. W.; Keller, L. P.; Jerolmack, D. J.; hide

    2014-01-01

    The martian meteorite Northwest Africa (NWA) 7034 and pairings represent the first brecciated hand sample available for study from the martian surface [1]. Detailed investigations of NWA 7034 have revealed substantial lithologic diversity among the clasts [2-3], making NWA 7034 a polymict breccia. NWA 7034 consists of igneous clasts, impact-melt clasts, and "sedimentary" clasts represented by prior generations of brecciated material. In the present study we conduct a detailed textural and geochemical analysis of the sedimentary clasts.

  18. Transmission electron microscope analyses of alteration phases in martian meteorite MIL 090032

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Ishii, H. A.; Bradley, J. P.; Taylor, G. J.

    2014-06-01

    The nakhlite group of martian meteorites found in the Antarctic contain varying abundances of both martian and terrestrial secondary alteration phases. The aim of this study was to use transmission electron microscopy (TEM) to compare martian and terrestrial alteration embodied within a single nakhlite martian meteorite find - MIL 090032. Martian alteration veins in MIL 090032 are composed of poorly ordered Fe-smectite phyllosilicate. This poorly-ordered smectite appears to be equivalent to the nanocrystalline phyllosilicate/hydrated amorphous gel phase previously described in the martian alteration veins of other nakhlites. Chemical differences in this nanocrystalline phyllosilicate between different nakhlites imply localised alteration, which occurred close to the martian surface in MIL 090032. Both structurally and compositionally the nakhlite nanocrystalline phyllosilicate shows similarities to the amorphous/poorly ordered phase recently discovered in martian soil by the Mars Curiosity Rover at Rocknest, Gale Crater. Terrestrially derived alteration phases in MIL 090032 include jarosite and gypsum, amorphous silicates, and Fe-oxides and hydroxides. Similarities between the mineralogy and chemistry of the MIL 090032 terrestrial and martian alteration phases suggest the alteration conditions on Mars were similar to those in the Antarctic. At both sites a small amount of fluid at low temperatures infiltrated the rock and became acidic as a result of the conversion of Fe2+ to Fe3+ under oxidising conditions.

  19. Habitability Conditions Constrained by Martian Meteorites: Implications for Microbial Colonization and Mars Sample Return

    NASA Astrophysics Data System (ADS)

    Shivak, J. N.; Banerjee, N.; Flemming, R. L.

    2013-12-01

    We report the results of a comparative study of the crustal environmental conditions recorded by several Martian meteorites (Nakhla, Los Angeles, and Zagami). Though no samples have yet been returned from Mars, numerous meteorites are known and these provide the only samples of the Martian crust currently available for study. Terrestrial basalts and other mafic igneous rocks are analogous in many ways to much of the Martian crust, as evidenced by the composition of known Martian meteorites and measurements from planetary missions [1]. Microorganisms are known to thrive in the terrestrial geosphere and make use of many different substrates within rock in the subsurface of the Earth [2]. The action of aqueous solutions in the Martian crust has been well established through the study of alteration mineral assemblages present in many Martian meteorites, such as the nakhlites [3]. Aqueous activity in terrestrial chemolithoautotrophic habitats provides numerous energy and nutrient sources for microbes [4], suggesting the potential for habitable endolithic environments in Martian rocks. Fayalite in Nakhla has experienced extensive aqueous alteration to reddish-brown 'iddingsite' material within a pervasive fracture system. Textural imaging shows the replacement of primary olivine with various alteration phases and infiltration of this alteration front into host grains. Geochemical analysis of the alteration material shows the addition of iron and silica and removal of magnesium during alteration. Novel In situ Micro-XRD and Raman Spectroscopy of this material reveals a new assemblage consisting of iron oxides, smectite clays, carbonates, and a minor serpentine component. The alteration mineral assemblage here differs from several that have been previously reported [4] [5], allowing for a reevaluation of the environmental conditions during fluid action. Los Angeles and Zagami show no evidence of aqueous activity, though their primary basaltic mineralogies show many

  20. Hydrogen Isotopic Systematics of Nominally Anhydrous Phases in Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Tucker, Kera

    Hydrogen isotope compositions of the martian atmosphere and crustal materials can provide unique insights into the hydrological and geological evolution of Mars. While the present-day deuterium-to-hydrogen ratio (D/H) of the Mars atmosphere is well constrained (~6 times that of terrestrial ocean water), that of its deep silicate interior (specifically, the mantle) is less so. In fact, the hydrogen isotope composition of the primordial martian mantle is of great interest since it has implications for the origin and abundance of water on that planet. Martian meteorites could provide key constraints in this regard, since they crystallized from melts originating from the martian mantle and contain phases that potentially record the evolution of the H 2O content and isotopic composition of the interior of the planet over time. Examined here are the hydrogen isotopic compositions of Nominally Anhydrous Phases (NAPs) in eight martian meteorites (five shergottites and three nakhlites) using Secondary Ion Mass Spectrometry (SIMS). This study presents a total of 113 individual analyses of H2O contents and hydrogen isotopic compositions of NAPs in the shergottites Zagami, Los Angeles, QUE 94201, SaU 005, and Tissint, and the nakhlites Nakhla, Lafayette, and Yamato 000593. The hydrogen isotopic variation between and within meteorites may be due to one or more processes including: interaction with the martian atmosphere, magmatic degassing, subsolidus alteration (including shock), and/or terrestrial contamination. Taking into consideration the effects of these processes, the hydrogen isotope composition of the martian mantle may be similar to that of the Earth. Additionally, this study calculated upper limits on the H2O contents of the shergottite and nakhlite parent melts based on the measured minimum H2O abundances in their maskelynites and pyroxenes, respectively. These calculations, along with some petrogenetic assumptions based on previous studies, were subsequently used

  1. Investigations into an unknown organism on the martian meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Steele, A.; Goddard, D. T.; Stapleton, D.; Toporski, J. K.; Peters, V.; Bassinger, V.; Sharples, G.; Wynn-Williams, D. D.; McKay, D. S.

    2000-01-01

    Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.

  2. Meteorite constraints on Martian atmospheric loss and paleoclimate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cassata, William S.

    The evolution of Mars' atmosphere to its currently thin state incapable of supporting liquid water remains poorly understood and has important implications for Martian climate history. Martian meteorites contain trapped atmospheric gases that can be used to constrain both the timing and effectiveness of atmospheric escape processes. Here in this article, measurements of xenon isotopes in two ancient Martian meteorites, ALH 84001 and NWA 7034, are reported. The data indicate an early episode of atmospheric escape that mass fractionated xenon isotopes culminated within a few hundred million years of planetary formation, and little change to the atmospheric xenon isotopic compositionmore » has occurred since this time. In contrast, on Earth atmospheric xenon fractionation continued for at least two billion years (Pujol et al., 2011). Such differences in atmospheric Xe fractionation between the two planets suggest that climate conditions on Mars may have differed significantly from those on Archean Earth. For example, the hydrogen escape flux may not have exceeded the threshold required for xenon escape on Mars after 4.2–4.3 Ga, which indicates that Mars may have been significantly drier than Earth after this time.« less

  3. Meteorite constraints on Martian atmospheric loss and paleoclimate

    DOE PAGES

    Cassata, William S.

    2017-10-06

    The evolution of Mars' atmosphere to its currently thin state incapable of supporting liquid water remains poorly understood and has important implications for Martian climate history. Martian meteorites contain trapped atmospheric gases that can be used to constrain both the timing and effectiveness of atmospheric escape processes. Here in this article, measurements of xenon isotopes in two ancient Martian meteorites, ALH 84001 and NWA 7034, are reported. The data indicate an early episode of atmospheric escape that mass fractionated xenon isotopes culminated within a few hundred million years of planetary formation, and little change to the atmospheric xenon isotopic compositionmore » has occurred since this time. In contrast, on Earth atmospheric xenon fractionation continued for at least two billion years (Pujol et al., 2011). Such differences in atmospheric Xe fractionation between the two planets suggest that climate conditions on Mars may have differed significantly from those on Archean Earth. For example, the hydrogen escape flux may not have exceeded the threshold required for xenon escape on Mars after 4.2–4.3 Ga, which indicates that Mars may have been significantly drier than Earth after this time.« less

  4. Report of the Workshop on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H. (Editor); Herd, Christopher D. K. (Editor)

    2002-01-01

    Geochemical and petrologic studies of the Martian meteorites (nicknamed the SNCs) have proliferated in the past few years, from a wealth of new samples and the perfection of new analytical methods. An intriguing result from these studies is that the chemical and isotopic compositions of the Martian meteorites, all basalts or derived from basaltic magma, can be modeled as mixtures of a limited number of components. These mixing components were the focus of the workshop.

  5. Evidence for methane in Martian meteorites

    PubMed Central

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-01-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity. PMID:26079798

  6. Evidence for methane in Martian meteorites.

    PubMed

    Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

    2015-06-16

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  7. Solving the Martian meteorite age paradox with a widespread Uranium-rich reservoir on Mars

    NASA Astrophysics Data System (ADS)

    Bellucci, Jeremy; Nemchin, Alexander; Snape, Josh; Whitehouse, Martin; Kielman, Ross; Bland, Phil; Benedix, Gretchen

    2015-04-01

    Documenting major geochemical reservoirs on planetary bodies is a necessary prerequisite to understanding planetary evolution. Here we present Pb isotopic evidence for a pervasive Martian reservoir that evolved with a long-term 238U/204Pb (μ) value at least 2.4 times higher greater than those inferred from studies of all other Martian meteorites except 4.428 Ga clasts in NWA7533. Any significant mixing with this and an unradiogenic reservoir produces trends with steep slopes in Pb isotopic diagrams. The steep trend seen here can be used erroneously to define a crystallization age for Chassigny of 4.531±30 Ga (2σ), which is in conflict with all other isotopic systems that yield a widely accepted age of 1.39 Ga. Similar, steep trends have also been observed in the Shergottites and have been used to calculate a >4 Ga age and have also been attributed to terrestrial contamination. Our new Chassigny data however, argue that this mixing occurred on Mars and this radiogenic component is present in virtually every Martian meteorite. The presence of this radiogenic reservoir on Mars resolves the paradox between Pb isotopic data and all other radiogenic isotopic systems in Martian meteorites. Importantly, Chassigny and the Shergottites are likely derived from the northern hemisphere of Mars, while NWA 7533 originated from the Southern hemisphere, implying that the U-rich reservoir, which most likely represents some form of crust, must be widespread. The significant age difference between SNC meteorites and NWA 7533 also supports the preservation of this crust throughout Martian history.

  8. Spectroscopic Detection of Minerals in Martian Meteorites using Reflectance and Emittance Spectroscopy and Applications to Surface Mineralogy on Mars

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Hamilton, V. E.

    2001-12-01

    Martian meteorites provide direct information about crustal rocks on Mars. In this study we are measuring reflectance and emittance spectra of multiple Martian meteorites in order to characterize the spectral properties of the minerals present and to develop comprehensive criteria for remote detection of rocks and minerals. Previous studies have evaluated mid-IR emittance spectra [Hamilton et al., 1997] and visible/IR reflectance spectra [Bishop et al., 1998a,b] of Martian meteorites independently. The current study includes comparisons of the visible/NIR and mid-IR spectral regions and also involves comparison of mid-IR spectra measured using biconical reflectance and thermal emission techniques. Combining spectral analyses of Martian meteorite chips and powders enables characterization of spectral bands for remote detection of potential source regions for meteorite-like rocks on the surface of Mars using both Thermal Emission Spectrometer (TES) datasets and visible/NIR datasets from past and future missions. Identification of alteration minerals in these meteorites also provides insights into the alteration processes taking place on Mars. Analysis of TES data on Mars has identified global regions of basaltic and andesitic surface material [e.g. Bandfield et al., 2000; Christensen et al., 2000]; however neither of these spectral endmembers corresponds well to the spectra of Martian meteorites. Some preliminary findings suggest that small regions on the surface of Mars may relate to meteorite compositions [e.g. Hoefen et al., 2000; Hamilton et al., 2001]. Part of the difficulty in identifying meteorite compositions on Mars may be due to surface alteration. We hope to apply the results of our spectroscopic analyses of Martian meteorites, as well as fresh and altered basaltic material, toward analysis of composition on Mars using multiple spectral datasets. References: Bandfield J. et al., Science 287, 1626, 2000. Bishop J. et al., MAPS 33, 699, 1998a. Bishop J. et

  9. Transmission Electron Microscope Studies of Martian 'Iddingsite' in the Nakhlite Meteorite MIL 090032

    NASA Astrophysics Data System (ADS)

    Hallis, L.; Ishii, H.; Bradley, J. P.; Taylor, J.

    2012-12-01

    As with the other nakhlites, MIL 090032 contains iddingsite-like alteration veins in the olivine phenocrysts that reportedly originated on Mars[1]. These 'iddingsite' veins have been analysed in a number of the nakhlite meteorites[2], and the presence of hydrous silicate gel, smectite clays, siderite, Fe-oxides, gypsum and carbonate have been reported. The presence and proportion of these phases in the different nakhlites appears to relate to the composition and concentration of the martian brine that flowed through each, thus supporting the theory that the nakhlite secondary alteration phases were produced by an evaporation sequence on the surface of Mars[3]. We analyzed these martian 'iddingsite' veins in MIL 090032 with the aim of placing it and its three paired meteorites within the nakhlite alteration sequence. By expanding our knowledge of this alteration sequence, we will gain extra insight into the conditions on the martian surface at the time these 'iddingsite' veins formed (<1.3 Ga). We utilized the 80-300 kV aberration-corrected FEI Titan (Scanning) Transmission Electron Microscope (S-TEM) system at Lawrence Livermore National Laboratory to analyse a ~15×8μm Focused Ion Beam (FIB) section of an 'iddingsite' vein in MIL 090032. To allow the electrons to be transmitted through the FIB section, it was milled down to ~150 nm thickness. Our initial TEM data indicate this FIB section contains hydrous amorphous silicate gel towards the center, with areas of phyllosilicate (possibly nontronite) interspersed within this central zone. Towards the outer edge of the vein jarosite and then gypsum sulfates were present. At the very edge only partially broken down olivine was observed. The presence of phyllosilicate and silicate gel in this vein suggests the 'iddingsite' in MIL 090032 was produced by water-rich brine, and the abundance of sulfates suggests the brine was enriched in sulfur. This assemblage of minerals is most in line with that of the 'iddingsite

  10. Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

    NASA Technical Reports Server (NTRS)

    Harvey, Ralph P.; McKay, Gordon A.

    1997-01-01

    inclusions; those found within early-forming pigeonite, intermediate and late-forming Ti, Fe-oxides and sulfides, and intermediate to late-forming phosphates. In this summer' s study we have made a detailed study of all of the various forms of inclusions found within the 4 basaltic martian meteorites listed above. Glasses and minerals within the inclusions were analyzed using the Camera SX-100 Electron Microprobe in Building 31. The mineralogy and textural context of the inclusions will then be used to explore the crystallization history of these specimens, and to investigate any differences in crystallization history or parental magma compositions between these rocks. In this manner, the magmatic inclusions provide a road map backwards toward the 'parental' compositions for the basaltic martian meteorites and provide significant insight into the igneous processes found within the crust of Mars.

  11. Comparison of the LEW88516 and ALHA77005 martian meteorites: Similar but distinct

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Mckay, G. A.; Bogard, D. D.; Mittlefehldt, D. W.; Wang, M.-S.; Keller, L.; Lipschutz, M. E.; Lindstrom, M. M.; Garrison, D.

    1994-01-01

    By mineral and bulk compositions, the Lewis Cliff (LEW) 88516 meteorite is quite similar to the ALHA77005 martian meteorite. These two meteorites are not paired because their mineral compositions are distinct, they were found 500 km apart in ice fields with different sources for meteorites, and their terrestrial residence ages are different. Minerals in LEW88516 include: olivine, pyroxenes (low- and high-Ca), and maskelynite (ater plagioclase); and the minor minerals chromite, whitlockite, ilmenite, and pyrrhotite. Mineral grains in LEW88516 range up to a few mm. Texturally, the meteorite is complex, with regions of olivine and chromite poikilitically enclosed in pyroxene, regions of interstitial basaltic texture, and glass-rich (shock) veinlets. Olivine compositions range from Fo(sub 64) to Fo(sub 70), (avg. Fo(sub 67)), more ferroan and with more variation than in ALHA77005 (Fo(sub 69) to Fo(sub 73)). Pyroxene compositions fall between En(sub 77)Wo(sub 4) and En(sub 65)Wo(sub 15) and in clusters near En(sub 63)Wo(sub 9) and En(sub 53)Wo(sub 33), on average more magnesian and with more variation than in ALHA77005. Shock features in LEW88516 range from weak deformation through complete melting. Bulk chemical analyses by modal recombination of electron microprobe analyses, instrumental neutron activation, and radiochemical neutron activation confirm that LEW88516 is more closely related to ALHA77005 than to other known martian meteorites. Key element abundance ratios are typical of martian meteorites, as is it nonchondritic rare earth pattern. Differences between the chemical compositions of LEW88516 and ALHA77005 are consistent with slight differences in the proportions of their constituent minerals and not from fundamental petrogenetic differences. Noble gas abundances in LEW88516, like those in ALHA77005, show modest excesses of Ar-40 and Xe-129 from trapped (shock-implanted) gas. As with other ALHA77005 and the shergottite martian meteorites (except EETA79001

  12. Pressure demagnetization of the Martian crust: Ground truth from SNC meteorites

    NASA Astrophysics Data System (ADS)

    Bezaeva, Natalia S.; Rochette, Pierre; Gattacceca, Jérôme; Sadykov, Ravil A.; Trukhin, Vladimir I.

    2007-12-01

    We performed hydrostatic pressure demagnetization experiments up to 1.3 GPa on Martian meteorites: nakhlite NWA998 (magnetite-bearing), basaltic shergottites NWA1068 (pyrrhotite-bearing) and Los Angeles (titanomagnetite-bearing) as well as terrestrial rocks: rhyolite (hematite-bearing) and basalt (titanomagnetite-bearing), using a new non-magnetic high-pressure cell. The detailed description of measuring techniques and experimental set-up is presented. We found that under 1.3 GPa the samples lost up to 54% of their initial saturation isothermal remanent magnetization (IRM). Repeated loading resulted in a further decrease of magnetization of the samples. Our experiments show that the resistance of IRM to hydrostatic pressure is not exclusively controlled by the remanent coercivity of the sample, but is strongly dependant on its magnetic mineralogy. There is no simple equivalence between pressure demagnetization and alternating field demagnetization. The extrapolation of these results of pressure demagnetization of IRM of Martian meteorites to the demagnetization of the Martian crust by impacts is discussed.

  13. MN Carbonates in the Martian Meteorite Nakhla: Possible Evidence of Brine Evaporation

    NASA Technical Reports Server (NTRS)

    Bailey, J. V.; McKay, D. S.; Wentworth, S. J.

    2003-01-01

    The importance of secondary phases in martian meteorites lies in their potential to provide clues about the martian environments responsible for their formation. During this study, we analyzed a number of carbonate-bearing fracture surfaces from the Nakhla meteorite. Here we describe the physical and chemical properties of several manganese-calcium-rich siderites. Additionally, we describe a potential model for the formation and alteration of these carbonates, and we suggest constraints on the conditions responsible for their precipitation. Nakhla is an olivine-bearing clinopyroxenite with minor amounts of feldspar, FeS, and Fe oxides. Secondary mineral assemblages include vein filling clay with embedded iron oxides, a calcium sulfate, amorphous silica, chlorapatite, halite and carbonates. Bridges and Grady suggested that the carbonates in Nakhla formed from brine evaporation. Isotope studies of the Mn rich siderite are also consistent with formation from hydrothermal fluids with an upper T constraint of 170 C.

  14. Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere.

    PubMed

    Keppler, Frank; Vigano, Ivan; McLeod, Andy; Ott, Ulrich; Früchtl, Marion; Röckmann, Thomas

    2012-05-30

    Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.

  15. Scanning Electron Microscopy Investigation of a Sample Depth Profile Through the Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, Jan; Steele, Andrew; Westall, Frances; McKay, David S.

    2000-01-01

    The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

  16. Ar-Ar Dating of Martian Meteorite, Dhofar 378: An Early Shock Event?

    NASA Technical Reports Server (NTRS)

    Park, J.; Bogard, D. D.

    2006-01-01

    Martian meteorite, Dhofar 378 (Dho378) is a basaltic shergottite from Oman, weighing 15 g, and possessing a black fusion crust. Chemical similarities between Dho378 and the Los Angeles 001 shergottite suggests that they might have derived from the same Mars locale. The plagioclase in other shergottites has been converted to maskelenite by shock, but Dho378 apparently experienced even more intense shock heating, estimated at 55-75 GPa. Dho378 feldspar (approximately 43 modal %) melted, partially flowed and vesiculated, and then partially recrystallized. Areas of feldspathic glass are appreciably enriched in K, whereas individual plagioclases show a range in the Or/An ratio of approximately 0.18-0.017. Radiometric dating of martian shergottites indicate variable formation times of 160-475 Myr, whereas cosmic ray exposure (CRE) ages of shergottites indicate most were ejected from Mars within the past few Myr. Most determined Ar-39-Ar-40 ages of shergottites appear older than other radiometric ages because of the presence of large amounts of martian atmosphere or interior Ar-40. Among all types of meteorites and returned lunar rocks, the impact event that initiated the CRE age very rarely reset the Ar-Ar age. This is because a minimum time and temperature is required to facilitate Ar diffusion loss. It is generally assumed that the shock-texture characteristics in martian meteorites were produced by the impact events that ejected the rocks from Mars, although the time of these shock events (as opposed to CRE ages) are not directly dated. Here we report Ar-39-Ar-40 dating of Dho378 plagioclase. We suggest that the determined age dates the intense shock heating event this meteorite experienced, but that it was not the impact that initiated the CRE age.

  17. Possible Meteorites in the Martian Hills

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this approximately true-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 600 nanometers, 530 nanometers, and 480 nanometers.

  18. Composition and Color of Martian Soil from Oxidation of Meteoritic Material

    NASA Technical Reports Server (NTRS)

    Yen, A. S.

    2001-01-01

    Aqueous weathering is not necessary for formation of the martian soils. The chemical composition and oxidation state of the surface fines can be attributed to meteoritic influx. Additional information is contained in the original extended abstract.

  19. Biogenic Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Bazylinski, Dennis; Wentworth, Susan J.; McKay, David S.; Kirschvink, Joseph L.; Clemett, SImon J.; Bell, Mary Sue; Golden, D. C.; Gibson, Everett K., Jr.

    1999-01-01

    Fine-grained magnetite (Fe3O4) in martian meteorite ALH84001, generally less than 200 nm in size, is located primarily in the rims that surround the carbonate globules. There are two populations of ALH84001 magnetites, which are likely formed at low temperature by inorganic and biogenic processes. Nearly 27% of ALH84001 magnetite particles, also called elongated prisms, have characteristics which make them uniquely identifiable as biological precipitates. Additional information is contained in the original extended abstract.

  20. The Nakhla Martian Meteorite is a Cumulate Igenous Rock. Comment on "Glass-Bearing Inclusions in Nakhla (SNC Meteorite) Augite: Heterogeneously Trapped Phases"

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2003-01-01

    All the properties of the Nakhla Martian meteorite suggest that it is a cumulate igneous rock, formed from a basaltic parental magma. Anomalous magmatic inclusions in Nakhla s augite grains can be explained by disequilibrium processes during crystal growth, and have little significance in the geological history of the meteorite.

  1. Life on Mars: chemical arguments and clues from Martian meteorites.

    PubMed

    Brack, A; Pillinger, C T

    1998-08-01

    Primitive terrestrial life-defined as a chemical system able to transfer its molecular information via self-replication and to evolve-probably originated from the evolution of reduced organic molecules in liquid water. Several sources have been proposed for the prebiotic organic molecules: terrestrial primitive atmosphere (methane or carbon dioxide), deep-sea hydrothermal systems, and extraterrestrial meteoritic and cometary dust grains. The study of carbonaceous chondrites, which contain up to 5% by weight of organic matter, has allowed close examination of the delivery of extraterrestrial organic material. Eight proteinaceous amino acids have been identified in the Murchison meteorite among more than 70 amino acids. Engel reported that L-alanine was surprisingly more abundant than D-alanine in the Murchison meteorite. Cronin also found excesses of L-enantiomers for nonprotein amino acids. A large collection of micrometeorites has been recently extracted from Antarctic old blue ice. In the 50- to 100-micron size range, carbonaceous micrometeorites represent 80% of the samples and contain 2% of carbon, on average. They might have brought more carbon than that involved in the present surficial biomass. The early histories of Mars and Earth clearly show similarities. Liquid water was once stable on the surface of Mars, attesting the presence of an atmosphere capable of deccelerating C-rich micrometeorites. Therefore, primitive life may have developed on Mars as well and fossilized microorganisms may still be present in the near subsurface. The Viking missions to Mars in 1976 did not find evidence of either contemporary or past life, but the mass spectrometer on the lander aeroshell determined the atmospheric composition, which has allowed a family of meteorites to be identified as Martian. Although these samples are essentially volcanic in origin, it has been recognized that some of them contain carbonate inclusions and even veins that have a carbon isotopic

  2. Comparison of Martian meteorites with earth composition: Study of effective atomic numbers in the energy range 1 keV-100 GeV

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ün, Adem, E-mail: ademun25@yahoo.com; Han, İbrahim, E-mail: ibrahimhan25@hotmail.com; Ün, Mümine, E-mail: mun@agri.edu.tr

    2016-04-18

    Effective atomic (Z{sub eff}) and electron numbers (N{sub eff}) for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV and also for sixteen significant energies of commonly used radioactive sources. The values of Z{sub eff} and N{sub eff} for all sample were obtained from the DirectZeff program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  3. Search for Past Life on Mars: Possible Relict Biogenic Activity in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    McKay, David S.; Gibson, Everett K., Jr.; Thomas-Keprta, Kathie L.; Vali, Hojatollah; Romanek, Christopher S.; Clemett, Simon J.; Chillier, Xavier D. F.; Maechling, Claude R.; Zare, Richard N.

    1996-01-01

    Fresh fracture surfaces of the martian meteorite ALH84001 contain abundant polycyclic aromatic hydrocarbons (PAHs). These fresh fracture surfaces also display carbonate globules. Contamination studies suggest the PAHs are indigenous to the meteorite. High resolution scanning and transmission electron microscopy study of surface textures and internal structures of selected carbonate globules show that the globules contain fine-grained, secondary phases of single-domain magnetite and Fe-monosulfides. The carbonate globules are similar in texture and size to some terrestrial bacterially induced carbonate precipitates. Although inorganic formation is possible, formation of the globules by biogenic processes could explain many of the observed features including the PAHs. The PAHs, the carbonate globules, and their associated secondary mineral phases and textures could thus be fossil remains of a past martian biota.

  4. The Shergottite Age Paradox and the Relative Probabilities of Ejecting Martian Meteorites of Differing Ages

    NASA Technical Reports Server (NTRS)

    Borg, L. E.; Shih, C.-Y.; Nyquist, L. E.

    1998-01-01

    The apparent paradox that the majority of impacts yielding Martian meteorites appear to have taken place on only a few percent of the Martian surface can be resolved if all the shergottites were ejected in a single event rather than in multiple events as expected from variations in their cosmic ray exposure and crystallization ages. If the shergottite-ejection event is assigned to one of three craters in the vicinity of Olympus Mons that were previously identified as candidate source craters for the SNC (Shergottites, Nakhlites, Chassigny) meteorites, and the nakhlite event to another candidate crater in the vicinity of Ceraunius Tholus, the implied ages of the surrounding terranes agree well with crater density ages. EN,en for high cratering rates (minimum ages), the likely origin of the shergottites is in the Tharsis region, and the paradox of too many meteorites from too little terrane remains for multiple shergottite-ejection events. However, for high cratering rates it is possible to consider sources for the nakhlltes which are away from the Tharsis region. The meteorite-yielding impacts may have been widely dispersed with sources of the young SNC meteorites in the northern plains, and the source of the ancient orthopyroxenite, ALH84001, in the ancient southern uplands. Oblique-impact craters can be identified with the sources of the nakhlites and the orthopyroxenite,, respectively, in the nominal cratering rate model, and with the shergottites and orthopyroxenite, respectively, in the high cratering rate model. Thus, oblique impacts deserve renewed attention as an ejection mechanism for Martian meteorites.

  5. The provenance, formation, and implications of reduced carbon phases in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Steele, Andrew; McCubbin, Francis M.; Fries, Marc D.

    2016-11-01

    This review is intended to summarize the current observations of reduced carbon in Martian meteorites, differentiating between terrestrial contamination and carbon that is indigenous to Mars. Indeed, the identification of Martian organic matter is among the highest priority targets for robotic spacecraft missions in the next decade, including the Mars Science Laboratory and Mars 2020. Organic carbon compounds are essential building blocks of terrestrial life, so the occurrence and origin (biotic or abiotic) of organic compounds on Mars is of great significance; however, not all forms of reduced carbon are conducive to biological systems. This paper discusses the significance of reduced organic carbon (including methane) in Martian geological and astrobiological systems. Specifically, it summarizes current thinking on the nature, sources, and sinks of Martian organic carbon, a key component to Martian habitability. Based on this compilation, reduced organic carbon on Mars, including detections of methane in the Martian atmosphere, is best described through a combination of abiotic organic synthesis on Mars and infall of extraterrestrial carbonaceous material. Although conclusive signs of Martian life have yet to be revealed, we have developed a strategy for life detection on Mars that can be utilized in future life-detection studies.

  6. Estimating different eruptive style volcanic areas of Mars from NASA Martian Meteorites Compendium data

    NASA Astrophysics Data System (ADS)

    Mari, Nicola; Verrino, Miriam

    2016-04-01

    The geomorphological characteristics of the Martian surface suggest that both effusive and explosive eruptive behaviour occurred. We investigated whether data about magma viscosity could be extrapolated from Mars SNCs (Shergotty, Nakhla, and Chassigny classes) meteorites, by using available geochemical and petrographic data from the NASA Martian Meteorites Compendium. Viscosity was used to characterize how eruptive style could change in different volcanic regions of planet Mars. Data about composition and crystallinity of 41 SNCs meteorites were used and classified, avoiding meteorites with poor/incomplete database. We assumed Mars as a one-plate planet, fO2 = QFM, and H2O wt% = 0 for each sample. Collected data from the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) identified the source regions for almost all the studied SNCs meteorites. As input for thermodynamic simulations we first needed to find the depth and pressure of the magmatic source for each meteorite sample through available Thermal Emission Imaging System (THEMIS). Data about average surface temperatures was used to establish whether a magmatic source is shallow or deep. Successively, we found the magma source depth (and pressure) by using the relationship with the heights of the volcanic edifice. The subsolidus equilibration temperatures found through petrologic softwares were used to calculate viscosity. Results indicate a crystallization temperature in a range from 1,120°C to 843°C, follow by a variation in viscosity from 101,43 to 105,97 Pa s. Viscosity seems to be higher in Tharsis, Elysium, Amazonis, and Syrtis Major regions than the remnant areas. According to past experimental studies about magma viscosity, we classified the eruptive style into effusive (101-103,5 Pa s), intermediate (103,5-104,5 Pa s), and explosive (104,5-106 Pa s). The Hellas Basin, Argyre Basin, Ganges Chasma, Eos Chasma, and Nili Fossae regions show an eruptive behaviour between effusive and intermediate

  7. Prospects for Chronological Studies of Martian Rocks and Soils

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.

    2008-01-01

    Chronological information about Martian processes comes from two sources: Crater-frequency studies and laboratory studies of Martian meteorites. Each has limitations that could be overcome by studies of returned Martian rocks and soils. Chronology of Martian volcanism: The currently accepted chronology of Martian volcanic surfaces relies on crater counts for different Martian stratigraphic units [1]. However, there is a large inherent uncertainty for intermediate ages near 2 Ga ago. The effect of differing preferences for Martian cratering chronologies [1] is shown in Fig. 1. Stoeffler and Ryder [2] summarized lunar chronology, upon which Martian cratering chronology is based. Fig. 2 shows a curve fit to their data, and compares to it a corresponding lunar curve from [3]. The radiometric ages of some lunar and Martian meteorites as well as the crater-count delimiters for Martian epochs [4] also are shown for comparison to the craterfrequency curves. Scaling the Stoeffler-Ryder curve by a Mars/Moon factor of 1.55 [5] places Martian shergottite ages into the Early Amazonian to late Hesperian epochs, whereas using the lunar curve of [3] and a Mars/Moon factor 1 consigns the shergottites to the Middle-to-Late Amazonian, a less probable result. The problem is worsened if a continually decreasing cratering rate since 3 Ga ago is accepted [6]. We prefer the adjusted St ffler-Ryder curve because it gives better agreement with the meteorite ages (Fig.

  8. The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

    NASA Astrophysics Data System (ADS)

    Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.; Muttik, Nele; Ziegler, Karen; Shearer, Charles K.; Bell, Aaron S.; Santos, Alison R.; Burger, Paul V.; Simon, Justin I.; Tappa, Michael J.; McCubbin, Francis M.; Gattacceca, Jérôme; Lagroix, France; Sanborn, Matthew E.; Yin, Qing-Zhu; Cassata, William S.; Borg, Lars E.; Lindvall, Rachel E.; Kruijer, Thomas S.; Brennecka, Gregory A.; Kleine, Thorsten; Nishiizumi, Kunihiko; Caffee, Marc W.

    2017-12-01

    Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ∼QFM) on the liquidus to higher oxygen fugacity (∼QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystalline and shock-amorphized plagioclase (An50-62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. We obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a second igneous unit from

  9. The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

    DOE PAGES

    Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.; ...

    2017-09-01

    Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ~QFM) on the liquidus to higher oxygen fugacity (~QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystallinemore » and shock-amorphized plagioclase (An 50–62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. Here, we obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/ 144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε 143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. Finally, NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a

  10. The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.

    Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ~QFM) on the liquidus to higher oxygen fugacity (~QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystallinemore » and shock-amorphized plagioclase (An 50–62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. Here, we obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/ 144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε 143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. Finally, NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a

  11. Mineral Biomarkers in Martian Meteorite Allan Hills 84001?

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Bazylinski, D. A.; Wentworth, S. J.; McKay, D. S.; Golden, D. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    The occurrence of fine-grained magnetite in the Fe-rich rims surrounding carbonate globules in the martian meteorite ALH84001, originally described in , have been proposed as fossil remains of primitive martian organisms. Here we report observations on size and shape distributions of magnetites from ALH84001 and compare them to biogenic and inorganic magnetite crystals of terrestrial origin. While some magnetite morphology is not unequivocally diagnostic for its biogenicity, such as cubodial forms of magnetite, which are common in inorganically formed magnetites, other morphologies of magnetite (parallel-epiped or elongated prismatic and arrowhead forms) are more likely signatures of biogenic activity. Some ALH 84001 magnetite particles described below have unique morphology and length-to-width ratios that are indistinguishable from a variety of terrestrial biogenic magnetite and distinct from all known inorganic forms of magnetite.

  12. Magnesium isotope systematics in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  13. Nature of the Martian uplands: Effect on Martian meteorite age distribution and secondary cratering

    NASA Astrophysics Data System (ADS)

    Hartmann, William K.; Barlow, Nadine G.

    2006-10-01

    Martian meteorites (MMs) have been launched from an estimated 5-9 sites on Mars within the last 20 Myr. Some 80-89% of these launch sites sampled igneous rock formations from only the last 29% of Martian time. We hypothesize that this imbalance arises not merely from poor statistics, but because the launch processes are dominated by two main phenomena: first, much of the older Martian surface is inefficient in launching rocks during impacts, and second, the volumetrically enormous reservoir of original cumulate crust enhances launch probability for 4.5 Gyr old rocks. There are four lines of evidence for the first point, not all of equal strength. First, impact theory implies that MM launch is favored by surface exposures of near-surface coherent rock (≤102 m deep), whereas Noachian surfaces generally should have ≥102 m of loose or weakly cemented regolith with high ice content, reducing efficiency of rock launch. Second, similarly, both Mars Exploration Rovers found sedimentary strata, 1-2 orders of magnitude weaker than Martian igneous rocks, favoring low launch efficiency among some fluvial-derived Hesperian and Noachian rocks. Even if launched, such rocks may be unrecognized as meteorites on Earth. Third, statistics of MM formation age versus cosmic-ray exposure (CRE) age weakly suggest that older surfaces may need larger, deeper craters to launch rocks. Fourth, in direct confirmation, one of us (N. G. B.) has found that older surfaces need larger craters to produce secondary impact crater fields (cf. Barlow and Block 2004). In a survey of 200 craters, the smallest Noachian, Hesperian, and Amazonian craters with prominent fields of secondaries have diameters of ˜45 km, ˜19 km, and ˜10 km, respectively. Because 40% of Mars is Noachian, and 74% is either Noachian or Hesperian, the subsurface geologic characteristics of the older areas probably affect statistics of recognized MMs and production rates of secondary crater populations, and the MM and secondary

  14. The Martian sources of the SNC meteorites (two, not one), and what can and can't be learned from the SNC meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    1993-01-01

    The SNC meteorites, which almost certainly originate in the Martian crust, have been inferred to come from a single impact crater site, but no known crater fits all criteria. Formation at two separate sites (S from one, NC from the other) is more consistent with the sum of petrologic, geochronologic, and cosmochronologic data. If the source craters for the SNC meteorites can be located, Mars science will advance considerably. However, many significant questions cannot be answered by the SNC meteorites. These questions await a returned sample.

  15. (U-Th)/He ages of phosphates from Zagami and ALHA77005 Martian meteorites: Implications to shock temperatures

    NASA Astrophysics Data System (ADS)

    Min, Kyoungwon; Farah, Annette E.; Lee, Seung Ryeol; Lee, Jong Ik

    2017-01-01

    Shock conditions of Martian meteorites provide crucial information about ejection dynamics and original features of the Martian rocks. To better constrain equilibrium shock temperatures (Tequi-shock) of Martian meteorites, we investigated (U-Th)/He systematics of moderately-shocked (Zagami) and intensively shocked (ALHA77005) Martian meteorites. Multiple phosphate aggregates from Zagami and ALHA77005 yielded overall (U-Th)/He ages 92.2 ± 4.4 Ma (2σ) and 8.4 ± 1.2 Ma, respectively. These ages correspond to fractional losses of 0.49 ± 0.03 (Zagami) and 0.97 ± 0.01 (ALHA77005), assuming that the ejection-related shock event at ∼3 Ma is solely responsible for diffusive helium loss since crystallization. For He diffusion modeling, the diffusion domain radius is estimated based on detailed examination of fracture patterns in phosphates using a scanning electron microscope. For Zagami, the diffusion domain radius is estimated to be ∼2-9 μm, which is generally consistent with calculations from isothermal heating experiments (1-4 μm). For ALHA77005, the diffusion domain radius of ∼4-20 μm is estimated. Using the newly constrained (U-Th)/He data, diffusion domain radii, and other previously estimated parameters, the conductive cooling models yield Tequi-shock estimates of 360-410 °C and 460-560 °C for Zagami and ALHA77005, respectively. According to the sensitivity test, the estimated Tequi-shock values are relatively robust to input parameters. The Tequi-shock estimates for Zagami are more robust than those for ALHA77005, primarily because Zagami yielded intermediate fHe value (0.49) compared to ALHA77005 (0.97). For less intensively shocked Zagami, the He diffusion-based Tequi-shock estimates (this study) are significantly higher than expected from previously reported Tpost-shock values. For intensively shocked ALHA77005, the two independent approaches yielded generally consistent results. Using two other examples of previously studied Martian meteorites

  16. Highly Siderophile Element Abundances in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Neal, C. R.; Ely, J. C.

    2001-01-01

    Critical evaluation of new and literature data for highly siderophile elements (HSE) in Martian (SNC) meteorites allows several first order conclusions to be drawn. (i) Re concentrations in SNC meteorites are nearly constant (within a factor of two) and do not correlate with rock type. Exceptions to this rule are Chassigny and Dar al Gani (DaG) 476, both of which are inferred to have experienced terrestrial Re contamination. (ii) Fractionations between Rh and Pd are small. Excluding Shergotty, the Rh/Pd ratio of the SNC suite is 0.22\\pm0.05. (iii) Os and Ir contents vary by about four orders of magnitude; and positive correlations with MgO, Cr, and Ni suggest that these variations are not controlled by sulfide fractionation. A possible exception is the orthopyroxenite ALH84001, whose HSE's (including Ni, which is compatible in opx) are very low. (iv) Zagami, Shergotty, and Nakhla have nearly identical HSE signatures. Shergotty and Zagami have experienced assimilation-fractional crystallization (AFC) and have "crustal" Sr and Nd isotopic signatures. Conversely, the Nakhla parent was a small degree partial melt of a depleted mantle that interacted little with the Martian crust. These observations suggest that "evolved" HSE signatures can be produced by either fractional crystallization or small degrees of partial melting. (v) Chassigny and other mafic SNC's have HSE signatures that are very distinct from those of Nakhla-Zagami-Shergotty. The HSE elemental ratios of mafic SNC's approach chondritic, implying that the Martian mantle has nearly chondritic relative abundances of the HSE's. (vi) This chondritic HSE signature is observed in SNC's of various ages, suggesting that this is an ancient feature that has not evolved over time. (vii) No correlation is observed between HSE's and signatures of crustal contamination (e.g., Sr isotopes), indicating that the HSE signatures of the SNC suite are not derived from the crust. (vii) The Ru/Pd for the SNC suite ratio is about

  17. Possible Meteorites in the Martian Hills (False Color)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    From its winter outpost at 'Low Ridge' inside Gusev Crater, NASA's Mars Exploration Rover Spirit took this spectacular, color mosaic of hilly, sandy terrain and two potential iron meteorites. The two light-colored, smooth rocks about two-thirds of the way up from the bottom of the frame have been labeled 'Zhong Shan' and 'Allan Hills.'

    The two rocks' informal names are in keeping with the rover science team's campaign to nickname rocks and soils in the area after locations in Antarctica. Zhong Shang is an Antarctic base that the People's Republic of China opened on Feb. 26, 1989, at the Larsemann Hills in Prydz Bay in East Antarctica. Allan Hills is a location where researchers have found many Martian meteorites, including the controversial ALH84001, which achieved fame in 1996 when NASA scientists suggested that it might contain evidence for fossilized extraterrestrial life. Zhong Shan was the given name of Dr. Sun Yat-sen (1866-1925), known as the 'Father of Modern China.' Born to a peasant family in Guangdong, Sun moved to live with his brother in Honolulu at age 13 and later became a medical doctor. He led a series of uprisings against the Qing dynasty that began in 1894 and eventually succeeded in 1911. Sun served as the first provisional president when the Republic of China was founded in 1912.

    The Zhong Shan and Allan Hills rocks, at the left and right, respectively, have unusual morphologies and miniature thermal emission spectrometer signatures that resemble those of a rock known as 'Heat Shield' at the Meridiani site explored by Spirit's twin, Opportunity. Opportunity's analyses revealed Heat Shield to be an iron meteorite.

    Spirit acquired this false-color image on the rover's 872nd Martian day, or sol (June 16, 2006), using exposures taken through three of the panoramic camera's filters, centered on wavelengths of 750 nanometers, 530 nanometers, and 430 nanometers. The image is presented in false color to emphasize differences among

  18. A Search for Amino Acids and Nucleobases in the Martian Meteorite Roberts Massif 04262 Using Liquid Chromatography-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Burton, Aaron S.; Elsila, Jamie E.; Baker, Eleni M.; Smith, Karen E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-01-01

    The investigation into whether Mars contains signatures of past or present life is of great interest to science and society. Amino acids and nucleobases are compounds that are essential for all known life on Earth and are excellent target molecules in the search for potential Martian biomarkers or prebiotic chemistry. Martian meteorites represent the only samples from Mars that can be studied directly in the laboratory on Earth. Here, we analyzed the amino acid and nucleobase content of the shergottite Roberts Massif (RBT) 04262 using liquid chromatography-mass spectrometry. We did not detect any nucleobases above our detection limit in formic acid extracts; however, we did measure a suite of protein and nonprotein amino acids in hot-water extracts with high relative abundances of beta-alanine and gamma-amino-eta-butyric acid. The presence of only low (to absent) levels of several proteinogenic amino acids and a lack of nucleobases suggest that this meteorite fragment is fairly uncontaminated with respect to these common biological compounds. The distribution of straight-chained amine-terminal eta-omega-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites. A carbon isotope ratio of -24(0/00) +/- 6(0/00) for beta-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of eta-omega-amino acids may be due to a high temperature Fischer-Tropschtype synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  19. Organic Carbon Features Identified in the Nakhla Martian Meteorite

    NASA Technical Reports Server (NTRS)

    Mckay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; Gibson, E. K., Jr.; Le, L.; Rahman, Z.; Wentworth, S. J.

    2011-01-01

    We report, for the first time, the identification of specific carbonaceous phases, present within iddingsite alteration zones of the Nakhla meteorite that possess discrete, well defined, structurally coherent morphologies. These structures bear superficial similarity to the carbonaceous nanoglobules [1] found in primitive chondrites interplanetary dust particles, although they are an order-of-magnitude larger in size. Introduction: It has been known for many years that some members of the Martian meteorite clan contain organic matter [e.g., 2-4]. Based on both isotopic measurements [5] and circumstantial observations [4] (e.g., the similarity organic signatures present in both Antarctic finds and non-Antarctic falls) a credible argument has been made for a preterrestrial origin for the majority of these organics. The Nakhla meteorite is of particular interest in that it has been shown to contain both an acid-labile organic fraction as well as an acid-insoluble high molecular weight organic component [4]. Pyrolysis-gas chromatography-mass spectrometry of the latter component indicates it to be composed of aromatic and alkyl-aromatic functionalities bound into a macromolecule phase through ether linkages [4]. However, the spatial, textural and mineralogical associations of this carbonaceous macromolecular material have remained elusive [6].

  20. Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of the Martian Meteorites

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This volume contains abstracts that have been accepted for presentation at the conference on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites, September 11-12, 2002, in Houston, Texas. Administration and publications support for this meeting were provided by the staff of the Publications and Program Services Department at the Lunar and Planetary Institute.

  1. PYTi-NiCr Signatures in the Columbia Hills are Present in Certain Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Clark, B. C.; Gellert, R.; Ming, D. W.; Morris, R. V.; Mittlefehldt, D. W.; Squyres, S. W.

    2006-01-01

    Uniquely high levels of phosphorus and titanium were observed in several samples [1-3] by the APXS x-ray fluorescence measurements as the MER Spirit rover climbed Husband Hill (Columbia Hills, Gusev crater, Mars). A careful study of many such samples and their geochemical variability has revealed additional elements in this pattern, and that the derived multi-element signature is also unambiguously manifested in several martian meteorites.

  2. Northwest Africa 7034: New Unique Water-rich Martian Meteorite from the Early Amazonian Epoch

    NASA Astrophysics Data System (ADS)

    Agee, C. B.; Wilson, N.; Ziegler, K. G.; McCubbin, F. M.; Polyak, V.; Nunn, M.; Sharp, Z. D.; Asmerom, Y.; Thiemens, M. H.

    2012-12-01

    Northwest Africa (NWA) 7034 is a porphyritic basaltic breccia that shares some geochemical characterstics with known martian meteorites (SNC), but also possesses some unique characteristics that would exclude it from the current SNC grouping. Instead, it has a major and minor element composition that is a remarkably good match with the geochemistry of the rocks and soil at Gusev Crater measured by the Spirit rover and the average martian crust composition from the Odyssey Orbiter gamma ray spectrometer. The mismatch of orbiter and rover data with SNC meteorites has been a perplexing enigma, however with the discovery of NWA 7034 we may now have found a "missing link" between martian meteorites and space craft data. A five-point isochon gives an Rb-Sr age for NWA 7034 of 2.089±0.081 Ga (2σ) (MSWD=6.6) and an initial 87Sr/86Sr ratio of 0.71359±54. The Sm-Nd data for the same samples show more scatter, with an isochron of 2.19±1.4 Ga (2σ). NWA 7034 is REE enriched crustal rock (La x58 CI) and strongly light REE over heavy REE enriched (La/Yb)N=2.3, with negative-Eu anomaly (Eu/Eu*=0.67). The whole rock has 143Nd/144Nd=0.511756 and 147Sm/144Nd=0.1664, giving a calculated initial (source value) 143Nd/144Nd=0.509467 (initial ɛNd=-9.1) which requires that it be derived from an enriched martian reservoir, with an inferred time-integrated 147Sm/144Nd=0.1689, assuming separation from a chondrite-like martian mantle 4.5 Ga. An age of ~2.1 Ga for NWA 7034 would make it the first meteorite sample from the early Amazonian or late Hesperian epoch in Mars geologic history. Oxygen isotope analyses of NWA 7034 were performed by laser fluorination at UNM on acid-washed bulk sample and at UCSD on vacuum pre-heated (1000°C) bulk sample and give mean values Δ17O=0.57±0.05‰ n=10 and Δ17O=0.50±0.03‰ n=2, respectively. These interlab values are in good agreement, but are significantly higher than literature values for SNC meteorites (Δ17O range 0.15-0.45‰). There may be

  3. Meteoritic basalts

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1989-01-01

    The objectives were to: explain the abundances of siderophile elements in the SNC meteorite suite, of putative Martian origin; discover the magmatic origins and possibly magma compositions behind the Nakhla meteorite, one of the SNC meteorites; and a re-evaluation of the petrology of Angra dos Reis, a unique meteorite linked to the earliest planetary bodies of the solar nebula. A re-evaluation of its petrography showed that the accepted scenario for its origin, as a cumulate igneous rock, was not consistent with the meteorite's textures (Treiman). More likely is that the meteorite represents a prophyritic igneous rock, originally with magma dominant. Studies of the Nakhla meteorite, of possible Martian origin, although difficult, were successful. It became necessary to reject the basic categorization of Nakhla: that is was a cumulate igneous rock. Detailed studies of the chemical zoning of Nakhlas' minerals, coupled with the failure of experimental studies to yield expected results, forced the conclusion that Nakhla is not a cumulate rock in the usual sense: a rock composed of igneous crystals and intercrystal magma. Study of the siderophile element abundances in the SNC meteorite groups involved trying to find reasonable core formation processes and parameters that would reproduce the observed abundances. Modelling was successful, and delimited a range of models which overlap with those reasonable from geophysical constraints.

  4. Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon.

    PubMed

    Moser, D E; Chamberlain, K R; Tait, K T; Schmitt, A K; Darling, J R; Barker, I R; Hyde, B C

    2013-07-25

    Invaluable records of planetary dynamics and evolution can be recovered from the geochemical systematics of single meteorites. However, the interpreted ages of the ejected igneous crust of Mars differ by up to four billion years, a conundrum due in part to the difficulty of using geochemistry alone to distinguish between the ages of formation and the ages of the impact events that launched debris towards Earth. Here we solve the conundrum by combining in situ electron-beam nanostructural analyses and U-Pb (uranium-lead) isotopic measurements of the resistant micromineral baddeleyite (ZrO2) and host igneous minerals in the highly shock-metamorphosed shergottite Northwest Africa 5298 (ref. 8), which is a basaltic Martian meteorite. We establish that the micro-baddeleyite grains pre-date the launch event because they are shocked, cogenetic with host igneous minerals, and preserve primary igneous growth zoning. The grains least affected by shock disturbance, and which are rich in radiogenic Pb, date the basalt crystallization near the Martian surface to 187 ± 33 million years before present. Primitive, non-radiogenic Pb isotope compositions of the host minerals, common to most shergottites, do not help us to date the meteorite, instead indicating a magma source region that was fractionated more than four billion years ago to form a persistent reservoir so far unique to Mars. Local impact melting during ejection from Mars less than 22 ± 2 million years ago caused the growth of unshocked, launch-generated zircon and the partial disturbance of baddeleyite dates. We can thus confirm the presence of ancient, non-convecting mantle beneath young volcanic Mars, place an upper bound on the interplanetary travel time of the ejected Martian crust, and validate a new approach to the geochronology of the inner Solar System.

  5. Producing Martian Lithologies with Geophysically-Constrained Martian Mantle Compositions

    NASA Astrophysics Data System (ADS)

    Minitti, M. E.; Fei, Y.; Bertka, C. M.

    2008-12-01

    The Martian meteorites, rocks measured by the Mars Exploration Rovers (MER) and lithologies detected by orbital assets represent a diversity of igneous rocks that collectively provide insight into the formation and evolution of Mars. Experimental studies aimed at reproducing the observed igneous lithologies have met with varying degrees of success [e.g., 1,2,3], No study has yet been able to reproduce both Martian meteorite parent magmas and the basalts measured by MER at Gusev Crater [e.g., 1,3]. We attempted a different approach to successfully reproducing Martian igneous lithologies by using geophysical constraints on Martian bulk Fe (wt.%), Fe/Si and mantle Mg# [4,5] to identify mixtures of chondrite compositions that formed plausible Martian mantle compositions. We identified two candidate chondrite mixtures for Mars, CM+L and H+L. We synthesized the CM+L and H+L compositions from oxide, carbonate and phosphate powders and fixed them at an oxygen fugacity below the magnetite-wüstite buffer (MW-1). We conducted experiments at 2 GPa (corresponding to ~150 km in the Martian mantle) between 1300-1600 °C for 4-48 hours in the end-loaded piston cylinder apparatus at the Geophysical Laboratory. Thusfar, we have also conducted experiments at 4 GPa (corresponding to ~320 km in the Martian mantle) between 1425-1475 °C for 210-240 minutes in a Walker-type multi-anvil apparatus at the Geophysical Laboratory. We utilized an 18/11 (octahedron edge length/truncated edge length, in mm) assembly. In both assembly types, the sample was contained within a graphite capsule welded into a Pt tube. We analyzed the experiment products in electron probes at either the Geophysical Laboratory or Arizona State University. Fe and Mg contents of olivine, orthopyroxene and melt were used to assess the attainment of equilibrium for each run product. No significant difference exists between the CM+L and H+L experiment products. The near-solidus phase assemblage of the 2-GPa experiments is

  6. Constraining the Source Craters of the Martian Meteorites: Implications for Prioritiziation of Returned Samples from Mars

    NASA Astrophysics Data System (ADS)

    Herd, C. D. K.; Tornabene, L. L.; Bowling, T. J.; Walton, E. L.; Sharp, T. G.; Melosh, H. J.; Hamilton, J. S.; Viviano, C. E.; Ehlmann, B. L.

    2018-04-01

    We have made advances in constraining the potential source craters of the martian meteorites to a relatively small number. Our results have implications for Mars chronology and the prioritization of samples for Mars Sample Return.

  7. Petrogenesis of Igneous-Textured Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    Santos, A. R.; Agee, C. B.; Humayun, M.; McCubbin, F. M.; Shearer, C. K.

    2016-01-01

    The martian meteorite Northwest Africa 7034 (and pairings) is a breccia that samples a variety of materials from the martian crust. Several previous studies have identified multiple types of igneous-textured clasts within the breccia [1-3], and these clasts have the potential to provide insight into the igneous evolution of Mars. One challenge presented by studying these small rock fragments is the lack of field context for this breccia (i.e., where on Mars it formed), so we do not know how many sources these small rock fragments are derived from or the exact formation his-tory of these sources (i.e., are the sources mantle de-rived melt or melts contaminated by a meteorite impactor on Mars). Our goal in this study is to examine specific igneous-textured clast groups to determine if they are petrogenetically related (i.e., from the same igneous source) and determine more information about their formation history, then use them to derive new insights about the igneous history of Mars. We will focus on the basalt clasts, FTP clasts (named due to their high concentration of iron, titanium, and phosphorous), and mineral fragments described by [1] (Fig. 1). We will examine these materials for evidence of impactor contamination (as proposed for some materials by [2]) or mantle melt derivation. We will also test the petrogenetic models proposed in [1], which are igneous processes that could have occurred regardless of where the melt parental to the clasts was formed. These models include 1) derivation of the FTP clasts from a basalt clast melt through silicate liquid immiscibility (SLI), 2) derivation of the FTP clasts from a basalt clast melt through fractional crystallization, and 3) a lack of petrogenetic relationship between these clast groups. The relationship between the clast groups and the mineral fragments will also be explored.

  8. Martian Igneous Geochemistry: The Nature of the Martian Mantle

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.

    2012-01-01

    Mafic igneous rocks probe the interiors of their parent objects, reflecting the compositions and mineralogies of their source regions, and the magmatic processes that engendered them. Incompatible trace element contents of mafic igneous rocks are widely used to constrain the petrologic evolution of planets. We focus on incompatible element ratios of martian meteorites to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most martian meteorites contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. Martian meteorites form two main petrologic/ age groupings; a 1.3 Ga group composed of clinopyroxenites (nakhlites) and dunites (chassignites), and a <1 Ga group composed of basalts and lherzolites (shergottites).

  9. Testing the survival of microfossils in an artificial martian sedimentary meteorite: the STONE 6 Experiment

    NASA Astrophysics Data System (ADS)

    Foucher, Frédéric; Westall, Frances; Brandstaetter, Franz; Demets, Rene; Parnell, John; Cockell, Charles; Edwards, Howell; Jean-Michel, B.; Brack, André; Kurat, Gero

    Conditions on early Mars during the Noachian (-4.5 to -3.5 Ga) were possibly suitable for the emergence of life [1,3] even though water bodies were probably not permanent and could have been destroyed by frequent impacts. Since Mars does not appear to have had plate tectonics, the remains of this hypothetic life could be found within Noachian sediments. In addition to proving the existence of extraterrestrial life, such a discovery would be very helpful for studies related to the origin and early evolution of life on Earth. Indeed, although life most likely appeared on Earth before 4 Ga ago, no suitable (i.e. well-preserved) rocks containing traces of life older than 3.5 billion years exist; older rocks are either too metamorphosed or have been destroyed by plate tectonics. Because of the harsh conditions on Noachian Mars compared to those of the early Earth, the martian organisms are likely to have remained in a very primitive state of evolution and will thus be very difficult to observe in situ. One way to investigate potential traces of life in martian rocks would be to study sedimentary meteorites from Mars. However, all the 54 martian meteorites found so far are volcanic rocks [4]. Is this because sedimentary rocks do not survive the original impact to escape Mars, or the stresses of entry into the Earth's atmosphere? In order to test the latter effects, a series of experiments were devised to test the survivability of different types of sediments during Earth atmosphere entry, the STONE experiments. In particular, the present experiment STONE 6 tested a Noachian sedimentary analogue that consisted of a 3.45 Ga-old silicified volcanic sand containing ancient traces of life [5]. The volcanic sand (chert) from the Pilbara, Australia, containing organic microfossils [6] was embedded in the heat shield of a FOTON space capsule that underwent atmospheric entry on the 26th September, 2007. After landing, the first observation was the white colour of the fusion crust

  10. Characterization of Martian Soil Fines Fraction in SNC Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2003-01-01

    Some impact-melt glasses in shergottite meteorites contain large abundances of martian atmospheric noble gases with high (129)Xe/(132)Xe ratios, accompanied by varying (87)Sr/(86)Sr (initial) ratios. These glasses contain Martian Soil Fines (MSF) probably from young volcanic terrains such as Tharsis or Elysium Mons. The composition of the MSF bearing samples is different from the average bulk composition of the host rock. These samples show the following charecteristics: a) simultaeneous enrichment of the felsic component and depletion of the mafic component relative to the host phase and b) significant secondary sulfur/sulfate excesses over the host material. The degree of enrichment and associated depletion varies from one sample to another. Earlier, we found large enrichments of felsic (Al, Ca, Na and K) component and depletion of mafic (Fe, Mg, Mn and Ti) component in several impact melt glass veins and pods of samples ,77 ,78 , 18, and ,20A in EET79001 accompanied by large sulfur/sulfate excesses. Based on these results, we proposed a model where the comminution of basaltic rocks takes place by meteoroid bombardment on the martian surface, leading to the generation of fine-grained soil near the impact sites. This fine-grained soil material is subsequently mobilized by saltation and deflation processes on Mars surface due to pervasive aeolian activity. This movement results in mechanical fractionation leading to the felsic enrichment and mafic depletion in the martian dust. We report, here, new data on an impact-melt inclusion ,507 (PAPA) from EET79001, Lith B and ,506 (ALPHA) from EET79001, Lith A and compare the results with those obtained on Shergotty impact melt glass (DBS).

  11. The origin of organic matter in the Martian meteorite ALH84001.

    PubMed

    Becker, L; Popp, B; Rust, T; Bada, J L

    1999-01-01

    Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common carbon sources on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery of meteoritic or cometary debris to the surface of Mars.

  12. The origin of organic matter in the Martian meteorite ALH84001.

    PubMed

    Becker, L; Popp, B; Rust, T; Bada, J L

    1999-03-30

    Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common sources of carbon on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery, of meteoritic or cometary debris to the surface of Mars.

  13. Evidence for life in a martian meteorite?

    PubMed

    McSween, H Y

    1997-07-01

    The controversial hypothesis that the ALH84001 meteorite contains relics of ancient martian life has spurred new findings, but the question has not yet been resolved. Organic matter probably results, at least in part, from terrestrial contamination by Antarctic ice meltwater. The origin of nanophase magnetites and sulfides, suggested, on the basis of their sizes and morphologies, to be biogenic remains contested, as does the formation temperature of the carbonates that contain all of the cited evidence for life. The reported nonfossils may be magnetite whiskers and platelets, probably grown from a vapor. New observations, such as the possible presence of biofilms and shock metamorphic effects in the carbonates, have not yet been evaluated. Regardless of the ultimate conclusion, this controversy continues to help define strategies and sharpen tools that will be required for a Mars exploration program focused on the search for life.

  14. Lead in Martian Meteorites-- Observations and Inconsistencies: I. Chassigny

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Simon, J. I.; Usui, T.

    2017-01-01

    The history of Pb isotope analyses of the martian meteorites (SNC) and their interpretations is laden with difficulties. Two different analytical groups have interpreted their ancient (= 4 Ga) shergottite Pb ages as primary [1-5]. A Nakhla age of approximately 4.3 Ga has been interpreted to be primary as well [2]. This is in stark contrast to the young (= 1.4 Ga) crystallization ages defined by the Rb-Sr, Sm-Nd, Lu-Hf, and KAr systems [6]. Possibly, a better interpretation for the ancient Pb ages is that they reflect the formation times of the various SNC source regions [7]. A difficulty in dealing with Pb is that terrestrial contamination is ubiquitous, unlike the other chronometer systems noted above. This issue is complicated by the fact that radioactive decay causes localized mineral damage. So washing and leaching to remove Pb contamination tends to remove in situ radiogenic Pb. This issue is further compounded because U and Th are often concentrated in phosphates and other minor phases, so the leaching process tends to remove these, especially phosphates. Another difficulty is that it is not clear whether the observed Pb isotopic variation in leachates, residues, and ion-microprobe analyses is due to terrestrial or to indigenous martian Pb contamination [e.g., 8]. A third difficulty is that the shergottites on the one hand, and the nakhlites and chassignites on the other, appear to have come from separate source regions with different chemical compositions [e.g., 7]. Thus, it is expected that their Pb isotopic characteristics would be different. And even if all these meteorite types came from the same source region, their igneous ages differ considerably. The nakhlites and chassignites are 1.4 Ga and the shergottites are = 600 Ma [e.g., 6]. This age difference alone should assure that the two distinct SNC groups have differing Pb isotopic signatures.

  15. Organic Carbon Exists in Mars Meteorites: Where is it on the Martian Surface?

    NASA Technical Reports Server (NTRS)

    McKay, D. S.; Clemett, S. J.; Gibson, E. K., Jr.; Thomas-Keprta, K. L.; Wentworth, S. J.

    2010-01-01

    The search for organic carbon on Mars has been a major challenge. The first attempt was the Viking GC-MS in situ experiment which gave inconclusive results at two sites oil. After the discovery that the SNC meteorites were from Mars, reported C isotopic compositional information which suggested a reduced C component present in the Martian meteorites reported the presence of reduced C components (i.e., polycyclic aromatic hydrocarbons) associated with the carbonate globules in ALH84001. Jull et al. noted in Nakhla there was acid insoluble C component present with more than 75% of its C lacking any C-14, which is modern-day terrestrial carbon. This C fraction was believed to be either indigenous martian or ancient meteoritic carbon. Fisk et al. have shown textural evidence along with C-enriched areas within fractures in Nakhla and ALH84001. Westall et al. have shown the presence of a large irregular fragment of organic material completely embedded within a chip of ALH84001. Interior samples from the Naklnla SNC made available by the British Museum of Natural History, were analyzed. Petrographic examination of Nakhla showed evidence of fractures (approx.0.5 microns wide) filled with dark brown to black dendritic material with characteristics similar to those observed by. Iddingsite is also present along fractures in olivine. Fracture filling and dendritic material was examined by SEM-EDX, TEM-EDX, Focused Electron Beam microscopy, Laser Raman Spectroscopy, Nano-SIMS Ion Micro-probe, and Stepped-Combustion Static Mass Spectrometry. Observations from the first three techniques are discussed.

  16. UV Raman imaging--a promising tool for astrobiology: comparative Raman studies with different excitation wavelengths on SNC Martian meteorites.

    PubMed

    Frosch, Torsten; Tarcea, Nicolae; Schmitt, Michael; Thiele, Hans; Langenhorst, Falko; Popp, Jürgen

    2007-02-01

    The great capabilities of UV Raman imaging have been demonstrated on the three Martian meteorites: Sayh al Uhaymir, Dar al Gani, and Zagami. Raman spectra without disturbing fluorescence and with high signal-to-noise-ratios and full of spectral features were derived. This result is of utmost importance for the development of powerful instruments for space missions. By point scanning the surfaces of the meteorite samples, it was possible for the first time to construct UV-Raman images out of the array of Raman spectra. Deep-UV Raman images are to the best of our knowledge presented for the first time. The images were used for a discussion of the chemical-mineralogical composition and texture of the meteorite surfaces. Comparative Raman studies applying visible and NIR Raman excitation wavelengths demonstrate a much better performance for UV Raman excitation. This comparative study of different Raman excitation wavelengths at the same sample spots was done by constructing a versatile, robust sample holder with a fixed micro-raster. The overall advantages of UV resonance Raman spectroscopy in terms of sensitivity and selectivity are demonstrated and discussed. Finally the application of this new technique for a UV Raman instrument for envisaged astrobiological focused space missions is suggested.

  17. Putative Indigenous Carbon-Bearing Alteration Features in Martian Meteorite Yamato 000593

    PubMed Central

    Gibson, Everett K.; Thomas-Keprta, Kathie L.; Clemett, Simon J.; McKay, David S.

    2014-01-01

    Abstract We report the first observation of indigenous carbonaceous matter in the martian meteorite Yamato 000593. The carbonaceous phases are heterogeneously distributed within secondary iddingsite alteration veins and present in a range of morphologies including areas composed of carbon-rich spheroidal assemblages encased in multiple layers of iddingsite. We also observed microtubular features emanating from iddingsite veins penetrating into the host olivine comparable in shape to those interpreted to have formed by bioerosion in terrestrial basalts. Key Words: Meteorite—Yamato 000593—Mars—Carbon. Astrobiology 14, 170–181. PMID:24552234

  18. Isotopic Composition of Trapped and Cosmogenic Noble Gases in Several Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Garrison, Daniel H.; Bogard, Donald D.

    1997-01-01

    Isotopic abundances of the noble gases were measured in the following Martian meteorites: two shock glass inclusions from EET79001, shock vein glass from Shergotty and Y793605, and whole rock samples of ALH84001 and QUE94201. These glass samples, when combined with literature data on a separate single glass inclusion from EET79001 and a glass vein from Zagami, permit examination of the isotopic composition of Ne, Ar, Kr, and Xe trapped from the Martian atmosphere in greater detail. The isotopic composition of Martian Ne, if actually present in these glasses, remains poorly defined. The Ar-40/Ar-36 ratio of Martian atmospheric Ar may be much less than the ratio measured by Viking and possibly as low as approx. 1900. The atmospheric Ar-36/Ar-38 ratio is less than or equal to 4.0. Martian atmospheric Kr appears to be enriched in lighter isotopes by approx. 0.4%/amu compared to both solar wind Kr and to the Martian composition previously reported. The Martian atmospheric Ar-36/Xe-132 and Kr-84/Xe-132 Xe elemental ratios are higher than those reported by Viking by factors of approx. 3.3 and approx. 2.5, respectively. Cosmogenic gases indicate space exposure ages of 13.9 +/- 1 Myr for ALH84001 and 2.7 +/- 0.6 Myr for QUE94201. Small amounts of Ne-21 produced by energetic solar protons may be present in QUE94201, but are not present in ALH84001 or Y793605. The space exposure age for Y793605 is 4.9 +/- 0.6 Myr and appears to be distinctly older than the ages for basaltic shergottites.

  19. Modern terrestrial analogues for the carbonate globules in Martian meteorite ALH84001.

    PubMed

    Kazmierczak, Józef; Kempe, Stephan

    2003-04-01

    Modern carbonate globules, located in cracks of submerged volcanic rocks and in calcareous pinnacles in alkaline (sodic) Lake Van, Turkey, appear to be analogues for the approximately 3.9 billion-year-old carbonate globules in Martian meteorite ALH84001. These terrestrial globules have similar diameters and are chemically and mineralogically zoned. Furthermore, they display surface and etching structures similar to those described from ALH84001, which were interpreted as fossilized microbial forms. These terrestrial carbonates formed at low temperatures where Ca-rich groundwaters enter the lake. Chemical, mineralogical, microbiological, and biomolecular methods were used in an attempt to decipher the process responsible for the genesis of these structures. Although the exact mode of formation of Lake Van carbonates remains an enigma, their similarity to the Martian globules indicates that the ALH84001 carbonates may have formed in similar setting on ancient Mars.

  20. Martian carbon dioxide: Clues from isotopes in SNC meteorites

    NASA Technical Reports Server (NTRS)

    Karlsson, H. R.; Clayton, R. N.; Mayeda, T. K.; Jull, A. J. T.; Gibson, E. K., Jr.

    1993-01-01

    Attempts to unravel the origin and evolution of the atmosphere and hydrosphere on Mars from isotopic data have been hampered by the impreciseness of the measurements made by the Viking Lander and by Earth-based telescopes. The SNC meteorites which are possibly pieces of the Martian surface offer a unique opportunity to obtain more precise estimates of the planet's volatile inventory and isotopic composition. Recently, we reported results on oxygen isotopes of water extracted by pyrolysis from samples of Shergotty, Zagami, Nakhla, Chassigny, Lafayette, and EETA-79001. Now we describe complementary results on the stable isotopic composition of carbon dioxide extracted simultaneously from those same samples. We will also report on C-14 abundances obtained by accelerator mass spectrometry (AMS) for some of these CO2 samples.

  1. Combining meteorites and missions to explore Mars.

    PubMed

    McCoy, Timothy J; Corrigan, Catherine M; Herd, Christopher D K

    2011-11-29

    Laboratory studies of meteorites and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a martian origin came with the discovery of trapped atmospheric gases in one meteorite. Since then, the study of martian meteorites and findings from missions have been linked. Although the meteorite source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most martian meteorites are young (< 1.3 Ga), the spread of whole rock isotopic compositions results from crystallization of a magma ocean > 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from martian meteorites conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the meteorites is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential.

  2. Yamato 980459: Crystallization of Martian Magnesian Magma

    NASA Technical Reports Server (NTRS)

    Koizumi, E.; Mikouchi, T.; McKay, G.; Monkawa, A.; Chokai, J.; Miyamoto, M.

    2004-01-01

    Recently, several basaltic shergottites have been found that include magnesian olivines as a major minerals. These have been called olivinephyric shergottites. Yamato 980459, which is a new martian meteorite recovered from the Antarctica by the Japanese Antarctic expedition, is one of them. This meteorite is different from other olivine-phyric shergottites in several key features and will give us important clues to understand crystallization of martian meteorites and the evolution of Martian magma.

  3. Shock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate

    DOE PAGES

    Adcock, C. T.; Tschauner, O.; Hausrath, E. M.; ...

    2017-03-06

    Meteorites represent the only samples available for study on Earth of a number of planetary bodies. The minerals within meteorites therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite-whitlockite solid solution series. For example, the anhydrous nature of merrillite in Martian meteorites has been interpreted as evidence of water-limited late-stage Martian melts. However, recent research on apatite in the same meteorites suggests higher water content in melts. One complication of using meteorites rather than direct samples is the shock compression all meteorites havemore » experienced, which can alter meteorite mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to meteorites, including Martian meteorites. The results open the possibility that at least part of meteoritic merrillite may have originally been H + -bearing whitlockite with implications for interpreting meteorites and the need for future sample return.« less

  4. Shock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Adcock, C. T.; Tschauner, O.; Hausrath, E. M.

    Meteorites represent the only samples available for study on Earth of a number of planetary bodies. The minerals within meteorites therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite-whitlockite solid solution series. For example, the anhydrous nature of merrillite in Martian meteorites has been interpreted as evidence of water-limited late-stage Martian melts. However, recent research on apatite in the same meteorites suggests higher water content in melts. One complication of using meteorites rather than direct samples is the shock compression all meteorites havemore » experienced, which can alter meteorite mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to meteorites, including Martian meteorites. The results open the possibility that at least part of meteoritic merrillite may have originally been H + -bearing whitlockite with implications for interpreting meteorites and the need for future sample return.« less

  5. Shock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate

    PubMed Central

    Adcock, C. T.; Tschauner, O.; Hausrath, E. M.; Udry, A.; Luo, S. N.; Cai, Y.; Ren, M.; Lanzirotti, A.; Newville, M.; Kunz, M.; Lin, C.

    2017-01-01

    Meteorites represent the only samples available for study on Earth of a number of planetary bodies. The minerals within meteorites therefore hold the key to addressing numerous questions about our solar system. Of particular interest is the Ca-phosphate mineral merrillite, the anhydrous end-member of the merrillite–whitlockite solid solution series. For example, the anhydrous nature of merrillite in Martian meteorites has been interpreted as evidence of water-limited late-stage Martian melts. However, recent research on apatite in the same meteorites suggests higher water content in melts. One complication of using meteorites rather than direct samples is the shock compression all meteorites have experienced, which can alter meteorite mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to meteorites, including Martian meteorites. The results open the possibility that at least part of meteoritic merrillite may have originally been H+-bearing whitlockite with implications for interpreting meteorites and the need for future sample return. PMID:28262701

  6. Mineralization of Bacteria in Terrestrial Basaltic Rocks: Comparison With Possible Biogenic Features in Martian Meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    The identification of biogenic features altered by diagenesis or mineralization is important in determining whether specific features in terrestrial rocks and in meteorites may have a biogenic origin. Unfortunately, few studies have addressed the formation of biogenic features in igneous rocks, which may be important to these phenomena, including the controversy over possible biogenic features in basaltic martian meteorite ALH84001. To explore the presence of biogenic features in igneous rocks, we examined microcosms growing in basaltic small-scale experimental growth chambers or microcosms. Microbial communities were harvested from aquifers of the Columbia River Basalt (CRB) group and grown in a microcosm containing unweathered basalt chips and groundwater (technique described in. These microcosms simulated natural growth conditions in the deep subsurface of the CRB, which should be a good terrestrial analog for any putative martian subsurface ecosystem that may have once included ALH84001. Here we present new size measurements and photomicrographs comparing the putative martian fossils to biogenic material in the CRB microcosms. The range of size and shapes of the biogenic features on the CRB microcosm chips overlaps with and is similar to those on ALH84001 chips. Although this present work does not provide evidence for the biogenicity of ALH84001 features, we believe that, based on criteria of size, shape, and general morphology, a biogenic interpretation for the ALH84001 features remains plausible.

  7. Combining meteorites and missions to explore Mars

    PubMed Central

    McCoy, Timothy J.; Corrigan, Catherine M.; Herd, Christopher D. K.

    2011-01-01

    Laboratory studies of meteorites and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a martian origin came with the discovery of trapped atmospheric gases in one meteorite. Since then, the study of martian meteorites and findings from missions have been linked. Although the meteorite source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most martian meteorites are young (< 1.3 Ga), the spread of whole rock isotopic compositions results from crystallization of a magma ocean > 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from martian meteorites conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the meteorites is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential. PMID:21969535

  8. The Northwest Africa (NWA) 5790 meteorite: A mesostasis-rich nakhlite with little or no Martian aqueous alteration

    NASA Astrophysics Data System (ADS)

    Tomkinson, Tim; Lee, Martin R.; Mark, Darren F.; Dobson, Katherine J.; Franchi, Ian A.

    2015-02-01

    Northwest Africa (NWA) 5790 is the most recently discovered member of the nakhlite group. Its mineralogy differs from the other nakhlites with a high abundance mesostasis (38.1 ± 3.6 vol%) and scarcity of olivine (4.0 ± 2.2 vol%). Furthermore, zoning of augite phenocrysts, and other petrographic and chemical characteristics suggest that NWA 5790 samples the chilled margin of its parent lava flow/sill. NWA 5790 contains calcite and rare clay minerals that are evidence for its exposure to liquid water. The calcite forms a cement to coatings of dust on the outer surface of the find and extends into the interior of the meteorite within veins. The presence of microbial remains within the coating confirms that the dust and its carbonate cement are terrestrial in origin, consistent with the carbon and oxygen isotope composition of the calcite. The clay minerals are finely crystalline and comprise ~0.003 vol% of the meteorite. δD values of the clay minerals range from -212 ± 109‰ to -96 ± 132‰, and cannot be used to distinguish between a terrestrial or Martian origin. As petrographic results are also not definitive, we conclude that secondary minerals produced by Martian groundwaters are at best very rare within NWA 5790. The meteorite has therefore sampled a region of the lava flow/sill with little or no exposure to the aqueous solutions that altered other nakhlites. This isolation could relate to the scarcity of olivine in NWA 5790 because dissolution of olivine in other nakhlites by Martian groundwaters enhanced their porosity and permeability, and provided solutes for secondary minerals.

  9. Ar-40/Ar-39 Studies of Martian Meteorite RBT 04262 and Terrestrial Standards

    NASA Technical Reports Server (NTRS)

    Park, J.; Herzog, G. F.; Turrin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Nagao, K.; Nyquist, L. E.

    2014-01-01

    Park et al. recently presented an Ar-40/Ar-39 dating study of maskelynite separated from the Martian meteorite RBT 04262. Here we report an additional study of Ar-40/Ar-39 patterns for smaller samples, each consisting of only a few maskelynite grains. Considered as a material for Ar-40/Ar-39 dating, the shock-produced glass maskelynite has both an important strength (relatively high K concentration compared to other mineral phases) and some potentially problematic weaknesses. At Rutgers, we have been analyzing small grains consisting of a single phase to explore local effects that might be averaged and remain hidden in larger samples. Thus, to assess the homogeneity of the RBT maskelynite and for comparison with the results of, we analyzed six approx. 30 microgram samples of the same maskelynite separate they studied. Furthermore, because most Ar-40/Ar-39 are calculated relative to the age of a standard, we present new Ar-40/Ar-39 age data for six standards. Among the most widely used standards are sanidine from Fish Canyon (FCs) and various hornblendes (hb3gr, MMhb-1, NL- 25), which are taken as primary standards because their ages have been determined by independent, direct measurements of K and A-40.

  10. Magnetite Formation from Thermal Decomposition of Siderite: Implications for Inorganic Magnetite Formation in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Morris, RIchard V.

    2002-01-01

    A biogenic mechanism for formation of a subpopulation magnetite in Martian meteorite ALH84001 has been suggested [McKay et al., 1996; Thomas-Keprta, et al., 2000]. We are developing experimental evidence for an alternating working hypothesis, that the subpopulation was produced inorganically by the thermal decomposition of siderite [Golden et al., 2000].

  11. Terrestrial microbes in martian and chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Airieau, S.; Picenco, Y.; Andersen, G.

    2007-08-01

    Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

  12. Magnetic studies on Shergotty and other SNC meteorites

    NASA Technical Reports Server (NTRS)

    Cisowski, S. M.

    1986-01-01

    The results of a study of basic magnetic properties of meteorites within the SNC group, including the four known shergottites and two nakhlites, are presented. An estimate is made of the strength of the magnetic field which produced the remanent magnetization of the Shergotty meteorite, for the purpose of constraining the choices for the parent body of these SNC meteorites. Remanence measurements in several subsamples of Shergotty and Zagami meteorites reveal a large variation in intensity that does not seem to be related to the abundance of remanence carriers. The other meteorites carry only weak remanence, suggesting weak magnetizing fields as the source of their magnetic signal. A paleointensity experiment on a weakly magnetized subsample of Shergotty revealed a low temperature component of magnetization acquired in a field of 2000 gammas, and a high temperature component reflecting a paleofield strength of between 250 and 1000 gammas. The weak field environment that these meteorites seem to reflect is consistent with either a Martian or asteroidal origin, but inconsistent with a terrestrial origin.

  13. Meteoritic basalts. Final report, 1986-1989

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Treiman, A.H.

    1989-10-01

    The objectives were to: explain the abundances of siderophile elements in the SNC meteorite suite, of putative Martian origin; discover the magmatic origins and possibly magma compositions behind the Nakhla meteorite, one of the SNC meteorites; and a re-evaluation of the petrology of Angra dos Reis, a unique meteorite linked to the earliest planetary bodies of the solar nebula. A re-evaluation of its petrography showed that the accepted scenario for its origin, as a cumulate igneous rock, was not consistent with the meteorite's textures (Treiman). More likely is that the meteorite represents a prophyritic igneous rock, originally with magma dominant.more » Studies of the Nakhla meteorite, of possible Martian origin, although difficult, were successful. It became necessary to reject the basic categorization of Nakhla: that is was a cumulate igneous rock. Detailed studies of the chemical zoning of Nakhlas' minerals, coupled with the failure of experimental studies to yield expected results, forced the conclusion that Nakhla is not a cumulate rock in the usual sense: a rock composed of igneous crystals and intercrystal magma. Study of the siderophile element abundances in the SNC meteorite groups involved trying to find reasonable core formation processes and parameters that would reproduce the observed abundances. Modelling was successful, and delimited a range of models which overlap with those reasonable from geophysical constraints.« less

  14. What Were the Major Factors That Controlled Mineralogical Similarities and Differences of Basaltic, Lherzolitic and Clinopyroxentic Martian Meteorites Within Each Group

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Miyamoto, M.; McKay, G. A.

    1998-01-01

    Twelve martian meteorites that have been re- covered so far are classified into five groups (basalt, lherzolite, clinopyroxenite, dunite, and orthopyroxenite) mainly from petrology and chemistry. Among them, the dunite and orthopyroxenite groups consist of only one meteorite each (dunite: Chassigny, orthopyroxenite: ALH 84001). The basalt group is the largest group and consists of four meteorites (Shergotty, Zagani, EETA 79001, and QUE 94201). The lherzolitic and clinopyroxenitic groups include three meteorites each (Lherzolite: ALH 77005, LEW 88516, and Y793605, clinopyroxenite: Nakhla, Governador Valadares, and Lafayette). These meteorites within each group are generally similar to the others, but none of them is paired with the others. In this abstract, we discuss the major factors that controlled mineralogical similarities and differences of basaltic, lherzolitic, and clinopyroxenitic meteorites within each group. This may help in understanding their petrogenesis and original locations on Mars in general.

  15. Truncated Hexa-Octahedral Magnetite Crystals in Martian Meteorite ALH84001: Evidence of Biogenic Activity on Early Mars

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K.; Clemett, S. J.; Schwartz, C.; McIntosh, J. R.; Bazylinski, D. A.; Kirschvink, J.; McKay, D. S.; Gibson, E. K.; Vali, H.; Romanek, C. S.

    2004-01-01

    The landmark paper by McKay et al. [1] cited four lines of evidence associated with the Martian meteorite ALH84001 to support the hypothesis that life existed on Mars approximately 4 Ga ago. Now, more than five years later, attention has focused on the ALH84001 magnetite grains embedded within carbonate globules in the ALH84001 meteorite. We have suggested that up to approx.25% of the ALH84001 magnetite crystals are products of biological activity [e.g., 2]. The remaining magnetites lack sufficient characteristics to constrain their origin. The papers of Thomas Keprta et al. were criticized arguing that the three dimensional structure of ALH84001 magnetite crystals can only be unambiguously determined using electron tomographic techniques. Clemett et al. [3] confirmed that magnetites produced by magnetotactic bacteria strain MV-I display a truncated hexa-octahedral geometry using electron tomography and validated the use of the multi-tilt classical transmission microscopy technique used by [2]. Recently the geometry of the purported martian biogenic magnetites was shown be identical to that for MV-1 magnetites using electron tomography [6].

  16. Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; Martian Meteorites, Carbonaceous Chondrites and Standard Rocks

    NASA Technical Reports Server (NTRS)

    Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.

    2011-01-01

    Recently significantly large mass fractionation of stable chlorine isotopes has been reported for terrestrial and lunar samples [1,2]. In addition, in view of possible early solar system processes [3] and also potential perchlorate-related fluid/microbial activities on the Martian surface [4,5], a large chlorine isotopic fractionation might be expected for some types of planetary materials. Due to analytical difficulties of isotopic and elemental analyses, however, current chlorine analyses for planetary materials are controversial among different laboratories, particularly between IRMS (gas source mass spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1,6,7] for isotopic analyses, as well as between those doing pyrohydrolysis and other groups [i.e. 6,8]. Additional careful investigations of Cl isotope and elemental abundances are required to confirm real chlorine isotope and elemental variations for planetary materials. We have developed a TIMS technique combined with HF-leaching/ion chromatography at NASA JSC that is applicable to analysis of small amounts of meteoritic and planetary materials. We present here results for several standard rocks and meteorites, including Martian meteorites.

  17. Close-up of a Mars Meteorite

    NASA Image and Video Library

    2018-02-13

    Close-up of a slice of a meteorite scientists have determined came from Mars. This slice will likely be used here on Earth for testing a laser instrument for NASA's Mars 2020 rover; a separate slice will go to Mars on the rover. Martian meteorites are believed to be the result of impacts to the Red Planet's surface, resulting in rock being heaved into the atmosphere. After traveling through space for eons, some of these rocks entered Earth's atmosphere. Scientists determine whether they are true Martian meteorites based on their rock and noble gas chemistry and mineralogy. The gases trapped in these meteorites bear the unique fingerprint of the Martian atmosphere, as recorded by NASA's Viking mission in 1976. The rock types also show clear signs of igneous processing not possible on smaller bodies, such as asteroids. https://photojournal.jpl.nasa.gov/catalog/PIA22246

  18. Carbonaceous structures in the Tissint Martian Meteorite: evidence of a biogenetic origin

    NASA Astrophysics Data System (ADS)

    Wallis, Jamie; Wickramasinghe, N. C.; Wallis, Daryl H.; Miyake, Nori; Wallis, M. K.; Hoover, Richard B.

    2015-09-01

    We report for the first time in situ observations of 5-50μm spherical carbonaceous structures in the Tissint Martian meteorite comprising of pyrite (FeS2) cores and carbonaceous outer coatings. The structures are characterized as smooth immiscible spheres with curved boundaries occasionally following the contours of the pyrite inclusion. The structures bear striking resemblance to similar-sized immiscible carbonaceous spheres found in hydrothermal calcite vein deposits in the Mullaghwornia Quarry in central Ireland. Similar structures have been reported in Proterozoic and Ordovician sandstones from Canada as well as in a variety of astronomical sources including carbonaceous chondrites, chondritic IDPs and primitive chondritic meteorites. SEM and X-Ray elemental mapping confirmed the presence of organic carbon filling the crack and cleavage space in the pyroxene substrate, with further evidence of pyrite acting as an attractive substrate for the collection of organic matter. The detection of precipitated carbon collecting around pyrite grains is at variance with an igneous origin as proposed for the reduced organic component in Tissint, and is more consistent with a biogenetic origin.

  19. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  20. Indigenous Carbonaceous Matter in the Nakhla Mars Meteorite

    NASA Technical Reports Server (NTRS)

    Clemett, S. J.; Thomas-Keprta, K. L.; Rahman, Z.; Le, L.; Wentworth, S. J.; Gibson, E. K.; McKay, D. S.

    2016-01-01

    Detailed microanalysis of the Martian meteorite Nakhla has shown there are morphologically distinct carbonaceous features spatially associated with low-T aqueous alteration phases including salts and id-dingsite. A comprehensive suite of analytical instrumentation including optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), two-step laser mass spectrometry (mu-L(sup 2)MS), laser mu-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nanoscale secondary ion mass spectrometry (NanoSIMS) are being used to characterize the carbonaceous matter and host mineralogy. The search for carbonaceous matter on Mars has proved challenging. Viking Landers failed to unambiguously detect simple organics at either of the two landing sites although the Martian surface is estimated to have acquired at least 10(exp15) kg of C as a consequence of meteoritic accretion over the last several Ga. The dearth of organics at the Martian surface has been attributed to various oxidative processes including UV photolysis and peroxide activity. Consequently, investigations of Martian organics need to be focused on the sub-surface regolith where such surface processes are either severely attenuated or absent. Fortuitously since Martian meteorites are derived from buried regolith materials they provide a unique opportunity to study Martian organic geochemistry.

  1. Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted Shergottites

    NASA Technical Reports Server (NTRS)

    Shih, C.-Y.; Nyquist, L. E.; Park, J.; Agee, Carl B.

    2014-01-01

    Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (23%) in a fine-grained matrix of pyroxene (55%), maskelynitized plagioclase (15%), opaques (4%) and melt pockets (3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of 25 GPa and 2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (1 Ma [1, 6, 7]) and Dho 019 (20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.

  2. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-01-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars. This project identifies all phases found in LAR 12240 and 12095 and analyzes them for major and trace elements. The textural relationships among these phases are examined in order to develop a crystallization history of the magma(s) that formed these basalts.

  3. Insights into the Martian Regolith from Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    McCubbin, Francis M.; Boyce, Jeremy W.; Szabo, Timea; Santos, Alison R.; Domokos, Gabor; Vazquez, Jorge; Moser, Desmond E.; Jerolmack, Douglas J.; Keller, Lindsay P.; Tartese, Romain

    2015-01-01

    Everything we know about sedimentary processes on Mars is gleaned from remote sensing observations. Here we report insights from meteorite Northwest Africa (NWA) 7034, which is a water-rich martian regolith breccia that hosts both igneous and sedimentary clasts. The sedimentary clasts in NWA 7034 are poorly-sorted clastic siltstones that we refer to as protobreccia clasts. These protobreccia clasts record aqueous alteration process that occurred prior to breccia formation. The aqueous alteration appears to have occurred at relatively low Eh, high pH conditions based on the co-precipitation of pyrite and magnetite, and the concomitant loss of SiO2 from the system. To determine the origin of the NWA 7034 breccia, we examined the textures and grain-shape characteristics of NWA 7034 clasts. The shapes of the clasts are consistent with rock fragmentation in the absence of transport. Coupled with the clast size distribution, we interpret the protolith of NWA 7034 to have been deposited by atmospheric rainout resulting from pyroclastic eruptions and/or asteroid impacts. Cross-cutting and inclusion relationships and U-Pb data from zircon, baddelleyite, and apatite indicate NWA 7034 lithification occurred at 1.4-1.5 Ga, during a short-lived hydrothermal event at 600-700 C that was texturally imprinted upon the submicron groundmass. The hydrothermal event caused Pb-loss from apatite and U-rich metamict zircons, and it caused partial transformation of pyrite to submicron mixtures of magnetite and maghemite, indicating the fluid had higher Eh than the fluid that caused pyrite-magnetite precipitation in the protobreccia clasts. NWA 7034 also hosts ancient 4.4 Ga crustal materials in the form of baddelleyites and zircons, providing up to a 2.9 Ga record of martian geologic history. This work demonstrates the incredible value of sedimentary basins as scientific targets for Mars sample return missions, but it also highlights the importance of targeting samples that have not been

  4. Gypsum, jarosite, and hydrous iron-phosphate in Martian meteorite Roberts Massif 04262: Implications for sulfate geochemistry on Mars.

    NASA Astrophysics Data System (ADS)

    Greenwood, J. P.

    2008-12-01

    Gypsum has been identified on Mars by MEX OMEGA [1] and jarosite identified via MER-B lander [2] and both minerals are examples of the importance of calcium and iron sulfates in Martian weathering processes. The weathering of Martian basalt to form Ca and iron sulfates should be an important process on Mars. Martian jarosite has been identified in MIL 03346 [3] and Ca-sulfate has been identified in EETA 79001 [4], but both phases have yet to be identified in the same Martian sample. In Roberts Massif 04262, an olivine-phyric shergottite, iron-sulfide and calcium-phosphate minerals are undergoing reaction (dissolution and reprecipitation?) to form gypsum, jarosite, and an iron-phosphate phase, presumably during the meteorite's residence in Antarctica. If true, then an acidic and oxidizing fluid was present in this meteorite, due to the formation of jarosite which requires fluid of this type to form [5]. The weathering of iron-sulfides on Earth to form acidic and oxidizing fluids is common, thus this can be reconciled with the formation of an acidic fluid in a basic rock. Presumably, under more extensive weathering of silicate minerals in Martian basalt, the pH would be raised to values where jarosite would not be stable. While the weathering of RBT 04262 is likely occurring in Antarctica, a similar susceptibility of the apatite and pyrrhotite to incipient weathering on Mars may be expected. Oxidizing crustal fluids on Mars may attack iron- sulfides first in Martian basalts. The weathering of iron-sulfides leads to increasing acidity of fluids, which would enhance the dissolution of the calcium-phosphate minerals [6]. The formation of jarosite, gypsum, and iron-phosphate minerals during the early stages of weathering of Martian basalts may be an important process on Mars globally. [1] Gendrin, A. et al. (2005) Science, 307, 1587-1591. [2] Klingelhöfer et al. (2004) Science, 306, 1740- 1745. [3] Vicenzi E. P. et al. (2007) LPSC XXXVIII, Abstract 2335. [4] Gooding J

  5. EBSD analysis of the Shergottite Meteorites: New developments within the technique and their implication on what we know about the preferred orientation of Martian minerals

    NASA Astrophysics Data System (ADS)

    Stephen, N.; Benedix, G. K.; Bland, P.; Berlin, J.; Salge, T.; Goran, D.

    2011-12-01

    What we know about the geology and mineralogy of the Martian surface has been characterised by both the use of remote sensing techniques and the analysis of Martian meteorites. Various techniques are employed to conduct these analyses including crystallographic, geochemical and spectral measurements, all of which enable us to infer a geological history for these rocks. Several references have been made to the potential for preferred orientation of crystals within the Shergottites [1] and their implication for the cooling history of the respective magmas on Mars [2]. We have already shown that a preferred orientation of the two pyroxenes, augite and pigeonite, can be seen in the Zagami meteorite using electron back-scatter diffraction (EBSD) analysis [3]. However, when compared to previous modal studies of the same meteorites [4], it becomes apparent that the current EBSD datasets for Martian meteorites are incomplete. Indexing of some minerals can be hampered by the lack of available matches within library databases for EBSD, or become difficult to resolve between minerals where crystallographic differences between similar minerals fall below the technical limitations of the instrument [3]. Recent advances in EBSD technologies combined with the simultaneous acquisition of energy-dispersive spectra (EDS) however now allow us to determine a more comprehensive set of analyses in a much shorter period of time, fully resolving even similar minerals where areas have been left with no indexing previously [5]. Preliminary investigations suggest that the new technology can successfully index >90% of the sample. The most recent EBSD analyses potentially reveals previously unseen fabrics in the meteorites alongside the EDS hyper-spectral imaging helping to resolve any unknown or questionable phases within them. In this study we will present new data from an investigation using EDS alongside EBSD analysis on 2 Shergottite meteorites, SAU 005 and Zagami, to further resolve

  6. Origins of Magnetite Nanocrystals in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Mckay, David S.; Gibson, Everett K.; Wentworth, Susan J.

    2009-01-01

    The Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks. These carbonate disks are believed to have precipitated 3.9 Ga ago at beginning of the Noachian epoch on Mars during which both the oldest extant Martian surfaces were formed, and perhaps the earliest global oceans. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these magnetites are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of mag- netite and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. For example, the magnetites might have already been present in the aqueous fluids from which the carbonates were believed to have been deposited. We have sought to resolve between these hypotheses through the detailed characterized of the compo- sitional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded. Extensive use of focused ion beam milling techniques has been utilized for sample preparation. We then compared our observations with those from experimental thermal decomposition studies of sideritic carbonates under a range of plausible geological heating scenarios. We conclude that the vast majority of the nanocrystal magnetites present in the car- bonate disks could not have formed by any of the currently proposed thermal decomposition scenarios. Instead, we find there is considerable evidence in support of an alternative allochthonous origin for the magnetite unrelated to any shock or thermal processing of the carbonates.

  7. Formation of a Martian Pyroxenite: A Comparative Study of the Nakhlite Meteorites and Theo's Flow

    NASA Technical Reports Server (NTRS)

    Friedman, R. C.; Taylor, G. J.; Treiman, A. H.

    1999-01-01

    The unusual composition of the nakhlites, a group of pyroxenitic martian meteorites with young ages, presents an opportunity to learn about nonbasaltic magmatic activity on another planet. However, the limited number of these meteorites makes unraveling their history difficult. A promising terrestrial analog for the formation of the nakhlites is Theo's Flow in Ontario, Canada. This atypical, 120 m-thick flow differentiated in place, forming distinct layered lithologies of peridotite, pyroxenite, and gabbro. Theo's pyroxenite and the nakhlites share strikingly similar petrographies, with concentrated euhedral to subhedral augite grains set in a plagioclase-rich matrix. These two suites of rocks also share specific petrologic features, mineral and whole-rock compositional features, and size and spatial distributions of cumulus grains. The numerous similarities suggest that the nakhlites formed by a similar mechanism in a surface lava flow or shallow intrusion. Their formation could have involved settling of crystals in a phenocryst-laden flow or in situ nucleation and growth of pyroxenes in an ultramafic lava flow. The latter case is more likely and requires steady-state nucleation and growth of clusters of pyroxene grains (and olivine in the nakhlites), circulating in a strongly convecting melt pool, followed by settling and continued growth in a thickening cumulate pile. Trapped pockets of intercumulus liquid in the pile gradually evolved, finally growing Fe-enriched rims on cumulus grains. With sufficient evolution, the melt reached plagioclase supersaturation, causing rapid growth of plagioclase sprays and late-stage mesostasis growth.

  8. Nakhla: a Martian Meteorite with Indigenous Organic Carbonaceous Features

    NASA Technical Reports Server (NTRS)

    McKay, D. S.; Gibson, E. K.; Thomas-Keprta, K. L.; Clemett, S. J.; Le, L.; Rahman, Z.; Wentworth, S. J.

    2011-01-01

    The Nakhla meteorite possesses discrete, well defined, structurally coherent morphologies of carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of organic phases the presence of pre-terrestrial organics is now recognized. Within the microcrystalline layers of Nakhla s iddingsite, discrete clusters of salt crystals are present. These salts are predominantly halite (NaCl) with minor MgCl2 crystals. Some CaSO4, likely gypsum, appears to be partially intergrown with some of the halite. EDX mapping shows discrete C-rich features are interspersed among these crystals. A hollow semi-spherical bowl structure ( 3 m ) has been identified and analyzed after using a focused ion beam (FIB) to cut a transverse TEM thin section of the feature and the underlying iddingsite. TEM/EDX analysis reveals that the feature is primarily carbonaceous containing C with lesser amounts of Si, S, Ca, Cl, F, Na, and minor Mn and Fe; additionally a small peak consistent with N, which has been previously seen in Nakhla carbonaceous matter, is also present. Selected area electron diffraction (SAED) shows that this C-rich material is amorphous (lacking any long-range crystallographic order) and is not graphite or carbonate. Micro-Raman spectra acquired from the same surface from which the FIB section was extracted demonstrate a typical kerogen-like D and G band structure with a weak absorption peak at 1350 and a stronger peak at 1600/cm. The C-rich feature is intimately associated with both the surrounding halite and underlying iddingsite matrix. Both iddingsite and salts are interpreted as having formed as evaporate assemblages from progressive evaporation of water bodies on Mars. This assemblage, sans the carbonaceous moieties, closely resembles iddingsite alteration features previously described which were interpreted as indigenous Martian assemblages. These distinctive macromolecular carbonaceous structures in Nakhla may represent

  9. Comparing Meteorite and Spacecraft Noble Gas Measurements to Trace Processes in the Martian Crust and Atmosphere

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.

    2014-12-01

    Our knowledge of the noble gas abundances and isotopic compositions in the Martian crust and atmosphere come from two sources, measurements of meteorites from Mars and in situ measurements by spacecraft. Measurements by the Viking landers had large uncertainties, but were precise enough to tie the meteorites to Mars. Hence most of the questions we have are currently defined by meteorite measurements. Curiosity's SAM has confirmed that the Ar isotopic composition of the atmosphere is highly fractionated, presumably representing atmospheric loss that can now be modeled with more confidence. What turns out to be a more difficult trait to explain is the fact that the ratio of Kr/Xe in nakhlites, chassignites and ALH84001 is distinct from the atmospheric ratio, as defined by measurements from shergottites. This discrepancy has been suggested to be a result of atmosphere/groundwater/rock interaction, polar clathrate formation, or perhaps local temperature conditions. More detailed atmospheric measurements, along with targeted simulation experiments, will be needed to make full use of this anomaly.

  10. Isotopic Evidence for a Martian Regolith Component in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Sutton, S.

    2009-01-01

    Noble gas measurements in gas-rich impact-melt (GRIM) glasses in EET79001 shergottite showed that their elemental and isotopic composition is similar to that of the Martian atmosphere [1-3]. The GRIM glasses contain large amounts of Martian atmospheric gases. Those measurements further suggested that the Kr isotopic composition of Martian atmosphere is approximately similar to that of solar Kr. The (80)Kr(sub n) - (80)Kr(sub M) mixing ratio in the Martian atmosphere reported here is approximately 3%. These neutron-capture reactions presumably occurred in the glass-precursor regolith materials containing Sm- and Br- bearing mineral phases near the EET79001/ Shergotty sites on Mars. The irradiated materials were mobilized into host rock voids either during shock-melting or possibly by earlier aeolian / fluvial activity.

  11. A reduced organic carbon component in martian basalts.

    PubMed

    Steele, A; McCubbin, F M; Fries, M; Kater, L; Boctor, N Z; Fogel, M L; Conrad, P G; Glamoclija, M; Spencer, M; Morrow, A L; Hammond, M R; Zare, R N; Vicenzi, E P; Siljeström, S; Bowden, R; Herd, C D K; Mysen, B O; Shirey, S B; Amundsen, H E F; Treiman, A H; Bullock, E S; Jull, A J T

    2012-07-13

    The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycyclic aromatic hydrocarbons were detected along with MMC phases in Dar al Gani 476. The association of organic carbon within magmatic minerals indicates that martian magmas favored precipitation of reduced carbon species during crystallization. The ubiquitous distribution of abiotic organic carbon in martian igneous rocks is important for understanding the martian carbon cycle and has implications for future missions to detect possible past martian life.

  12. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    DOE PAGES

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    2015-12-12

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteoritesmore » and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at

  13. Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

    High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteoritesmore » and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at

  14. The Meteoritical Bulletin, No. 97

    NASA Astrophysics Data System (ADS)

    Weisberg, Michael K.; Smith, Caroline; Benedix, Gretchen; Herd, Christopher D. K.; Righter, Kevin; Haack, Henning; Yamaguchi, Akira; Chennaoui Aoudjehane, Hasnaa; Grossman, Jeffrey N.

    2010-03-01

    In this edition of The Meteoritical Bulletin, a total of 506 newly approved meteorite names with their relevant data are reported. These include 354 from northwest Africa, 31 from the Americas, 15 from Antarctica (Koreamet), 85 from Asia, 20 from Australia, and 1 from Europe. Among these meteorites are 2 falls, Grimsby (Canada) and Santa Lucia (2008) (Argentina). Also described are a CM with low degree of alteration, new ungrouped chondrites and achondrites, and 4 Martian meteorites.

  15. Evidence From Hydrogen Isotopes in Meteorites for a Martian Permafrost

    NASA Technical Reports Server (NTRS)

    Usui, T.; Alexander, C. M. O'D.; Wang, J.; Simon, J. I.; Jones, J. H.

    2014-01-01

    Fluvial landforms on Mars suggest that it was once warm enough to maintain persistent liquid water on its surface. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. We have investigated the evolution of surface water/ ice and its interaction with the atmosphere by measurements of hydrogen isotope ratios (D/H: deuterium/ hydrogen) of martian meteorites. Hydrogen is a major component of water (H2O) and its isotopes fractionate significantly during hydrological cycling between the atmosphere, surface waters, ground ice, and polar cap ice. Based on in situ ion microprobe analyses of three geochemically different shergottites, we reported that there is a water/ice reservoir with an intermediate D/H ratio (delta D = 1,000?2500 %) on Mars. Here we present the possibility that this water/ice reservoir represents a ground-ice/permafrost that has existed relatively intact over geologic time.

  16. On the weathering of Martian igneous rocks

    NASA Technical Reports Server (NTRS)

    Dreibus, G.; Waenke, H.

    1992-01-01

    Besides the young crystallization age, one of the first arguments for the martian origin of shergottite, nakhlite, and chassignite (SNC) meteorites came from the chemical similarity of the meteorite Shergotty and the martian soil as measured by Viking XRF analyses. In the meantime, the discovery of trapped rare gas and nitrogen components with element and isotope ratios closely matching the highly characteristic ratios of the Mars atmosphere in the shock glasses of shergottite EETA79001 was further striking evidence that the SNC's are martian surface rocks. The martian soil composition as derived from the Viking mission, with its extremely high S and Cl concentrations, was interpreted as weathering products of mafic igneous rocks. The low SiO2 content and the low abundance of K and other trace elements in the martian soils point to a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust. However, the chemical evolution of the martian regolith and soil in respect to surface reaction with the planetary atmosphere or hydrosphere is poorly understood. A critical point in this respect is that the geochemical evidence as derived from the SNC meteorites suggests that Mars is a very dry planet that should have lost almost all its initially large water inventory during its accretion.

  17. What we have learned about Mars from SNC meteorites

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.

    1994-01-01

    The SNC meteorites are thought to be igneous martian rocks, based on their young crystallization ages and a close match between the composition of gases implanted in them during shock and the atmosphere of Mars. A related meteorite, ALH84001, may be older and thus may represent ancient martian crust. These petrologically diverse basalts and ultramafic rocks are mostly cumulates, but their parent magmas share geochemical and radiogenic isotopic characteristics that suggest they may have formed by remelting the same mantle source region at different times. Information and inferences about martian geology drawn from these samples include the following: Planetary differentiation occured early at approximately 4.5 GA, probably concurrently with accretion. The martian mantle contains different abundances of moderately volatile and siderophile elements and is more Fe-rich than that of the Earth, which has implications for its mineralogy, density, and origin. The estimated core composition has a S abundance near the threshold value for inner core solidification. The former presence of a core dynamo may be suggested by remanent magnetization in Shergottite-Nakhlite-Chassignite (SNC) meteorites, although these rocks may have been magnetized during shock. The mineralogy of martian surface units, inferred from reflectance spectra, matches that of basaltic shergottites, but SNC lithologies thought to have crystallized in the subsurface are not presently recognized. The rheological properties of martian magmas are more accurately derived form these metorites than from observations of martian flow morphology, although the sampled range of magma compositions islimited. Estimates of planetary water abundance and the amount of outgassed water based on these meteorites are contridictory but overlap estimates based on geological observations and atmospheric measurements. Stable isotope measurements indicate that the martian hydrosphere experienced only limited exchange with the

  18. Oxygen Isotopic Analyses of Water Extracted from the Martian Meteorite NWA 7034

    NASA Astrophysics Data System (ADS)

    Nunn, M.; Agee, C. B.; Thiemens, M. H.

    2012-12-01

    Introduction: The NWA 7034 meteorite has been identified as Martian, but it is distinct from the Shergottite-Nakhlite-Chassignite (SNC) grouping of meteorites in its petrology (it is the only known Martian basaltic breccia) and bulk silicate oxygen isotopic composition (Δ17O = 0.56 ± 0.06 ‰, where Δ17O = δ17O - 0.528 x δ18O, compared to the average SNC Δ17O ≈ 0.3 ‰) [e.g., 1-2]. We report here measurements of the oxygen isotopic composition of water extracted from NWA 7034 by stepwise heating. Methods: A piece (~1.2g) of NWA 7034 was pumped to vacuum until outgassing had stopped before heating to 50, 150, 320, 500, and 1000°C. The sample was maintained at each temperature step for at least one hour while collecting evolved volatiles in a liquid nitrogen cold trap. Water was selectively converted to molecular oxygen, the oxygen isotopic composition of which was then measured on a double collecting isotope ratio mass spectrometer. Results: Our stepwise heating experiments indicate NWA 7034 contains 3330ppm water, and this water has an average oxygen isotopic composition of Δ17O = 0.330 ± 0.011‰. The oxygen isotopic composition of water in NWA 7034 is unlike that of the silicates from which it is extracted (Δ17O = 0.56 ± 0.06 ‰) but is comparable to the average SNC silicate composition (Δ17O ≈ 0.3 ‰). However, there is no consensus on the oxygen isotopic composition of water in SNCs because aliquots of water extracted from different samples (separate pieces of a single meteorite or from different meteorites) have different oxygen isotopic compositions [3]. Furthermore, carbonates and sulfates extracted from SNCs also possess distinct oxygen isotopic compositions [4]. The variation in oxygen isotopic composition among these phases most likely results from the existence of isotopically distinct oxygen reservoirs on Mars that were not equilibrated. On Earth, interaction of ozone (O3) and carbon dioxide (CO2) leads to a mass independent oxygen

  19. Evidence for shock heating and constraints on Martian surface temperatures revealed by 40Ar/ 39Ar thermochronometry of Martian meteorites

    NASA Astrophysics Data System (ADS)

    Cassata, William S.; Shuster, David L.; Renne, Paul R.; Weiss, Benjamin P.

    2010-12-01

    The thermal histories of Martian meteorite are important for the interpretation of petrologic, geochemical, geochronological, and paleomagnetic constraints that they provide on the evolution of Mars. In this paper, we quantify 40Ar/ 39Ar ages and Ar diffusion kinetics of Martian meteorites Allan Hills (ALH) 84001, Nakhla, and Miller Range (MIL) 03346. We constrain the thermal history of each meteorite and discuss the resulting implications for their petrology, paleomagnetism, and geochronology. Maskelynite in ALH 84001 yields a 40Ar/ 39Ar isochron age of 4163 ± 35 Ma, which is indistinguishable from recent Pb-Pb ( Bouvier et al., 2009a) and Lu-Hf ages ( Lapen et al., 2010). The high precision of this result arises from clear resolution of a reproducible trapped 40Ar/ 36Ar component in maskelynite in ALH 84001 ( 40Ar/ 36Ar = 632 ± 90). The maskelynite 40Ar/ 39Ar age predates the Late Heavy Bombardment and likely represents the time at which the original natural remanent magnetization (NRM) component observed in ALH 84001 was acquired. Nakhla and MIL 03346 yield 40Ar/ 39Ar isochron ages of 1332 ± 24 and 1339 ± 8 Ma, respectively, which we interpret to date crystallization. Multi-phase, multi-domain diffusion models constrained by the observed Ar diffusion kinetics and 40Ar/ 39Ar age spectra suggest that localized regions within both ALH 84001 and Nakhla were intensely heated for brief durations during shock events at 1158 ± 110 and 913 ± 9 Ma, respectively. These ages may date the marginal melting of pyroxene in each rock, mobilization of carbonates and maskelynite in ALH 84001, and NRM overprints observed in ALH 84001. The inferred peak temperatures of the shock heating events (>1400 °C) are sufficient to mobilize Ar, Sr, and Pb in constituent minerals, which may explain some of the dispersion observed in 40Ar/ 39Ar, Rb-Sr, and U-Th-Pb data toward ages younger than ˜4.1 Ga. The data also place conservative upper bounds on the long-duration residence

  20. Silver contents and Cu/Ag ratios in Martian meteorites and the implications for planetary differentiation

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2017-11-01

    Silver and Cu show very similar partitioning behavior in sulfide melt-silicate melt and metal-silicate systems at low and high pressure-temperature (P-T) experimental conditions, implying that mantle melting, fractional crystallization and core-mantle differentiation have at most modest (within a factor of 3) effects on Cu/Ag ratios. For this reason, it is likely that Cu/Ag ratios in mantle-derived magmatic products of planetary bodies reflect that of the mantle and, in some circumstances, also the bulk planet composition. To test this hypothesis, new Ag mass fractions and Cu/Ag ratios in different groups of Martian meteorites are presented and compared with data from chondrites and samples from the Earth's mantle. Silver contents in lherzolitic, olivine-phyric and basaltic shergottites and nakhlites range between 1.9 and 12.3 ng/g. The data display a negative trend with MgO content and correlate positively with Cu contents. In spite of displaying variable initial Ɛ143Nd values and representing a diverse spectrum of magmatic evolution and physiochemical conditions, shergottites and nakhlites display limited variations of Cu/Ag ratios (1080 ± 320, 1 s, n = 14). The relatively constant Cu/Ag suggests limited fractionation of Ag from Cu during the formation and evolution of the parent magmas, irrespectively of whether sulfide saturation was attained or not. The mean Cu/Ag ratio of Martian meteorites thus reflects that of the Martian mantle and constrains its Ag content to 1.9 ± 0.7 ng/g (1 s). Carbonaceous and enstatite chondrites display a limited range of Cu/Ag ratios of mostly 500-2400. Ordinary chondrites show a larger scatter of Cu/Ag up to 4500, which may have been caused by Ag redistribution during parent body metamorphism. The majority of chondrites have Cu/Ag ratios indistinguishable from the Martian mantle value, indicating that Martian core formation strongly depleted Cu and Ag contents, but probably did not significantly change the Cu/Ag ratio of the

  1. Terrestrial microbes in martian and chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Airieau, S.; Piceno, Y.; Andersen, G.

    2007-08-01

    Good extraterrestrial analogs for microbiology are SNC meteorites as Mars analogs, and chondrites as early planet analogs. Chondrites and SNCs are used to trace processes in the early solar system and on Mars. Yet, questions about terrestrial contamination and its effects on the isotopic, chemical and mineral characteristics often arise. A wide biodiversity was found in 21 chondrites of groups CR, CV, CK, CO from ANSMET, CI and CM Falls, and 8 SNCs. Studies documented the alteration of meteorites by weathering and biology [1]-[6], and during aqueous extraction for oxygen isotopic analysis [7], visible biofilms grew in the meteorite solutions in days. To assess biological isotopic and chemical impacts, cultures were incubated 11 months and analyzed by PCR. The sequences for 2 isolates from EET 87770 and Leoville were of a good quality with long sequence reads. In EET 87770, the closest matches were in the genus Microbacterium. Soil and plant isolates were close relatives by sequence comparison. Bacillus, a common soil bacterial genus, grew in a Leoville culture. All SNCs exhibited biological activity measured independently by LAL but only 1 colony was successfully cultured from grains of the SNC Los Angeles. Isotopic analyses of samples with various amounts of microbial contamination could help quantified isotopic impact of microbes on protoplanetary chemistry in these rocks. References: [1] Gounelle, M.& Zolensky M. (2001) LPS XXXII, Abstract #999. [2] Fries, M. et al. (2005) Meteoritical Society Meeting 68, Abstract # 5201. [3] Burckle, L. H. & Delaney, J. S (1999) Meteoritics & Planet. Sci., 32, 475. [4] Whitby, C. et al. (2000) LPS XXXI, Abstract #1732. [5] Tyra M. et al., (2007) Geochim. Cosmochim. Acta, 71, 782 [6] Toporski, J. & Steele A., (2007) Astrobiology, 7, 389 [7]Airieau, S. et al (2005) Geochim. Cosmochim. Acta, 69, 4166.

  2. A Hypothesis for the Abiotic and Non-Martian Origins of Putative Signs of Ancient Martian Life in ALH84001

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    2001-01-01

    Putative evidence of martian life in ALH84001 can be explained by abiotic and non-martian processes consistent with the meteorite's geological history. Additional information is contained in the original extended abstract.

  3. Meteorites and the Evolution of Our Solar System

    NASA Technical Reports Server (NTRS)

    Nava, David F.

    1999-01-01

    The study of meteorites has long been of intense interest ever since these objects were discovered to be of extraterrestrial origin. Meteorite research contributes to unraveling the mysteries in understanding the formation and evolution processes of our solar system. Meteorites, of which there are a variety of widely diverse types of chemical and mineralogical compositions, are the most ancient of solar system objects that can be studied in the laboratory. They preserve a unique historical record of the astronomical and astrophysical events of our solar system. This record is being discerned by a host of ever evolving analytical laboratory methods. Recent discoveries of what are believed to be Martian meteorites, lunar meteorites, a meteorite containing indigenous water, and the recovery from the Cretaceous layer of a small meteorite fragment thought to be from the dinosaur-killing asteroid have fueled additional excitement for studying meteorites.

  4. Lunar Mare Basalts as Analogues for Martian Volcanic Compositions: Evidence from Visible, Near-IR, and Thermal Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Graff, T. G.; Morris, R. V.; Christensen, P. R.

    2003-01-01

    The lunar mare basalts potentially provide a unique sample suite for understanding the nature of basalts on the martian surface. Our current knowledge of the mineralogical and chemical composition of the basaltic material on Mars comes from studies of the basaltic martian meteorites and from orbital and surface remote sensing observations. Petrographic observations of basaltic martian meteorites (e.g., Shergotty, Zagami, and EETA79001) show that the dominant phases are pyroxene (primarily pigeonite and augite), maskelynite (a diaplectic glass formed from plagioclase by shock), and olivine [1,2]. Pigeonite, a low calcium pyroxene, is generally not found in abundance in terrestrial basalts, but does often occur on the Moon [3]. Lunar samples thus provide a means to examine a variety of pigeonite-rich basalts that also have bulk elemental compositions (particularly low-Ti Apollo 15 mare basalts) that are comparable to basaltic SNC meteorites [4,5]. Furthermore, lunar basalts may be mineralogically better suited as analogues of the martian surface basalts than the basaltic martian meteorites because the plagioclase feldspar in the basaltic Martian meteorites, but not in the lunar surface basalts, is largely present as maskelynite [1,2]. Analysis of lunar mare basalts my also lead to additional endmember spectra for spectral libraries. This is particularly important analysis of martian thermal emission spectra, because the spectral library apparently contains a single pigeonite spectrum derived from a synthetic sample [6].

  5. Comparison of Martian Meteorites and Martian Regolith as Shield Materials for Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Thibeault, Sheila A.; Simonsen, Lisa C.; Wilson, John W.

    1998-01-01

    Theoretical calculations of radiation attenuation due to energetic galactic cosmic rays behind Martian rock and Martian regolith material have been made to compare their utilization as shields for advanced manned missions to Mars because the detailed chemical signature of Mars is distinctly different from Earth. The modified radiation fields behind the Martian rocks and the soil model were generated by solving the Boltzmann equation using a HZETRN system with the 1977 Solar Minimum environmental model. For the comparison of the attenuation characteristics, dose and dose equivalent are calculated for the five different subgroups of Martian rocks and the Martian regolith. The results indicate that changes in composition of subgroups of Martian rocks have negligible effects on the overall shielding properties because of the similarity of their constituents. The differences for dose and dose equivalent of these materials relative to those of Martian regolith are within 0.5 and 1 percent, respectively. Therefore, the analysis of Martian habitat construction options using in situ materials according to the Martian regolith model composition is reasonably accurate. Adding an epoxy to Martian regolith, which changes the major constituents of the material, enhances shielding properties because of the added hydrogenous constituents.

  6. Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites

    NASA Astrophysics Data System (ADS)

    Kurosawa, Kosuke; Okamoto, Takaya; Genda, Hidenori

    2018-02-01

    Hypervelocity ejection of material by impact spallation is considered a plausible mechanism for material exchange between two planetary bodies. We have modeled the spallation process during vertical impacts over a range of impact velocities from 6 to 21 km/s using both grid- and particle-based hydrocode models. The Tillotson equations of state, which are able to treat the nonlinear dependence of density on pressure and thermal pressure in strongly shocked matter, were used to study the hydrodynamic-thermodynamic response after impacts. The effects of material strength and gravitational acceleration were not considered. A two-dimensional time-dependent pressure field within a 1.5-fold projectile radius from the impact point was investigated in cylindrical coordinates to address the generation of spalled material. A resolution test was also performed to reject ejected materials with peak pressures that were too low due to artificial viscosity. The relationship between ejection velocity veject and peak pressure Ppeak was also derived. Our approach shows that "late-stage acceleration" in an ejecta curtain occurs due to the compressible nature of the ejecta, resulting in an ejection velocity that can be higher than the ideal maximum of the resultant particle velocity after passage of a shock wave. We also calculate the ejecta mass that can escape from a planet like Mars (i.e., veject > 5 km/s) that matches the petrographic constraints from Martian meteorites, and which occurs when Ppeak = 30-50 GPa. Although the mass of such ejecta is limited to 0.1-1 wt% of the projectile mass in vertical impacts, this is sufficient for spallation to have been a plausible mechanism for the ejection of Martian meteorites. Finally, we propose that impact spallation is a plausible mechanism for the generation of tektites.

  7. Pulmonary Inflammatory Responses to Acute Meteorite Dust Exposures - to Acute Meteorite Dust Exposures - Exploration

    NASA Technical Reports Server (NTRS)

    Harrington, A. D.; McCubbin, F. M.; Kaur, J.; Smirnov, A.; Galdanes, K.; Schoonen, M. A. A.; Chen, L. C.; Tsirka, S. E.; Gordon, T.

    2017-01-01

    New initiatives to begin lunar and martian colonization within the next few decades are illustrative of the resurgence of interest in space travel. One of NASA's major concerns with extended human space exploration is the inadvertent and repeated exposure to unknown dust. This highly interdisciplinary study evaluates both the geochemical reactivity (e.g. iron solubility and acellular reactive oxygen species (ROS) generation) and the relative toxicity (e.g. in vitro and in vivo pulmonary inflammation) of six meteorite samples representing either basalt or regolith breccia on the surface of the Moon, Mars, and Asteroid 4Vesta. Terrestrial mid-ocean ridge basalt (MORB) is also used for comparison. The MORB demonstrated higher geochemical reactivity than most of the meteorite samples but caused the lowest acute pulmonary inflammation (API). Notably, the two martian meteorites generated some of the highest API but only the basaltic sample is significantly reactive geochemically. Furthermore, while there is a correlation between a meteorite's soluble iron content and its ability to generate acellular ROS, there is no direct correlation between a particle's ability to generate ROS acellularly and its ability to generate API. However, assorted in vivo API markers did demonstrate strong positive correlations with increasing bulk Fenton metal content. In summary, this comprehensive dataset allows for not only the toxicological evaluation of astromaterials but also clarifies important correlations between geochemistry and health.

  8. Metal-saturated sulfide assemblages in NWA 2737: Evidence for impact-related sulfur devolatilization in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Lorand, Jean-Pierre; Barrat, Jean-Alix; Chevrier, Vincent; Sautter, Violaine; Pont, Sylvain

    2012-11-01

    Abstract-NWA 2737, a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> from the Chassignite subclass, contains minute amounts (0.010 ± 0.005 vol%) of metal-saturated Fe-Ni sulfides. These latter bear evidence of the strong shock effects documented by abundant Fe nanoparticles and planar defects in Northwest Africa (NWA) 2737 olivine. A Ni-poor troilite (Fe/S = 1.0 ± 0.01), sometimes Cr-bearing (up to 1 wt%), coexists with micrometer-sized taenite/tetrataenite-type native Ni-Fe alloys (Ni/Fe = 1) and Fe-Os-Ir-(Ru) alloys a few hundreds of nanometers across. The troilite has exsolved flame-like pentlandite (Fe/Fe + Ni = 0.5-0.6). Chalcopyrite is almost lacking, and no pyrite has been found. As a hot desert find, NWA 2737 shows astonishingly fresh sulfides. The composition of troilite coexisting with Ni-Fe alloys is completely at odds with Chassigny and Nahkla sulfides (pyrite + metal-deficient monoclinic-type pyrrhotite). It indicates strongly reducing crystallization conditions (close to IW), several log units below the fO2 conditions inferred from chromites compositions and accepted for Chassignites (FMQ-1 log unit). It is proposed that reduction in sulfides into base and precious metal alloys is operated via sulfur degassing, which is supported by the highly resorbed and denticulated shape of sulfide blebs and their spongy textures. Shock-related S degassing may be responsible for considerable damages in magmatic sulfide structures and sulfide assemblages, with concomitant loss of magnetic properties as documented in some other <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100024179','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100024179"><span>Origin of Magnetite Crystals in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001 Carbonate Disks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas-Keprta, K.L.; Clemett, S.J.; McKay, D.S.; Gibson, E. K.; Wentworth, S. J.</p> <p>2010-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks which are believed to have precipitated approx.3.9 Ga ago at beginning of the Noachian epoch. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these Fe3O4 are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of Fe3O4 and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. We have sought to resolve between these hypotheses through the detailed characterized of the compositional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded [1]. We focus this discussion on the composition of ALH84001 magnetites and then compare these observations with those from our thermal decomposition <span class="hlt">studies</span> of sideritic carbonates under a range of plausible geological heating scenarios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040089238&hterms=Biofilms+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBiofilms%2Bformation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040089238&hterms=Biofilms+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBiofilms%2Bformation"><span>Bacterial mineralization patterns in basaltic aquifers: implications for possible life in <span class="hlt">martian</span> <span class="hlt">meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Coleman, A.; Gibson, E. K. Jr; Romanek, C. S.</p> <p>1998-01-01</p> <p>To explore the formation and preservation of biogenic features in igneous rocks, we have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in <span class="hlt">martian</span> <span class="hlt">meteorite</span> ALH84001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970010356','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970010356"><span>A Petrographic History of <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001: Two Shocks and an Ancient Age</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.</p> <p>1995-01-01</p> <p>ALH84001 is an igneous <span class="hlt">meteorite</span>, an orthopyroxenite of <span class="hlt">martian</span> origin. It contains petrographic evidence of two shock metamorphic events, separated by thermal and chemical events. The evidence for two shock events suggests that ALH84001 is ancient and perhaps a sample of the <span class="hlt">martian</span> highlands. From petrography and mineral chemistry, the history of ALH84001 must include: crystallization from magma, a first shock (impact) metamorphism, thermal metamorphism, low-temperature chemical alteration, and a second shock (impact) metamorphism. Originally, ALH84001 was igneous, an orthopyroxene-chromite cumulate. In the first shock event, the igneous rock was cut by melt-breccia or cataclastic veinlets, now bands of equigranular fine-grained pyroxene and other minerals (crush zones). Intact fragments of the cumulate were fractured and strained (now converted to polygonized zones). The subsequent thermal metamorphism (possibly related to the first shock) annealed the melt-breccia or cataclastic veinlets to their present granoblastic texture and permitted chemical homogenization of all mineral species present. The temperature of metamorphism was at least 875 C, based on mineral thermometers. Next, Mg-Fe-Ca carbonates and pyrite replaced plagioclase in both clasts and granular bands, producing ellipsoidal carbonate globules with sub-micron scale compositional stratigraphy, repeated identically in all globules, The second shock event produced microfault offsets of carbonate stratigraphy and other mineral contacts, radial fractures around chromite and maskelynite, and strain birefringence in pyroxene. Maskelynite could not have been preserved from the first shock event, because it would have crystallized back to plagioclase. The <span class="hlt">martian</span> source area for ALH84001 must permit this complex, multiple impact history. Very few craters on young igneous surfaces are on or near earlier impact features. It is more likely that ALH84001 was ejected from an old igneous unit (Hesperian or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52.2411B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52.2411B"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 105</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouvier, Audrey; Gattacceca, Jérôme; Grossman, Jeffrey; Metzler, Knut</p> <p>2017-11-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 105 contains 2666 <span class="hlt">meteorites</span> including 12 falls (Aouinet Legraa, Banma, Buritizal, Ejby, Kamargaon, Moshampa, Mount Blanco, Murrili, Osceola, Sariçiçek, Sidi Ali Ou Azza, Stubenberg), with 2244 ordinary chondrites, 142 HED achondrites, 116 carbonaceous chondrites, 37 Lunar <span class="hlt">meteorites</span>, 20 enstatite chondrites, 20 iron <span class="hlt">meteorites</span>, 20 ureilites, 19 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 12 Rumuruti chondrites, 10 primitive achondrites, 9 mesosiderites, 5 angrites, 4 pallasites, 4 ungrouped achondrites, 2 ungrouped chondrites, 1 enstatite achondrite, and 1 relict <span class="hlt">meteorite</span>, and with 1545 from Antarctica, 686 from Africa, 245 from Asia, 147 from South America, 22 from North America, 14 from Europe, 5 from Oceania, 1 from unknown origin. Note: 5 <span class="hlt">meteorites</span> from Russia were counted as European. It also includes a list of approved new Dense Collection Areas and a nomenclature of the Aletai (IIIE-an) iron <span class="hlt">meteorites</span> from Xinjiang, China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52.1014R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52.1014R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 103</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Agee, Carl B.</p> <p>2017-05-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 103 contains 2582 <span class="hlt">meteorites</span> including 10 falls (Ardón, Demsa, Jinju, Križevci, Kuresoi, Novato, Tinajdad, Tirhert, Vicência, Wolcott), with 2174 ordinary chondrites, 130 HED achondrites, 113 carbonaceous chondrites, 41 ureilites, 27 lunar <span class="hlt">meteorites</span>, 24 enstatite chondrites, 21 iron <span class="hlt">meteorites</span>, 15 primitive achondrites, 11 mesosiderites, 10 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 6 Rumuruti chondrites, 5 ungrouped achondrites, 2 enstatite achondrites, 1 relict <span class="hlt">meteorite</span>, 1 pallasite, and 1 angrite, and with 1511 from Antarctica, 588 from Africa, 361 from Asia, 86 from South America, 28 from North America, and 6 from Europe. Note: 1 <span class="hlt">meteorite</span> from Russia was counted as European. The complete contents of this bulletin (244 pages) are available on line. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available on line at <url href="http://www.lpi.usra.edu/meteor/">http://www.lpi.usra.edu/meteor/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010044721&hterms=Xxxii&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DXxxii','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010044721&hterms=Xxxii&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DXxxii"><span>A Parent Magma for the Nakhla <span class="hlt">Martian</span> <span class="hlt">Meteorite</span>: Reconciliation of Estimates from 1-Bar Experiments, Magmatic Inclusions in Olivine, and Magmatic Inclusions in Augite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.; Goodrich, Cyrena Anne</p> <p>2001-01-01</p> <p>The composition of the parent magma for the Nakhla (<span class="hlt">martian</span>) <span class="hlt">meteorite</span> has been estimated from mineral-melt partitioning and from magmatic inclusions in olivine and in augite. These independent lines of evidence have converged on small range of likely compositions. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001834','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001834"><span>Evidence from Olivine-Hosted Melt Inclusions that the <span class="hlt">Martian</span> Mantle has a Chondritic D/H Ratio and that Some Young Basalts have Assimilated Old Crust</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, Tomohiro; Alexander, O'D.; Wang, J.; Simon, J. I.; Jones, J. H.</p> <p>2012-01-01</p> <p>Magmatic degassing of volatile elements affects the climate and near-surface environment of Mars. Telescopic and <span class="hlt">meteorite</span> <span class="hlt">studies</span> have revealed that the <span class="hlt">Martian</span> atmosphere and near-surface materials have D/H ratios 5-6 times terrestrial values [e.g., 1, 2]. Such high D/H ratios are interpreted to result from the preferential loss of H relative to heavier D from the <span class="hlt">Martian</span> atmosphere, assuming that the original <span class="hlt">Martian</span> water inventory had a D/H ratio similar to terrestrial values and to H in primitive <span class="hlt">meteorites</span> [e.g., 1, 3]. However, the primordial <span class="hlt">Martian</span> D/H ratio has, until now, not been well constrained. The uncertainty over the <span class="hlt">Martian</span> primordial D/H ratio has arisen both from the scarcity of primitive <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and as a result of contamination by terrestrial and, perhaps, <span class="hlt">Martian</span> surface waters that obscure the signature of the <span class="hlt">Martian</span> mantle. This <span class="hlt">study</span> reports a comprehensive dataset of magmatic volatiles and D/H ratios in <span class="hlt">Martian</span> primary magmas based on low-contamination, in situ ion microprobe analyses of olivine-hosted melt inclusions from both depleted [Yamato 980459 (Y98)] and enriched [Larkman Nunatak 06319 (LAR06)] <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span>. Analyses of these primitive melts provide definitive evidence that the <span class="hlt">Martian</span> mantle has retained a primordial D/H ratio and that young <span class="hlt">Martian</span> basalts have assimilated old <span class="hlt">Martian</span> crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2201L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2201L"><span>NanoSIMS analysis of organic carbon from the Tissint <span class="hlt">Martian</span> <span class="hlt">meteorite</span>: Evidence for the past existence of subsurface organic-bearing fluids on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Yangting; El Goresy, Ahmed; Hu, Sen; Zhang, Jianchao; Gillet, Philippe; Xu, Yuchen; Hao, Jialong; Miyahara, Masaaki; Ouyang, Ziyuan; Ohtani, Eiji; Xu, Lin; Yang, Wei; Feng, Lu; Zhao, Xuchao; Yang, Jing; Ozawa, Shin</p> <p>2014-12-01</p> <p>Two petrographic settings of carbonaceous components, mainly filling open fractures and occasionally enclosed in shock-melt veins, were found in the recently fallen Tissint <span class="hlt">Martian</span> <span class="hlt">meteorite</span>. The presence in shock-melt veins and the deuterium enrichments (δD up to +1183‰) of these components clearly indicate a pristine <span class="hlt">Martian</span> origin. The carbonaceous components are kerogen-like, based on micro-Raman spectra and multielemental ratios, and were probably deposited from fluids in shock-induced fractures in the parent rock of Tissint. After precipitation of the organic matter, the rock experienced another severe shock event, producing the melt veins that encapsulated a part of the organic matter. The C isotopic compositions of the organic matter (δ13C = -12.8 to -33.1‰) are significantly lighter than <span class="hlt">Martian</span> atmospheric CO2 and carbonate, providing a tantalizing hint for a possible biotic process. Alternatively, the organic matter could be derived from carbonaceous chondrites, as insoluble organic matter from the latter has similar chemical and isotopic compositions. The presence of organic-rich fluids that infiltrated rocks near the surface of Mars has significant implications for the <span class="hlt">study</span> of <span class="hlt">Martian</span> paleoenvironment and perhaps to search for possible ancient biological activities on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040059919&hterms=Soil+solution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSoil%2Bsolution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040059919&hterms=Soil+solution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSoil%2Bsolution"><span>Chemical Weathering Records of <span class="hlt">Martian</span> Soils Preserved in the <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> EET79001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Wentworth, S. J.; McKay, D. S.</p> <p>2004-01-01</p> <p>Impact-melt glasses, rich in <span class="hlt">Martian</span> atmospheric gases, contain <span class="hlt">Martian</span> soil fines (MSF) mixed with other coarse-grained regolith fractions which are produced during impact bombardment on Mars surface. An important characteristic of the MSF fraction is the simultaneous enrichment of felsic component accompanied by the depletion of mafic component relative to the host phase in these glasses. In addition, these glasses yield large sulfur abundances due to the occurrence of secondary mineral phases such as sulfates produced during acid-sulfate weathering of the regolith material near the <span class="hlt">Martian</span> surface. Sulfurous gases released into atmosphere by volcanoes on Mars are oxidized to H2SO4 which deposit back on the surface of Mars as aerosol particles. Depending on the water availability, sulfuric acids dissolve into solutions which aggressively decompose the Fe-Mg silicates in the <span class="hlt">Martian</span> regolith. During chemical weathering, structural elements such as Fe, Mg and Ca (among others) are released into the transgressing solutions. These solutions leach away the soluble components of Mg, Ca and Na, leaving behind insoluble iron as Fe3(+) hydroxysulfate mixed with poorly crystalline hydroxide- precipitates under oxidizing conditions. In this <span class="hlt">study</span>, we focus on the elemental distribution of FeO and SO3 in the glass veins of EET79001, 507 sample, determined by Electron Microprobe and FE SEM measurements at JSC. This glass sample is an aliquot of a bigger glass inclusion ,104 analysed by where large concentrations of <span class="hlt">Martian</span> atmospheric noble gases are found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002M%26PSA..37..157R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002M%26PSA..37..157R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 86</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, Sara S.; Zipfel, Jutta; Grossman, Jeffrey N.; Grady, Monica M.</p> <p>2002-07-01</p> <p><span class="hlt">Meteoritical</span> Bulletin No. 86 lists information for 11 54 newly classified <span class="hlt">meteorites</span>, comprising 661 from Antarctica, 218 from Africa, 207 from Asia (203 of which are from Oman), 62 from North America, 3 from South America, and 3 from Europe. Information is provided for 5 falls (El Idrissia, Undulung, Dashoguz, El Tigre, and Yafa). Noteworthy specimens include 7 <span class="hlt">martian</span> <span class="hlt">meteorites</span> (Dhofar 378, Grove Mountains 99027, Northwest Africa 856, 1068, and 1110, and Sayh al Uhaymir 060 and 090); 4 lunar <span class="hlt">meteorites</span> (Dhofar 301, 302, 303, and 489); 9 new iron <span class="hlt">meteorites</span>; a mesosiderite (Northwest Africa 1242); an ungrouped stony-iron <span class="hlt">meteorite</span> (Dar al Gani 962); and a wide variety of other interesting stony <span class="hlt">meteorites</span>, including CH, CK, CM, CR, CV, R, enstatite, unequilibrated ordinary, and ungrouped chondrites, primitive achondrites, howardite-eucrite-diogenite (HED) achondrites, and ureilites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070018211','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070018211"><span>Experimental Shock Decomposition of Siderite and the Origin of Magnetite in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bell, Mary Sue</p> <p>2007-01-01</p> <p>Shock recovery experiments to determine whether magnetite could be produced by the decomposition of iron-carbonate were initiated. Naturally occurring siderite was first characterized by electron microprobe (EMP), transmission electron microscopy (TEM), Mossbauer spectroscopy, and magnetic susceptibility measurements to be sure that the starting material did not contain detectable magnetite. Samples were shocked in tungsten-alloy holders (W=90%, Ni=6%, Cu=4%) to further insure that any iron phases in the shock products were contributed by the siderite rather than the sample holder. Each sample was shocked to a specific pressure between 30 to 49 GPa. Previously reported results of TEM analyses on 49 GPa experiments indicated the presence of nano-phase spinel-structured iron oxide. Transformation of siderite to magnetite as characterized by TEM was found in the 49 GPa shock experiment. Compositions of most magnetites are greater than 50% Fe sup(+2) in the octahedral site of the inverse spinel structure. Magnetites produced in shock experiments display the same range of single-domain, superparamagnetic sizes (approx. 50 100 nm), compositions (100% magnetite to 80% magnetite-20% magnesioferrite), and morphologies (equant, elongated, euhedral to subhedral) as magnetites synthesized by Golden et al. (2001) or magnetites grown naturally by MV1 magnetotactic bacteria, and as the magnetites in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001. Fritz et al. (2005) previously concluded that ALH84001 experienced approx. 32 GPa pressure and a resultant thermal pulse of approx. 100 - 110 C. However, ALH84001 contains evidence of local temperature excursions high enough to 1 melt feldspar, pyroxene, and a silica-rich phase. This 49 GPa experiment demonstrates that magnetite can be produced by the shock decomposition of siderite as a result of local heating to greater than 470 C. Therefore, magnetite in the rims of carbonates in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 could be a product of shock devolatilization of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27..216D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27..216D"><span>LEW 88516: A <span class="hlt">Meteorite</span> Compositionally Close to the "<span class="hlt">Martian</span> Mantle"</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dreibus, G.; Jochum, K. H.; Palme, H.; Spettel, B.; Wlotzka, F.; Wanke, H.</p> <p>1992-07-01</p> <p>Several samples from a total of 250 mg of the recently discovered Antarctic shergottite LEW 88516 were analysed for major and trace elements by neutron activation techniques, SSMS, and a carbon-sulfur analyser. Results are presented in Table 1, together with data on ALHA 77005 (Wanke et al., 1976). This and earlier results (Boynton et al., 1992; Lindstrom et al.,1992) show the close compositional similarity of Lew 88516 to ALHA 77005. A major difference between the two shergottites is the much lower iodine content of the ALHA 77005 <span class="hlt">meteorite</span>. The absence of similar variations in Br and Cl confirms earlier suggestions of an Antarctic source for the I excess. In a Mg/Si vs. Al/Si diagram (Fig. 1) the LEW 88516 <span class="hlt">meteorite</span> plots at the intersection of a Shergotty parent (SPB) body fractionation trend and a line connecting enstatite chondrites and CM chondrites. The position of LEW 88516 and also of ALHA 77005 in the vicinity of ordinary chondrites is indicative of their relatively primitive composition. Lithophile trace elements show some enhancement of Sc and V over heavy REE and depletion of light REE, suggesting either a residual character for the two <span class="hlt">meteorites</span> or assimilation of a cumulate phase during their formation. Comparatively high Ni and Co also reflect the more mafic character of the two <span class="hlt">meteorites</span>. The present analysis and the earlier data on ALHA 77005 unambiguously demonstrate the presence of Ir in an abundance range typical for the terrestrial upper mantle. A similar Ir level was found in Chassigny, but the more fractionated Shergotty has 100 times lower Ir contents. The presence of Ir in the <span class="hlt">martian</span> mantle samples may be the result of sulfide-silicate equilibration. The sulfides in Lew 88516 are small pyrrhotite grains (5-30 micron, 52 atom% S) and occur often together with ilmenite, at grain boundaries of the major silicate minerals. Sulfides contain an average of 1.8% Ni. However, the major fraction of Ni must reside in oxides and/or silicates as the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040060016&hterms=Planets+Their+moons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThe%2BPlanets%2BTheir%2Bmoons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040060016&hterms=Planets+Their+moons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThe%2BPlanets%2BTheir%2Bmoons"><span>Lunar and Planetary Science XXXV: <span class="hlt">Meteorites</span> to and from the Moon and Mars: My Planet or Yours?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The titles in this section include: 1) <span class="hlt">Meteorites</span> from Mars - Constraints from Numerical Modeling; 2) Iron Oxidation Products in <span class="hlt">Martian</span> Ordinary Chondrite Finds as Possible Indicators of Liquid Water Exposure at Mars Exploration Rover Landings Sites; 3) <span class="hlt">Meteorites</span> on Mars; 4) Sulfide Stability of Planetary Basalts; 5) Exposure and Terrestrial Histories of New Lunar and <span class="hlt">Martian</span> <span class="hlt">Meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70026875','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70026875"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 88, 2004 July</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Russell, S.S.; Folco, L.; Grady, M.M.; Zolensky, M.E.; Jones, R.; Righter, K.; Zipfel, J.; Grossman, J.N.</p> <p>2004-01-01</p> <p>The <span class="hlt">Meteoritical</span> Bulletin No. 88 lists information for 1610 newly classified <span class="hlt">meteorites</span>, comprising 753 from Antarctica, 302 from Africa, 505 from Asia (495 of which are from Oman), 40 from North America, 5 from South America, 4 from Europe, and 1 of unknown origin. Information is provided for 9 falls (Alby sur Che??ran, Al Zarnkh, Devgaon, Kamioka, Kendrapara, Maromandia, New Orleans, Sivas, and Villalbeto de la Pen??a). Noteworthy specimens include a eucrite fall (Alby sur Che??ran), 6 <span class="hlt">martian</span> <span class="hlt">meteorites</span>, 13 lunar <span class="hlt">meteorites</span>, and 12 irons including one weighing 3 metric ions (Dronino). ?? <span class="hlt">Meteoritical</span> Society, 2004.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=14668','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=14668"><span>Pre-Global Surveyor evidence for <span class="hlt">Martian</span> ground water</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Donahue, Thomas M.</p> <p>2001-01-01</p> <p>A time-dependent theory for the evolution of water on Mars is presented. Using this theory and invoking a large number of observational constraints, I argue that these constraints require that a large reservoir of water exists in the <span class="hlt">Martian</span> crust at depths shallow enough to interact strongly with the atmosphere. The constraints include the abundance of atmospheric water vapor, escape fluxes of hydrogen and deuterium, D/H ratios in the atmosphere and in hydrous minerals found in one <span class="hlt">Martian</span> <span class="hlt">meteorite</span>, alteration of minerals in other <span class="hlt">meteorites</span>, and fluvial features on the <span class="hlt">Martian</span> surface. These results are consonant with visual evidence for recent groundwater seepage obtained by the Mars Global Surveyor satellite. PMID:11158555</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.210....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.210....1B"><span>The role of sulfides in the fractionation of highly siderophile and chalcophile elements during the formation of <span class="hlt">martian</span> shergottite <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baumgartner, Raphael J.; Fiorentini, Marco L.; Lorand, Jean-Pierre; Baratoux, David; Zaccarini, Federica; Ferrière, Ludovic; Prašek, Marko K.; Sener, Kerim</p> <p>2017-08-01</p> <p>The shergottite <span class="hlt">meteorites</span> are ultramafic to mafic igneous rocks whose parental magmas formed from partial melting of the <span class="hlt">martian</span> mantle. This <span class="hlt">study</span> reports in-situ laser ablation inductively coupled plasma mass spectrometry analyses for siderophile and chalcophile major and trace elements (i.e., Co, Ni, Cu, As, Se, Ag, Sb, Te, Pb, Bi, and the highly siderophile platinum-group elements, PGE: Os, Ir, Ru, Rh, Pt and Pd) of magmatic Fe-Ni-Cu sulfide assemblages from four shergottite <span class="hlt">meteorites</span>. They include three geochemically similar incompatible trace element- (ITE-) depleted olivine-phyric shergottites (Yamato-980459, Dar al Gani 476 and Dhofar 019) that presumably formed from similar mantle and magma sources, and one distinctively ITE-enriched basaltic shergottite (Zagami). The sulfides in the shergottites have been variably modified by alteration on Earth and Mars, as well as by impact shock-shock related melting/volatilization during <span class="hlt">meteorite</span> ejection. However, they inherit and retain their magmatic PGE signatures. The CI chondrite-normalized PGE concentration patterns of sulfides reproduce the whole-rock signatures determined in previous <span class="hlt">studies</span>. These similarities indicate that sulfides exerted a major control on the PGE during shergottite petrogenesis. However, depletions of Pt (and Ir) in sulfide relative to the other PGE suggest that additional phases such discrete Pt-Fe-Ir alloys have played an important role in the concentration of these elements. These alloys are expected to have enhanced stability in reduced and FeO-rich shergottite magmas, and could be a common feature in <span class="hlt">martian</span> igneous systems. A Pt-rich PGM was found to occur in a sulfide assemblage in Dhofar 019. However, its origin may be related to impact shock-related sulfide melting and volatilisation during <span class="hlt">meteorite</span> ejection. In the ITE-depleted olivine-phyric shergottites, positive relationships exist between petrogenetic indicators (e.g., whole-rock Mg-number) and most moderately to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P23E..07F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P23E..07F"><span>Continued Evidence for Input of Chlorine into the <span class="hlt">Martian</span> Crust from Degassing of Chlorine-Rich <span class="hlt">Martian</span> Magmas with Implications for Potential Habitability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Filiberto, J.; Gross, J.</p> <p>2014-12-01</p> <p>The chlorine-concentration (or salinity) of a fluid affects the potential for that fluid to be a habitable environment, with most known terrestrial organisms preferring low salinity fluids [1, 2]. The <span class="hlt">Martian</span> crust (as analyzed by the Gamma Ray Spectrometer) is chlorine-rich with up to 0.8 wt% Cl; while the MER rovers Spirit and Opportunity as well as MSL Curiosity have analyzed rocks with even higher chlorine concentrations [e.g., 3]. This suggests that any potential fluid flowing through the crust would have high chlorine concentrations and therefore high salinity. Here we investigate the bulk and mineral chemistry of the SNC <span class="hlt">meteorites</span> to constrain the pre-eruptive chlorine concentrations of <span class="hlt">Martian</span> magmas as the potential source of chlorine in the <span class="hlt">Martian</span> crust. Bulk SNC <span class="hlt">meteorites</span> have Cl concentrations similar to terrestrial Mid Ocean Ridge Basalts which would suggest a Cl content of the <span class="hlt">Martian</span> interior similar to that of the Earth [4]. However, based on Cl/La ratios, the <span class="hlt">Martian</span> interior actually has 2-3 times more Cl than the Earth [5]. This is also reflected in the composition of Cl-rich minerals within the SNC <span class="hlt">meteorites</span> [5, 6] and suggests that the pre-eruptive parental magmas to the SNC <span class="hlt">meteorites</span> were Cl-rich. Eruption and degassing of such Cl-rich magmas would have delivered Cl to the <span class="hlt">Martian</span> crust, thereby increasing the salinity of any fluids within the crust. [1] Rothschild L.J. and R.L. Mancinelli (2001) Nature. 409: 1092-1101. [2] Sharp Z.D. and D.S. Draper (2013) EPSL. 369-370: 71-77. [3] Taylor G.J. et al. (2010) GRL. 37: L12204. [4]. Burgess R. et al (2013) GCA 77: 793. [5] Filiberto J. and A.H. Treiman (2009) Geology. 37: 1087-1090. [6] McCubbin F.M. et al. (2013) MaPS. 48: 819-853.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042098&hterms=oxygen+planets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doxygen%2Bplanets','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042098&hterms=oxygen+planets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doxygen%2Bplanets"><span>A model composition for Mars derived from the oxygen isotopic ratios of <span class="hlt">martian</span>/SNC <span class="hlt">meteorites</span>. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delaney, J. S.</p> <p>1994-01-01</p> <p>Oxygen is the most abundant element in most <span class="hlt">meteorites</span>, yet the ratios of its isotopes are seldom used to constrain the compositional history of achondrites. The two major achondrite groups have O isotope signatures that differ from any plausible chondritic precursors and lie between the ordinary and carbonaceous chondrite domains. If the assumption is made that the present global sampling of chondritic <span class="hlt">meteorites</span> reflects the variability of O reservoirs at the time of planetessimal/planet aggregation in the early nebula, then the O in these groups must reflect mixing between known chondritic reservoirs. This approach, in combination with constraints based on Fe-Mn-Mg systematics, has been used previously to model the composition of the basaltic achondrite parent body (BAP) and provides a model precursor composition that is generally consistent with previous eucrite parent body (EPB) estimates. The same approach is applied to Mars exploiting the assumption that the SNC and related <span class="hlt">meteorites</span> sample the <span class="hlt">martian</span> lithosphere. Model planet and planetesimal compositions can be derived by mixing of known chondritic components using O isotope ratios as the fundamental compositional constraint. The major- and minor-element composition for Mars derived here and that derived previously for the basaltic achondrite parent body are, in many respects, compatible with model compositions generated using completely independent constraints. The role of volatile elements and alkalis in particular remains a major difficulty in applying such models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P51H..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P51H..06B"><span>Evolution of the <span class="hlt">martian</span> mantle as recorded by igneous rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balta, J. B.; McSween, H. Y.</p> <p>2013-12-01</p> <p><span class="hlt">Martian</span> igneous rocks provide our best window into the current state of the <span class="hlt">martian</span> mantle and its evolution after accretion and differentiation. Currently, those rocks have been examined in situ by rovers, characterized in general from orbiting spacecraft, and analyzed in terrestrial laboratories when found as <span class="hlt">meteorites</span>. However, these data have the potential to bias our understanding of <span class="hlt">martian</span> magmatism, as most of the available <span class="hlt">meteorites</span> and rover-analyzed rocks come from the Amazonian (<2 Ga) and Hesperian (~3.65 Ga) periods respectively, while igneous rocks from the Noachian (>3.8 Ga) have only been examined by orbiters and as the unique <span class="hlt">meteorite</span> ALH 84001. After initial differentiation, the main planetary-scale changes in the structure of Mars which impact igneous compositions are cooling of the planet and thickening of the crust with time. As the shergottite <span class="hlt">meteorites</span> give ages <500 Ma1, they might be expected to represent thick-crust, recent volcanism. Using spacecraft measurements of volcanic compositions and whole rock compositions of <span class="hlt">meteorites</span>, we demonstrate that the shergottite <span class="hlt">meteorites</span> do not match the composition of the igneous rocks composing the young volcanoes on Mars, particularly in their silica content, and no crystallization or crustal contamination trend reproduces the volcanoes from a shergottite-like parent magma. However, we show that the shergottite magmas do resemble older <span class="hlt">martian</span> rocks in composition and mineralogy. The Noachian-aged <span class="hlt">meteorite</span> ALH 84001 has similar radiogenic-element signatures to the shergottites and may derive from a similar mantle source despite the age difference2. Thus, shergottite-like magmas may represent melting of mantle sources that were much more abundant early in <span class="hlt">martian</span> history. We propose that the shergottites represent the melting products of an originally-hydrous <span class="hlt">martian</span> mantle, containing at least several hundred ppm H2O. Dissolved water can increase the silica content of magmas and thus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51..663S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..663S"><span>Ni/S/Cl systematics and the origin of impact-melt glasses in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Elephant Moraine 79001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schrader, Christian M.; Cohen, Barbara A.; Donovan, John J.; Vicenzi, Edward P.</p> <p>2016-04-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> Elephant Moraine A79001 (EET 79001) has received considerable attention for the unusual composition of its shock melt glass, particularly its enrichment in sulfur relative to the host shergottite. It has been hypothesized that <span class="hlt">Martian</span> regolith was incorporated into the melt or, conversely, that the S-enrichment stems from preferential melting of sulfide minerals in the host rock during shock. We present results from an electron microprobe <span class="hlt">study</span> of EET 79001 including robust measurements of major and trace elements in the shock melt glass (S, Cl, Ni, Co, V, and Sc) and minerals in the host rock (Ni, Co, and V). We find that both S and major element abundances can be reconciled with previous hypotheses of regolith incorporation and/or excess sulfide melt. However, trace element characteristics of the shock melt glass, particularly Ni and Cl abundances relative to S, cannot be explained either by the incorporation of regolith or sulfide minerals. We therefore propose an alternative hypothesis whereby, prior to shock melting, portions of EET 79001 experienced acid-sulfate leaching of the mesostasis, possibly groundmass feldspar, and olivine, producing Al-sulfates that were later incorporated into the shock melt, which then quenched to glass. Such activity in the <span class="hlt">Martian</span> near-surface is supported by observations from the Mars Exploration Rovers and laboratory experiments. Our preimpact alteration model, accompanied by the preferential survival of olivine and excess melting of feldspar during impact, explains the measured trace element abundances better than either the regolith incorporation or excess sulfide melting hypothesis does.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.P31A2028A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.P31A2028A"><span>Craters of the Moon National Monument as a Terrestrial Mars Analog: Examination of Mars Analog Phosphate Minerals, Phosphate Mineral Shock-Recovery Experiments, and Phosphate Minerals in <span class="hlt">Martian</span> <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adcock, C. T.; Hausrath, E.; Tschauner, O. D.; Udry, A.</p> <p>2015-12-01</p> <p><span class="hlt">Martian</span> analogs, <span class="hlt">meteorites</span>, and data from unmanned missions have greatly advanced our understanding of <span class="hlt">martian</span> surface and near-surface processes. In particular, terrestrial analogs allow us to investigate Mars-relevant geomorphic, geochemical, petrogenetic, and hydrologic processes, as well as potential habitability. Craters of the Moon National Monument (COTM), located on the Snake River Plain of Idaho in the United States, represents a valuable phosphate-rich Mars analog, allowing us to examine phosphate minerals, important as volatile indicators and potential nutrient providers, under Mars-relevant conditions. COTM is in an arid to semi-arid environment with sub-freezing lows much of the year. Though wetter than present day Mars (24 - 38 cm MAP) [1], COTM may be analogous to a warmer and wetter past Mars. The area is also the locale of numerous lava flows, a number of which have been dated (2,000 to >18,000 y.b.p.) [2]. The flows have experienced weathering over time and thus represent a chronosequence with application to weathering on Mars. The flows have unusual chemistries, including high average phosphate contents (P2O5 1.75 wt% n=23 flows) [2], close to those in rocks analyzed at Gusev Crater, Mars (P2O5 1.79 wt% n=18 rocks) [3]. The Mars-like high phosphorus contents indicate a potential petrogenetic link and are also of astrobiological interest. Further, current samples of Mars phosphate minerals are limited to <span class="hlt">meteorites</span> which have been heavily shocked - COTM represents a potential pre-shock and geochemical analog to Mars. We investigated weathering on COTM basalts and shock effects on Mars-relevant phosphate minerals. We used scanning electron microscopy, backscattered electron imagery, and X-Ray analysis/mapping to investigate COTM thin sections. Synchrotron diffraction was used to investigate <span class="hlt">martian</span> <span class="hlt">meteorites</span> and laboratory shocked Mars/COTM-relevant minerals for comparison. Results of our investigations indicate porosity development correlates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49E...1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49E...1R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 100, 2014 June</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruzicka, Alex; Grossman, Jeffrey N.; Garvie, Laurence</p> <p>2014-08-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 100 contains 1943 <span class="hlt">meteorites</span> including 8 falls (Boumdeid [2011], Huaxi, Košice, Silistra, Sołtmany, Sutter's Mill, Thika, Tissint), with 1575 ordinary chondrites, 139 carbonaceous chondrites, 96 HED achondrites, 25 ureilites, 18 primitive achondrites, 17 iron <span class="hlt">meteorites</span>, 15 enstatite chondrites, 11 lunar <span class="hlt">meteorites</span>, 10 mesosiderites, 10 ungrouped achondrites, 8 pallasites, 8 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 6 Rumuruti chondrites, 3 enstatite achondrites, and 2 angrites, and with 937 from Antarctica, 592 from Africa, 230 from Asia, 95 from South America, 44 from North America, 36 from Oceania, 6 from Europe, and 1 from an unknown location. This will be the last Bulletin published in the current format. Information about approved <span class="hlt">meteorites</span> can be obtained from the <span class="hlt">Meteoritical</span> Bulletin Database (MBD) available online at http://www.lpi.usra.edu/meteor/</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P51E3990A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P51E3990A"><span>Thirteen Iron <span class="hlt">Meteorites</span> Found at Gale Crater, Meridiani Planum, and Gusev Crater — Exogenic Witnesses to Weathering Processes Near the <span class="hlt">Martian</span> Equator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashley, J.</p> <p>2014-12-01</p> <p>At least 20 <span class="hlt">meteorites</span> and <span class="hlt">meteorite</span> candidates have now been found by science teams at three Mars rover landing sites, all within 15 degrees of the <span class="hlt">martian</span> equator. Thirteen of these are iron <span class="hlt">meteorites</span>, comprising 65% of the population — an order of magnitude greater abundance than found among witnessed iron falls in Earth-based collections (~6%). Chondritic <span class="hlt">meteorites</span>, which comprise some 86% of Earth-based falls, are conspicuously absent from the Mars inventory. The reasons for this disproportion may involve a) post-fall environmental resistance differences favoring iron survivability; b) fragmentation from impact shock (and possibly internal weathering stresses associated with oxide production in desert environments [1]); combined with c) selection biases arising from residual chondritic fragments appearing less conspicuous. Impact features along rover traverses often show evidence of dark materials likely to be impactor fragments [e.g., 2], which could represent the missing chondritic fraction. The reactivity of reduced (metallic) iron to aqueous alteration, combined with the near equatorial and widely distributed locations of these rocks, makes them particularly useful to the assessment of climate models arguing for geologically recent ice at the <span class="hlt">martian</span> equator. Exposure histories involving alternating wind/water cycles are imprinted on several Meridiani irons, for example [3]. Evidence for oxide coating removal demonstrates the current epoch to be one of coating destruction, not production, showing that atmospheric exposure alone is insufficient to produce the coating. Cavernous weathering is likely associated with acidic corrosion, while evidence of aeolian scouring is found in Widmanstätten patterns, sharp-crested scallops, regmaglypt enlargement, and abundant pitting. Further <span class="hlt">study</span> of these features could help constrain wind direction and velocity during epochs of sculpting [e.g., 4], and assist in exposure age estimation. References: [1] Ashley J. W</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840015441&hterms=meteorite+weathered&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmeteorite%2Bweathered','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840015441&hterms=meteorite+weathered&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmeteorite%2Bweathered"><span>Weathered stony <span class="hlt">meteorites</span> from Victoria Land, Antarctica, as possible guides to rock weathering on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, J. L.</p> <p>1984-01-01</p> <p>Parallel <span class="hlt">studies</span> of <span class="hlt">Martian</span> geomorphic features and their analogs on Earth continue to be fruitful in deciphering the geologic history of Mars. In the context of rock weathering, the Earth-analog approach is admirably served by the <span class="hlt">study</span> of <span class="hlt">meteorites</span> recovered from ice sheets in Antarctica. The weathering environment of Victoria Land possesses several Mars-like attributes. Four of the five Antarctic <span class="hlt">meteorites</span> being <span class="hlt">studied</span> contain rust and EETA79005 further possesses a conspicuous, dark, weathering rind on one side. Secondary minerals (rust and salts) occur both on the surfaces and interiors of some of the samples and textural evidence indicates that such secondary mineralization contributed to physical weathering (by salt riving) of the rocks. Several different rust morphologies occur and emphasis is being placed on identifying the phase compositions of the various rust occurrances. A thorough understanding of terrestrial weathering features of the <span class="hlt">meteorites</span> is a prerequisite for identifying possible <span class="hlt">Martian</span> weathering features (if such features exist) that might be postulated to occur in some <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003506','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003506"><span>Two Distinct Secondary Carbonate Species in OC <span class="hlt">Meteorites</span> from Antarctica are Possible Analogs for Mars Carbonates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evans, M. E.; Niles, P. B.; Locke, D. R.; Chapman, P.</p> <p>2016-01-01</p> <p><span class="hlt">Meteorites</span> falling in Antarctica are captured in ice and stored until the glacial flow transports them to the surface where they can be collected. Prior to collection, they are altered during interactions between the rock, the cryosphere, and the hydrosphere. The purpose of this <span class="hlt">study</span> is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from Ordinary Chondrite (OC) <span class="hlt">meteorites</span> collected in Antarctica. This facilitates better understanding of terrestrial weathering in <span class="hlt">martian</span> <span class="hlt">meteorites</span> as well as mechanisms for weathering in cold, arid environments as an analog to Mars. OC samples were selected for analysis based upon size and collection proximity to known <span class="hlt">martian</span> <span class="hlt">meteorites</span>. They were also selected based on petrologic type (3+) such that they were likely to be carbonate-free before falling to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120008253','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120008253"><span>Strategies for Distinguishing Abiotic Chemistry from <span class="hlt">Martian</span> Biochemistry in Samples Returned from Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glavin, D. P.; Burton, A. S.; Callahan, M. P.; Elsila, J. E.; Stern, J. C.; Dworkin, J. P.</p> <p>2012-01-01</p> <p>A key goal in the search for evidence of extinct or extant life on Mars will be the identification of chemical biosignatures including complex organic molecules common to all life on Earth. These include amino acids, the monomer building blocks of proteins and enzymes, and nucleobases, which serve as the structural basis of information storage in DNA and RNA. However, many of these organic compounds can also be formed abiotically as demonstrated by their prevalence in carbonaceous <span class="hlt">meteorites</span> [1]. Therefore, an important challenge in the search for evidence of life on Mars will be distinguishing between abiotic chemistry of either <span class="hlt">meteoritic</span> or <span class="hlt">martian</span> origin from any chemical biosignatures from an extinct or extant <span class="hlt">martian</span> biota. Although current robotic missions to Mars, including the 2011 Mars Science Laboratory (MSL) and the planned 2018 ExoMars rovers, will have the analytical capability needed to identify these key classes of organic molecules if present [2,3], return of a diverse suite of <span class="hlt">martian</span> samples to Earth would allow for much more intensive laboratory <span class="hlt">studies</span> using a broad array of extraction protocols and state-of-theart analytical techniques for bulk and spatially resolved characterization, molecular detection, and isotopic and enantiomeric compositions that may be required for unambiguous confirmation of <span class="hlt">martian</span> life. Here we will describe current state-of-the-art laboratory analytical techniques that have been used to characterize the abundance and distribution of amino acids and nucleobases in <span class="hlt">meteorites</span>, Apollo samples, and comet- exposed materials returned by the Stardust mission with an emphasis on their molecular characteristics that can be used to distinguish abiotic chemistry from biochemistry as we know it. The <span class="hlt">study</span> of organic compounds in carbonaceous <span class="hlt">meteorites</span> is highly relevant to Mars sample return analysis, since exogenous organic matter should have accumulated in the <span class="hlt">martian</span> regolith over the last several billion years and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RMxAC..44..133V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RMxAC..44..133V"><span>The SNC <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, M. E.</p> <p>2014-10-01</p> <p>The SNC (Shergotty-Nakhla-Chassigny) group, are achondritic <span class="hlt">meteorites</span>. Of all SNC <span class="hlt">meteorites</span> recognized up to date, shergottites are the most abundant group. The petrographic <span class="hlt">study</span> of Shergotty began several years ago when Tschermak, (1872) identified this rock as an extraterrestrial basalt. Oxygen isotopes in SNC <span class="hlt">meteorites</span> indicate that these rocks are from a single planetary body (Clayton and Mayeda, 1983). Because the abundance patterns of rare gases trapped in glasses from shock melts (e.g., Pepin, 1985) turned out to be very similar to the <span class="hlt">Martian</span> atmosphere (as analyzed by the Viking landers, Owen, 1976), the SNC <span class="hlt">meteorites</span> are believed to originate from Mars (e.g. McSween, 1994). Possibly, they were ejected from the <span class="hlt">Martian</span> surface either in a giant impact or in several impact events (Meyer 2006). Although there is a broad consensus for nakhlites and chassignites being -1.3Ga old, the age of the shergottites is a matter of ongoing debates. Different lines of evidences indicate that these rocks are young (180Ma and 330-475Ma), or very old (> 4Ga). However, the young age in shergottites could be the result of a resetting of these chronometers by either strong impacts or fluid percolation on these rocks (Bouvier et al., 2005-2009). Thus, it is important to check the presence of secondary processes, such as re-equilibration or pressure-induce metamorphism (El Goresy et al., 2013) that can produce major changes in compositions and obscure the primary information. A useful tool, that is used to reconstruct the condition prevailing during the formation of early phases or the secondary processes to which the rock was exposed, is the <span class="hlt">study</span> of glass-bearing inclusions hosted by different mineral phases. I will discuss the identification of extreme compositional variations in many of these inclusions (Varela et al. 2007-2013) that constrain the assumption that these objects are the result of closed-system crystallization. The question then arises whether these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...856L..36H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...856L..36H"><span>Implantation of <span class="hlt">Martian</span> Materials in the Inner Solar System by a Mega Impact on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hyodo, Ryuki; Genda, Hidenori</p> <p>2018-04-01</p> <p>Observations and <span class="hlt">meteorites</span> indicate that the <span class="hlt">Martian</span> materials are enigmatically distributed within the inner solar system. A mega impact on Mars creating a <span class="hlt">Martian</span> hemispheric dichotomy and the <span class="hlt">Martian</span> moons can potentially eject <span class="hlt">Martian</span> materials. A recent work has shown that the mega-impact-induced debris is potentially captured as the <span class="hlt">Martian</span> Trojans and implanted in the asteroid belt. However, the amount, distribution, and composition of the debris has not been <span class="hlt">studied</span>. Here, using hydrodynamic simulations, we report that a large amount of debris (∼1% of Mars’ mass), including <span class="hlt">Martian</span> crust/mantle and the impactor’s materials (∼20:80), are ejected by a dichotomy-forming impact, and distributed between ∼0.5–3.0 au. Our result indicates that unmelted <span class="hlt">Martian</span> mantle debris (∼0.02% of Mars’ mass) can be the source of <span class="hlt">Martian</span> Trojans, olivine-rich asteroids in the Hungarian region and the main asteroid belt, and some even hit the early Earth. The evidence of a mega impact on Mars would be recorded as a spike of 40Ar–39Ar ages in <span class="hlt">meteorites</span>. A mega impact can naturally implant <span class="hlt">Martian</span> mantle materials within the inner solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023756','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023756"><span>The <span class="hlt">Meteoritical</span> Bulletin, no. 85, 2001 September</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grossman, J.N.; Zipfel, J.</p> <p>2001-01-01</p> <p><span class="hlt">Meteoritical</span> Bulletin No. 85 lists information for 1376 newly classified <span class="hlt">meteorites</span>, comprising 658 from Antarctica, 409 from Africa, 265 from Asia (262 of which are from Oman), 31 from North America, 7 from South America, 3 from Australia, and 3 from Europe. Information is provided for 11 falls (Dergaon, Dunbogan, Gujba, Independence, Itqiy, Mora??vka, Oued el Hadjar, Sayama, Sologne, Valera, and Worden). Noteworthy non-Antarctic specimens include 5 <span class="hlt">martian</span> <span class="hlt">meteorites</span> (Dar al Gani 876, Northwest Africa 480 and 817, and Sayh al Uhaymir 051 and 094); 6 lunar <span class="hlt">meteorites</span> (Dhofar 081, 280, and 287, and Northwest Africa 479, 482, and 773); an ungrouped enstatite-rich <span class="hlt">meteorite</span> (Itqiy); a Bencubbin-like <span class="hlt">meteorite</span> (Gujba); 9 iron <span class="hlt">meteorites</span>; and a wide variety of other interesting stony <span class="hlt">meteorites</span>, including CH, CK, CM, CO, CR, CV, R, enstatite, and unequilibrated ordinary chondrites, primitive achondrites, HED achondrites, and ureilites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001696','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001696"><span>Nitrogen-Bearing, Indigenous Carbonaceous Matter in the Nakhla Mars <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas-Keprta, K. L.; Clemett, S. J.; Messenger, S.; Rahman, Z.; Gibson, E. K.; Wentworth, S. J.; McKay, D. S.</p> <p>2017-01-01</p> <p>We report the identification of discrete assemblages of nitrogen (N)-rich organic matter entrapped within interior fracture surfaces of the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Nakhla. Based on context, composition and isotopic measurements this organic matter is of demonstrably <span class="hlt">martian</span> origin. The presence of N-bearing organic species is of considerable importance to the habitable potential and chemical evolution of the <span class="hlt">martian</span> regolith.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010574','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010574"><span>New <span class="hlt">Meteorite</span> Type NWA 8159 Augite Basalt: Specimen from a Previously Unsampled Location on Mars?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Agee, C. B.; Muttik, N.; Ziegler, K.; Walton, E. L.; Herd, C. D. K.; McCubbin, F. M.; Santos, A. R.; Simon, J. I.; Peters, T. J.; Tappa, M. J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20140010574'); toggleEditAbsImage('author_20140010574_show'); toggleEditAbsImage('author_20140010574_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20140010574_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20140010574_hide"></p> <p>2014-01-01</p> <p>Up until recently the orthopyroxenite ALH 84001, a singleton <span class="hlt">martian</span> <span class="hlt">meteorite</span> type, was the only sample that did not fit within the common SNC types. However with the discovery of the unique basaltic breccia NWA 7034 pairing group [1] the diversity of <span class="hlt">martian</span> <span class="hlt">meteorites</span> beyond SNC types was expanded, and now with Northwest Africa (NWA) 8159, and its possible pairing NWA 7635 [2], the diversiy is expanded further with a third unique non-SNC <span class="hlt">meteorite</span> type. The existence of <span class="hlt">meteorite</span> types beyond the narrow range seen in SNCs is what might be expected from a random cratering sampling of a geologically long-lived and complex planet such as Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAfES.134..644K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAfES.134..644K"><span><span class="hlt">Meteorite</span> falls in Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khiri, Fouad; Ibhi, Abderrahmane; Saint-Gerant, Thierry; Medjkane, Mohand; Ouknine, Lahcen</p> <p>2017-10-01</p> <p>The <span class="hlt">study</span> of <span class="hlt">meteorites</span> provides insight into the earliest history of our solar system. From 1800, about the year <span class="hlt">meteorites</span> were first recognized as objects falling from the sky, until December 2014, 158 observed <span class="hlt">meteorite</span> falls were recorded in Africa. Their collected mass ranges from 1.4 g to 175 kg with the 1-10 kg cases predominant. The average rate of African falls is low with only one fall recovery per 1.35-year time interval (or 0.023 per year per million km2). This African collection is dominated by ordinary chondrites (78%) just like in the worldwide falls. The seventeen achondrites include three <span class="hlt">Martian</span> <span class="hlt">meteorite</span> falls (Nakhla of Egypt, Tissint of Morocco and Zagami of Nigeria). Observed Iron <span class="hlt">meteorite</span> falls are relatively rare and represent only 5%. The falls' rate in Africa is variable in time and in space. The number of falls continues to grow since 1860, 80% of which were recovered during the period between 1910 and 2014. Most of these documented <span class="hlt">meteorite</span> falls have been recovered from North-Western Africa, Eastern Africa and Southern Africa. They are concentrated in countries which have a large surface area and a large population with a uniform distribution. Other factors are also favorable for observing and collecting <span class="hlt">meteorite</span> falls across the African territory, such as: a genuine <span class="hlt">meteorite</span> education, a semi-arid to arid climate (clear sky throughout the year most of the time), croplands or sparse grasslands and possible access to the fall location with a low percentage of forest cover and dense road network.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011P%26SS...59..423P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011P%26SS...59..423P"><span>Decomposition of mineral absorption bands using nonlinear least squares curve fitting: Application to <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and CRISM data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parente, Mario; Makarewicz, Heather D.; Bishop, Janice L.</p> <p>2011-04-01</p> <p>This <span class="hlt">study</span> advances curve-fitting modeling of absorption bands of reflectance spectra and applies this new model to spectra of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> ALH 84001 and EETA 79001 and data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). This <span class="hlt">study</span> also details a recently introduced automated parameter initialization technique. We assess the performance of this automated procedure by comparing it to the currently available initialization method and perform a sensitivity analysis of the fit results to variation in initial guesses. We explore the issues related to the removal of the continuum, offer guidelines for continuum removal when modeling the absorptions and explore different continuum-removal techniques. We further evaluate the suitability of curve fitting techniques using Gaussians/Modified Gaussians to decompose spectra into individual end-member bands. We show that nonlinear least squares techniques such as the Levenberg-Marquardt algorithm achieve comparable results to the MGM model ( Sunshine and Pieters, 1993; Sunshine et al., 1990) for <span class="hlt">meteorite</span> spectra. Finally we use Gaussian modeling to fit CRISM spectra of pyroxene and olivine-rich terrains on Mars. Analysis of CRISM spectra of two regions show that the pyroxene-dominated rock spectra measured at Juventae Chasma were modeled well with low Ca pyroxene, while the pyroxene-rich spectra acquired at Libya Montes required both low-Ca and high-Ca pyroxene for a good fit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P33B..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P33B..01M"><span>Analyses from Near (<span class="hlt">Meteorites</span>) and Far (Spacecraft): Complementary Approaches to Planetary Geochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McSween, H. Y.</p> <p>2013-12-01</p> <p>Spacecraft missions have transformed planets from astronomical objects into geologic worlds, but geochemical remote sensing has limits. Considerably greater geologic insights are possible for a few bodies to which we can confidently assign <span class="hlt">meteorite</span> samples. Mars and asteroid 4 Vesta demonstrate the advances provided by coupling spacecraft remote sensing data and laboratory analyses of <span class="hlt">meteorites</span>. <span class="hlt">Martian</span> <span class="hlt">meteorites</span> sample at least 7 as-yet unidentified sites but are strongly biased towards young crystallization ages compared to <span class="hlt">Martian</span> surface ages. Geochemical comparison with generally older rocks analyzed by Mars rovers APXS reveals evolutionary differences [1] that might be explained by water or redox state. Trace elements and radiogenic isotopes, readily measured in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> but not yet possible by remote sensing, constrain the planet's volatile inventory, the chronology of magmatism, and the compositions of mantle source regions and the bulk planet [2]. The origin and geochemical cycling of water that orbiters indicate once sculpted Mars' geomorphology and now resides in the <span class="hlt">Martian</span> subsurface is revealed by measurements of stable isotopes and of apatite OH in <span class="hlt">meteorites</span>. Although sedimentary rocks are nearly absent from the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> collection, determining the processes that produced the regolith and the nature and source of organic matter on Mars are facilitated by comparing rover analyses of soils with <span class="hlt">meteorite</span> data. In a similar way, analyses of Vesta by the Dawn orbiting spacecraft [3] are leveraged by laboratory analyses of the howardite, eucrite, diogenite (HED) <span class="hlt">meteorites</span> [4]. Visible/near-infrared spectra of HEDs provide the calibration necessary for lithologic mapping of Vesta's surface, revealing an ancient eucrite crust, diogenite excavated from a huge crater, and a pervasive regolith of howardite. Gamma-ray and neutron data from Vesta are similarly interpreted by comparison with <span class="hlt">meteorite</span> elemental abundances. The unexpected</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V33D3135C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V33D3135C"><span>Significance of the cosmogenic argon correction in deciphering the 40Ar/39Ar ages of the Nakhlite (<span class="hlt">Martian</span>) <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cohen, B. E.; Cassata, W.; Mark, D. F.; Tomkinson, T.; Lee, M. R.; Smith, C. L.</p> <p>2015-12-01</p> <p>All <span class="hlt">meteorites</span> contain variable amounts of cosmogenic 38Ar and 36Ar produced during extraterrestrial exposure, and in order to calculate reliable 40Ar/39Ar ages this cosmogenic Ar must be removed from the total Ar budget. The amount of cosmogenic Ar has usually been calculated from the step-wise 38Ar/36Ar, minimum 36Ar/37Ar, or average 38Arcosmogenic/37Ar from the irradiated <span class="hlt">meteorite</span> fragment. However, if Cl is present in the <span class="hlt">meteorite</span>, then these values will be disturbed by Ar produced during laboratory neutron irradiation of Cl. Chlorine is likely to be a particular issue for the Nakhlite group of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, which can contain over 1000 ppm Cl [1]. An alternative method for the cosmogenic Ar correction uses the <span class="hlt">meteorite</span>'s exposure age as calculated from an un-irradiated fragment and step-wise production rates based on the measured Ca/K [2]. This calculation is independent of the Cl concentration. We applied this correction method to seven Nakhlites, analyzed in duplicate or triplicate. Selected samples were analyzed at both Lawrence Livermore National Laboratory and SUERC to ensure inter-laboratory reproducibility. We find that the cosmogenic argon correction of [2] has a significant influence on the ages calculated for individual steps, particularly for those at lower temperatures (i.e., differences of several tens of million years for some steps). The lower-temperature steps are more influenced by the alternate cosmogenic correction method of [2], as these analyses yielded higher concentrations of Cl-derived 38Ar. As a result, the Nakhlite data corrected using [2] yields step-heating spectra that are flat or nearly so across >70% of the release spectra (in contrast to downward-stepping spectra often reported for Nakhlite samples), allowing for the calculation of precise emplacement ages for these <span class="hlt">meteorites</span>. [1] Cartwright J. A. et al. (2013) GCA, 105, 255-293. [2] Cassata W. S., and Borg L. E. (2015) 46th LPSC, Abstract #2742.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRE..113.6004P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRE..113.6004P"><span><span class="hlt">Martian</span> dunite NWA 2737: Integrated spectroscopic analyses of brown olivine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pieters, Carle M.; Klima, Rachel L.; Hiroi, Takahiro; Dyar, M. Darby; Lane, Melissa D.; Treiman, Allan H.; Noble, Sarah K.; Sunshine, Jessica M.; Bishop, Janice L.</p> <p>2008-06-01</p> <p>A second <span class="hlt">Martian</span> <span class="hlt">meteorite</span> has been identified that is composed primarily of heavily shocked dunite, Northwest Africa (NWA) 2737. This <span class="hlt">meteorite</span> has several similarities to the Chassigny dunite cumulate, but the olivine is more Mg rich and, most notably, is very dark and visually brown. Carefully coordinated analyses of NWA 2737 whole-rock and olivine separates were undertaken using visible and near-infrared reflectance, midinfrared emission and reflectance, and Mössbauer spectroscopic <span class="hlt">studies</span> of the same samples along with detailed petrography, chemistry, scanning electron microscopy, and transmission electron microscopy analyses. Midinfrared spectra of this sample indicate that the olivine is fully crystalline and that its molecular structure remains intact. The unusual color and spectral properties that extend from the visible through the near-infrared part of the spectrum are shown to be due to nanophase metallic iron particles dispersed throughout the olivine during a major shock event on Mars. Although a minor amount of Fe3+ is present, it cannot account for the well-documented unusual optical properties of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> NWA 2737. Perhaps unique to the <span class="hlt">Martian</span> environment, this ``brown'' olivine exhibits spectral properties that can potentially be used to remotely explore the pressure-temperature history of surface geology as well as assess surface composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000113833&hterms=PDB&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPDB','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000113833&hterms=PDB&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPDB"><span>Isotope Geochemistry of Possible Terrestrial Analogue for <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mojzsis, Stephen J.</p> <p>2000-01-01</p> <p>We have <span class="hlt">studied</span> the microdomain oxygen and carbon isotopic compositions by SIMS of complex carbonate rosettes from spinel therzolite xenoliths, hosted by nepheline basanite, from the island of Spitsbergen (Norway). The Quaternary volcanic rocks containing the xenoliths erupted into a high Arctic environment and through relatively thick continental crust containing carbonate rocks. We have attempted to constrain the sources of the carbonates in these rocks by combined O-18/O-16 and C-13/C-12 ratio measurements in 25 micron diameter spots of the carbonate and compare them to previous work based primarily on trace-element distributions. The origin of these carbonates can be interpreted in terms of either contamination by carbonate country rock during ascent of the xenoliths in the host basalt, or more probably by hydrothermal processes after emplacement. The isotopic composition of these carbonates from a combined delta.18O(sub SMOW) and delta.13C(sub PDB) standpoint precludes a primary origin of these minerals from the mantle. Here a description is given of the analysis procedure, standardization of the carbonates, major element compositions of the carbonates measured by electron microprobe, and their correlated C and O isotope compositions as measured by ion microprobe. Since these carbonate rosettes may represent a terrestrial analogue to the carbonate "globules" found in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> ALH84001 interpretations for the origin of the features found in the Spitsbergen may be of interest in constraining the origin of these carbonate minerals on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011942','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011942"><span>Identification of new <span class="hlt">meteorite</span>, Mihonoseki (L), from broken fragments in Japan</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miura, Y.; Noma, Y.</p> <p>1993-01-01</p> <p>New <span class="hlt">meteorite</span> of Mihonoseki fallen in Shimane-ken was identified by fine broken pieces by using an energy-dispersive scanning electron microprobe analyzer. It shows fusion-crust (i.e. Fe-Si melt), <span class="hlt">meteoritic</span> minerals (kamacite, taenite, troilite, amorphous plagioclase etc.) and chrondrule with clear glassy rim. Mineralogical, and petrological data of several fine grains suggest that broken fragments of Mihonoseki are L3/4 chondritic <span class="hlt">meteorite</span> which is the first identification in a Japanese fallen <span class="hlt">meteorite</span>. The prompt identification method of <span class="hlt">meteorite</span>-fragments will be applied to the next lunar, <span class="hlt">Martian</span> and asteroid explorations, as well as <span class="hlt">meteorite</span> falls on the terrestrial surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70025811','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70025811"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 87, 2003 July</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Russell, S.S.; Zipfel, J.; Folco, L.; Jones, R.; Grady, M.M.; McCoy, T.; Grossman, J.N.</p> <p>2003-01-01</p> <p><span class="hlt">Meteoritical</span> Bulletin No. 87 lists information for 1898 newly classified <span class="hlt">meteorites</span>, comprising 1048 from Antarctica, 462 from Africa, 356 from Asia (355 of which are from Oman), 18 from North America, 5 from South America, 5 from Europe, and 3 from Australia. Information is provided for 10 falls (Beni M'hira, Elbert, Gasseltepaoua, Hiroshima, Kilabo, Neuschwanstein, Park Forest, Pe??, Pe??te??lkole??, and Thuathe). Two of these-Kilabo and Thuathe-fell on the same day. Orbital characteristics could be calculated for Neuschwanstein. Noteworthy specimens include 8 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> (5 from Sahara, 2 from Oman and 1 from Antarctica), 13 lunar <span class="hlt">meteorites</span> (all except one from Oman), 3 irons, 3 pallasites, and many carbonaceous chondrites and achondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012904','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012904"><span>Looking for a Source of Water in <span class="hlt">Martian</span> Basltic Breccia NWA 7034</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Muttik, N.; Agee, C. B.; McCubbin, F. M.; McCuttcheon, W. A.; Provencio, P. P.; Keller, L. P.; Santos, A. R..; Shearer, C. K.</p> <p>2014-01-01</p> <p>The recently described <span class="hlt">martian</span> <span class="hlt">meteorite</span> NWA 7034 has high water content compared to other SNC <span class="hlt">meteorites</span>. Deuterium to hydrogen isotope ratio measurements indicates that there are two distinct delta-D components in NWA 7034, a low temperature (150-500degC) light component around -100per mille and a high temperature (300-1000degC) heavy component around +300per mille. NWA 7034 contains iron-rich phases that are likely secondary aqueous alteration products. They are commonly found as spheroidal objects of various sizes that are often rich in Fe-Ti oxides and possibly iron hydroxides. Iron oxides and oxyhydroxides are very common in weathered rocks and soils on Earth and Mars and they are important components of terrestrial and <span class="hlt">Martian</span> dust. In NWA 7034 iron-rich phases are found throughout the fine-grained basaltic groundmass of the <span class="hlt">meteorite</span>. The total amount of <span class="hlt">martian</span> H2O in NWA 7034 is reported to be 6000 ppm, and in this <span class="hlt">study</span> we attempt to determine the phase distribution of this H2O by texturally describing and characterizing hydrous phases in NWA 7034, using Fourier transform infrared spectrometry (FTIR) and transmission electron microscopy (TEM).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008M%26PS...43..829T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008M%26PS...43..829T"><span>Petrology of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Northwest Africa 998</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treiman, Allan H.; Irving, Anthony J.</p> <p>2008-05-01</p> <p>Nakhlite Northwest Africa (NWA) 998 is an augite-rich cumulate igneous rock with mineral compositions and oxygen isotopic composition consistent with an origin on Mars. This 456-gram, partially fusion-crusted <span class="hlt">meteorite</span> consists of (by volume) ˜75% augite (core composition Wo39En39Fs22), ˜9% olivine (Fo35), ˜7% plagioclase (Ab61An35) as anhedra among augite and olivine, ˜3.5% low-calcium pyroxenes (pigeonite and orthopyroxene) replacing or forming overgrowths on olivine and augite, ˜1% titanomagnetite, and other phases including potassium feldspar, apatite, pyrrhotite, chalcopyrite, ilmenite, and fine-grained mesostasis material. Minor secondary alteration materials include "iddingsite" associated with olivine (probably <span class="hlt">Martian</span>), calcite crack fillings, and iron oxide/hydroxide staining (both probably terrestrial). Shock effects are limited to minor cataclasis and twinning in augite. In comparison to other nakhlites, NWA 998 contains more low-calcium pyroxenes and its plagioclase crystals are blockier. The large size of the intercumulus feldspars and the chemical homogeneity of the olivine imply relatively slow cooling and chemical equilibration in the late- and post-igneous history of this specimen, and mineral thermometers give subsolidus temperatures near 730 °C. Oxidation state was near that of the QFM buffer, from about QFM-2 in earliest crystallization to near QFM in late crystallization, and to about QFM + 1.5 in some magmatic inclusions. The replacement or overgrowth of olivine by pigeonite and orthopyroxene (with or without titanomagnetite), and the marginal replacement of augite by pigeonite, are interpreted to result from late-stage reactions with residual melts (consistent with experimental phase equilibrium relationships). Apatite is concentrated in planar zones separating apatite-free domains, which suggests that residual magma (rich in P and REE) was concentrated in planar (fracture?) zones and possibly migrated through them. Loss of late magma</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR23B2346S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR23B2346S"><span>Shock-Induced Phase Transitions in the <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Tissint: Mechanisms and Constraints on Shock Pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharp, T. G.; Hu, J.; Walton, E. L.</p> <p>2013-12-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorites</span> are important samples for understanding the origin and age of the <span class="hlt">Martian</span> crust. All of these samples have been shocked to some degree during their ejection from Mars or earlier. Tissint, a picritic shergottite, has many high-pressure phases that have been used to constrain shock conditions and suggest a deep crustal origin [1] and to argue for multiple impact events [2]. Here we investigate the products and mechanisms of various olivine transformation reactions. Olivine in and adjacent to shock-melt veins and pockets is transformed into high-pressure minerals. In the hottest parts of the sample, olivine dissociated into 50-nm crystals of magnesiowüstite intergrown with either a pyroxene-composition glass or with low-Ca clinopyroxene. In both cases, the olivine is inferred to have transformed to silicate perovskite + magnesiowüstite during shock with subsequent breakdown of the perovskite after pressure release. Olivine along the margins of shock veins transformed into ringwoodite. Polycrystalline ringwoodite formed at the olivine-melt interface wheras coherent ringwoodite lamellae formed farther from the melt. These ringwoodite lamellae have the same topotaxial relationship to olivine as seen in static high-pressure experiments [3] and shocked <span class="hlt">meteorites</span> [4]: (100)Ol || {111}Rw and [011]Ol || <110>Rw. The various olivine reactions can be explained by a single shock to above 24 GPa where only the highest temperatures allowed the dissociation of olivine to silicate-perovskite plus magnesiowüstite. The silicate perovskite in the melt pocket transformed to pyroxene because the melt pocket remained very hot after pressure release. At lower temperatures, the kinetically easier polymorphic transformation of olivine to metastable ringwoodite occurred. At the lowest temperatures, this reaction was facilitated by nucleation of ringwoodite lamellae on stacking faults in olivine. The variation in assemblages that we see are consistent with a single shock</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LPICo2071.6088O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LPICo2071.6088O"><span><span class="hlt">Martian</span> Methane Cycle and Organic Compounds from <span class="hlt">Martian</span> Regolith Breccia NWA7533 by Orbitrap Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orthous-Daunay, F.-R.; Thissen, R.; Flandinet, L.; Bonal, L.; Vuitton, V.; Beck, P.; Hashiguchi, M.; Naraoka, H.</p> <p>2018-04-01</p> <p>We compare the organic mixture of a carbon rich <span class="hlt">martian</span> <span class="hlt">meteorite</span> and carbonaceous chondrites. The major difference lies in the absence of polymeric patterns in NWA7533. We interpret this as a destruction of exogenous polymers under Mars conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17480167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17480167"><span>Observations from a 4-year contamination <span class="hlt">study</span> of a sample depth profile through <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Nakhla.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Toporski, Jan; Steele, Andrew</p> <p>2007-04-01</p> <p>Morphological, compositional, and biological evidence indicates the presence of numerous well-developed microbial hyphae structures distributed within four different sample splits of the Nakhla <span class="hlt">meteorite</span> obtained from the British Museum (allocation BM1913,25). By examining depth profiles of the sample splits over time, morphological changes displayed by the structures were documented, as well as changes in their distribution on the samples, observations that indicate growth, decay, and reproduction of individual microorganisms. Biological staining with DNA-specific molecular dyes followed by epifluorescence microscopy showed that the hyphae structures contain DNA. Our observations demonstrate the potential of microbial interaction with extraterrestrial materials, emphasize the need for rapid investigation of Mars return samples as well as any other returned or impactor-delivered extraterrestrial materials, and suggest the identification of appropriate storage conditions that should be followed immediately after samples retrieved from the field are received by a handling/curation facility. The observations are further relevant in planetary protection considerations as they demonstrate that microorganisms may endure and reproduce in extraterrestrial materials over long (at least 4 years) time spans. The combination of microscopy images coupled with compositional and molecular staining techniques is proposed as a valid method for detection of life forms in <span class="hlt">martian</span> materials as a first-order assessment. Time-resolved in situ observations further allow observation of possible (bio)dynamics within the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008M%26PS...43..571C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008M%26PS...43..571C"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 93, 2008 March</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Connolly, Harold C.; Smith, Caroline; Benedix, Gretchen; Folco, Luigi; Righter, Kevin; Zipfel, Jutta; Yamaguchi, Akira; Aoudjehane, Hasnaa Chennaoui</p> <p>2008-03-01</p> <p>In this edition of the <span class="hlt">Meteoritical</span> Bulletin, 1443 approved <span class="hlt">meteorite</span> names with their relevant data are reported, one from a specific location within Africa, 211 from Northwest Africa, 5 from KOREAMET, 598 from the Chinese Antarctic Expedition, 23 from the Americas, 151 from Asia, three from Australia, two from Europe, two from NOVA, and 447 from ANSMET that were not reported in the <span class="hlt">Meteoritical</span> Bulletin no. 87. Also reported are 4 falls from the Americas. Some highlights of approved <span class="hlt">meteorites</span> are 10 lunar (including NWA 5000, an 11.528 kg sample), 3 <span class="hlt">Martian</span>, 4 irons (one from Indonesia), 2 ureilites, 5 mesosiderites, 1 pallasite, 6 brachinites, 3 CV3s, 4 CO3s, 8 CMs, 12 CK3s, and many more. Finally, the Committee on Nomenclature of the <span class="hlt">Meteoritical</span> Society announces two new names series in North America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720027371&hterms=pavement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpavement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720027371&hterms=pavement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpavement"><span>Nature of the <span class="hlt">Martian</span> surface as inferred from the particle-size distribution of lunar-surface material.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mason, C. C.</p> <p>1971-01-01</p> <p>Analysis of lunar particle size distribution data indicates that the surface material is composed of two populations. One population is caused by comminution from the impact of the larger-sized <span class="hlt">meteorites</span>, while the other population is caused by the melting of fine material by the impact of smaller-sized <span class="hlt">meteorites</span>. The results are referred to Mars, and it is shown that the <span class="hlt">Martian</span> atmosphere would vaporize the smaller incoming <span class="hlt">meteorites</span> and retard the incoming <span class="hlt">meteorites</span> of intermediate and large size, causing comminution and stirring of the particulate layer. The combination of comminution and stirring would result in fine material being sorted out by the prevailing circulation of the <span class="hlt">Martian</span> atmosphere and the material being transported to regions where it could be deposited. As a result, the <span class="hlt">Martian</span> surface in regions of prevailing upward circulation is probably covered by either a rubble layer or by desert pavement; regions of prevailing downward circulation are probably covered by sand dunes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028720','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028720"><span>The mineralogic evolution of the <span class="hlt">Martian</span> surface through time: Implications from chemical reaction path modeling <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Plumlee, G. S.; Ridley, W. I.; Debraal, J. D.; Reed, M. H.</p> <p>1993-01-01</p> <p>Chemical reaction path calculations were used to model the minerals that might have formed at or near the <span class="hlt">Martian</span> surface as a result of volcano or <span class="hlt">meteorite</span> impact driven hydrothermal systems; weathering at the <span class="hlt">Martian</span> surface during an early warm, wet climate; and near-zero or sub-zero C brine-regolith reactions in the current cold climate. Although the chemical reaction path calculations carried out do not define the exact mineralogical evolution of the <span class="hlt">Martian</span> surface over time, they do place valuable geochemical constraints on the types of minerals that formed from an aqueous phase under various surficial and geochemically complex conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030071123&hterms=life+Norway&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlife%2BNorway','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030071123&hterms=life+Norway&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlife%2BNorway"><span>Hydrothermal Origin for Carbonate Globules in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001: A Terrestrial Analogue from Spitsbergen (Norway)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; Bunch, Ted</p> <p>2002-01-01</p> <p>Carbonate minerals in the ancient <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 are the only known solid phases that bear witness to the processing of volatile and biologically critical compounds (CO2, H2O) on early Mars. Similar carbonates have been found in xenoliths and their host basalts from Quaternary volcanic centers in northern Spitsbergen (Norway). These carbonates were deposited by hot (i.e., hydrothermal) waters associated with the volcanic activity. By analogy with the Spitsbergen carbonates, the ALH84001 carbonates were probably also deposited by hot water. Hydrothermal activity was probably common and widespread on Early Mars, which featured abundant basaltic rocks, water as ice or liquid, and heat from volcanos and asteroid impacts. On Earth, descendants of the earliest life forms still prefer hydrothermal environments, which are now shown to have been present on early Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007M%26PS...42.1647C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007M%26PS...42.1647C"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 92, 2007 September</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Connolly, Harold C.; Smith, Caroline; Benedix, Gretchen; Folco, Luigi; Righter, Kevin; Zipfel, Jutta; Yamaguchi, Akira; Aoudjehane, Hasnaa Chennaoui</p> <p></p> <p>In this editon of The <span class="hlt">Meteoritical</span> Bulletin, 1394 recognized <span class="hlt">meteorites</span> are reported, 27 from specific locations within Africa, 133 from Northwest Africa, 1227 from Antartica (from ANSMET, PNRA, and PRIC expeditions), and 7 from Asia. The <span class="hlt">Meteoritical</span> Bulletin announces the approval of four new names series by the Nomenclature Committee of the <span class="hlt">Meteoritical</span> Society, two from Africa and one from Asia, including Al Haggounia, from Al Haggounia, Morocco, which is projected to be on the order of 3 metric tons of material related to enstatite chondrites and aubrites. Approved are two falls from Africa, Bassikounou (Mauretania) and Gashua (Nigeria). Approved from areas other than Antarctica are one lunar, two <span class="hlt">Martian</span>, 32 other achondrites, three mesosiderites, two pallasites, one CM, two CK, one CR2, two CV3, one CR2, and four R chondrites. The Nomenclature Committee of the <span class="hlt">Meteoritical</span> Society 48 newly approved relict <span class="hlt">meteorites</span> from two new name series, Österplana and Gullhögen (both from Sweden).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111577&hterms=formation+mineral+oxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dformation%2Bmineral%2Boxide','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111577&hterms=formation+mineral+oxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dformation%2Bmineral%2Boxide"><span>Fe-Ti-Cr-Oxides in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> EETA79001 <span class="hlt">Studied</span> by Point-counting Procedure Using Raman Spectroscopy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.</p> <p>2003-01-01</p> <p>Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this <span class="hlt">study</span> is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We <span class="hlt">studied</span> the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to <span class="hlt">study</span> the Fe-Ti-Cr-oxides in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> EETA79001, especially effects of compositional and structural variations on their Raman features.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PS...47..416S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PS...47..416S"><span>Oral histories in <span class="hlt">meteoritics</span> and planetary science—XVI: Donald D. Bogard</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sears, Derek W. G.</p> <p>2012-03-01</p> <p>Donald D. Bogard (Don, Fig. 1) became interested in <span class="hlt">meteorites</span> after seeing the Fayetteville <span class="hlt">meteorite</span> in an undergraduate astronomy class at the University of Arkansas. During his graduate <span class="hlt">studies</span> with Paul Kuroda at Arkansas, Don helped discover the Xe decay products of 244Pu. After a postdoctoral period at Caltech, where he learned much from Jerry Wasserburg, Peter Eberhardt, Don Burnett, and Sam Epstein, Don became one of a number of young Ph.D. scientists hired by NASA's Manned Spacecraft Center to set up the Lunar Receiving Laboratory (LRL) and to perform a preliminary examination of Apollo samples. In collaboration with Oliver Schaeffer (SUNY), Joseph Zähringer (Max Planck, Heidelberg), and Raymond Davis (Brookhaven National Laboratory), he built a gas analysis laboratory at JSC, and the noble gas portion of this laboratory remained operational until he retired in 2010. At NASA, Don worked on the lunar regolith, performed pioneering work on cosmic ray produced noble gas isotopes and Ar-Ar dating, the latter for important insights into the thermal and shock history of <span class="hlt">meteorites</span> and lunar samples. During this work, he discovered that the trapped gases in SNC <span class="hlt">meteorites</span> were very similar to those of the <span class="hlt">Martian</span> atmosphere and thus established their <span class="hlt">Martian</span> origin. Among Don's many administrative accomplishments are helping to establish the Antarctic <span class="hlt">meteorite</span> and cosmic dust processing programs at JSC and serving as a NASA-HQ discipline scientist, where he advanced peer review and helped create new programs. Don is a recipient of NASA's Scientific Achievement and Exceptional Service Medals and the <span class="hlt">Meteoritical</span> Society's Leonard Medal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.451..251L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.451..251L"><span>Rare-earth-element minerals in <span class="hlt">martian</span> breccia <span class="hlt">meteorites</span> NWA 7034 and 7533: Implications for fluid-rock interaction in the <span class="hlt">martian</span> crust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Yang; Ma, Chi; Beckett, John R.; Chen, Yang; Guan, Yunbin</p> <p>2016-10-01</p> <p>Paired <span class="hlt">martian</span> breccia <span class="hlt">meteorites</span>, Northwest Africa (NWA) 7034 and 7533, are the first <span class="hlt">martian</span> rocks found to contain rare-earth-element (REE) phosphates and silicates. The most common occurrence is as clusters of anhedral monazite-(Ce) inclusions in apatite. Occasionally, zoned, irregular merrillite inclusions are also present in apatite. Monazite-bearing apatite is sometimes associated with alkali-feldspar and Fe-oxide. Apatite near merrillite and monazite generally contains more F and OH (F-rich region) than the main chlorapatite host and forms irregular boundaries with the main host. Locally, the composition of F-rich regions can reach pure fluorapatite. The chlorapatite hosts are similar in composition to isolated apatite without monazite inclusions, and to euhedral apatite in lithic clasts. The U-Th-total Pb ages of monazite in three apatite are 1.0 ± 0.4Ga (2σ), 1.1 ± 0.5Ga (2σ), and 2.8 ± 0.7Ga (2σ), confirming a <span class="hlt">martian</span> origin. The texture and composition of monazite inclusions are mostly consistent with their formation by the dissolution of apatite and/or merrillite by fluid at elevated temperatures (>100 °C). In NWA 7034, we observed a monazite-chevkinite-perrierite-bearing benmoreite or trachyandesite clast. Anhedral monazite and chevkinite-perrierite grains occur in a matrix of sub-micrometer REE-phases and silicates inside the clast. Monazite-(Ce) and -(Nd) and chevkinite-perrierite-(Ce) and -(Nd) display unusual La and Ce depletion relative to Sm and Nd. In addition, one xenotime-(Y)-bearing pyrite-ilmenite-zircon clast with small amounts of feldspar and augite occurs in NWA 7034. One xenotime crystal was observed at the edge of an altered zircon grain, and a cluster of xenotime crystals resides in a mixture of alteration materials. Pyrite, ilmenite, and zircon in this clast are all highly altered, zircon being the most likely source of Y and HREE now present in xenotime. The association of xenotime with zircon, low U and Th contents, and the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.3290M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.3290M"><span>Organic Carbon Exists in Mars <span class="hlt">Meteorites</span>: where is it on the <span class="hlt">Martian</span> Surface?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McKay, David; Clemett, Simon; Gibson, Everett; Thomas-Keprta, Kathie; Wentworth, Susan</p> <p></p> <p>The search for organic carbon on Mars has been a major challenge. The first attempt was the Viking GC-MS in situ experiment which gave inconclusive results at two sites on Mars [1]. After the discovery that the SNC <span class="hlt">meteorites</span> were from Mars [2], [3-5] reported C isotopic compositional information which suggested a reduced C component present in the <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. [6 7] reported the presence of reduced C components (i.e., polycyclic aromatic hydrocarbons) associated with the carbonate globules in ALH84001. Jull et al. [8] noted in Nakhla there was an acid insoluble C component present with more than 75% of its C lacking any 14 C, which is modern-day terrestrial carbon. This C fraction was believed to be either indigenous <span class="hlt">martian</span> or ancient <span class="hlt">meteoritic</span> carbon. Fisk et al. [9, 10] have shown textural evidence along with C-enriched areas within fractures in Nakhla and ALH84001. Westall et al. [11] have shown the presence of a large irregular fragment of organic material completely embedded within a chip of ALH84001. Interior samples from the Nakhla SNC made available by the British Museum of Natural His-tory, were analyzed. Petrographic examination [12] of Nakhla showed evidence of fractures ( 0.5 m wide) filled with dark brown to black dendritic material with characteristics similar to those observed by [10]. Iddingsite is also present along fractures in olivine. Fracture filling and dendritic material was examined by SEM-EDX, TEM-EDX, Focused Electron Beam mi-croscopy, Laser Raman Spectroscopy, Nano-SIMS Ion Micro-probe, and Stepped-Combustion Static Mass Spectrometry. Observations from the first three techniques are discussed in [12 and 13]. Nano-SIMS Ion Microprobe <span class="hlt">studies</span> of the C-bearing fractures, containing the optically dark dendritic material, show direct correlation between C- and CN- abundances. Ion abun-dances for epoxy are distinct from those of the dendritic material[12] . Laser Raman Spectrometry was utilized to examine the optically dark dendritic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012903','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012903"><span>A TEM Investigation of the Fine-Grained Matrix of the <span class="hlt">Martian</span> Basaltic Breccia NWA 7034</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Muttik, N.; Keller, L. P.; Agee, C. B.; McCubbin, F. M.; Santos, A. R.; Rahman, Z.</p> <p>2014-01-01</p> <p>The <span class="hlt">martian</span> basaltic breccia NWA 7034 is characterized by fine-grained groundmass containing several different types of mineral grains and lithologic clasts. The matrix composition closely resembles <span class="hlt">Martian</span> crustal rock and soil composition measured by recent rover and orbiter missions. The first results of NWA 7034 suggest that the brecciation of this <span class="hlt">martian</span> <span class="hlt">meteorite</span> may have formed due to eruptive volcanic processes; however, impact related brecciation processes have been proposed for paired <span class="hlt">meteorites</span> NWA 7533 and NWA 7475]. Due to the very fine grain size of matrix, its textural details are difficult to resolve by optical and microprobe observations. In order to examine the potential nature of brecciation, transmission electron microscopy (TEM) <span class="hlt">studies</span> combined with focused ion-beam technique (FIB) has been undertaken. Here we present the preliminary observations of fine-grained groundmass of NWA 7034 from different matrix areas by describing its textural and mineralogical variations and micro-structural characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........31E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........31E"><span><span class="hlt">Studying</span> Antarctic Ordinary Chondrite (OC) and Miller Range (MIL) Nakhlite <span class="hlt">Meteorites</span> to Assess Carbonate Formation on Earth and Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, Michael Ellis</p> <p></p> <p>Carbonates are found in <span class="hlt">meteorites</span> collected from Antarctica. The stable isotope composition of these carbonates records their formation environment on either Earth or Mars. The first research objective of this dissertation is to characterize the delta18O and delta 13C values of terrestrial carbonates formed on Ordinary Chondrites (OCs) collected in regions near known <span class="hlt">martian</span> <span class="hlt">meteorites</span>. The second objective is to characterize the delta18O and delta13C values of <span class="hlt">martian</span> carbonates from Nakhlites collected from the Miller Range (MIL). The third objective is to assess environmental changes on Mars since the Noachian period. The OCs selected had no pre-terrestrial carbonates so any carbonates detected are presumed terrestrial in origin. The <span class="hlt">study</span> methodology is stepped extraction of CO2 created from phosphoric acid reaction with <span class="hlt">meteorite</span> carbonate. Stable isotope results show that two distinct terrestrial carbonate species (Ca-rich and Fe/Mg-rich) formed in Antarctica on OCs from a thin-film of meltwater containing dissolved CO2. Carbon isotope data suggests the terrestrial carbonates formed in equilibrium with atmospheric CO2 delta 13C = -7.5‰ at >15°C. The wide variation in delta 18O suggests the carbonates did not form in equilibrium with meteoric water alone, but possibly formed from an exchange of oxygen isotopes in both water and dissolved CO2. Antarctica provides a model for carbonate formation in a low water/rock ratio, near 0°C environment like modern Mars. Nakhlite parent basalt formed on Mars 1.3 billion years ago and the <span class="hlt">meteorites</span> were ejected by a single impact approximately 11 million years ago. They traveled thru space before eventually falling to the Earth surface 10,000-40,000 years ago. Nakhlite samples for this research were all collected from the Miller Range (MIL) in Antarctica. The Nakhlite stable isotope results show two carbonate species (Ca-rich and Fe/Mg-rich) with a range of delta18O values that are similar to the terrestrial OC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013096','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013096"><span>Northwest Africa 8159: An approximately 2.3 Billion Year Old <span class="hlt">Martian</span> Olivine-Bearing Augite Basalt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Simon, J. I.; Peters, T. J.; Tappa, M. J.; Agee, C. B.</p> <p>2014-01-01</p> <p>Based on petrology, mineralogy, and bulk composition, the new NWA 8159 <span class="hlt">martian</span> <span class="hlt">meteorite</span> is distinct from all known samples from Mars. In particular, the augite compositional trends are unique, but most similar to those of nakhite intercumulus. Whether NWA 8159 represents a new lithology or is related to a known <span class="hlt">meteorite</span> group remains to be determined. Sr and Nd isotopic analyses will allow comparison of source characteristics with SNC and other new ungrouped <span class="hlt">meteorites</span> (e.g., NWA 7635). Here we report initial Rb-Sr and Sm-Nd isotopic results for NWA 8159 with the objective to determine its formation age and to potentially identify similarities and potential source affinities with other <span class="hlt">martian</span> rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007400','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007400"><span>Iron Redox Systematics of Shergottites and <span class="hlt">Martian</span> Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin; Danielson, L. R.; Martin, A. M.; Newville, M.; Choi, Y.</p> <p>2010-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorites</span> record a range of oxygen fugacities from near the IW buffer to above FMQ buffer [1]. In terrestrial magmas, Fe(3+)/ SigmaFe for this fO2 range are between 0 and 0.25 [2]. Such variation will affect the stability of oxides, pyroxenes, and how the melt equilibrates with volatile species. An understanding of the variation of Fe(3+)/SigmaFe for <span class="hlt">martian</span> magmas is lacking, and previous work has been on FeO-poor and Al2O3-rich terrestrial basalts. We have initiated a <span class="hlt">study</span> of the iron redox systematics of <span class="hlt">martian</span> magmas to better understand FeO and Fe2O3 stability, the stability of magnetite, and the low Ca/high Ca pyroxene [3] ratios observed at the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980021283','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980021283"><span><span class="hlt">Meteorites</span>, Microfossils and Exobiology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.</p> <p>1997-01-01</p> <p>The discovery of evidence for biogenic activity and possible microfossils in a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> may have initiated a paradigm shift regarding the existence of extraterrestrial microbial life. Terrestrial extremophiles that live in deep granite and hydrothermal vents and nanofossils in volcanic tuffs have altered the premise that microbial life and microfossils are inconsistent with volcanic activity and igneous rocks. Evidence for biogenic activity and microfossils in <span class="hlt">meteorites</span> can no longer be dismissed solely because the <span class="hlt">meteoritic</span> rock matrix is not sedimentary. <span class="hlt">Meteorite</span> impact-ejection and comets provide mechanisms for planetary cross-contamination of biogenic chemicals, microfossils, and living microorganisms. Hence, previously dismissed evidence for complex indigenous biochemicals and possible microfossils in carbonaceous chondrites must be re-examined. Many similar, unidentifiable, biological-like microstructures have been found in different carbonaceous chondrites and the prevailing terrestrial contaminant model is considered suspect. This paper reports the discovery of microfossils indigenous to the Murchison <span class="hlt">meteorite</span>. These forms were found in-situ in freshly broken, interior surfaces of the <span class="hlt">meteorite</span>. Environmental Scanning Electron Microscope (ESEM) and optical microscopy images indicate that a population of different biological-like forms are represented. Energy Dispersive Spectroscopy reveals these forms have high carbon content overlaying an elemental distribution similar to the matrix. Efforts at identification with terrestrial microfossils and microorganisms were negative. Some forms strongly resemble bodies previously isolated in the Orgueil <span class="hlt">meteorite</span> and considered microfossils by prior researchers. The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this <span class="hlt">meteorite</span> at diverse times during the past 4.5 billion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111064&hterms=Zeolite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DZeolite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111064&hterms=Zeolite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DZeolite"><span>Zeolite Formation and Weathering Processes Within the <span class="hlt">Martian</span> Regolith: An Antarctic Analog</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibson, E. K.; McKay, D. S.; Wentworth, S. J.; Socki, R. A.</p> <p>2003-01-01</p> <p>As more information is obtained about the nature of the surface compositions and processes operating on Mars, it is clear that significant erosional and depositional features are present on the surface. Apparent aqueous or other fluid activity on Mars has produced many of the erosional and outflow features observed. Evidence of aqueous activity on Mars has been reported by earlier <span class="hlt">studies</span>. Gooding and colleagues championed the cause of pre-terrestrial aqueous alteration processes recorded in <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Oxygen isotope <span class="hlt">studies</span> on <span class="hlt">Martian</span> <span class="hlt">meteorites</span> by Karlsson et al. and Romenek et al. gave evidence for two separate water reservoirs on Mars. The oxygen isotopic compositions of the host silicate minerals was different from the oxygen isotopic composition of the secondary alteration products within the SNC <span class="hlt">meteorites</span>. This implied that the oxygen associated with fluids which produced the secondary alteration was from volatiles which were possibly added to the planetary inventory after formation of the primary silicates from which the SNC s were formed. The source of the oxygen may have been from a cometary or volatile-rich veneer added to the planet in its first 600 million years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040059926&hterms=Workers+india&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWorkers%2Bindia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040059926&hterms=Workers+india&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWorkers%2Bindia"><span>Volatile Behavior in Lunar and Terrestrial Basalts During Shock: Implications for <span class="hlt">Martian</span> Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chaklader, Johny; Shearer, C. K.; Hoerz, F.; Newsom, H. E.</p> <p>2004-01-01</p> <p>The amount of water in <span class="hlt">martian</span> magmas has significant ramifications for the <span class="hlt">martian</span> atmosphere-hydrosphere cycle. Large D-enrichments have been observed in kaersutitic amphiboles in Zagami, Chassigny and Shergotty <span class="hlt">meteorites</span> (delta-D values up to 4400 per mil) suggesting that substantial amounts of H escaped Mars in its past. Furthermore, <span class="hlt">martian</span> <span class="hlt">meteorites</span> with inclusions of biotite and apatite imply possible origins in a hydrous mantle. However, whether <span class="hlt">martian</span> magmas ever possessed considerable proportions of water remains controversial and unclear. The H-content of mica and amphibole melt inclusions has been found to be low, while bulk-rock H2O content is also low ranging from 0.013 to 0.035 wt. % in Shergotty. Hydrous <span class="hlt">martian</span> magmas were considered responsible for light lithophile element (LLE) zoning patterns observed in Nakhlite and Shergottite pyroxenes. Since LLEs, such as Li and B, partition into aqueous fluids at temperatures greater than 350 C, workers interpreted Li-B depletions in pyroxene rims as evidence that supercritical fluid exsolution occurred during magma degassing. In that many <span class="hlt">martian</span> basalts experienced substantial shock (15-45 GPa) it is possible that the magmatic volatile record preserved in <span class="hlt">martian</span> basalts has been disturbed. Previous shock experiments suggest that shock processes may effect water content and H/D. To better understand the possible effects of shock on this volatile record, we are <span class="hlt">studying</span> the redistribution of volatile elements in naturally and experimentally shocked basalts. Here, we report the initial results from shocked basalts associated with the Lonar Crater, India and an experimentally shocked lunar basalt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LPICo2071.6096T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LPICo2071.6096T"><span>The Rosetta Stones of Mars — Should <span class="hlt">Meteorites</span> be Considered as Samples of Opportunity for Mars Sample Return?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tait, A. W.; Schröder, C.; Ashley, J. W.; Velbel, M. A.; Boston, P. J.; Carrier, B. L.; Cohen, B. A.; Bland, P. A.</p> <p>2018-04-01</p> <p>We summarize insights about Mars gained from investigating <span class="hlt">meteorites</span> found on Mars. Certain types of <span class="hlt">meteorites</span> can be considered standard probes inserted into the <span class="hlt">martian</span> environment. Should they be considered for Mars Sample Return?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LPICo2084.4005A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LPICo2084.4005A"><span><span class="hlt">Meteoritic</span> Evidence for Multiple Early Enriched Reservoirs in the <span class="hlt">Martian</span> Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armytage, R. M. G.; Debaille, V.; Brandon, A. D.; Agee, C. B.</p> <p>2018-05-01</p> <p>From isotopic systematics, the <span class="hlt">martian</span> crustal reservoir represented by NWA 7034 cannot be the enriched end-member for the shergottites. This suggests multiple enriched reservoirs in the <span class="hlt">martian</span> mantle formed by several differentiation events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100017340','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100017340"><span>A High Resolution Microprobe <span class="hlt">Study</span> of EETA79001 Lithology C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schrader, Christian M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.</p> <p>2010-01-01</p> <p>Antarctic <span class="hlt">meteorite</span> EETA79001 has received substantial attention for possibly containing a component of <span class="hlt">Martian</span> soil in its impact glass (Lithology C) [1]. The composition of <span class="hlt">Martian</span> soil can illuminate near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Impact melts in <span class="hlt">meteorites</span> represent our most direct samples of <span class="hlt">Martian</span> regolith. We present the initial findings from a high-resolution electron microprobe <span class="hlt">study</span> of Lithology C from <span class="hlt">Martian</span> <span class="hlt">meteorite</span> EETA79001. As this <span class="hlt">study</span> develops we aim to extract details of a potential soil composition and to examine <span class="hlt">Martian</span> surface processes using elemental ratios and correlations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990079409&hterms=magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnesium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990079409&hterms=magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnesium"><span>Meteoric Magnesium Ions in the <span class="hlt">Martian</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pesnell, William Dean; Grebowsky, Joseph</p> <p>1999-01-01</p> <p>From a thorough modeling of the altitude profile of <span class="hlt">meteoritic</span> ionization in the <span class="hlt">Martian</span> atmosphere we deduce that a persistent layer of magnesium ions should exist around an altitude of 70 km. Based on current estimates of the meteoroid mass flux density, a peak ion density of about 10(exp 4) ions/cm is predicted. Allowing for the uncertainties in all of the model parameters, this value is probably within an order of magnitude of the correct density. Of these parameters, the peak density is most sensitive to the meteoroid mass flux density which directly determines the ablated line density into a source function for Mg. Unlike the terrestrial case, where the metallic ion production is dominated by charge-exchange of the deposited neutral Mg with the ambient ions, Mg+ in the <span class="hlt">Martian</span> atmosphere is produced predominantly by photoionization. The low ultraviolet absorption of the <span class="hlt">Martian</span> atmosphere makes Mars an excellent laboratory in which to <span class="hlt">study</span> meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the <span class="hlt">Martian</span> highlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05759&hterms=elephants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Delephants','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05759&hterms=elephants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Delephants"><span><span class="hlt">Meteorite</span> Linked to Rock at Meridiani</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/>This <span class="hlt">meteorite</span>, a basalt lava rock nearly indistinguishable from many Earth rocks, provided the first strong proof that <span class="hlt">meteorites</span> could come from Mars. Originally weighing nearly 8 kilograms (17.6 pounds), it was collected in 1979 in the Elephant Moraine area of Antarctica. The side of the cube at the lower left in this image measures 1 centimeter (0.4 inches). <p/>This picture shows a sawn face of this fine-grained gray rock. (The vertical stripes are saw marks.) The black patches in the rock are melted rock, or glass, formed when a large <span class="hlt">meteorite</span> hit Mars near the rock. The <span class="hlt">meteorite</span> impact probably threw this rock, dubbed 'EETA79001,' off Mars and toward Antarctica on Earth. The black glass contains traces of <span class="hlt">martian</span> atmosphere gases. <p/>The Mars Exploration Rover Opportunity has discovered that a rock dubbed 'Bounce' at Meridiani Planum has a very similar mineral composition to this <span class="hlt">meteorite</span> and likely shares common origins. Bounce itself is thought to have originated outside the area surrounding Opportunity's landing site; an impact or collision likely threw the rock away from its primary home.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27021613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27021613"><span>Searching for the Source Crater of Nakhlite <span class="hlt">Meteorites</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kereszturi, A; Chatzitheodoridis, E</p> <p>2016-11-01</p> <p>We surveyed the <span class="hlt">Martian</span> surface in order to identify possible source craters of the nakhlite <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. We investigated rayed craters that are assumed to be younger than 11 Ma, on lava surfaces with a solidification age around 1.2 Ga. An area of 17.3 million km 2 Amazonian lava plains was surveyed and 53 rayed craters were identified. Although most of them are smaller than the threshold limit that is estimated as minimum of launching fragments to possible Earth crossing trajectories, their observed size frequency distribution agrees with the expected areal density from cratering models characteristic for craters that are less than few tens of Ma old. We identified 6 craters larger than 3 km diameter constituting the potentially best source craters for nakhlites. These larger candidates are located mostly on a smooth lava surface, and in some cases, on the earlier fluvial-like channels. In three cases they are associated with fluidized ejecta lobes and rays - although the rays are faint in these craters, thus might be older than the other craters with more obvious rays. More work is therefore required to accurately estimate ages based on ray system for this purpose. A more detailed search should further link remote sensing <span class="hlt">Martian</span> data with the in-situ laboratory analyses of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, especially in case of high altitude, steep terrains, where the crater rays seems to rarely survive several Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940031650','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940031650"><span>Pigeonholing planetary <span class="hlt">meteorites</span>: The lessons of misclassification of EET87521 and ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lindstrom, M. M.; Treiman, A. H.; Mittlefehldt, D. W.</p> <p>1994-01-01</p> <p>The last few years have provided two noteworthy examples of misclassifications of achondritic <span class="hlt">meteorites</span> because the samples were new kinds of <span class="hlt">meteorites</span> from planetary rather than asteroidal parent bodies. Basaltic lunar <span class="hlt">meteorite</span> EET87521 was misclassified as a eucrite and SNC (<span class="hlt">martian</span>) orthopyroxenite ALH84001 was misclassified as a diogenite. In classifying <span class="hlt">meteorites</span> we find what we expect: we pigeonhole <span class="hlt">meteorites</span> into known categories most of which were derived from the more common asteroidal <span class="hlt">meteorites</span>. But the examples of EET8752 and ALH84001 remind us that planets are more complex than asteroids and exhibit a wider variety of rock types. We should expect variety in planetary <span class="hlt">meteorites</span> and we need to know how to recognize them when we have them. Our intent here is to show that our asteroidal perspective is inappropriate for planetary <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042162&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlindstrom','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042162&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlindstrom"><span>What would we miss if we characterized the Moon and Mars with just planetary <span class="hlt">meteorites</span>, remote mapping, and robotic landers?. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lindstrom, M. M.</p> <p>1994-01-01</p> <p>Exploration of the Moon and planets began with telescopic <span class="hlt">studies</span> of their surfaces, continued with orbiting spacecraft and robotic landers, and will culminate with manned exploration and sample return. For the Moon and Mars we also have accidental samples provided by impacts on their surfaces, the lunar and <span class="hlt">martian</span> <span class="hlt">meteorites</span>. How much would we know about the lunar surface if we only had lunar <span class="hlt">meteorites</span>, orbital spacecraft, and robotic exploration, and not the Apollo and Luna returned samples? What does this imply for Mars? With <span class="hlt">martian</span> <span class="hlt">meteorites</span> and data from Mariner, Viking, and the future Pathfinder missions, how much could we learn about Mars? The basis of most of our detailed knowledge about the Moon is the Apollo samples. They provide ground truth for the remote mapping, timescales for lunar processes, and samples from the lunar interior. The Moon is the foundation of planetary science and the basis for our interpretation of the other planets. Mars is similar to the Moon in that impact and volcanism are the dominant processes, but Mars' surface has also been affected by wind and water, and hence has much more complex surface geology. Future geochemical or mineralogical mapping of Mars' surface should be able to tell us whether the dominant rock types of the ancient southern highlands are basaltic, anorthositic, granitic, or something else, but will not be able to tell us the detailed mineralogy, geochemistry, or age. Without many more <span class="hlt">martian</span> <span class="hlt">meteorites</span> or returned samples we will not know the diversity of <span class="hlt">martian</span> rocks, and therefore will be limited in our ability to model <span class="hlt">martian</span> geological evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.215....1T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.215....1T"><span>Evaluation of <span class="hlt">meteorites</span> as habitats for terrestrial microorganisms: Results from the Nullarbor Plain, Australia, a Mars analogue site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tait, Alastair W.; Wilson, Siobhan A.; Tomkins, Andrew G.; Gagen, Emma J.; Fallon, Stewart J.; Southam, Gordon</p> <p>2017-10-01</p> <p>Unambiguous identification of biosignatures on Mars requires access to well-characterized, long-lasting geochemical standards at the planet's surface that can be modified by theoretical <span class="hlt">martian</span> life. Ordinary chondrites, which are ancient <span class="hlt">meteorites</span> that commonly fall to the surface of Mars and Earth, have well-characterized, narrow ranges in trace element and isotope geochemistry compared to <span class="hlt">martian</span> rocks. Given that their mineralogy is more attractive to known chemolithotrophic life than the basaltic rocks that dominate the <span class="hlt">martian</span> surface, exogenic rocks (e.g., chondritic <span class="hlt">meteorites</span>) may be good places to look for signs of prior life endemic to Mars. In this <span class="hlt">study</span>, we show that ordinary chondrites, collected from the arid Australian Nullarbor Plain, are commonly colonized and inhabited by terrestrial microorganisms that are endemic to this Mars analogue site. These terrestrial endolithic and chasmolithic microbial contaminants are commonly found in close association with hygroscopic veins of gypsum and Mg-calcite, which have formed within cracks penetrating deep into the <span class="hlt">meteorites</span>. Terrestrial bacteria are observed within corrosion cavities, where troilite (FeS) oxidation has produced jarosite [KFe3(SO4)2(OH)6]. Where terrestrial microorganisms have colonized primary silicate minerals and secondary calcite, these mineral surfaces are heavily etched. Our results show that inhabitation of <span class="hlt">meteorites</span> by terrestrial microorganisms in arid environments relies upon humidity and pH regulation by minerals. Furthermore, microbial colonization affects the weathering of <span class="hlt">meteorites</span> and production of sulfate, carbonate, Fe-oxide and smectite minerals that can preserve chemical and isotopic biosignatures for thousands to millions of years on Earth. <span class="hlt">Meteorites</span> are thus habitable by terrestrial microorganisms, even under highly desiccating environmental conditions of relevance to Mars. They may therefore be useful as chemical and isotopic ;standards; that preserve evidence of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52.2017T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52.2017T"><span>High-pressure minerals in shocked <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tomioka, Naotaka; Miyahara, Masaaki</p> <p>2017-09-01</p> <p>Heavily shocked <span class="hlt">meteorites</span> contain various types of high-pressure polymorphs of major minerals (olivine, pyroxene, feldspar, and quartz) and accessory minerals (chromite and Ca phosphate). These high-pressure minerals are micron to submicron sized and occur within and in the vicinity of shock-induced melt veins and melt pockets in chondrites and lunar, howardite-eucrite-diogenite (HED), and <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Their occurrence suggests two types of formation mechanisms (1) solid-state high-pressure transformation of the host-rock minerals into monomineralic polycrystalline aggregates, and (2) crystallization of chondritic or monomineralic melts under high pressure. Based on experimentally determined phase relations, their formation pressures are limited to the pressure range up to 25 GPa. Textural, crystallographic, and chemical characteristics of high-pressure minerals provide clues about the impact events of <span class="hlt">meteorite</span> parent bodies, including their size and mutual collision velocities and about the mineralogy of deep planetary interiors. The aim of this article is to review and summarize the findings on natural high-pressure minerals in shocked <span class="hlt">meteorites</span> that have been reported over the past 50 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810053534&hterms=originals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doriginals','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810053534&hterms=originals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doriginals"><span>On the original igneous source of <span class="hlt">Martian</span> fines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baird, A. K.; Clark, B. C.</p> <p>1981-01-01</p> <p>The composition of the silicate portion of <span class="hlt">Martian</span> regolith fines indicates derivation of the fines from mafic to ultramafic rocks, probably rich in pyroxene. Rock types similar in chemical and mineralogical composition include terrestrial Archean basalts and certain achondrite <span class="hlt">meteorites</span>. If these igneous rocks weathered nearly isochemically, the nontronitic clays proposed earlier as an analog to <span class="hlt">Martian</span> fines could be formed. Flood basalts of pyroxenitic lavas may be widespread and characteristic of early volcanism on Mars, analogous to maria flood basalts on the moon and early Precambrian basaltic komatiites on earth. Compositional differences between lunar, terrestrial, and <span class="hlt">Martian</span> flood basalts may be related to differences in planetary sizes and mantle compositions of the respective planetary objects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816619C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816619C"><span><span class="hlt">Meteorite</span> crater impact <span class="hlt">study</span>: a new way to <span class="hlt">study</span> seismology at school with exciting experiments, and an example of <span class="hlt">meteorite</span> astroblema in France (Rochechouart)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrer, Diane; Berenguer, Jean-Luc; MacMurray, Andrew</p> <p>2016-04-01</p> <p>The InSIGHT mission to Mars (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) supported by NASA, IPGP and CNES, is a great opportunity for teachers and pupils to <span class="hlt">study</span> the Red planet, but also to <span class="hlt">study</span> other fields of geology at school, such as seismology. With our pupils, we are following the InSight mission and we look forward to analyze seismic data registered by the SEIS seismometer , once it will be available (the InSight mission will launch in 2018 from California, and will land to Mars in 2018 or 2019). As this mission needs <span class="hlt">meteorite</span> impacts to generate seismic waves ( to discover the <span class="hlt">Martian</span> interior structure) , we've decided to model those <span class="hlt">meteorite</span> strikes in the classroom. With our pupils, we've modeled <span class="hlt">meteorite</span> impact craters with different impactors , such as tennis balls, baseballs, or pingpong balls, and used an analogue substratum made by flour and cocoa. Then, we kept on going our geophysical investigation , <span class="hlt">studying</span> several parameters. For instance, we've <span class="hlt">studied</span> the link between size of impactor and size of crater , the link between mass of impactor and Crater Formation, and the link between velocity of impactor and crater formation. In this geophysical approach , potential energy and kinetic energy can be introduced in terms of energy transfer as the impactor falls ( calculation of the velocity of impact and plotting that against crater diameter using v = (2gh)1/2). For each crater formation made in class by students, we have registered seismological data thanks to Audacity software, and <span class="hlt">study</span> the seismic signal propagation. This exemple of hands-on activity with pupils, and its wide range of geophysical calculation shows how we can do simple experiment modeling <span class="hlt">meteorite</span> crater impact and exploit registered seismological data at school. We've finaly focused our work with the very famous example of the astroblema of Rochechouart in the South-west of France ( crater formation : - 214 My) , in which it's easy to</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.200..280H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.200..280H"><span>Effects of shock and <span class="hlt">Martian</span> alteration on Tissint hydrogen isotope ratios and water content</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hallis, L. J.; Huss, G. R.; Nagashima, K.; Taylor, G. J.; Stöffler, D.; Smith, C. L.; Lee, M. R.</p> <p>2017-03-01</p> <p>The Tissint <span class="hlt">meteorite</span>, a picritic shergottite, fell to Earth in Morocco on the 18th of July 2011, and is only the fifth <span class="hlt">Martian</span> <span class="hlt">meteorite</span> witnessed to fall. Hydrogen isotope ratios and water contents are variable within different minerals in Tissint. Ringwoodite and shock melt pockets contain elevated D/H ratios relative to terrestrial values (δD = 761-4224‰). These high ratios in recrystallized phases indicate significant implantation of hydrogen from the D-rich <span class="hlt">Martian</span> atmosphere during shock. In contrast, although olivine has detectable water abundances (230-485 ppm), it exhibits much lower D/H ratios (δD = +88 to -150‰), suggesting this water was not implanted from the <span class="hlt">Martian</span> atmosphere. The minimal terrestrial weathering experienced by Tissint gives confidence that the olivine-hosted water has a <span class="hlt">Martian</span> origin, but its high concentration indicates direct inheritance from the parental melt is improbable, especially given the low pressure of olivine crystallisation. Incorporation of a low δD crustal fluid, or deuteric alteration during crystallisation, could explain the relatively high water contents and low D/H ratios in Tissint olivine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020002133&hterms=organic+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dorganic%2Bsoil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020002133&hterms=organic+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dorganic%2Bsoil"><span>SNC <span class="hlt">Meteorites</span>, Organic Matter and a New Look at Viking</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Warmflash, David M.; Clemett, Simon J.; McKay, David S.</p> <p>2001-01-01</p> <p>Recently, evidence has begun to grow supporting the possibility that the Viking GC-MS would not have detected certain carboxylate salts that could have been present as metastable oxidation products of high molecular weight organic species. Additionally, despite the instrument's high sensitivity, the possibility had remained that very low levels of organic matter, below the instrument's detection limit, could have been present. In fact, a recent <span class="hlt">study</span> indicates that the degradation products of several million microorganisms per gram of soil on Mars would not have been detected by the Viking GC-MS. Since the strength of the GC-MS findings was considered enough to dismiss the biology packet, particularly the LR results, any subsequent evidence suggesting that organic molecules may in fact be present on the <span class="hlt">Martian</span> surface necessitates a re-evaluation of the Viking LR data. In addition to an advanced mass spectrometer to look for isotopic signatures of biogenic processes, future lander missions will include the ability to detect methane produced by methanogenic bacteria, as well as techniques based on biotechnology. Meanwhile, the identification of Mars samples already present on Earth in the form of the SNC <span class="hlt">meteorites</span> has provided us with the ability to <span class="hlt">study</span> samples of the <span class="hlt">Martian</span> upper crust a decade or more in advance of any planned sample return missions. While contamination issues are of serious concern, the presence of indigenous organic matter in the form of polycyclic aromatic hydrocarbons has been detected in the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> ALH84001 and Nakhla, while there is circumstantial evidence for carbonaceous material in Chassigny. The radiochronological ages of these <span class="hlt">meteorites</span> are 4.5 Ga, 1.3 Ga, and 165 Ma respectively representing a span of time in Earth history from the earliest single-celled organisms to the present day. Given this perspective on organic material, a biological interpretation to the Viking LR results can no longer be ruled out. In the LR</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090011793','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090011793"><span>Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and <span class="hlt">Martian</span> Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.</p> <p>2009-01-01</p> <p>The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in <span class="hlt">martian</span> rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of <span class="hlt">martian</span> rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of <span class="hlt">martian</span> rocks by conducting laboratory simulation experiments on terrestrial basalts and <span class="hlt">martian</span> <span class="hlt">meteorites</span>. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, <span class="hlt">Martian</span> <span class="hlt">meteorite</span> analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of <span class="hlt">martian</span> surface rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.418...91P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.418...91P"><span>Tracking the source of the enriched <span class="hlt">martian</span> <span class="hlt">meteorites</span> in olivine-hosted melt inclusions of two depleted shergottites, Yamato 980459 and Tissint</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Moriwaki, R.; Economos, R. C.; Schmitt, A. K.; McKeegan, K. D.</p> <p>2015-05-01</p> <p>The apparent lack of plate tectonics on all terrestrial planets other than Earth has been used to support the notion that for most planets, once a primitive crust forms, the crust and mantle evolve geochemically-independent through time. This view has had a particularly large impact on models for the evolution of Mars and its silicate interior. Recent data indicating a greater potential that there may have been exchange between the <span class="hlt">martian</span> crust and mantle has led to a search for additional geochemical evidence to support the alternative hypothesis, that some mechanism of crustal recycling may have operated early in the history of Mars. In order to <span class="hlt">study</span> the most juvenile melts available to investigate <span class="hlt">martian</span> mantle source(s) and melting processes, the trace element compositions of olivine-hosted melt inclusions for two incompatible-element-depleted olivine-phyric shergottites, Yamato 980459 (Y98) and Tissint, and the interstitial glass of Y98, have been measured by Secondary Ionization Mass Spectrometry (SIMS). Chondrite-normalized Rare Earth Element (REE) patterns for both Y98 and Tissint melt inclusions, and the Y98 interstitial glass, are characteristically light-REE depleted and parallel those of their host rock. For Y98, a clear flattening and upward inflection of La and Ce, relative to predictions based on middle and heavier REE, provides evidence for involvement of an enriched component early in their magmatic history; either inherited from a metasomatized mantle or crustal source, early on and prior to extensive host crystallization. Comparing these melt inclusion and interstitial glass analyses to existing melt inclusion and whole-rock data sets for the shergottite <span class="hlt">meteorite</span> suite, defines mixing relationships between depleted and enriched end members, analogous to mixing relationships between whole rock Sr and Nd isotopic measurements. When considered in light of their petrologic context, the origin of these trace element enriched and isotopically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080010782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080010782"><span>Moessbauer and Electron Microprobe <span class="hlt">Studies</span> of Density Separates of <span class="hlt">Martian</span> Nakhlite Mil03346: Implications for Interpretation of Moessbauer Spectra Acquired by the Mars Exploration Rovers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, R. V.; McKay, G. A.; Agresti, D. G.; Li, Loan</p> <p>2008-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> MIL03346 is described as an augite-rich cumulate rock with approx.80%, approx.3%, and approx.21% modal phase proportions of augite (CPX), olivine and glassy mesostasis, respectively, and is classified as a nakhlite [1]. The Mossbauer spectrum for whole rock (WR) MIL 03346 is unusual for <span class="hlt">Martian</span> <span class="hlt">meteorites</span> in that it has a distinct magnetite subspectrum (7% subspectral area) [2]. The <span class="hlt">meteorite</span> also has products of pre-terrestrial aqueous alteration ("iddingsite") that is associated primarily with the basaltic glass and olivine. The Mossbauer spectrometers on the Mars Exploration Rovers have measured the Fe oxidation state and the Fe mineralogical composition of rocks and soils on the planet s surface since their landing in Gusev Crater and Meridiani Planum in January, 2004 [3,4]. The MIL 03346 <span class="hlt">meteorite</span> provides an opportunity to "ground truth" or refine Fe phase identifications. This is particularly the case for the so-called "nanophase ferric oxide" (npOx) component. NpOx is a generic name for a ferric rich product of oxidative alteration. On Earth, where we can take samples apart and <span class="hlt">study</span> individual phases, examples of npOx include ferrihydrite, schwertmannite, akagaaneite, and superparamagnetic (small particle) goethite and hematite. It is also possible for ferric iron to be associated to some unknown extent with igneous phases like pyroxene. We report here an electron microprobe (EMPA) and Moessbauer (MB) <span class="hlt">study</span> of density separates of MIL 03346. The same separates were used for isotopic <span class="hlt">studies</span> by [5]. Experimental techniques are described by [6,7].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940017195','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940017195"><span>An attempt to comprehend <span class="hlt">Martian</span> weathering conditions through the analysis of terrestrial palagonite samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Douglas, C.; Wright, I. P.; Bell, J. B.; Morris, R. V.; Golden, D. C.; Pillinger, C. T.</p> <p>1993-01-01</p> <p>Spectroscopic observations of the <span class="hlt">Martian</span> surface in the invisible to near infrared (0.4-1.0 micron), coupled with measurements made by Viking, have shown that the surface is composed of a mixture of fine-grained weathered and nonweathered minerals. The majority of the weathered components are thought to be materials like smectite clays, scapolite, or palagonite. Until materials are returned for analysis there are two possible ways of proceeding with an investigation of <span class="hlt">Martian</span> surface processes: (1) the <span class="hlt">study</span> of weathering products in <span class="hlt">meteorites</span> that have a <span class="hlt">Martian</span> origin (SNC's), and (2) the analysis of certain terrestrial weathering products as analogs to the material found in SNC's, or predicted to be present on the <span class="hlt">Martian</span> surface. We describe some preliminary measurements of the carbon chemistry of terrestrial palagonite samples that exhibit spectroscopic similarities with the <span class="hlt">Martian</span> surface. The data should aid the understanding of weathering in SNC's and comparisons between terrestrial palagonites and the <span class="hlt">Martian</span> surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940017205','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940017205"><span>Wet inside and out? Constraints on water in the <span class="hlt">Martian</span> mantle and on outgassed water, based on melt inclusions in SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, H. Y., Jr.; Harvey, R. P.</p> <p>1993-01-01</p> <p>Constraints on the volatile inventory and outgassing history of Mars are critical to understanding the origin of ancient valley systems and paleoclimates. Planetary accretion models for Mars allow either a volatile-rich or volatile-poor mantle, depending on whether the accreted materials were fully oxidized or whether accretion was homogeneous so that water was lost through reaction with metallic iron. The amount of water that has been outgassed from the interior is likewise a contentious subject, and estimates of globally distributed water based on various geochemical and geological measurements vary from a few meters to more than a thousand meters. New data on SNC <span class="hlt">meteorites</span>, which are thought to be <span class="hlt">Martian</span> igneous rocks, provide constraints on both mantle and outgassed water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001754','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001754"><span>Isotopic Composition of Carbonates in Antarctic Ordinary Chondrites and Miller Range Nakhlites: Insights into <span class="hlt">Martian</span> Amazonian Aqueous Alteration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evans, M. E.; Niles, P. B.; Chapman, P.</p> <p>2017-01-01</p> <p>The <span class="hlt">martian</span> surface contains features of ancient fluvial systems. Stable isotope analysis of carbonates that form in aqueous systems can reveal their formation conditions. The Nakhlite <span class="hlt">meteorites</span> originally formed on Mars 1.3 Ga and were later exposed to aqueous fluids that left behind carbonate minerals [1], thus analysis of these carbonates can provide data to understand Amazonian climate conditions on Mars. Carbonates found in the Nakhlite <span class="hlt">meteorites</span> contain a range of delta(sup 13)C values, which may be either <span class="hlt">martian</span> carbonates or terrestrial contamination. To better under-stand terrestrial weathering products and <span class="hlt">martian</span> carbonate formation processes, we conducted a set of carbonate isotope analyses on Antarctic <span class="hlt">meteorites</span> focusing on Miller Range (MIL) Nakhlites as well as Ordinary Chondrites (OCs) (Figure 1)[1-11] [12]. OCs of petrology type H, L, and LL 3-6 were selected since they are not expected to contain preterrestrial carbonates, yet they have visible evaporite minerals on the fusion crust indicating terrestrial alteration. These cryogenically formed terrestrial carbonates may also provide an analog for cryogenic carbonate formation on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AcAau.140..452E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AcAau.140..452E"><span>Weldability of an iron <span class="hlt">meteorite</span> by Friction Stir Spot Welding: A contribution to in-space manufacturing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, William Todd; Neely, Kelsay E.; Strauss, Alvin M.; Cook, George E.</p> <p>2017-11-01</p> <p>Friction Stir Welding has been proposed as an efficient and appropriate method for in space welding. It has the potential to serve as a viable option for assembling large scale space structures. These large structures will require the use of natural in space materials such as those available from iron <span class="hlt">meteorites</span>. Impurities present in most iron <span class="hlt">meteorites</span> limit its ability to be welded by other space welding techniques such as electron beam laser welding. This <span class="hlt">study</span> investigates the ability to weld pieces of in situ Campo del Cielo <span class="hlt">meteorites</span> by Friction Stir Spot Welding. Due to the rarity of the material, low carbon steel was used as a model material to determine welding parameters. Welded samples of low carbon steel, invar, and Campo del Cielo <span class="hlt">meteorite</span> were compared and found to behave in similar ways. This <span class="hlt">study</span> shows that <span class="hlt">meteorites</span> can be Friction Stir Spot Welded and that they exhibit properties analogous to that of FSSW low carbon steel welds. Thus, iron <span class="hlt">meteorites</span> can be regarded as another viable option for in-space or <span class="hlt">Martian</span> construction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002993','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002993"><span>The Carbonates in ALH 84001 Record the Evolution of the <span class="hlt">Martian</span> Atmosphere Through Multiple Formation Events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shaheen, R.; Niles, P. B.; Corrgan, C.</p> <p>2012-01-01</p> <p>Current <span class="hlt">Martian</span> conditions restrict the presence of liquid water due to low temperatures (approx 210K), a thin atmosphere (approx 7mb), and intense UV radiation. However, past conditions on Mars may have been different with the possibility that the ancient <span class="hlt">Martian</span> climate was warm and wet with a dense CO2 atmosphere. The cycling of carbon on Mars through atmospheric CO2 and carbonate minerals is critical for deciphering its climate history. In particular stable isotopes contained in carbonates can provide information of their origin and formation environment as well as possibly hinting at the composition of global reservoirs such as atmospheric CO2. <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH 84001 contains widely <span class="hlt">studied</span> carbonate rosettes that have been dated to approx. 3.9 Ga and have been used to interpret climatic conditions present at that time. However, there is mount-ing evidence for multiple episodes of carbonate formation in ALH 84001 with potentially distinct isotopic compositions. This <span class="hlt">study</span> seeks to tease out these different carbonate assemblages using stepped phosphoric acid dissolution and analysis of carbon and triple oxygen stable isotopes. In addition, we report SIMS analyses of the delta O-18 several petrographically unusual carbonate phases in the <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003501','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003501"><span>Constraints on Mantle Plume Melting Conditions in the <span class="hlt">Martian</span> Mantle Based on Improved Melting Phase Relationships of Olivine-Phyric Shergottite Yamato 980459</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kiefer, Walter S.; Rapp, Jennifer F.; Usui, Tomohiro; Draper, David S.; Filiberto, Justin</p> <p>2016-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> Yamato 980459 (hereafter Y98) is an olivine-phyric shergottite that has been interpreted as closely approximating a <span class="hlt">martian</span> mantle melt [1-4], making it an important constraint on adiabatic decompression melting models. It has long been recognized that low pressure melting of the Y98 composition occurs at extremely high temperatures relative to <span class="hlt">martian</span> basalts (1430 degC at 1 bar), which caused great difficulties in a previous attempt to explain Y98 magma generation via a mantle plume model [2]. However, previous <span class="hlt">studies</span> of the phase diagram were limited to pressures of 2 GPa and less [2, 5], whereas decompression melting in the present-day <span class="hlt">martian</span> mantle occurs at pressures of 3-7 GPa, with the shallow boundary of the melt production zone occurring just below the base of the thermal lithosphere [6]. Recent experimental work has now extended our knowledge of the Y98 melting phase relationships to 8 GPa. In light of this improved petrological knowledge, we are therefore reassessing the constraints that Y98 imposes on melting conditions in <span class="hlt">martian</span> mantle plumes. Two recently discovered olivine- phyric shergottites, Northwest Africa (NWA) 5789 and NWA 6234, may also be primary melts from the <span class="hlt">martian</span> mantle [7, 8]. However, these latter <span class="hlt">meteorites</span> have not been the subject of detailed experimental petrology <span class="hlt">studies</span>, so we focus here on Y98.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980055128','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980055128"><span>Natural thermoluminescence of Antarctic <span class="hlt">meteorites</span> and related <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benoit, Paul H.; Sears, Derek W. G.</p> <p>1998-01-01</p> <p>The natural thermoluminescence (TL) laboratory's primary purpose is to provide data on newly recovered Antarctic <span class="hlt">meteorites</span> that can be included in discovery announcements and to investigate the scientific implications of the data. Natural TL levels of <span class="hlt">meteorites</span> are indicators of recent thermal history and terrestrial history, and the data can be used to <span class="hlt">study</span> the orbital/radiation history of groups of <span class="hlt">meteorites</span> (e.g., H chondrites) or to <span class="hlt">study</span> the processes leading to the concentration of <span class="hlt">meteorites</span> at certain sites in Antarctica. An important application of these data is the identification of fragments, or "pairs" of <span class="hlt">meteorites</span> produced during atmospheric passage or during terrestrial weathering. Thermoluminescence data are particularly useful for pairing within the most common <span class="hlt">meteorite</span> classes, which typically exhibit very limited petrographic and chemical diversity. Although not originally part of the laboratory's objectives, TL data are also useful in the identification and classification of petrographically or mineralogically unusual <span class="hlt">meteorites</span>, including unequilibrated ordinary chondrites and some basaltic achondrites. In support of its primary mission, the laboratory also engages in TL <span class="hlt">studies</span> of modern falls, finds from hot deserts, and terrestrial analogs and conducts detailed <span class="hlt">studies</span> of the TL properties of certain classes of <span class="hlt">meteorites</span>. These <span class="hlt">studies</span> include the measurement of TL profiles in <span class="hlt">meteorites</span>, the determination of TL levels of finds from the Sahara and the Nullarbor region of Australia, and comparison of TL data to other indicators of irradiation or terrestrial history, such as cosmogenic noble gas and radionuclide abundances. Our current work can be divided into five subcategories, (a) TL survey of Antarctic <span class="hlt">meteorites</span>, (b) pairing and field relations of Antarctic <span class="hlt">meteorites</span>, (c) characterization of TL systematics of <span class="hlt">meteorites</span>, (d) comparison of natural TL and other terrestrial age indicators for Antarctic <span class="hlt">meteorites</span>, and for <span class="hlt">meteorites</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013pimo.conf..168I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013pimo.conf..168I"><span>New Mars <span class="hlt">meteorite</span> fall in Morocco: collecting observations and determining the spatial distribution in the strewnfield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ibhi, Abderrahmane</p> <p>2013-01-01</p> <p>The existence of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> in the region of Tissint (Tata, Morocco) dropped by a very bright fireball on July 18, 2011, had been notified to a group of scientists of the Ibn Zohr University of Agadir, Morocco, at the beginning of January 2012, by a nomad of Tata who had found a small fragment in the region. As soon as a scientific expedition arrived at the place of the <span class="hlt">meteorite</span> fall, the members of the laboratory of Geo-heritage and Geo-materials Science started gathering information and collecting the debris of this <span class="hlt">Martian</span> <span class="hlt">meteorite</span>. The Tissint fireball has been observed and reported by numerous witnesses across the southeastern Morocco. The event was extremely valuable to the scientific community: it was the brightest and most comprehensively observed fireball in Morocco's known astronomical history. We are now in a position to draw the distribution ellipse of the fall, which starts at Jbel Al Gallab and continues in east-southeastern direction, above big rocky plateaus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19423810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19423810"><span>Elemental composition of the <span class="hlt">Martian</span> crust.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McSween, Harry Y; Taylor, G Jeffrey; Wyatt, Michael B</p> <p>2009-05-08</p> <p>The composition of Mars' crust records the planet's integrated geologic history and provides clues to its differentiation. Spacecraft and <span class="hlt">meteorite</span> data now provide a global view of the chemistry of the igneous crust that can be used to assess this history. Surface rocks on Mars are dominantly tholeiitic basalts formed by extensive partial melting and are not highly weathered. Siliceous or calc-alkaline rocks produced by melting and/or fractional crystallization of hydrated, recycled mantle sources, and silica-poor rocks produced by limited melting of alkali-rich mantle sources, are uncommon or absent. Spacecraft data suggest that <span class="hlt">martian</span> <span class="hlt">meteorites</span> are not representative of older, more voluminous crust and prompt questions about their use in defining diagnostic geochemical characteristics and in constraining mantle compositional models for Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014P%26SS...92...16M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014P%26SS...92...16M"><span>Possible mechanism for explaining the origin and size distribution of <span class="hlt">Martian</span> hematite spherules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Misra, Anupam K.; Acosta-Maeda, Tayro E.; Scott, Edward R. D.; Sharma, Shiv K.</p> <p>2014-03-01</p> <p>Mysterious hematite spherules, also known as “blueberries”, observed at Meridiani Planum on Mars have been widely accepted as concretions which are formed by precipitation of aqueous fluids. One of the biggest mysteries is that all observed <span class="hlt">Martian</span> blueberries are limited in size with maximum diameter of 6.2 mm. In contrast, terrestrial concretions are not size limited. In this article, we discuss significant differences between <span class="hlt">Martian</span> blueberries and Earth concretion analogs. Puzzling observations from Mars Exploration Rovers Opportunity and Spirit suggest that the spherules may not be concretions but are cosmic spherules formed by ablation of <span class="hlt">meteorites</span>. The perfect spherical shape of spherules, their observed size limit, and all other physical properties are easily explained by a <span class="hlt">meteorite</span> ablation model. Evidence that some of these spherules are only few years old strongly constrains concretion and other growth mechanisms related to aqueous processes that require the existence of water on Mars in its recent history. The large number of hematite spherules in Meridiani Planum may be due to a big rare iron <span class="hlt">meteorite</span> impact event in this region sometime in the past.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800051895&hterms=Martian+Organic+Matter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMartian%2BOrganic%2BMatter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800051895&hterms=Martian+Organic+Matter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMartian%2BOrganic%2BMatter"><span>The photolytic degradation and oxidation of organic compounds under simulated <span class="hlt">Martian</span> conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oro, J.; Holzer, G.</p> <p>1979-01-01</p> <p>Cosmochemical considerations suggest various potential sources for the accumulation of organic matter on Mars. However the Viking Molecular Analysis did not indicate any indigenous organic compounds on the surface of Mars. Their disappearance from the top layer is most likely caused by the combined action of the high solar radiation flux and various oxidizing species in the <span class="hlt">Martian</span> atmosphere and regolith. In this <span class="hlt">study</span> the stability of several organic substances and a sample of the Murchison <span class="hlt">meteorite</span> was tested under simulated <span class="hlt">Martian</span> conditions. After adsorption on powdered quartz, samples of adenine, glycine and naphthalene were irradiated with UV light at various oxygen concentrations and exposure times. In the absence of oxygen, adenine and glycine appeared stable over the given irradiation period, whereas a definite loss was observed in the case of naphthalene, as well as in the volatilizable and pyrolizable content of the Murchison <span class="hlt">meteorite</span>. The presence of oxygen during UV exposure caused a significant increase in the degradation rate of all samples. It is likely that similar processes have led to the destruction of organic materials on the surface of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..165H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..165H"><span>Alteration assemblages in the Miller Range and Elephant Moraine regions of Antarctica: Comparisons between terrestrial igneous rocks and <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hallis, L. J.</p> <p>2013-02-01</p> <p>The weathering products present in igneous terrestrial Antarctic samples were analyzed, and compared with those found in the four Miller Range nakhlite <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The aim of these comparisons was to determine which of the alteration phases in the Miller Range nakhlites are produced by terrestrial weathering, and what effect rock composition has on these phases. Antarctic terrestrial samples MIL 05031 and EET 96400, along with the Miller Range nakhlites MIL 03346 and 090032, were found to contain secondary alteration assemblages at their externally exposed surfaces. Despite the difference in primary mineralogy, the assemblages of these rocks consist mostly of sulfates (jarosite in MIL 05031, jarosite and gypsum in EET 96400) and iddingsite-like Fe-clay. As neither of the terrestrial samples contains sulfur-bearing primary minerals, and these minerals are rare in the Miller Range nakhlites, it appears that SO42-, possibly along with some of the Na+, K+, and Ca+ in these phases, was sourced from wind-blown sea spray and biogenic emissions from the southern ocean. Cl enrichment in the terrestrially derived "iddingsite" of MIL 05031 and MIL 03346, and the presence of halite at the exterior edge of MIL 090032, can also be explained by this process. However, jarosite within and around the olivine-bound melt inclusions of MIL 090136 is present in the interior of the <span class="hlt">meteorite</span> and, therefore, is probably the product of preterrestrial weathering on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP21B1006R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP21B1006R"><span>Remanence carrying minerals in <span class="hlt">meteorites</span>: a journey through an exotic jungle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rochette, P.; Gattacceca, J.; Uehara, M.</p> <p>2011-12-01</p> <p>Well-known remanence carrying minerals in <span class="hlt">meteorites</span> are magnetite and pyrrhotite, familiar on Earth, and Fe-Ni metal alloys. In Fe-Ni metal the difficulty in interpreting paleomagnetic data is due to the presence of multiple metastable phases which follow complex transformation paths during thermal treatment. A minor phase, tetrataenite (ordered Fe0.5Ni0.5), usually carries most of the remanence [1]. It is intimately mixed with high susceptibility phases (kamacite and taenite), implying strong interaction effects. FeNi phosphide and carbide (schreibersite and cohenite), often associated with metal, are usually overlooked although they may be responsible for the remanence of enstatite chondrites and some lunar basalts, with Tc around 200°C. They are also likely responsible for the claim of "magnetic carbon" found in Canyon Diablo <span class="hlt">meteorite</span> [2]. Sulfides, a wide variety of which occurs in <span class="hlt">meteorites</span>, provide even more thrill. Concerning pyrrhotite, there is still imperfect understanding of the observation that not monoclinic but hexagonal pyrrhotite is the ferromagnetic phase present in some <span class="hlt">martian</span> <span class="hlt">meteorites</span> and Rumuruti chondrites. The most common sulfide in <span class="hlt">meteorites</span>, troilite (FeS), is an antiferromagnet (TN= 320°C), showing a susceptibility anomaly at 140°C. Recently a transition toward weak ferromagnetism has been proposed below 60-70 K [3]. However it has been shown subsequently that this weak ferromagnetism is due to impurities of chromite [4] an ubiquitous phase in <span class="hlt">meteorites</span> that becomes ferromagnetic below a Tc of 40 to 150 K (a wide range linked to the various possible substitutions). Other sulfides found in <span class="hlt">meteorites</span> show low temperature transitions. Alabandite ( (Fe,Mn)S) and Daubreelite (FeCr2S4) have been reviewed in [3]. Chalcopyrite (FeCuS2), an antiferromagnet at room temperature, shows magnetic ordering of Cu+ ions at 50 K with appearance of weak ferromagnetism [5]. Magnetic properties of cubanite (Fe2CuS3), a RT ferrimagnet found in CI</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGP23C1348B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGP23C1348B"><span>Looking for <span class="hlt">Martian</span> True Polar Wander in mutually oriented slices of ALH84001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buz, J.; Murphy, T. G.; Kirschvink, J. L.</p> <p>2016-12-01</p> <p>True polar wander (TPW) on Mars has been hypothesized based on a variety of observations including geoid instability [1], locations of apparent polar deposits [2], and locations of magnetic anomalies [3, 4]. A proposed driving force for TPW is redistribution of mass on the surface of the planet such as by extensive volcanism events [5]. The majority of TPW modeling research has been using orbital datasets and modeling. However, laboratory analyses of <span class="hlt">Martian</span> samples should also be conducted to test for <span class="hlt">Martian</span> TPW. The <span class="hlt">Martian</span> <span class="hlt">meteorite</span>, ALH84001, is a prime sample for observing <span class="hlt">Martian</span> TPW because of its preservation of thermal remanent magnetization from Mars [6]. Previous work on the sample has demonstrated that the interior of the <span class="hlt">meteorite</span> was not heated above 40 C during transport from Mars to Earth and that there is a heterogeneous magnetization within the <span class="hlt">meteorite</span> [7]. Within the <span class="hlt">meteorite</span> are a series of fracture-filling carbonate blebs which contain magnetite and pyrrhotite with original remanence. These carbonates are presumed to have precipitated onto the <span class="hlt">meteorite</span> [8]. We have divided a fracture-containing portion of the <span class="hlt">meteorite</span> into three sets of sequential, mutually oriented slices. Using an ultra-high resolution scanning SQuID magnetometer we are able to visualize the magnetization within each slice. We are able to model each magnetic scan as a series of discrete dipoles using a modification from Lima and Weiss [9]. Our results demonstrate that within one of our slice sequences the dipoles lie along a great circle path. Dipoles lying along an arc in a stereographic projection can be interpreted as resulting from TPW if there is a significant amount of time from start to end of magnetization. Our ongoing work includes continued analysis and scanning of our slices as well as statistical tests for confirming if the dipoles lie along an arc. [1] Sprenke, KF et al. 2005 Icarus 174(2) 486-9 [2] Perron, JT et al. 2007 Nature 447(7146) 840-3 [3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=magma&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmagma','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=magma&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmagma"><span>Signatures in <span class="hlt">Martian</span> Volatiles and the Magma Sources of NC <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marti, K.; Mathew, K. J.</p> <p>2004-01-01</p> <p>We report nitrogen and xenon isotopic signatures in Yamato nakhlites and use the data to assess properties of the magma source of NC <span class="hlt">meteorites</span> in planet Mars. The Chassigny <span class="hlt">meteorite</span> was investigated by Floran et al, who classified it as a cumulate dunite with hydrous amphibole-bearing melt inclusions with no preferred orientation of the olivines. Their inferred composition of the parent magma, which was based on electron microprobe analyses, has been questioned. The trace and minor elements in minerals were analyzed in nakhlites and in Chassigny and the authors conclude that nakhlites may represent samples from different horizons of the same lithologic unit, but that Chassigny was not co-magmatic with the nakhlites.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1800.5316C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1800.5316C"><span>NWA 8114: Analysis of Xenon in this Unique <span class="hlt">Martian</span> <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crowther, S. A.; Jastrzebski, N. D.; Nottingham, M.; Theis, K. J.; Gilmour, J. D.</p> <p>2014-09-01</p> <p>The Xe composition of NWA 8114 is dominated by <span class="hlt">martian</span> atmospheric xenon, with contributions from terrestrial atmospheric contamination at low temperature and fissiogenic xenon at high temperature. The overall systematics are similar to Nakhla.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.584S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.584S"><span>Noble Gases in the Lunar <span class="hlt">Meteorites</span> Calcalong Creek and QUE 93069</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swindle, T. D.; Burkland, M. K.; Grier, J. A.</p> <p>1995-09-01</p> <p>Although the world's collections contain comparable numbers of <span class="hlt">martian</span> and lunar <span class="hlt">meteorites</span> (about 10 each), their ejection histories seem to be quite different [1]. We have sampled no more than four <span class="hlt">martian</span> craters, but almost every one of the lunar <span class="hlt">meteorites</span> apparently represents a separate cratering event. Furthermore, most lunar <span class="hlt">meteorites</span> were apparently ejected from the top meter of the surface, unlike any of the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. We have measured noble gases in two bulk samples of the lunar <span class="hlt">meteorite</span> QUE93069 and three of Calcalong Creek, ranging in size from 7 to 15 mg. Averaged results are given in Table 1. Both <span class="hlt">meteorites</span> contain solar-wind-implanted noble gas. QUE 93069, which is a mature anorthositic regolith breccia [2], contains amounts comparable to the most gas-rich lunar <span class="hlt">meteorites</span>. The relatively low 40Ar/36Ar ratios of both <span class="hlt">meteorites</span> suggest surface exposures no more than 2.5 Ga ago [3]. Calcalong Creek has readily observable spallogenic gas. The 131Xe/126Xe ratio of 4.8+/-0.3 corresponds to an average shielding depth of slightly more than 40 gm/cm^2 [4]. In common with many lunar breccias, Calcalong Creek has been exposed to cosmic rays for several hundred Ma (calculations based on [4] and [5]). The 3He apparent exposure age is much shorter, suggesting diffusive loss of He. To determine the detailed exposure history, it is necessary to have measurements of cosmogenic radionuclides. Our samples were too small to measure 81Kr, but [6] have measured 10Be, 26Al and 36Cl. Their data are consistent with either extended exposure at <70 gm/cm^2 in the lunar regolith followed by a short (200,000 years) transit to Earth, or with ejection from several meters depth about 2 Ma ago [6]. Our data, requiring several hundred Ma of exposure at an average depth of 40-50 gm/cm^2, are clearly more consistent with the first scenario. The only other lunar <span class="hlt">meteorite</span> which could have been ejected at the same time is MAC 88104/5 [1], but the chemical differences</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4230006','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4230006"><span>Chloromethane release from carbonaceous <span class="hlt">meteorite</span> affords new insight into Mars lander findings</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Keppler, Frank; Harper, David B.; Greule, Markus; Ott, Ulrich; Sattler, Tobias; Schöler, Heinz F.; Hamilton, John T. G.</p> <p>2014-01-01</p> <p>Controversy continues as to whether chloromethane (CH3Cl) detected during pyrolysis of <span class="hlt">Martian</span> soils by the Viking and Curiosity Mars landers is indicative of organic matter indigenous to Mars. Here we demonstrate CH3Cl release (up to 8 μg/g) during low temperature (150–400°C) pyrolysis of the carbonaceous chondrite Murchison with chloride or perchlorate as chlorine source and confirm unequivocally by stable isotope analysis the extraterrestrial origin of the methyl group (δ2H +800 to +1100‰, δ13C −19.2 to +10‰,). In the terrestrial environment CH3Cl released during pyrolysis of organic matter derives from the methoxyl pool. The methoxyl pool in Murchison is consistent both in magnitude (0.044%) and isotope signature (δ2H +1054 ± 626‰, δ13C +43.2 ± 38.8‰,) with that of the CH3Cl released on pyrolysis. Thus CH3Cl emissions recorded by Mars lander experiments may be attributed to methoxyl groups in undegraded organic matter in <span class="hlt">meteoritic</span> debris reaching the <span class="hlt">Martian</span> surface being converted to CH3Cl with perchlorate or chloride in <span class="hlt">Martian</span> soil. However we cannot discount emissions arising additionally from organic matter of indigenous origin. The stable isotope signatures of CH3Cl detected on Mars could potentially be utilized to determine its origin by distinguishing between terrestrial contamination, <span class="hlt">meteoritic</span> infall and indigenous <span class="hlt">Martian</span> sources. PMID:25394222</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E7010K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E7010K"><span>Chloromethane release from carbonaceous <span class="hlt">meteorite</span> affords new insight into Mars lander findings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keppler, Frank; Harper, David B.; Greule, Markus; Ott, Ulrich; Sattler, Tobias; Schöler, Heinz F.; Hamilton, John T. G.</p> <p>2014-11-01</p> <p>Controversy continues as to whether chloromethane (CH3Cl) detected during pyrolysis of <span class="hlt">Martian</span> soils by the Viking and Curiosity Mars landers is indicative of organic matter indigenous to Mars. Here we demonstrate CH3Cl release (up to 8 μg/g) during low temperature (150-400°C) pyrolysis of the carbonaceous chondrite Murchison with chloride or perchlorate as chlorine source and confirm unequivocally by stable isotope analysis the extraterrestrial origin of the methyl group (δ2H +800 to +1100‰, δ13C -19.2 to +10‰,). In the terrestrial environment CH3Cl released during pyrolysis of organic matter derives from the methoxyl pool. The methoxyl pool in Murchison is consistent both in magnitude (0.044%) and isotope signature (δ2H +1054 +/- 626‰, δ13C +43.2 +/- 38.8‰,) with that of the CH3Cl released on pyrolysis. Thus CH3Cl emissions recorded by Mars lander experiments may be attributed to methoxyl groups in undegraded organic matter in <span class="hlt">meteoritic</span> debris reaching the <span class="hlt">Martian</span> surface being converted to CH3Cl with perchlorate or chloride in <span class="hlt">Martian</span> soil. However we cannot discount emissions arising additionally from organic matter of indigenous origin. The stable isotope signatures of CH3Cl detected on Mars could potentially be utilized to determine its origin by distinguishing between terrestrial contamination, <span class="hlt">meteoritic</span> infall and indigenous <span class="hlt">Martian</span> sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25394222','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25394222"><span>Chloromethane release from carbonaceous <span class="hlt">meteorite</span> affords new insight into Mars lander findings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keppler, Frank; Harper, David B; Greule, Markus; Ott, Ulrich; Sattler, Tobias; Schöler, Heinz F; Hamilton, John T G</p> <p>2014-11-13</p> <p>Controversy continues as to whether chloromethane (CH3Cl) detected during pyrolysis of <span class="hlt">Martian</span> soils by the Viking and Curiosity Mars landers is indicative of organic matter indigenous to Mars. Here we demonstrate CH3Cl release (up to 8 μg/g) during low temperature (150-400°C) pyrolysis of the carbonaceous chondrite Murchison with chloride or perchlorate as chlorine source and confirm unequivocally by stable isotope analysis the extraterrestrial origin of the methyl group (δ(2)H +800 to +1100‰, δ(13)C -19.2 to +10‰,). In the terrestrial environment CH3Cl released during pyrolysis of organic matter derives from the methoxyl pool. The methoxyl pool in Murchison is consistent both in magnitude (0.044%) and isotope signature (δ(2)H +1054 ± 626‰, δ(13)C +43.2 ± 38.8‰,) with that of the CH3Cl released on pyrolysis. Thus CH3Cl emissions recorded by Mars lander experiments may be attributed to methoxyl groups in undegraded organic matter in <span class="hlt">meteoritic</span> debris reaching the <span class="hlt">Martian</span> surface being converted to CH3Cl with perchlorate or chloride in <span class="hlt">Martian</span> soil. However we cannot discount emissions arising additionally from organic matter of indigenous origin. The stable isotope signatures of CH3Cl detected on Mars could potentially be utilized to determine its origin by distinguishing between terrestrial contamination, <span class="hlt">meteoritic</span> infall and indigenous <span class="hlt">Martian</span> sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5966191','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5966191"><span>Chronology of <span class="hlt">martian</span> breccia NWA 7034 and the formation of the <span class="hlt">martian</span> crustal dichotomy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wimpenny, Joshua</p> <p>2018-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> Northwest Africa (NWA) 7034 and its paired stones are the only brecciated regolith samples from Mars with compositions that are representative of the average <span class="hlt">martian</span> crust. These samples therefore provide a unique opportunity to constrain the processes of metamorphism and alteration in the <span class="hlt">martian</span> crust, which we have investigated via U-Pu/Xe, 40Ar/39Ar, and U-Th-Sm/He chronometry. U-Pu/Xe ages are comparable to previously reported Sm-Nd and U-Pb ages obtained from NWA 7034 and confirm an ancient (>4.3 billion years) age for the source lithology. After almost 3000 million years (Ma) of quiescence, the source terrain experienced several hundred million years of thermal metamorphism recorded by the K-Ar system that appears to have varied both spatially and temporally. Such protracted metamorphism is consistent with plume-related magmatism and suggests that the source terrain covered an areal extent comparable to plume-fed edifices (hundreds of square kilometers). The retention of such expansive, ancient volcanic terrains in the southern highlands over billions of years suggests that formation of the <span class="hlt">martian</span> crustal dichotomy, a topographic and geophysical divide between the heavily cratered southern highlands and smoother plains of the northern lowlands, likely predates emplacement of the NWA 7034 source terrain—that is, it formed within the first ~100 Ma of planetary formation. PMID:29806017</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29806017','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29806017"><span>Chronology of <span class="hlt">martian</span> breccia NWA 7034 and the formation of the <span class="hlt">martian</span> crustal dichotomy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cassata, William S; Cohen, Benjamin E; Mark, Darren F; Trappitsch, Reto; Crow, Carolyn A; Wimpenny, Joshua; Lee, Martin R; Smith, Caroline L</p> <p>2018-05-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> Northwest Africa (NWA) 7034 and its paired stones are the only brecciated regolith samples from Mars with compositions that are representative of the average <span class="hlt">martian</span> crust. These samples therefore provide a unique opportunity to constrain the processes of metamorphism and alteration in the <span class="hlt">martian</span> crust, which we have investigated via U-Pu/Xe, 40 Ar/ 39 Ar, and U-Th-Sm/He chronometry. U-Pu/Xe ages are comparable to previously reported Sm-Nd and U-Pb ages obtained from NWA 7034 and confirm an ancient (>4.3 billion years) age for the source lithology. After almost 3000 million years (Ma) of quiescence, the source terrain experienced several hundred million years of thermal metamorphism recorded by the K-Ar system that appears to have varied both spatially and temporally. Such protracted metamorphism is consistent with plume-related magmatism and suggests that the source terrain covered an areal extent comparable to plume-fed edifices (hundreds of square kilometers). The retention of such expansive, ancient volcanic terrains in the southern highlands over billions of years suggests that formation of the <span class="hlt">martian</span> crustal dichotomy, a topographic and geophysical divide between the heavily cratered southern highlands and smoother plains of the northern lowlands, likely predates emplacement of the NWA 7034 source terrain-that is, it formed within the first ~100 Ma of planetary formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028691','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028691"><span>Constraints on the <span class="hlt">Martian</span> cratering rate imposed by the SNC <span class="hlt">meteorites</span> and Vallis Marineris layered deposits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brandenburg, J. E.</p> <p>1993-01-01</p> <p>Following two independent lines of evidence -- estimates of the age and formation time of a portion of the <span class="hlt">Martian</span> geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC <span class="hlt">meteorites</span> -- it appears that the <span class="hlt">Martian</span> cratering rate must be double the lunar rate or even higher. This means models such as NHII or NHIII (Neukum and Hiller models II and III), which estimate the <span class="hlt">Martian</span> cratering rate as being several times lunar are probably far closer to reality on Mars than lunar rates. The effect of such a shift is profound: Mars is transformed from a rather Moon-like place into a planet with vigorous dynamics, multiple large impacts, erosion, floods, and volcanism throughout its history. A strong shift upward in cratering rates on Mars apparently solves some glaring problems; however, it creates others. The period of time during which Earth-like atmospheric conditions existed, the liquid water era on Mars, persists in NHIII up to only 0.5 b.y. ago. Scenarios of extended Earth-like conditions on Mars have been discounted in the past because they would have removed many of the craters from the early bombardment era found in the south. It does appear that some process of crater removal was quite vigorous in the north during Mars' past. Evidence exists that the northern plains may have been the home of long-lived seas or perhaps even a paleo-ocean, so models exist for highly localized destruction of craters in the north. However, the question of how the ancient crater population could be preserved in the south under a long liquid-water era found in any high-cratering-rate models is a serious question that must be addressed. It does appear to be a higher-order problem because it involves low-energy dynamics acting in localized areas, i.e., erosion of craters in the south of Mars, whereas the two problems with the low-cratering-rate models involve high-energy events acting over large areas: the formation of the Vallis Marineris</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890008935&hterms=duricrust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dduricrust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890008935&hterms=duricrust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dduricrust"><span><span class="hlt">Martian</span> regolith geochemistry and sampling techniques</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clark, B. C.</p> <p>1988-01-01</p> <p>Laboratory <span class="hlt">study</span> of samples of the intermediate and fine-grained regolith, including duricrust peds, is a fundamental prerequisite for understanding the types of physical and chemical weathering processes on Mars. The extraordinary importance of such samples is their relevance to understanding past changes in climate, availability (and possible physical state) of water, eolian forces, the thermal and chemical influences of volcanic and impact processes, and the inventory and fates of <span class="hlt">Martian</span> volatiles. Fortunately, this regolith material appears to be ubiquitous over the <span class="hlt">Martian</span> surface, and should be available at many different landing sites. Viking data has been interpreted to indicate a smectite-rich regolith material, implying extensive weathering involving aqueous activity and geochemical alteration. An all-igneous source of the <span class="hlt">Martian</span> fines has also been proposed. The X-ray fluorescence measurement data set can now be fully explained in terms of a simple two-component model. The first component is silicate, having strong geochemical similarities with Shergottites, but not other SNC <span class="hlt">meteorites</span>. The second component is salt. Variations in these components could produce silicate and salt-rich beds, the latter being of high potential importance for microenvironments in which liquid water (brines) could exist. It therefore would be desirable to scan the surface of the regolith for such prospects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988msrs.work...61C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988msrs.work...61C"><span><span class="hlt">Martian</span> regolith geochemistry and sampling techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, B. C.</p> <p></p> <p>Laboratory <span class="hlt">study</span> of samples of the intermediate and fine-grained regolith, including duricrust peds, is a fundamental prerequisite for understanding the types of physical and chemical weathering processes on Mars. The extraordinary importance of such samples is their relevance to understanding past changes in climate, availability (and possible physical state) of water, eolian forces, the thermal and chemical influences of volcanic and impact processes, and the inventory and fates of <span class="hlt">Martian</span> volatiles. Fortunately, this regolith material appears to be ubiquitous over the <span class="hlt">Martian</span> surface, and should be available at many different landing sites. Viking data has been interpreted to indicate a smectite-rich regolith material, implying extensive weathering involving aqueous activity and geochemical alteration. An all-igneous source of the <span class="hlt">Martian</span> fines has also been proposed. The X-ray fluorescence measurement data set can now be fully explained in terms of a simple two-component model. The first component is silicate, having strong geochemical similarities with Shergottites, but not other SNC <span class="hlt">meteorites</span>. The second component is salt. Variations in these components could produce silicate and salt-rich beds, the latter being of high potential importance for microenvironments in which liquid water (brines) could exist. It therefore would be desirable to scan the surface of the regolith for such prospects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020041721&hterms=LIE+ME+STYLE&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DLIE%2BTO%2BME%2BSTYLE','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020041721&hterms=LIE+ME+STYLE&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DLIE%2BTO%2BME%2BSTYLE"><span>Hydrogeological Interpretation of Candidate Origin Sites for <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gulick, Virginia C.; McKay, Chris; Cuzzi, Jeffrey N. (Technical Monitor)</p> <p>1996-01-01</p> <p>Barlow (this meeting) has identified two potential source craters for the <span class="hlt">martian</span> <span class="hlt">meteorite</span> ALH84001. The craters are at 11.7 deg S, 243.3 deg W (Mare Tyrrhenum site) and 14.0 deg S, 343.5 deg W (Sinus Sabaeus site). As noted by Barlow, both craters lie in the heavily cratered terrain (HCT) and are adjacent to fluvial valleys, Here I explore the fluvial history of these areas based upon the surrounding valley morphology. The most prominent valley network at the Sabaeus site is Evros Vallis. This wide, flat-floored valley is approximately 600 km long with an average width of 2.5 km and a depth of 220 m. The eroded volume of the entire Evros network is approximately 6 x 10(exp 11) cc. This is typical for networks located in the heavily cratered terrain (e.g. Warrego and Parana Valles). Evros is also an isolated valley system. No similar networks are found in the surrounding terrain. Thus it is unlikely that Evros formed as a result of widespread rainfall. A localized water source, such as discharge of a hydrothermal system or localized melting of snowfall, seems more consistent Previous modeling has demonstrated that only hydrothermal systems associated with high permeability subsurfaces can discharge sufficient water to form a valley network. The bulk of the discharge from such systems is consequently low temperature, slightly heated water Precipitation of calcium carbonate by low temperature fluids is consistent with most interpretations of the geochemistry of ALH84001. Available imagery at the Tyrrhenum site is of lesser quality. While eroded units of the HCT are nearby, there are no comparable well developed valley networks at this site. Erosion is instead manifested predominantly as gullies on slopes. This style of erosion suggests that water was not present at this site for the length of time as at the more integrated Sabaeus site. The superposition of fluidized ejecta blankets suggests however that ground water or ground ice was still present at this locality</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910016770&hterms=Physical+Review&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPhysical%2BReview','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910016770&hterms=Physical+Review&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPhysical%2BReview"><span>Physical and chemical properties of the <span class="hlt">Martian</span> soil: Review of resources</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stoker, C. R.; Gooding, James L.; Banin, A.; Clark, Benton C.; Roush, Ted</p> <p>1991-01-01</p> <p>The chemical and physical properties of <span class="hlt">Martian</span> surface materials are reviewed from the perspective of using these resources to support human settlement. The resource potential of <span class="hlt">Martian</span> sediments and soils can only be inferred from limited analyses performed by the Viking Landers (VL), from information derived from remote sensing, and from analysis of the SNC <span class="hlt">meteorites</span> thought to be from Mars. Bulk elemental compositions by the VL inorganic chemical (x ray fluorescence) analysis experiments have been interpreted as evidence for clay minerals (possibly smectites) or mineraloids (palagonite) admixed with sulfate and chloride salts. The materials contained minerals bearing Fe, Ti, Al, Mg and Si. <span class="hlt">Martian</span> surface materials may be used in many ways. <span class="hlt">Martian</span> soil, with appropriate preconditioning, can probably be used as a plant growth medium, supplying mechanical support, nutrient elements, and water at optimal conditions to the plants. Loose <span class="hlt">Martian</span> soils could be used to cover structures and provide radiation shielding for surface habitats. <span class="hlt">Martian</span> soil could be wetted and formed into abode bricks used for construction. Duricrete bricks, with strength comparable to concrete, can probably be formed using compressed muds made from <span class="hlt">martian</span> soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150015828','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150015828"><span>Re-Os Isotopic Constraints on the Chemical Evolution and Differentiation of the <span class="hlt">Martian</span> Mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brandon, Alan D.; Walker, Richard J.</p> <p>2002-01-01</p> <p>The (187)Re-187Os isotopic systematics of SNC <span class="hlt">meteorites</span>, thought to be from Mars, provide valuable information regarding the chemical processes that affected the <span class="hlt">Martian</span> mantle, particularly with regard to the relative abundances of highly siderophile elements (HSE). Previously published data (Birck and Allegre 1994, Brandon et al. 2000), and new data obtained since these <span class="hlt">studies</span>, indicate that the HSE and Os isotopic composition of the <span class="hlt">Martian</span> mantle was primarily set in its earliest differentiation history. If so, then these <span class="hlt">meteorites</span> provide key constraints on the processes that lead to variation in HSE observed in not only Mars, but also Earth, the Moon and other rocky bodies in the Solar System. Processes that likely have an effect on the HSE budgets of terrestrial mantles include core formation, magma ocean crystallization, development of juvenile crust, and the addition of a late veneer. Each of these processes will result in different HSE variation and the isotopic composition of mantle materials and mantle derived lavas. Two observations on the SNC data to present provide a framework for which to test the importance of each of these processes. First, the concentrations of Re and Os in SNC <span class="hlt">meteorites</span> indicate that they are derived from a mantle that has similar concentrations to the Earth's mantle. Such an observation is consistent with a model where a chondritic late veneer replenished the Earth and <span class="hlt">Martian</span> mantles subsequent to core formation on each planet. Alternative models to explain this observation do exist, but will require additional data to test the limitations of each. Second, Re-Os isotopic results from Brandon et al. (2000) and new data presented here, show that initial yos correlates with variations in the short-lived systems of (182)Hf- (182)W and (142)Sm-142Nd in the SNC <span class="hlt">meteorites</span> (epsilon(sub W) and epsilon(sub 142Nd)). These systematics require an isolation of mantle reservoirs during the earliest differentiation history of Mars, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001706','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001706"><span>Distinct Chlorine Isotopic Reservoirs on Mars: Implications for Character, Extent and Relative Timing of Crustal Interaction with Mantle-Derived Magmas, Evolution of the <span class="hlt">Martian</span> Atmosphere, and the Building Blocks of an Early Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, C. K.; Messenger, S.; Sharp, Z. D.; Burger, P. V.; Nguyen, N.; McCubbin, F. M.</p> <p>2017-01-01</p> <p>The style, magnitude, timing, and mixing components involved in the interaction between mantle derived <span class="hlt">Martian</span> magmas and <span class="hlt">Martian</span> crust have long been a point of debate. Understanding this process is fundamental to deciphering the composition of the <span class="hlt">Martian</span> crust and its interaction with the atmosphere, the compositional diversity and oxygen fugacity variations in the <span class="hlt">Martian</span> mantle, the bulk composition of Mars and the materials from which it accreted, and the noble gas composition of Mars and the Sun. Recent <span class="hlt">studies</span> of the chlorine isotopic composition of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> imply that although the variation in delta (sup 37) Cl is limited (total range of approximately14 per mille), there appears to be distinct signatures for the <span class="hlt">Martian</span> crust and mantle. However, there are potential issues with this interpretation. New Cl isotope data from the SAM (Sample Analysis at Mars) instrument on the Mars Science Lab indicate a very wide range of Cl isotopic compositions on the <span class="hlt">Martian</span> surface. Recent measurements by [10] duplicated the results of [7,8], but placed them within the context of SAM surface data. In addition, <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Chassigny contains trapped noble gases with isotopic ratios similar to solar abundance, and has long been considered a pristine, mantle derived sample. However, previous <span class="hlt">studies</span> of apatite in Chassigny indicate that crustal fluids have interacted with regions interstitial to the cumulus olivine. The initial Cl isotope measurements of apatite in Chassigny suggest an addition of crustal component to this lithology, apparently contradicting the rare gas data. Here, we examine the Cl isotopic composition of multiple generations and textures of apatite in Chassigny to extricate the crustal and mantle components in this <span class="hlt">meteorite</span> and to reveal the style and timing of the addition of crustal components to mantle-derived magmas. These data reveal distinct <span class="hlt">Martian</span> Cl sources whose signatures have their origins linked to both the early Solar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.208..198G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.208..198G"><span>Effective radium-226 concentration in <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girault, Frédéric; Perrier, Frédéric; Moreira, Manuel; Zanda, Brigitte; Rochette, Pierre; Teitler, Yoram</p> <p>2017-07-01</p> <p>The analysis of noble gases in <span class="hlt">meteorites</span> provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in <span class="hlt">meteorites</span>. The knowledge of transfer properties of noble gases for each individual <span class="hlt">meteorite</span> could benefit from using radon-222, radioactive daughter of radium-226. The radon-222 emanating power is commonly quantified by the effective radium-226 concentration (ECRa), the product of the bulk radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of <span class="hlt">meteorite</span> samples, which usually have mass smaller than 15 g and ECRa < 0.5 Bq kg-1. We report here the results obtained from 41 different <span class="hlt">meteorites</span>, based on 129 measurements on 70 samples using two variants of our method, showing satisfactory repeatability and a detection limit below 10-2 Bq kg-1 for a sample mass of 1 g. While two <span class="hlt">meteorites</span> remain below detection level, we obtain for 39 <span class="hlt">meteorites</span> heterogeneous ECRa values with mean (min-max range) of ca. 0.1 (0.018-1.30) Bq kg-1. Carbonaceous chondrites exhibit the largest ECRa values and eucrites the smallest. Such values are smaller than typical values from most terrestrial rocks, but comparable with those from Archean rocks (mean of ca. 0.18 Bq kg-1), an end-member of terrestrial rocks. Using uranium concentration from the literature, E is inferred from ECRa for all the <span class="hlt">meteorite</span> samples. Values of E for <span class="hlt">meteorites</span> (mean 40 ± 4%) are higher than E values for Archean rocks and reported values for lunar and <span class="hlt">Martian</span> soils. Exceptionally large E values likely suggest that the 238U-226Ra pair would not be at equilibrium in most <span class="hlt">meteorites</span> and that uranium and/or radium are most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030066133&hterms=parents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dparents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030066133&hterms=parents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dparents"><span>Cosmochemical <span class="hlt">Studies</span>: <span class="hlt">Meteorites</span> and their Parent Asteroids</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wasson, John T.</p> <p>2003-01-01</p> <p>This a final technical report that focuses on cosmochemical <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and their parent asteroids. The topics include: 1) Formation of iron <span class="hlt">meteorites</span> and other metal rich <span class="hlt">meteorites</span>; 2) New perspectives on the formation of chondrules; and 3) Consequences of large aerial bursts. Also a list of seven papers that received significant support from this research are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712534O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712534O"><span>Origin of the soluble species in the Tissint Mars <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oberlin, Elizabeth; Kounaves, Samuel; Claire, Mark; Gabriel-Ori, Gian; Taj-Edine, Kamal</p> <p>2015-04-01</p> <p>The Tissint <span class="hlt">martian</span> <span class="hlt">meteorite</span> is a high magnesium olivine shergottite that was observed falling on 18 July 2011 near the Oued Drâa valley, Morocco [1]. Fragments collected over the next several months in the remote desert region should thus represent minimally contaminated fragments of <span class="hlt">martian</span> surface and crustal material. We obtained interior fragments of Tissint from the Natural History Museum in London, and analyzed the soluble species using ion chromatography. Analyses showed trace levels of perchlorate (ClO4-) as well as several other species including nitrate (NO3-), chlorate (ClO3), and sulfate (SO42-). In order to differentiate the measured species in Tissint from possible terrestrial contamination, we collected soil samples from the Tissint strewn field, centered at approximately 50km ESE of Tata, and 48 km SSW of Tissint, near El Ga'ïdat plateau and both N and S of Oued El Gsaïb valley. Samples were collected from the surface and at depth from over 15 sites spanning the strewn field. The samples were then brought back to our laboratory and analyzed for a variety of soluble inorganic species. We also compare these values to those recently reported for the Mars <span class="hlt">meteorite</span> EETA79001 [2], which shares similar lithology, elemental abundance, and cosmic ray exposure age, to the Tissint <span class="hlt">meteorite</span>. [1] Chennaoui Aoudjehane, H., et al., (2012) Science 338, 785-788 [2] Kounaves, S.P., et al., (2014) Icarus, 229, 206-213</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100003417','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003417"><span>In Situ Investigation of Iron <span class="hlt">Meteorites</span> at Meridiani Planum Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fleischer, I.; Klingelhoefer, G.; Schroeder, C.; Morris, R. V.; Golombek, M.; Ashley, J. W.</p> <p>2010-01-01</p> <p>The Mars Exploration Rover Opportunity has encountered four iron <span class="hlt">meteorites</span> at its landing site in Meridiani Planum. The first one, informally named "Heat Shield Rock", measuring approx.30 by 15 cm, was encountered in January 2005 [1, 2] and officially recognized as the first iron <span class="hlt">meteorite</span> on the <span class="hlt">martian</span> surface with the name "Meridiani Planum" after the location of its find [3]. We will refer to it as "Heat Shield Rock" to avoid confusion with the site. Between July and October 2009, separated approx.10 km from Heat Shield Rock, three other iron <span class="hlt">meteorite</span> fragments were encountered, informally named "Block Island" (approx.60 cm across), "Shelter Island" (approx.50 by 20 cm), and "Mackinac Island" (approx.30 cm across). Heat Shield Rock and Block Island, the two specimens investigated in detail, are shown in Figure 1. Here, we focus on the <span class="hlt">meteorites</span> chemistry and mineralogy. An overview in the mission context is given in [4]; other abstracts discuss their morphology [5], photometric properties [6], and their provenance [7].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140001394','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140001394"><span>NWA 7034 <span class="hlt">Martian</span> Breccia: Disturbed Rb-Sr Systematics, Preliminary Is Approximately 4.4 Ga Sm-Nd Age</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Shih, C.-Y.; Peng, Zhan Xiong; Agee, C</p> <p>2013-01-01</p> <p>Agee et al. [1] reported a Rb-Sr age of 2.089 [plus or minus] 0.081 Ga for the unique <span class="hlt">Martian</span> <span class="hlt">meteoritic</span> breccia NWA 7034 making it the oldest <span class="hlt">Martian</span> basalt, dating to the early Am-azonian epoch [2] of <span class="hlt">Martian</span> geologic history. We have attempt-ed to confirm this exciting result. Our new Rb-Sr analyses show the Rb-Sr isotopic system to be disturbed, but preliminary Sm-Nd data suggest an even older age of approximately 4.4 Ga for at least some brec-cia components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026344','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026344"><span>Ar-Ar Dating of <span class="hlt">Martian</span> Chassignites, NWA2737 and Chassigny, and Nakhlite MIL03346</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, D. D.; Garrison, D. H.</p> <p>2006-01-01</p> <p>Until recently only three nakhlites and one chassignite had been identified among <span class="hlt">martian</span> <span class="hlt">meteorites</span>. These four exhibit very similar radiometric ages and cosmic ray exposure (CRE) ages, indicating that they may have derived from a common location on Mars and were ejected into space by a single impact. This situation is quite different from that of <span class="hlt">martian</span> shergottites, which exhibit a range of radiometric ages and CRE ages (1). Recently, several new nakhlites and a new <span class="hlt">martian</span> dunite (NWA2737) have been recognized. Here we report our results of Ar-39-Ar-40 dating for the MIL03346 nakhlite and the NWA2737 "chassignite", along with new results on Chassigny.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150019423','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150019423"><span>Evidence from Hydrogen Isotopes in <span class="hlt">Meteorites</span> for a Subsurface Hydrogen Reservoir on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, Tomohiro; Alexander, Conel M. O'D.; Wang, Jianhua; Simon, Justin I.; Jones, John H.</p> <p>2015-01-01</p> <p>The surface geology and geomorphology of Mars indicates that it was once warm enough to maintain a large body of liquid water on its surface, though such a warm environment might have been transient. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. We have conducted in situ hydrogen isotope (D/H) analyses of quenched and impact glasses in three <span class="hlt">Martian</span> <span class="hlt">meteorites</span> (Yamato 980459, EETA79001, LAR 06319) by Cameca ims-6f at Digital Terrain Models (DTM) following the methods of [1]. The hydrogen isotope analyses provide evidence for the existence of a distinct but ubiquitous water/ice reservoir (D/H = 2-3 times Earth's ocean water: Standard Mean Ocean Water (SMOW)) that lasted from at least the time when the <span class="hlt">meteorites</span> crystallized (173-472 Ma) to the time they were ejected by impacts (0.7-3.3 Ma), but possibly much longer [2]. The origin of this reservoir appears to predate the current <span class="hlt">Martian</span> atmospheric water (D/H equals approximately 5-6 times SMOW) and is unlikely to be a simple mixture of atmospheric and primordial water retained in the <span class="hlt">Martian</span> mantle (D/H is approximately equal to SMOW [1]). Given the fact that this intermediate-D/H reservoir (2-3 times SMOW) is observed in a diverse range of <span class="hlt">Martian</span> materials with different ages (e.g., SNC (Shergottites, Nakhlites, Chassignites) <span class="hlt">meteorites</span>, including shergottites such as ALH 84001; and Curiosity surface data [3]), we conclude that this intermediate-D/H reservoir is likely a global surficial feature that has remained relatively intact over geologic time. We propose that this reservoir represents either hydrated crust and/or ground ice interbedded within sediments. Our results corroborate the hypothesis that a buried cryosphere accounts for a large part of the initial water budget of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010M%26PS...45.1359C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010M%26PS...45.1359C"><span>Terrestrial and <span class="hlt">Martian</span> weathering signatures of xenon components in shergottite mineral separates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cartwright, J. A.; Ocker, K. D.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.</p> <p>2010-08-01</p> <p>Xenon-isotopic ratios, step-heating release patterns, and gas concentrations of mineral separates from <span class="hlt">Martian</span> shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of <span class="hlt">Martian</span> atmospheric xenon are similar in mineral separates from all <span class="hlt">meteorites</span>, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the <span class="hlt">Martian</span> and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, <span class="hlt">Martian</span> atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both <span class="hlt">Martian</span> and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the <span class="hlt">Martian</span> component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable 129Xe from the <span class="hlt">Martian</span> atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock's parent melt. Variable contents of excess 129Xe contrast with previously reported consistent concentrations of excess 40Ar, suggesting distinct sources contributed these gases to the parent magma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030012645&hterms=library&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlibrary','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030012645&hterms=library&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlibrary"><span><span class="hlt">Martian</span> Analogue Sample Characterization and Spectral Library Development at the Johnson Space Center</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, Richard V.</p> <p>2002-01-01</p> <p>An extensive collection of <span class="hlt">Martian</span> analogue samples housed at the Johnson Space Center is the focus of ongoing research by the JSC Mars soil genesis group and their collaborators. Because the major element composition of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and in situ analyses of <span class="hlt">Martian</span> soils and rocks indicate that Mars is predominantly an iron-rich basaltic world, the focus of active sample collection and analysis is basaltic materials and their hydrolytic (both aqueous and hydrothermal) and sulfatetic alteration products. Described below are the scope of the JSC Mars analogue sample collection, the characterization process, and plans to incorporate the data into spectral libraries for the Mars 2003 Mars Exploration Rover (MER) and Mars 2005 Mars Reconnaissance Orbiter (MRO) CRISM missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920019235','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920019235"><span>Papers Presented to the Workshop on the Evolution of the <span class="hlt">Martian</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>This volume contains papers that have been accepted for the Workshop on the Evolution of the <span class="hlt">Martian</span> Atmosphere. The abstracts presented in the paper cover such topics as: modeling of the mars atmosphere from early development to present including specific conditions affecting development; <span class="hlt">studies</span> of various atmospheric gases such as O2, SO2, CO2, NH3, and nitrogen; <span class="hlt">meteorite</span> impacts and their effects on the atmosphere; and water inventories and cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPSC...11..609K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPSC...11..609K"><span>Groups of <span class="hlt">meteorite</span>-producing meteoroids containing carbonaceous chondrite <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konovalova, N. A.; A.. Ibrohimov, A.; Kalashnikova, T. M.</p> <p>2017-09-01</p> <p>Proposed probable links of <span class="hlt">meteorite</span> and <span class="hlt">meteorite</span>-producing fireballs were been considered. Group associations between <span class="hlt">meteorite</span>-producing meteoroids and <span class="hlt">meteorites</span> were been determined for four carbonaceous chondrites Murchison, Maribo, Shutters Mill and Tagish Lake and potentially <span class="hlt">meteorite</span>-producing bolides on the basis of links of their orbits. In result the several <span class="hlt">meteorite</span>-producing sporadic slowly fireballs were found as the possible members of groups of four <span class="hlt">studied</span> carbonaceous chondrite <span class="hlt">meteorites</span>. One can presume that at present the identified groups may still contain large <span class="hlt">meteorite</span>-dropping bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17155889','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17155889"><span>Was Earth ever infected by <span class="hlt">martian</span> biota? Clues from radioresistant bacteria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pavlov, Anatoly K; Kalinin, Vitaly L; Konstantinov, Alexei N; Shelegedin, Vladimir N; Pavlov, Alexander A</p> <p>2006-12-01</p> <p>Here we propose that the radioresistance (tolerance to ionizing radiation) observed in several terrestrial bacteria has a <span class="hlt">martian</span> origin. Multiple inconsistencies with the current view of radioresistance as an accidental side effect of tolerance to desiccation are discussed. Experiments carried out 25 years ago were reproduced to demonstrate that "ordinary" bacteria can develop high radioresistance ability after multiple cycles of exposure to high radiation dosages followed by cycles of recovery of the bacterial population. We argue that "natural" cycles of this kind could have taken place only on the <span class="hlt">martian</span> surface, and we hypothesize that Mars microorganisms could have developed radioresistance in just several million years' time and, subsequently, have undergone transfer to Earth by way of <span class="hlt">martian</span> <span class="hlt">meteorites</span>. Our mechanism implies multiple and frequent exchanges of biota between Mars and Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980017923','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980017923"><span>Trace Element Geochemistry of <span class="hlt">Martian</span> Iddingsite in the Lafayette <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.; Lindstrom, David J.</p> <p>1997-01-01</p> <p>The Lafayette <span class="hlt">meteorite</span> contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the <span class="hlt">meteorite</span> and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, Al, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of approximately 50% Lafayette olivine + approximately 40% Lafayette siliceous glass + approximately 1O% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than implied by the model, which may suggest that the altering solutions were rich in Mg(2+).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005444','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005444"><span>Effect of Sulfur on Siderophile Element Partitioning Between Olivine and <span class="hlt">Martian</span> Primary Melt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.</p> <p>2011-01-01</p> <p>Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental <span class="hlt">studies</span> have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively <span class="hlt">studied</span> because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental <span class="hlt">studies</span> are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive shergottite melts [10] implies that S might have significantly influenced the Ni and Co partitioning into shergottite olivines. This <span class="hlt">study</span> conducts melting experiments on <span class="hlt">Martian</span> magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and <span class="hlt">Martian</span> primary melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000110466&hterms=fossils+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dfossils%2Bform','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000110466&hterms=fossils+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dfossils%2Bform"><span>Manganese, Metallogenium, and <span class="hlt">Martian</span> Microfossils</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stein, L. Y.; Nealson, K. H.</p> <p>1999-01-01</p> <p>Manganese could easily be considered an abundant element in the <span class="hlt">Martian</span> regolith, assuming that the composition of <span class="hlt">martian</span> <span class="hlt">meteorites</span> reflects the composition of the planet. Mineralogical analyses of 5 SNC <span class="hlt">meteorites</span> have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990109991&hterms=mass+spectrometry+review&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmass%2Bspectrometry%2Breview','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990109991&hterms=mass+spectrometry+review&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmass%2Bspectrometry%2Breview"><span>Analyses at High Spatial Resolution of Organic Molecules in Extraterrestrial Samples: Two-Step Laser Mass Spectrometry: Search for Polycyclic Aromatic Hydrocarbons in Antarctic <span class="hlt">Meteorite</span> and Micrometeorite Samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zare, Richard N.</p> <p>1998-01-01</p> <p>Perhaps the best way to summarize the past three-year grant period is to cite the publications and present a brief synopsis of each: 1. "Indigenous Polycyclic Aromatic Hydrocarbon Molecules in Circumstellar Graphite Grains." Bulk C-12/C-13 isotope ratios observed in some graphite grains extracted from primitive <span class="hlt">meteorites</span> point strongly to a circumstellar origin. By applying our technique of microprobe two-step laser desorption laser ionization mass spectrometry ((mu)L(sup 2)MS) to individual circumstellar graphite grains we have measured the C-12/C-13 isotope ratio of various polycyclic aromatic hydrocarbons (PAHS) found in these grains. 2. "Deuterium Enrichments in Cluster IDPS," Large enrichments in the D/H isotope ratios in IDPs likely arise from the preservation of presolar molecules. 3. "Evidence for thermalization of surface-disorder molecules at heating rates of 10(exp 8) K/s". A careful <span class="hlt">study</span> of the ((mu)L(sup 2)MS) of aniline-d(sub 7) from a single-crystal surface (0001) of sapphire (al2O3) shows that all measured properties are consistent with a thermal mechanism for desorption. 4. "Search for past life on Mars; possible relic biogenic activity in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH 84001. The authors examined the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH 84001 and found several lines of evidence compatible with existence of past primitive (single-cell) life on early Mars. 5. "Microprobe two-step laser mass spectrometry as an analytical tool for <span class="hlt">meteorite</span> samples". THis paper presents a comprehensive review of (mu)L(sup 2)MS and how this technique can be applied to <span class="hlt">meteoritic</span> samples. 6. "Indigenous polycyclic aromatic hydrocarbons in circumstellar graphite grains from primitive <span class="hlt">meteorites</span>". The C-12/C-13 isotope ratios were measured for PAHs in a total of 89 spherical graphite grains. 7. "Observation of indigenous polycyclic aromatic hydrocarbons in "Giant" carbonaceous antarctic micrometeorites." The (mu)L(sup 2)MS method was used to establish the nature and distribution of PAHs in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017oeps.book...16W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017oeps.book...16W"><span><span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Kun; Korotev, Randy</p> <p>2017-05-01</p> <p> general directions of <span class="hlt">meteoritic</span> <span class="hlt">studies</span> are: (1) mineralogy, identifying new minerals or mineral phases that rarely or seldom found on the Earth; (2) petrology, <span class="hlt">studying</span> the igneous and aqueous textures that given <span class="hlt">meteorites</span>' unique appearances and providing information about geologic processes on the bodies upon which the <span class="hlt">meteorites</span> originates; (3) geochemistry, characterizing their major, trace elemental and isotopic compositions and conducting interplanetary comparisons; and (4) chronology, dating the ages of the initial crystallization and later on impacting disturbances. <span class="hlt">Meteorites</span> are the only extraterrestrial samples other than Apollo lunar rocks that we can directly analyze in laboratories. Through the <span class="hlt">studies</span> of <span class="hlt">meteorites</span>, we have quested a vast amount of knowledge about the origin of the Solar System, the nature of the molecular cloud, the solar nebula, the nascent Sun and its planetary bodies including the Earth, Mars, Moon, and many asteroids. In fact, the 4.6-billion-year age of the whole Solar System is solely defined by the oldest age dated in <span class="hlt">meteorites</span>, which marked the beginning of everything we appreciate today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002847','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002847"><span>Correlations Between Surficial Sulfur and a REE Crustal Assimilation Signature in <span class="hlt">Martian</span> Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, J. H.; Franz, H. B.</p> <p>2015-01-01</p> <p>Compared to terrestrial basalts, the <span class="hlt">Martian</span> shergottite <span class="hlt">meteorites</span> have an extraordinary range of Sr and Nd isotopic signatures. In addition, the S isotopic compositions of many shergottites show evidence of interaction with the <span class="hlt">Martian</span> surface/ atmosphere through mass-independent isotopic fractionations (MIF, positive, non-zero delta(exp 33)S) that must have originated in the <span class="hlt">Martian</span> atmosphere, yet ultimately were incorporated into igneous sulfides (AVS - acid-volatile sulfur). These positive delta(exp 33)S signatures are thought to be governed by solar UV photochemical processes. And to the extent that S is bound to Mars and not lost to space from the upper atmosphere, a positive delta(exp 33)S reservoir must be mass balanced by a complementary negative reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.230B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.230B"><span>Enhancement of inorganic <span class="hlt">Martian</span> dust simulant with carbon component and its effects on key characteristics of glutamatergic neurotransmission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borisova, Tatiana; Krisanova, Natalia; Nazarova, Anastasiya; Borysov, Arseniy; Pastukhov, Artem; Pozdnyakova, Natalia; Dudarenko, Marina</p> <p>2016-07-01</p> <p>Evidence on the past existence of subsurface organic-bearing fluids on Mars was recently achieved basing on the investigation of organic carbon from the Tissint <span class="hlt">Martian</span> <span class="hlt">meteorite</span> (Lin et al., 2014). Tremendous amount of <span class="hlt">meteorites</span> containing abundant carbon and carbon-enriched dust particles have reached the Earth daily (Pizzarello and Shock 2010). National Institute of Environmental Health Sciences/National Institute of Health panel of research scientists revealed recently that accumulating evidences suggest that nano-sized air pollution may have a significant impact on central nervous system in health and disease (Block et al., Neurotoxicology, 2012). During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the central nervous system (Oberdorster et al., 2004). Based on above facts, the aims of this <span class="hlt">study</span> were: 1) to upgrade inorganic <span class="hlt">Martian</span> dust stimulant derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, nanodiamonds; 2) to analyse acute effects of upgraded stimulant on the key characteristic of synaptic neurotransmission and to compare its effects with those of inorganic dust and carbon components per se. Acute administration of carbon-containing <span class="hlt">Martian</span> dust analogue resulted in a significant decrease in Na+-dependent uptake of L-[14C]glutamate that is the major excitatory neurotransmitter in the central nervous system (CNS). The ambient level of the neurotransmitter in the preparation of isolated rat brain nerve terminals increased in the presence of carbon-contained <span class="hlt">Martian</span> dust analogue. This fact indicated that carbon component of native <span class="hlt">Martian</span> dust can have deleterious effects on extracellular glutamate homeostasis in the CNS, and so glutamatergic neurtransmission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050109883&hterms=mining+topography&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmining%2Btopography','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050109883&hterms=mining+topography&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmining%2Btopography"><span>Lunar and <span class="hlt">Martian</span> Sub-surface Habitat Structure Technology Development and Application</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boston, Penelope J.; Strong, Janet D.</p> <p>2005-01-01</p> <p>NASA's human exploration initiative poses great opportunity and great risk for manned missions to the Moon and Mars. Subsidace structures such as caves and lava tubes offer readily available and existing in-situ habitat options. Sub-surface dwellings can provide complete radiation, micro-<span class="hlt">meteorite</span> and exhaust plume shielding and a moderate and constant temperature environment; they are, therefore, excellent pre-existing habitat risk mitigation elements. Technical challenges to subsurface habitat structure development include surface penetration (digging and mining equipment), environmental pressurization, and psychological environment enhancement requirements. Lunar and <span class="hlt">Martian</span> environments and elements have many beneficial similarities. This will allow for lunar testing and design development of subsurface habitat structures for <span class="hlt">Martian</span> application; however, significant differences between lunar and <span class="hlt">Martian</span> environments and resource elements will mandate unique application development. Mars is NASA's ultimate exploration goal and is known to have many very large lava tubes. Other cave types are plausible. The Moon has unroofed rilles and lava tubes, but further research will, in the near future, define the extent of Lunar and <span class="hlt">Martian</span> differences and similarities. This paper will discuss Lunar and <span class="hlt">Martian</span> subsurface habitation technology development challenges and opportunities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910017749','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910017749"><span>Chemistry and mineralogy of <span class="hlt">Martian</span> dust: An explorer's primer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.</p> <p>1991-01-01</p> <p>A summary of chemical and mineralogical properties of <span class="hlt">Martian</span> surface dust is offered for the benefit of engineers or mission planners who are designing hardware or strategies for Mars surface exploration. For technical details and specialized explanations, references should be made to literature cited. Four sources used for information about <span class="hlt">Martian</span> dust composition: (1) Experiments performed on the Mars surface by the Viking Landers 1 and 2 and Earth-based lab experiments attempting to duplicate these results; (2) Infrared spectrophotometry remotely performed from Mars orbit, mostly by Mariner 9; (3) Visible and infrared spectrophotometry remotely performed from Earth; and (4) Lab <span class="hlt">studies</span> of the shergottite nakhlite chassignite (SNC) clan of <span class="hlt">meteorites</span>, for which compelling evidence suggests origin on Mars. Source 1 is limited to fine grained sediments at the surface whereas 2 and 3 contain mixed information about surface dust (and associated rock) and atmospheric dust. Source 4 has provided surprisingly detailed information but investigations are still incomplete.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080013502','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080013502"><span>Antarctic <span class="hlt">Meteorite</span> Newsletter, Volume 31, No. 1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Satterwhite, Cecilia (Editor); Righter, Kevin (Editor)</p> <p>2008-01-01</p> <p>This newsletter reports 418 new <span class="hlt">meteorites</span> from the 2004 and 2006 ANSMET seasons from the Cumulus Hills (CMS), LaPaz Ice Field (LAP), Graves Nunataks (GRA), Grosvenor Mountains (GRO), Larkman Nunatak (LAR), MacAlpine Hills (MAC), Miller Range (MIL), Roberts Massif (RBT), and Scott Glacier (SCO). These new samples include one iron, 1 eucrite, 1 mesosiderite, 6 CK chondrites (2 with pairing), 2 CV3 chondrites, 1 CM1, 7 CM2 (4 with pairing), 3 CR2 (2 with pairing), and one each of a type 3 L and H chondrites. The CK6 chondrites (LAR 06869, 06872, 06873) are unusual in that they have no discernable chondrules, extremely fine-grained texture, and are full of veins. This newsletter represents a break from recent newsletters in which we have announced many unusual and popular samples, including new lunar and <span class="hlt">martian</span> <span class="hlt">meteorites</span>, an unusual achondrite (GRA 06128 and 06129 the topic of a special session at this years LPSC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010045235&hterms=biology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbiology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010045235&hterms=biology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbiology"><span>Organic Matter in SNC <span class="hlt">Meteorites</span>: Is It Time to Re-Evaluate the Viking Biology Experimental Data?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Warmflash, D.; Clemett, S. J.; McKay, D. S.</p> <p>2001-01-01</p> <p>New data from SNC <span class="hlt">meteorites</span> suggests that organic material may be present in the <span class="hlt">martian</span> upper crust. This adds to possibility that the Viking biology experiments may have plausible biological interpretations as well as inorganic chemical interpretations Additional information is contained in the original extended abstract..</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51..981A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..981A"><span>New triple oxygen isotope data of bulk and separated fractions from SNC <span class="hlt">meteorites</span>: Evidence for mantle homogeneity of Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Arshad; Jabeen, Iffat; Gregory, David; Verish, Robert; Banerjee, Neil R.</p> <p>2016-05-01</p> <p>We report precise triple oxygen isotope data of bulk materials and separated fractions of several Shergotty-Nakhla-Chassigny (SNC) <span class="hlt">meteorites</span> using enhanced laser-assisted fluorination technique. This <span class="hlt">study</span> shows that SNCs have remarkably identical Δ17O and a narrow range in δ18O values suggesting that these <span class="hlt">meteorites</span> have assimilated negligibly small surface materials (<5%), which is undetectable in the oxygen isotope compositions reported here. Also, fractionation factors in coexisting silicate mineral pairs (px-ol and mask-ol) further demonstrate isotopic equilibrium at magmatic temperatures. We present a mass-dependent fractionation line for bulk materials with a slope of 0.526 ± 0.016 (1SE) comparable to the slope obtained in an earlier <span class="hlt">study</span> (0.526 ± 0.013; Franchi et al. 1999). We also present a new <span class="hlt">Martian</span> fractionation line for SNCs constructed from separated fractions (i.e., pyroxene, olivine, and maskelynite) with a slope of 0.532 ± 0.009 (1SE). The identical fractionation lines run above and parallel to our terrestrial fractionation line with Δ17O = 0.318 ± 0.016‰ (SD) for bulk materials and 0.316 ± 0.009‰ (SD) for separated fractions. The conformity in slopes and Δ17O between bulk materials and separated fractions confirm oxygen isotope homogeneity in the <span class="hlt">Martian</span> mantle though recent <span class="hlt">studies</span> suggest that the <span class="hlt">Martian</span> lithosphere may potentially have multiple oxygen isotope reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011745','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011745"><span>Tracking the <span class="hlt">Martian</span> Mantle Signature in Olivine-Hosted Melt Inclusions of Basaltic Shergottites Yamato 980459 and Tissint</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Moriwaki, R.; Economos, R.; Schmitt, A.; McKeegan, K.</p> <p>2014-01-01</p> <p>The <span class="hlt">Martian</span> shergottite <span class="hlt">meteorites</span> are basaltic to lherzolitic igneous rocks that represent a period of relatively young mantle melting and volcanism, approximately 600-150 Ma (e.g. [1,2]). Their isotopic and elemental composition has provided important constraints on the accretion, evolution, structure and bulk composition of Mars. Measurements of the radiogenic isotope and trace element concentrations of the shergottite <span class="hlt">meteorite</span> suite have identified two end-members; (1) incompatible trace element enriched, with radiogenic Sr and negative epsilon Nd-143, and (2) incompatible traceelement depleted, with non-radiogenic Sr and positive epsilon 143-Nd(e.g. [3-5]). The depleted component represents the shergottite <span class="hlt">martian</span> mantle. The identity of the enriched component is subject to debate, and has been proposed to be either assimilated ancient <span class="hlt">martian</span> crust [3] or from enriched domains in the <span class="hlt">martian</span> mantle that may represent a late-stage magma ocean crystallization residue [4,5]. Olivine-phyric shergottites typically have the highest Mg# of the shergottite group and represent near-primitive melts having experienced minimal fractional crystallization or crystal accumulation [6]. Olivine-hosted melt inclusions (MI) in these shergottites represent the most chemically primitive components available to understand the nature of their source(s), melting processes in the <span class="hlt">martian</span> mantle, and origin of enriched components. We present trace element compositions of olivine hosted melt inclusions in two depleted olivinephyric shergottites, Yamato 980459 (Y98) and Tissint (Fig. 1), and the mesostasis glass of Y98, using Secondary Ionization Mass Spectrometry (SIMS). We discuss our data in the context of understanding the nature and origin of the depleted <span class="hlt">martian</span> mantle and the emergence of the enriched component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11543579','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11543579"><span>Bacteria in the Tatahouine <span class="hlt">meteorite</span>: nanometric-scale life in rocks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gillet, P h; Barrat, J A; Heulin, T h; Achouak, W; Lesourd, M; Guyot, F; Benzerara, K</p> <p>2000-02-15</p> <p>We present a <span class="hlt">study</span> of the textural signature of terrestrial weathering and related biological activity in the Tatahouine <span class="hlt">meteorite</span>. Scanning and transmission electron microscopy images obtained on the weathered samples of the Tatahouine <span class="hlt">meteorite</span> and surrounding soil show two types of bacteria-like forms lying on mineral surfaces: (1) rod-shaped forms (RSF) about 70-80 nm wide and ranging from 100 nm to 600 nm in length; (2) ovoid forms (OVF) with diameters between 70 and 300 nm. They look like single cells surrounded by a cell wall. Only Na, K, C, O and N with traces of P and S are observed in the bulk of these objects. The chemical analyses and electron diffraction patterns confirm that the RSF and OVF cannot be magnetite or other iron oxides, iron hydroxides, silicates or carbonates. The sizes of the RSF and OVF are below those commonly observed for bacteria but are very similar to some bacteria-like forms described in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001. All the previous observations strongly suggest that they are bacteria or their remnants. This conclusion is further supported by microbiological experiments in which pleomorphic bacteria with morphology similar to the OVF and RSF objects are obtained from biological culture of the soil surrounding the <span class="hlt">meteorite</span> pieces. The present results show that bacteriomorphs of diameter less than 100 nm may in fact represent real bacteria or their remnants.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnuclear%2Bfusion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=nuclear+fusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnuclear%2Bfusion"><span>Atmospheric heating of <span class="hlt">meteorites</span>: Results from nuclear track <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jha, R.</p> <p>1984-01-01</p> <p>A quantitative model to estimate the degree of annealing of nuclear tracks in mineral grains subjected to a variable temperature history was proposed. This model is applied to <span class="hlt">study</span> the track annealing records in different <span class="hlt">meteorites</span> resulting from their atmospheric heating. Scale lengths were measured of complete and partial track annealing, delta X sub 1 and delta X sub 2, respectively. In mineral grain close to fusion crust in about a dozen <span class="hlt">meteorites</span>. Values of delta X sub 1 and delta X sub 2 depend on extent and duration of heating during atmospheric transit and hence on <span class="hlt">meteorite</span> entry parameters. To estimate track annealing, the temperature history during atmospheric heating at different distances from the crusted surface of the <span class="hlt">meteorite</span> is obtained by solving heat conduction equation in conjunction with <span class="hlt">meteorite</span> entry model, and use of the annealing model to evaluate the degree of annealing of tracks. It is shown that the measured values of delta X sub 1 and delta X sub 2 in three of the <span class="hlt">meteorites</span> <span class="hlt">studied</span> are consistent with values using preatmospheric mass, entry velocity and entry angle of these <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PS...47..806D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PS...47..806D"><span>Experimental determination of photostability and fluorescence-based detection of PAHs on the <span class="hlt">Martian</span> surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dartnell, Lewis R.; Patel, Manish R.; Storrie-Lombardi, Michael C.; Ward, John M.; Muller, Jan-Peter</p> <p>2012-05-01</p> <p>Even in the absence of any biosphere on Mars, organic molecules, including polycyclic aromatic hydrocarbons (PAHs), are expected on its surface due to delivery by comets and <span class="hlt">meteorites</span> of extraterrestrial organics synthesized by astrochemistry, or perhaps in situ synthesis in ancient prebiotic chemistry. Any organic compounds exposed to the unfiltered solar ultraviolet spectrum or oxidizing surface conditions would have been readily destroyed, but discoverable caches of <span class="hlt">Martian</span> organics may remain shielded in the subsurface or within surface rocks. We have <span class="hlt">studied</span> the stability of three representative polycyclic aromatic hydrocarbons (PAHs) in a Mars chamber, emulating the ultraviolet spectrum of unfiltered sunlight under temperature and pressure conditions of the <span class="hlt">Martian</span> surface. Fluorescence spectroscopy is used as a sensitive indicator of remaining PAH concentration for laboratory quantification of molecular degradation rates once exposed on the <span class="hlt">Martian</span> surface. Fluorescence-based instrumentation has also been proposed as an effective surveying method for prebiotic organics on the <span class="hlt">Martian</span> surface. We find the representative PAHs, anthracene, pyrene, and perylene, to have persistence half-lives once exposed on the <span class="hlt">Martian</span> surface of between 25 and 60 h of noontime summer UV irradiation, as measured by fluorescence at their peak excitation wavelength. This equates to between 4 and 9.6 sols when the diurnal cycle of UV light intensity on the <span class="hlt">Martian</span> surface is taken into account, giving a substantial window of opportunity for detection of organic fluorescence before photodegradation. This <span class="hlt">study</span> thus supports the use of fluorescence-based instrumentation for surveying recently exposed material (such as from cores or drill tailings) for native <span class="hlt">Martian</span> organic molecules in rover missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982AmSci..70..156C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982AmSci..70..156C"><span>Antarctic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cassidy, W. A.; Rancitelli, L. A.</p> <p>1982-04-01</p> <p>An abundance of <span class="hlt">meteorites</span> has been discovered on two sites in the Antarctic which may assist in the <span class="hlt">study</span> of the origins of <span class="hlt">meteorites</span> and the history of the solar system. Characteristics particular to those <span class="hlt">meteorites</span> discovered in this region are explained. These specimens, being well preserved due to the climate, have implications in the <span class="hlt">study</span> of the cosmic ray flux through time, the meteoroid complex in space, and cosmic ray exposure ages. Implications for the <span class="hlt">study</span> of the Antarctic, particularly the ice flow, are also discussed. Further discoveries of <span class="hlt">meteorites</span> in this region are anticipated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026155','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026155"><span>Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.</p> <p>2006-01-01</p> <p>Magnetite and sulfides in the black rims of carbonate globules in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 have been <span class="hlt">studied</span> extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the <span class="hlt">meteorite</span>. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003687','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003687"><span>Degradation <span class="hlt">studies</span> of <span class="hlt">Martian</span> impact craters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barlow, N. G.</p> <p>1991-01-01</p> <p>The amount of obliteration suffered by <span class="hlt">Martian</span> impact craters is quantified by comparing measurable attributes of the current crater shape to those values expected for a fresh crater of identical size. Crater diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh crater and a crater depth, floor width, rim height, central peak height, etc. was determined by empirical <span class="hlt">studies</span> performed on fresh <span class="hlt">Martian</span> impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by <span class="hlt">Martian</span> impact craters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IAUGA..2256033J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2256033J"><span><span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jenniskens, Peter</p> <p>2015-08-01</p> <p><span class="hlt">Meteorites</span> have long been known to offer a unique window into planetary formation processes at the time of solar system formation and into the materials that rained down on Earth at the time of the origin of life. Their material properties determine the impact hazard of Near Earth Asteroids. Some insight into how future laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and laboratory astrophysics simulations of relevant physical processes can help address open questions in these areas and generate new astronomical observations, comes from what was learned from the recent laboratory <span class="hlt">studies</span> of freshly fallen <span class="hlt">meteorites</span>. The rapid recovery of Almahata Sitta (a polymict Ureilite), Sutter's Mill (a CM chondrite regolith breccia), Novato (an L6 chondrite), and Chelyabinsk (an LL5 chondrite) each were followed by the creation of a <span class="hlt">meteorite</span> consortium, which grew to over 50 researchers in the case of Chelyabinsk. New technologies were used to probe the organic content of the <span class="hlt">meteorites</span> as well as their magnetic signatures, isotopic abundances, trapped noble gasses, and cosmogenic radio nucleides, amongst others. This has resulted in fascinating insight into the nature of the Ureilite parent body, the likely source region of the CM chondrites in the main asteroid belt, and the collisional environment of the CM parent body. This work has encouraged follow-up in the hope of catching more unique materials. Rapid response efforts are being developed that aim to recover <span class="hlt">meteorites</span> as pristinely as possible from falls for which the approach orbit was measured. A significant increase in the number of known approach orbits for different <span class="hlt">meteorite</span> types will help tie <span class="hlt">meteorite</span> types to their asteroid family source regions. Work so far suggests that future laboratory <span class="hlt">studies</span> may recognize multiple source regions for iron-rich ordinary chondrites, for example. Hope is that these source regions will give insight into the material properties of impacting asteroids. At least some future laboratory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11541744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11541744"><span>Organic degradation under simulated <span class="hlt">Martian</span> conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stoker, C R; Bullock, M A</p> <p>1997-05-25</p> <p>We report on laboratory experiments which simulate the breakdown of organic compounds under <span class="hlt">Martian</span> surface conditions. Chambers containing Mars-analog soil mixed with the amino acid glycine were evacuated and filled to 100 mbar pressure with a <span class="hlt">Martian</span> atmosphere gas mixture and then irradiated with a broad spectrum Xe lamp. Headspace gases were periodically withdrawn and analyzed via gas chromatography for the presence of organic gases expected to be decomposition products of the glycine. The quantum efficiency for the decomposition of glycine by light at wavelengths from 2000 to 2400 angstroms was measured to be 1.46 +/- 1.0 x 10(-6) molecules/photon. Scaled to Mars, this represents an organic destruction rate of 2.24 +/- 1.2 x 10(-4) g of C m-2 yr-1. We compare this degradation rate with the rate that organic compounds are brought to Mars as a result of <span class="hlt">meteoritic</span> infall to show that organic compounds are destroyed on Mars at rates far exceeding the rate that they are deposited by <span class="hlt">meteorites</span>. Thus the fact that no organic compounds were found on Mars by the Viking Lander Gas Chromatograph Mass Spectrometer experiment can be explained without invoking the presence of strong oxidants in the surface soils. The organic destruction rate may be considered as an upper bound for the globally averaged biomass production rate of extant organisms at the surface of Mars. This upper bound is comparable to the slow growing cryptoendolithic microbial communities found in dry Antarctica deserts. Finally, comparing these organic destruction rates to recently reported experiments on the stability of carbonate on the surface of Mars, we find that organic compounds may currently be more stable than calcite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JGR...10210881S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JGR...10210881S"><span>Organic degradation under simulated <span class="hlt">Martian</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stoker, Carol R.; Bullock, Mark A.</p> <p>1997-05-01</p> <p>We report on laboratory experiments which simulate the breakdown of organic compounds under <span class="hlt">Martian</span> surface conditions. Chambers containing Mars-analog soil mixed with the amino acid glycine were evacuated and filled to 100 mbar pressure with a <span class="hlt">Martian</span> atmosphere gas mixture and then irradiated with a broad spectrum Xe lamp. Headspace gases were periodically withdrawn and analyzed via gas chromatography for the presence of organic gases expected to be decomposition products of the glycine. The quantum efficiency for the decomposition of glycine by light at wavelengths from 2000 to 2400 Å was measured to be 1.46+/-1.0×10-6molecules/photon. Scaled to Mars, this represents an organic destruction rate of 2.24+/-1.2×10-4g of Cm-2yr-1. We compare this degradation rate with the rate that organic compounds are brought to Mars as a result of <span class="hlt">meteoritic</span> infall to show that organic compounds are destroyed on Mars at rates far exceeding the rate that they are deposited by <span class="hlt">meteorites</span>. Thus the fact that no organic compounds were found on Mars by the Viking Lander Gas Chromatograph Mass Spectrometer experiment can be explained without invoking the presence of strong oxidants in the surface soils. The organic destruction rate may be considered as an upper bound for the globally averaged biomass production rate of extant organisms at the surface of Mars. This upper bound is comparable to the slow growing cryptoendolithic microbial communities found in dry Antarctica deserts. Finally, comparing these organic destruction rates to recently reported experiments on the stability of carbonate on the surface of Mars, we find that organic compounds may currently be more stable than calcite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.191..203G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.191..203G"><span>Ancient impactor components preserved and reworked in <span class="hlt">martian</span> regolith breccia Northwest Africa 7034</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goderis, Steven; Brandon, Alan D.; Mayer, Bernhard; Humayun, Munir</p> <p>2016-10-01</p> <p>Northwest Africa (NWA) 7034 and paired stones represent unique samples of <span class="hlt">martian</span> polymict regolith breccia. Multiple breccia subsamples characterized in this work confirm highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, Pd) contents that are consistently elevated (e.g., Os ∼9.3-18.4 ppb) above indigenous <span class="hlt">martian</span> igneous rocks (mostly <5 ppb Os), equivalent to ∼3 wt% of admixed CI-type carbonaceous chondritic material, and occur in broadly chondrite-relative proportions. However, a protracted history of impactor component (metal and sulfide) breakdown and redistribution of the associated HSE has masked the original nature of the admixed <span class="hlt">meteorite</span> signatures. The present-day 187Os/188Os ratios of 0.119-0.136 record a wider variation than observed for all major chondrite types. Combined with the measured 187Re/188Os ratios of 0.154-0.994, the range in Os isotope ratios indicates redistribution of Re and Os from originally chondritic components early in the history of the regolith commencing at ∼4.4 Ga. Superimposed recent Re mobility reflects exposure and weathering at or near the <span class="hlt">martian</span> and terrestrial surfaces. Elevated Os concentrations (38.0 and 92.6 ppb Os), superchondritic Os/HSE ratios, and 187Os/188Os of 0.1171 and 0.1197 measured for two subsamples of the breccia suggest the redistribution of impactor material at ∼1.5-1.9 Ga, possibly overlapping with a (partial) resetting event at ∼1.4 Ga recorded by U-Pb isotope systematics in the breccia. <span class="hlt">Martian</span> alteration of the originally chondritic HSE host phases, to form Os-Ir-rich nuggets and Ni-rich pyrite, implies the influence of potentially impact-driven hydrothermal systems. Multiple generations of impactor component admixture, redistribution, and alteration mark the formation and evolution of the <span class="hlt">martian</span> regolith clasts and matrix of NWA 7034 and paired <span class="hlt">meteorites</span>, from the pre-Noachian until impact ejection to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.P51A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.P51A..01C"><span>Terrestrial Chemical Alteration of Hot Desert <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crozaz, G.; Floss, C.</p> <p>2001-12-01</p> <p>Large numbers of <span class="hlt">meteorites</span> have recently been recovered from terrestrial hot deserts. They include objects whose <span class="hlt">study</span> holds the promise of significantly increasing our knowledge of the origin and petrogenesis of rare groups of <span class="hlt">meteorites</span> (e.g., <span class="hlt">martian</span> and lunar rocks, ureilites, etc). However, these <span class="hlt">meteorites</span> have typically been exposed to harsh desert conditions for more than 10,000 yr since their fall on earth. A number of alterations have been described, including mineralogical and chemical changes (e.g., Crozaz and Wadhwa, 2001, and references therein). Through weathering, Fe-bearing minerals are progressively altered into clays and iron oxides and hydroxides, which often fill cracks and mineral fractures, together with terrestrial quartz and carbonates. In addition, for whole rock samples, elevated Ba, Sr, and U seem to be the telltale signs of terrestrial contamination (e.g., Barrat et al., 1999). In our work, we use the rare earth elements (REE) as monitors of terrestrial alteration. These elements are important because they are commonly used to decipher the petrogenesis and chronology of <span class="hlt">meteorites</span>. We have made in-situ concentration measurements, by secondary ion mass spectrometry (SIMS), of individual grains in shergottites (assumed to have formed on Mars), lunar, and angritic <span class="hlt">meteorites</span>. Terrestrial contamination, in the form of LREE enrichment and Ce anomalies, is encountered in the olivine and pyroxene, the two minerals with the lowest REE concentrations, of all objects analyzed. However, the contamination is highly heterogeneous, affecting some grains and not others of a given phase. Therefore, provided one uses a measurement technique such as SIMS to obtain data on individual grains and to identify the unaltered ones, it is still possible to obtain geochemical information about the origins of hot desert <span class="hlt">meteorites</span>. On the other hand, great caution must be exercised if one uses data for whole rocks or mineral separates. The U-Pb, Rb-Sr and Sm</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042188&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlindstrom','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042188&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D50%26Ntt%3Dlindstrom"><span>Geochemical evidence for mixing of three components in <span class="hlt">martian</span> orthopyroxenite ALH 84001. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mittlefehldt, D. W.; Lindstrom, M. M.</p> <p>1994-01-01</p> <p>ALH 84001, a ferroan <span class="hlt">martian</span> orthopyroxenite, originally consisted of three petrographically defined components: a cumulus assemblage of orthopyroxene + chromite, a trapped melt assemblage of orthopyroxene(?) + chromite + maskelynite + apatite + augite +/- pyrite, and a metasomatic assemblage of carbonate +/- pyrite. We present the results of Instrumental Neutron Activation Analysis (INAA) <span class="hlt">study</span> of five bulk samples of ALH 84001, combined with Scanning Ion Mass Spectrometer (SIMS) data on the orthopyroxene, in order to attempt to set limits on the geochemical characteristics of the latter two components, and therefore on the petrogenesis of ALH 84001. The INAA data support the petrographic observations, suggesting that there are at least three components in ALH 84001. We will assume that each of the three geochemically required components can be equated with one of the petrographically observed components. Both trapped melt and metasomatic components in ALH 84001 have higher Na than orthopyroxene based on compositions of maskelynite, apatite, and carbonate. For the metasomatic component, we will assume its Na content is that of carbonate, while for a trapped melt component, we will use a typical Na content inferred for <span class="hlt">martian</span> <span class="hlt">meteorite</span> parent melts, approximately 1 wt% Na2O. Under these assumptions, we can set limits on the Light Rare Earth Elements/Heavy Rare Earth Elements (LREE/HREE) ratios of the components, and use this information to compare the petrogenesis of ALH 84001 with other <span class="hlt">martian</span> <span class="hlt">meteorites</span>. The above calculations assume that the bulk samples are representative of different portions of ALH 84001. We will also evaluate the possible heterogeneous distribution of mineral phases in the bulk samples as the cause of compositional heterogeneity in our samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920019361&hterms=iodine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Diodine','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920019361&hterms=iodine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Diodine"><span>Forsterite/melt partitioning of argon and iodine: Implications for atmosphere formation by outgassing of an early <span class="hlt">Martian</span> magma ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, Donald S.; Drake, Michael J.; Swindle, Timothy D.</p> <p>1992-01-01</p> <p>Argon and Xe in the <span class="hlt">Martian</span> atmosphere are radiogenic relative to the <span class="hlt">Martian</span> mantle if the SNC <span class="hlt">meteorites</span> are from Mars. Decay of the short lived isotope I-129 to Xe-129 (t sub 1/2 = 16 m.y.) is the most plausible source of the radiogenic Xe. This short half life constrains any process responsible for the elevated Xe-129/Xe-132 ratio of the <span class="hlt">Martian</span> atmosphere to occur very early in solar system history. Musselwhite et al. proposed that the differential solubility of I and Xe in liquid water played a key role in producing the radiogenic signature in the <span class="hlt">Martian</span> atmosphere. Here we explore an alternative hypothesis involving purely igneous processes, and motivated in part by new experimental results on the partitioning of I and Xe between minerals and melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036629','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036629"><span>Evidence for Differential Comminution/Aeolian Sorting and Chemical Weathering of <span class="hlt">Martian</span> Soils Preserved in Mars <span class="hlt">Meteorite</span> EET79001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; McKay, David S.</p> <p>2004-01-01</p> <p>Impact-melt glasses containing <span class="hlt">Martian</span> atmospheric gases in Mars <span class="hlt">meteorite</span> EET79001 are formed from <span class="hlt">Martian</span> soil fines that had undergone meteoroid-comminution and aeolian sorting accompanied by chemical weathering near Mars surface. Using SiO2 and SO3 as proxy for silicates and salts respectively in Mars soils, we find that SiO2 and SO3 correlate negatively with FeO and MgO and positively with Al2O3 and CaO in these glasses, indicating that the mafic and felsic components are depleted and enriched relative to the bulk host (Lith A/B) respectively as in the case of Moon soils. Though the overall pattern of mineral fractionation is similar between the soil fines on Mars and Moon, the magnitudes of the enrichments/depletions differ between these sample-suites because of pervasive aeolian activity on Mars. In addition to this mechanical processing, the <span class="hlt">Martian</span> soil fines, prior to impact-melting, have undergone acid-sulfate dissolution under oxidizing/reducing conditions. The S03 content in EET79001,507 (Lith B) glass is approx.18% compared to < 2% in EET79001, 506 (Lith A). SiO2 and SO3 negatively correlate with each other in ,507 glasses similar to Pathfinder soils. The positive correlation found between FeO and SO3 in ,507 glasses as well as Pathfinder rocks and soils is consistent with the deposition of ferric-hydroxysulfate on regolith grains in an oxidizing environment. As in the case of Pathfinder soils, the Al 2O3 vs SiO2 positive correlation and FeO VS S102 negative correlation observed in ,507 glasses indicate that SiO2 from the regolith is mobilized as soluble silicic acid at low pH. The large off-set in the end-member FeO abundance ( SO3=0) between Pathfinder soil-free rock and sulfur-free rock in ,507 glass precursors suggests that the soils comprising the ,507 glasses contain much larger proportion of fine-grained <span class="hlt">Martian</span> soil fraction that registers strong mafic depletion relative to Lith B. This inference is strongly supported by the Al2O3 - SO3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999smtp.conf...41Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999smtp.conf...41Y"><span>Origin and Reactivity of the <span class="hlt">Martian</span> Soil: A 2003 Micromission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yen, Albert S.; Kim, S. Sam; Marshall, John; Murray, Bruce C.</p> <p>1999-09-01</p> <p>The role of water in the development of the <span class="hlt">martian</span> surface remains a fundamental scientific question. Did Mars have one or more "warm and wet" climatic episodes where liquid water was stable at the surface? If so, the mineral phases present in the soils should be consistent with a history of aqueous weathering. More generally, the formation of hydrated mineral phases on Mars is a strong indicator of past habitable surface environments. The primary purpose of this investigation is to help resolve the question of whether such aqueous indicators are present on Mars by probing the upper meter for diagnostic mineral species. According to Burns [1993], the formation of the ferric oxides responsible for the visible color of Mars are the result of dissolution of Fe (+2) phases from basalts followed by aqueous oxidation and precipitation of Fe" mineral assemblages. These precipitates likely included iron oxyhydroxides such as goethite (a-FeOOH) and lepidocrocite (g-FeOOH), but convincing evidence for these phases at the surface is still absent. The stability of these minerals is enhanced beneath the surface, and thus we propose a subsurface search for hydroxylated iron species as a test for a large-scale chemical weathering process based on interactions with liquid water. It is also possible that the ferric minerals on Mars are not aqueous alteration products of the rocks. A chemical <span class="hlt">study</span> of the Pathfinder landing site concluded that the soils are not directly derived from the surrounding rocks and are enhanced in Mg and Fe. The additional source of these elements might be from other regions of Mars and transported by winds, or alternatively, from exogenic sources. Gibson [1970] proposed that the spectral reflectivity of Mars is consistent with oxidized <span class="hlt">meteoritic</span> material. Yen and Murray [1998] further extend Gibson's idea and show, in the laboratory, that metallic iron can be readily oxidized to maghemite and hematite under present-day <span class="hlt">martian</span> surface conditions (in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000025370&hterms=organic+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dorganic%2Bsoil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000025370&hterms=organic+soil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dorganic%2Bsoil"><span>Origin and Reactivity of the <span class="hlt">Martian</span> Soil: A 2003 Micromission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yen, Albert S.; Kim, S. Sam; Marshall, John; Murray, Bruce C.</p> <p>1999-01-01</p> <p>The role of water in the development of the <span class="hlt">martian</span> surface remains a fundamental scientific question. Did Mars have one or more "warm and wet" climatic episodes where liquid water was stable at the surface? If so, the mineral phases present in the soils should be consistent with a history of aqueous weathering. More generally, the formation of hydrated mineral phases on Mars is a strong indicator of past habitable surface environments. The primary purpose of this investigation is to help resolve the question of whether such aqueous indicators are present on Mars by probing the upper meter for diagnostic mineral species. According to Burns [1993], the formation of the ferric oxides responsible for the visible color of Mars are the result of dissolution of Fe (+2) phases from basalts followed by aqueous oxidation and precipitation of Fe" mineral assemblages. These precipitates likely included iron oxyhydroxides such as goethite (a-FeOOH) and lepidocrocite (g-FeOOH), but convincing evidence for these phases at the surface is still absent. The stability of these minerals is enhanced beneath the surface, and thus we propose a subsurface search for hydroxylated iron species as a test for a large-scale chemical weathering process based on interactions with liquid water. It is also possible that the ferric minerals on Mars are not aqueous alteration products of the rocks. A chemical <span class="hlt">study</span> of the Pathfinder landing site concluded that the soils are not directly derived from the surrounding rocks and are enhanced in Mg and Fe. The additional source of these elements might be from other regions of Mars and transported by winds, or alternatively, from exogenic sources. Gibson [1970] proposed that the spectral reflectivity of Mars is consistent with oxidized <span class="hlt">meteoritic</span> material. Yen and Murray [1998] further extend Gibson's idea and show, in the laboratory, that metallic iron can be readily oxidized to maghemite and hematite under present-day <span class="hlt">martian</span> surface conditions (in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-S85-39565.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-S85-39565.html"><span><span class="hlt">METEORITE</span> - ASTRONOMY</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1985-08-28</p> <p>S85-39565 (For release August 1996) --- According to scientists, this 4.5 billion year old rock, labeled <span class="hlt">meteorite</span> ALH84001, is believed to have once been a part of Mars and to contain fossil evidence that primitive life may have existed on Mars more than 3.6 billion years ago. The rock is a portion of a <span class="hlt">meteorite</span> that was dislodged from Mars by a huge impact about 16 million years ago and that fell to Earth in Antarctica 13,000 years ago. The <span class="hlt">meteorite</span> was found in Allan Hills ice field, Antarctica, by an annual expedition of the National Science Foundation?s Antarctic <span class="hlt">Meteorite</span> Program in 1984. It is preserved for <span class="hlt">study</span> at the Johnson Space Center?s (JSC) <span class="hlt">Meteorite</span> Processing Laboratory in Houston, Texas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.537L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.537L"><span><span class="hlt">Meteorites</span> for K-12 Classrooms: NASA <span class="hlt">Meteorite</span> Educational Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lindstrom, M.; Allen, J.</p> <p>1995-09-01</p> <p>The fall of a new <span class="hlt">meteorite</span> is an event that catches the interest of the public in matters of science. The threat of a huge impact like last year's comet Shoemaker-Levy 9 gives us all reason to evaluate such potential risks. NASA's <span class="hlt">meteorite</span> educational materials use our natural interest in rocks from space to present classroom activities on planetary science. The <span class="hlt">meteorite</span> educational package includes a <span class="hlt">meteorite</span> sample disk, a teachers's guide and a slide set. The sample disk is a lucite disk containing chips of six different kinds of <span class="hlt">meteorites</span> (3 chondrites, achondrite, iron, stony-iron). EXPLORING <span class="hlt">METEORITE</span> MYSTERIES is a teacher's guide with background information and 19 hands-on or heads-on activities for grades 4-12. It was prepared in a partnership of planetary scientists and teachers. The slide set consists of 48 slides with captions to be used with the activities. The materials will be available in Fall 1995. Teachers may obtain a loan of the whole package from NASA Teacher Resource Centers; researchers may borrow them from the JSC <span class="hlt">meteorite</span> curator. The booklet is available separately from the same sources, and the slide set will be available from NASA CORE. EXPLORING <span class="hlt">METEORITE</span> MYSTERIES is an interdisciplinary planetary science unit which teaches basic science concepts and techniques together with math, reading, writing and social <span class="hlt">studies</span> The activities are done in a variety of different teaching styles which emphasize observation, experimentation and critical thinking. The activities are ideal for middle schools where teaming makes interdisciplinary units desireable, but most of the activities can be easily modified for grade levels from upper elementary through high school. <span class="hlt">Meteorites</span> are a natural subject for interdisciplinary teaching because their <span class="hlt">study</span> involves all fields of science and offers fascinating historical accounts and possibilities for creative expression. Topics covered in EXPLORING <span class="hlt">METEORITE</span> MYSTERES are centered around basic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=amoeba&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Damoeba','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850035523&hterms=amoeba&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Damoeba"><span>Petrographic <span class="hlt">studies</span> of refractory inclusions from the Murchison <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Macpherson, G. J.; Grossman, L.; Hashimoto, A.; Bar-Matthews, M.; Tanaka, T.</p> <p>1984-01-01</p> <p>Textural and mineral-chemical data on freeze-thaw disaggregated refractory inclusions from the Murchison <span class="hlt">meteorite</span> are reported. The data were obtained with neutron activation analysis, SEM, and spectroscopy, the <span class="hlt">study</span> revealed corundum-bearing inclusions, spinel-hibonite aggregates and spherules, and spinel-pyroxene and elivine-pyroxene inclusions. One of the three spinel-, pyroxene-, forsterite-rich inclusions had an amoeba-shaped spinel-pyroxene core, implying vapor-to-solid condensation and therefore crystallization from a melt. It is concluded that the <span class="hlt">meteorite</span> formation encompassed diverse nebular materials, and that further <span class="hlt">studies</span> of the <span class="hlt">meteorite</span> will enhance the data base on the planetary nebular processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.105..255C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.105..255C"><span><span class="hlt">Martian</span> fluid and <span class="hlt">Martian</span> weathering signatures identified in Nakhla, NWA 998 and MIL 03346 by halogen and noble gas analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cartwright, J. A.; Gilmour, J. D.; Burgess, R.</p> <p>2013-03-01</p> <p>We report argon (Ar) noble gas, Ar-Ar ages and halogen abundances (Cl, Br, I) of <span class="hlt">Martian</span> nakhlites Nakhla, NWA 998 and MIL 03346 to determine the presence of <span class="hlt">Martian</span> hydrous fluids and weathering products. Neutron-irradiated samples were either crushed and step-heated (Nakhla only), or simply step-heated using a laser or furnace, and analysed for noble gases using an extension of the 40Ar-39Ar technique to determine halogen abundances. The data obtained provide the first isotopic evidence for a trapped fluid that is Cl-rich, has a strong correlation with 40ArXS (40ArXS = 40Armeasured - 40Arradiogenic) and displays 40ArXS/36Ar of ˜1000 - consistent with the <span class="hlt">Martian</span> atmosphere. This component was released predominantly in the low temperature and crush experiments, which may suggest a fluid inclusion host. For the halogens, we observe similar Br/Cl and I/Cl ratios between the nakhlites and terrestrial reservoirs, which is surprising given the absence of crustal recycling, organic matter and frequent fluid activity on Mars. In particular, Br/Cl ratios in our Nakhla samples (especially olivine) are consistent with previously analysed <span class="hlt">Martian</span> weathering products, and both low temperature and crush analyses show a similar trend to the evaporation of seawater. This may indicate that surface brines play an important role on Mars and on halogen assemblages within <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and rocks. Elevated I/Cl ratios in the low temperature NWA 998 and MIL 03346 releases may relate to in situ terrestrial contamination, though we are unable to distinguish between low temperature terrestrial or <span class="hlt">Martian</span> components. Whilst estimates of the amount of water present based on the 36Ar concentrations are too high to be explained by a fluid component alone, they are consistent with a mixed-phase inclusion (gas and fluid) or with shock-implanted <span class="hlt">Martian</span> atmospheric argon. The observed fluid is dilute (low salinity, but high Br/Cl and I/Cl ratios), contains a <span class="hlt">Martian</span> atmospheric component</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860022893','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860022893"><span>The 10Be contents of SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pal, D. K.; Tuniz, C.; Moniot, R. K.; Savin, W.; Vajda, S.; Kruse, T.; Herzog, G. F.</p> <p>1986-01-01</p> <p>Several authors have explored the possibility that the Shergottites, Nakhlites, and Chassigny (SNC) came from Mars. The spallogenic gas contents of the SNC <span class="hlt">meteorites</span> have been used to: constrain the sizes of the SNC's during the last few million years; to establish groupings independent of the geochemical ones; and to estimate the likelihood of certain entries in the catalog of all conceivable passages from Mars to Earth. The particular shielding dependence of Be-10 makes the isotope a good probe of the irradiation conditions experienced by the SNC <span class="hlt">meteorites</span>. The Be-10 contents of nine members of the group were measured using the technique of accelerator mass spectrometry. The Be-10 contents of Nakhla, Governador Valadares, Chassigny, and probably Lafayette, about 20 dpm/kg, exceed the values expected from irradiation of the surface of a large body. The Be-10 data therfore do not support scenario III of Bogard et al., one in which most of the Be-10 in the SNC <span class="hlt">meteorites</span> would have formed on the <span class="hlt">Martian</span> surface; they resemble rather the Be-10 contents found in many ordinary chondrites subjected to 4 Pi exposures. The uncertainties of the Be-10 contents lead to appreciable errors in the Be-10 ages, t(1) = -1/lambda ln(1 Be-10/Be-10). Nonetheless, the Be-10 ages are consistent with the Ne-21 ages calculated assuming conventional, small-body production rates and short terrestrial ages for the finds. It is believed that this concordance strengthens the case for at least 3 different irradiation ages for the SNC <span class="hlt">meteorites</span>. Given the similar half-thicknesses of the Be-10 and Ne-21 production rates, the ratios of the Be-10 and Ne-21 contents do not appear consistent with common ages for any of the groups. In view of the general agreement between the Be-10 and Ne-21 ages it does not seem useful at this time to construct multiple-stage irradiation histories for the SNC <span class="hlt">meteorites</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26PSL.485...79B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26PSL.485...79B"><span>Pb evolution in the <span class="hlt">Martian</span> mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Bland, P.; Benedix, G. K.; Roszjar, J.</p> <p>2018-03-01</p> <p>The initial Pb compositions of one enriched shergottite, one intermediate shergottite, two depleted shergottites, and Nakhla have been measured by Secondary Ion Mass Spectrometry (SIMS). These values, in addition to data from previous <span class="hlt">studies</span> using an identical analytical method performed on three enriched shergottites, ALH 84001, and Chassigny, are used to construct a unified and internally consistent model for the differentiation history of the <span class="hlt">Martian</span> mantle and crystallization ages for <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The differentiation history of the shergottites and Nakhla/Chassigny are fundamentally different, which is in agreement with short-lived radiogenic isotope systematics. The initial Pb compositions of Nakhla/Chassigny are best explained by the late addition of a Pb-enriched component with a primitive, non-radiogenic composition. In contrast, the Pb isotopic compositions of the shergottite group indicate a relatively simple evolutionary history of the <span class="hlt">Martian</span> mantle that can be modeled based on recent results from the Sm-Nd system. The shergottites have been linked to a single mantle differentiation event at 4504 Ma. Thus, the shergottite Pb isotopic model here reflects a two-stage history 1) pre-silicate differentiation (4504 Ma) and 2) post-silicate differentiation to the age of eruption (as determined by concordant radiogenic isochron ages). The μ-values (238U/204Pb) obtained for these two different stages of Pb growth are μ1 of 1.8 and a range of μ2 from 1.4-4.7, respectively. The μ1-value of 1.8 is in broad agreement with enstatite and ordinary chondrites and that proposed for proto Earth, suggesting this is the initial μ-value for inner Solar System bodies. When plotted against other source radiogenic isotopic variables (Sri, γ187Os, ε143Nd, and ε176Hf), the second stage mantle evolution range in observed mantle μ-values display excellent linear correlations (r2 > 0.85) and represent a spectrum of <span class="hlt">Martian</span> mantle mixing-end members (depleted</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PEPI..272...50K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PEPI..272...50K"><span>Formation of a metastable hollandite phase from amorphous plagioclase: A possible origin of lingunite in shocked chondritic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kubo, Tomoaki; Kono, Mari; Imamura, Masahiro; Kato, Takumi; Uehara, Seiichiro; Kondo, Tadashi; Higo, Yuji; Tange, Yoshinori; Kikegawa, Takumi</p> <p>2017-11-01</p> <p>We conducted high-pressure experiments in plagioclase with different anorthite contents at 18-27 GPa and 25-1750 °C using both a laser-heated diamond anvil cell and a Kawai-type multi-anvil apparatus to clarify the formation conditions of the hollandite phase in shocked chondritic and <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Lingunite (NaAlSi3O8-rich hollandite) was found first to crystallize from amorphous oligoclase as a metastable phase before decomposing into the final stable state. This process might account for the origin of lingunite found along with maskelynite in shocked chondritic <span class="hlt">meteorites</span>. Metastable lingunite appeared at ∼20-24 GPa and ∼1100-1300 °C in laboratory tests lasting tens of minutes; however, it might also form at the higher temperatures and shorter time periods of shock events. In contrast, the hollandite phase was not observed during any stage of crystallization when using albite or labradorite as starting materials. The formation process of (Ca,Na)-hollandite in the labradorite composition found in <span class="hlt">Martian</span> shergottites remains unresolved. The orthoclase contents of the hollandite phase both in shocked <span class="hlt">meteorites</span> (2.4-8.2 mol%) and our oligoclase sample (3.9 mol%) are relatively high compared to the albite and labradorite samples (0.6 and 1.9 mol%, respectively). This might critically affect the crystallization kinetics of hollandite phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Sci...329.1334N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Sci...329.1334N"><span>Stable Isotope Measurements of <span class="hlt">Martian</span> Atmospheric CO2 at the Phoenix Landing Site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niles, Paul B.; Boynton, William V.; Hoffman, John H.; Ming, Douglas W.; Hamara, Dave</p> <p>2010-09-01</p> <p>Carbon dioxide is a primary component of the <span class="hlt">martian</span> atmosphere and reacts readily with water and silicate rocks. Thus, the stable isotopic composition of CO2 can reveal much about the history of volatiles on the planet. The Mars Phoenix spacecraft measurements of carbon isotopes [referenced to the Vienna Pee Dee belemnite (VPDB)] [δ13CVPDB = -2.5 ± 4.3 per mil (‰)] and oxygen isotopes [referenced to the Vienna standard mean ocean water (VSMOW)] (δ18OVSMOW = 31.0 ± 5.7‰), reported here, indicate that CO2 is heavily influenced by modern volcanic degassing and equilibration with liquid water. When combined with data from the <span class="hlt">martian</span> <span class="hlt">meteorites</span>, a general model can be constructed that constrains the history of water, volcanism, atmospheric evolution, and weathering on Mars. This suggests that low-temperature water-rock interaction has been dominant throughout <span class="hlt">martian</span> history, carbonate formation is active and ongoing, and recent volcanic degassing has played a substantial role in the composition of the modern atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001273','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001273"><span>Abundance and Isotopic Composition of Gases in the <span class="hlt">Martian</span> Atmosphere: First Results from the Mars Curiosity Rover</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mahaffy, Paul; Webster, Chris R.; Atreya, Sushil K.; Franz, Heather; Wong, Michael; Conrad, Pamela G.; Harpold, Dan; Jones, John J.; Leshin, Laurie, A.; Manning, Heidi; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150001273'); toggleEditAbsImage('author_20150001273_show'); toggleEditAbsImage('author_20150001273_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150001273_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150001273_hide"></p> <p>2013-01-01</p> <p>Repeated measurements of the composition of the Mars atmosphere from Curiosity Rover yield a (40)Ar/N2 ratio 1.7 times greater and the (40)Ar/(36)Ar ratio 1.6 times smaller than the Viking Lander values in 1976. The unexpected change in (40)Ar/N2 ratio probably results from different instrument characteristics although we cannot yet rule out some unknown atmospheric process. The new (40)Ar/(36)Ar ratio is more aligned with <span class="hlt">Martian</span> <span class="hlt">meteoritic</span> values. Besides Ar and N2 the Sample Analysis at Mars instrument suite on the Curiosity Rover has measured the other principal components of the atmosphere and the isotopes. The resulting volume mixing ratios are: CO2 0.960(+/- 0.007); (40)Ar 0.0193(+/- 0.0001); N2 0.0189(+/- 0.0003); O2 1.45(+/- 0.09) x 10(exp -3); and CO 5.45(+/- 3.62) x 10(exp 4); and the isotopes (40)Ar/(36)Ar 1.9(+/- 0.3) x 10(exp 3), and delta (13)C and delta (18)O from CO2 that are both several tens of per mil more positive than the terrestrial averages. Heavy isotope enrichments support the hypothesis of large atmospheric loss. Moreover, the data are consistent with values measured in <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, providing additional strong support for a <span class="hlt">Martian</span> origin for these rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR31A2280M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR31A2280M"><span>Discovery of Ahrensite γ-Fe2SiO4 and Tissintite (Ca,Na,[])AlSi2O6, Two New Shock-induced Minerals from the Tissint <span class="hlt">Martian</span> <span class="hlt">Meteorite</span>: a Nanomineralogy Investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, C.; Tschauner, O. D.; Liu, Y.; Sinogeikin, S. V.; Zhuravlev, K. K.; Prakapenka, V.; Dera, P. K.; Taylor, L. A.</p> <p>2013-12-01</p> <p>The recent <span class="hlt">Martian</span> <span class="hlt">meteorite</span> fall, Tissint, is a fresh olivine-phyric shergottite, with strong shock features. During our nano-mineralogy investigation of the Tissint <span class="hlt">meteorite</span> with a combined analytical scanning electron microscope and synchrotron diffraction approach, two new shock-induced minerals have been discovered; these provide new insights into understanding shock conditions and impact processes on Mars. Ahrensite (IMA 2013-028), the Fe-analogue (γ-Fe2SiO4) of ringwoodite, is a new high-pressure mineral identified in Tissint. Both ahrensite and ringwoodite occur in Tissint as fine-grained polycrystalline aggregates in the rims of olivines around some shock-melt pockets. The morphology and texture of these silicate-spinels suggest formation by a solid-state transformation from Fe-rich olivine. Associated with the ahrensite and ringwoodite, inside melt pockets, often resides a thin layer of vitrified silicate-perovskite and magnesio-wüstite or wüstite. Such transitions represent a unique pressure and temperature gradient. Tissintite (IMA 2013-027), (Ca,Na,[])AlSi2O6 with the C2/c clinopyroxene structure, is a new jadeite-like mineral in Tissint. It appears as fine-grained aggregates within plagioclase glass, inside many shock-melt pockets. Both ahrensite and tissintite are high-pressure minerals formed by shock during the impact event(s) on Mars that excavated and ejected the rock off Mars. We will discuss the path of structure analysis for both new-mineral cases. Such novel methodology be utilized for many cases of mineralogical phase identification or structure analysis; this demonstrates how nano-mineralogy can be addressed and how it may play a unique role in <span class="hlt">meteorite</span> and Mars rock research, in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MicST..29..133P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MicST..29..133P"><span>Enrichment of Inorganic <span class="hlt">Martian</span> Dust Simulant with Carbon Component can Provoke Neurotoxicity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pozdnyakova, Natalia; Pastukhov, Artem; Dudarenko, Marina; Borysov, Arsenii; Krisanova, Natalia; Nazarova, Anastasia; Borisova, Tatiana</p> <p>2017-02-01</p> <p>Carbon is the most abundant dust-forming element in the interstellar medium. Tremendous amount of <span class="hlt">meteorites</span> containing plentiful carbon and carbon-enriched dust particles have reached the Earth daily. National Institute of Health panel accumulates evidences that nano-sized air pollution components may have a significant impact on the central nervous system (CNS) in health and disease. During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the CNS. Based on above facts, here we present the <span class="hlt">study</span>, the aims of which were: 1) to upgrade inorganic <span class="hlt">Martian</span> dust simulant derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, nanodiamonds and carbon dots; 2) to analyse acute effects of upgraded simulant on key characteristics of synaptic neurotransmission; and 3) to compare above effects with those of inorganic dust and carbon components per se. Acute administration of carbon-containing <span class="hlt">Martian</span> dust analogues resulted in a significant decrease in transporter-mediated uptake of L-[14C]glutamate (the major excitatory neurotransmitter) and [3H]GABA (the main inhibitory neurotransmitter) by isolated rat brain nerve terminals. The extracellular level of both neurotransmitters increased in the presence of carbon-containing <span class="hlt">Martian</span> dust analogues. These effects were associated with action of carbon components of upgraded <span class="hlt">Martian</span> dust simulant, but not with its inorganic constituent. This fact indicates that carbon component of native <span class="hlt">Martian</span> dust can have deleterious effects on extracellular glutamate and GABA homeostasis in the CNS, and so glutamate- and GABA-ergic neurotransmission disballansing exitation and inhibition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000came.work..286S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000came.work..286S"><span>The <span class="hlt">Martian</span> Oasis Detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, P. H.; tomasko, M. G.; McEwen, A.; Rice, J.</p> <p>2000-07-01</p> <p>The next phase of unmanned Mars missions paves the way for astronauts to land on the surface of Mars. There are lessons to be learned from the unmanned precursor missions to the Moon and the Apollo lunar surface expeditions. These unmanned missions (Ranger, Lunar Orbiter, and Surveyor) provided the following valuable information, useful from both a scientific and engineering perspective, which was required to prepare the way for the manned exploration of the lunar surface: (1) high resolution imagery instrumental to Apollo landing site selection also tremendously advanced the state of Nearside and Farside regional geology; (2) demonstrated precision landing (less than two kilometers from target) and soft landing capability; (3) established that the surface had sufficient bearing strength to support a spacecraft; and (4) examination of the chemical composition and mechanical properties of the surface. The search for extinct or extant life on Mars will follow the water. However, geomorphic <span class="hlt">studies</span> have shown that Mars has had liquid water on its surface throughout its geologic history. A cornucopia of potential landing sites with water histories (lakes, floodplains, oceans, deltas, hydrothermal regions) presently exist. How will we narrow down site selection and increase the likelihood of finding the signs of life? One way to do this is to identify '<span class="hlt">Martian</span> oases.' It is known that the <span class="hlt">Martian</span> surface is often highly fractured and some areas have karst structures that support underground caves. Much of the water that formed the channels and valley networks is thought to be frozen underground. All that is needed to create the potential for liquid water is a near surface source of heat; recent lava flows and <span class="hlt">Martian</span> <span class="hlt">meteorites</span> attest to the potential for volcanic activity. If we can locate even one spot where fracturing, ice, and underground heat are co-located then we have the potential for an oasis. Such a discovery could truly excite the imaginations of both the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4297357','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4297357"><span>Dating the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami by the 87Rb-87Sr isochron method with a prototype in situ resonance ionization mass spectrometer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Scott Anderson, F; Levine, Jonathan; Whitaker, Tom J</p> <p>2015-01-01</p> <p>RATIONALE The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ∼270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ∼1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. METHODS We demonstrate the first use of laser ablation resonance ionization mass spectrometry for 87Rb-87Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. RESULTS To test whether we could meaningfully date planetary materials, we have analyzed a piece of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami. In each of four separate measurements we obtained 87Rb-87Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an 87Rb-87Sr age for this specimen of 360 ±90 Ma. CONCLUSIONS Our analyses of the Zagami <span class="hlt">meteorite</span> represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170009804','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170009804"><span><span class="hlt">Meteorite</span> Falls and the Fragmentation of <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Momeni, Daniel</p> <p>2016-01-01</p> <p>In order to understand the fragmentation of objects entering the atmosphere and why some produce more fragments than others, I have searched the <span class="hlt">Meteoritical</span> Society database for <span class="hlt">meteorites</span> greater than 20 kilograms that fell in the USA, China, and India. I also <span class="hlt">studied</span> the video and film records of 21 fireballs that produced <span class="hlt">meteorites</span>. A spreadsheet was prepared that noted smell, fireball, explosion, whistling, rumbling, the number of fragments, light, and impact sounds. Falls with large numbers of fragments were examined to look for common traits. These were: the Norton County aubrite, explosion and a flare greater than 100 fragments; the Forest City H5 chondrite explosion, a flare, a dust trail, 505 specimens; the Richardton H5 chondrite explosion and light, 71 specimens; the Juancheng H5 chondrite explosion, a rumbling, a flare, a dust trail,1000 specimens; the Tagish Lake C2 chondrite explosion, flare, dust trail, 500 specimens. I conclude that fragmentation is governed by the following: (1) Bigger meteors undergo more stress which results in more specimens; (2) Harder <span class="hlt">meteorites</span> also require more force to break them up which will cause greater fragmentation; (3) Force and pressure are directly proportional during falls. General observations made were; (1) <span class="hlt">Meteorites</span> produce fireballs sooner due to high friction; (2) Meteors tend to explode as well because of high stress; (3) Softer <span class="hlt">meteorites</span> tend to cause dust trails; (4) Some falls produce light as they fall at high velocity. I am grateful to NASA Ames for this opportunity and Derek Sears, Katie Bryson, and Dan Ostrowski for discussions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999DPS....31.6001P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999DPS....31.6001P"><span>Resolving the Many Mysteries of <span class="hlt">Martian</span> Soil: Lessons Learned from Apollo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pieters, C. M.</p> <p>1999-09-01</p> <p>If it were not for the return of lunar soil, we would still not understand why the spectrum of lunar soil is so unusual. We observe the intricacies of particles in the laboratory, but have never been able to duplicate the effects of weathering processes accumulated over time. We are in a directly parallel situation with our current understanding of <span class="hlt">Martian</span> soil from spectroscopic techniques. We know it contains a ferric component and we know something of its elemental composition; we know it is very fine grained; we know it is the cumulative weathering product of <span class="hlt">Martian</span> lithologies, some of which are known from <span class="hlt">meteorites</span>. A summary of several relevant lessons from <span class="hlt">studying</span> lunar soils include: 1) Physical and chemical processes fractionate the soils with respect to local rocks. 2) <span class="hlt">Meteoritic</span> contamination (largely from the constant rain of micrometeorites) cumulates in the soils. Lunar estimates are about 2-3 percent. 3) The fine fraction dominate observed optical properties, regardless of the presence of larger particles. Individual particles may accumulate coatings and rinds. 4) The spectral characteristics of the weathering products of iron dominate soil spectra. On the Moon it is highly reduced iron (typically 10's of nm in scale); on Mars it is highly oxidized (nano-phase?) iron. Modeling this 'gunk' or 'crud' is illusive. 5) Although weathering products dominate most spectra, signatures of the mineralogy of regional terrain can nevertheless be detected as subtle superimposed features. 6) Small-scale outcrops where soil has not been able to form or accumulate are critical markers of local lithology diversity. In planning exploration strategies using remote detectors, this latter lesson is particularly important and underlines the need for high resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.175..282B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.175..282B"><span>Barium isotope abundances in <span class="hlt">meteorites</span> and their implications for early Solar System evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bermingham, K. R.; Mezger, K.; Scherer, E. E.; Horan, M. F.; Carlson, R. W.; Upadhyay, D.; Magna, T.; Pack, A.</p> <p>2016-02-01</p> <p>Several nucleosynthetic processes contributed material to the Solar System, but the relative contributions of each process, the timing of their input into the solar nebula, and how well these components were homogenized in the solar nebula remain only partially constrained. The Ba isotope system is particularly useful in addressing these issues because Ba isotopes are synthesized via three nucleosynthetic processes (s-, r-, p-process). In this <span class="hlt">study</span>, high precision Ba isotope analyses of 22 different whole rock chondrites and achondrites (carbonaceous chondrites, ordinary chondrites, enstatite chondrites, <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, and eucrites) were performed to constrain the distribution of Ba isotopes on the regional scale in the Solar System. A melting method using aerodynamic levitation and CO2-laser heating was used to oxidize SiC, a primary carrier of Ba among presolar grains in carbonaceous chondrites. Destruction of these grains during the fusion process enabled the complete digestion of these samples. The Ba isotope data presented here are thus the first for which complete dissolution of the bulk <span class="hlt">meteorite</span> samples was certain. Enstatite chondrites, ordinary chondrites, and all achondrites measured here possess Ba isotope compositions that are not resolved from the terrestrial composition. Barium isotope anomalies are evident in most of the carbonaceous chondrites analyzed, but the 135Ba anomalies are generally smaller than previously reported for similarly sized splits of CM2 <span class="hlt">meteorites</span>. Variation in the size of the 135Ba anomaly is also apparent in fused samples from the same parent body (e.g., CM2 <span class="hlt">meteorites</span>) and in different pieces from the same <span class="hlt">meteorite</span> (e.g., Orgueil, CI). Here, we investigate the potential causes of variability in 135Ba, including the contribution of radiogenic 135Ba from the decay of 135Cs and incomplete homogenization of the presolar components on the <0.8 g sample scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010045226&hterms=tb&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtb','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010045226&hterms=tb&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtb"><span>Partitioning of Nd, Tb, Lu, and Hf Between Garnet and Ordinary Chondrite Melt at 5 to 9 GPa: Applications to <span class="hlt">Martian</span> Differentiation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Draper, D. S.; Chabot, N. L.; Xirouchakis, D.; Wasserman, A. A.; Agee, C. B.</p> <p>2001-01-01</p> <p>One explanation for Al and REE depletions in SNC <span class="hlt">meteorites</span> is early majorite fractionation in a deep <span class="hlt">martian</span> magma ocean. We report initial results from an experimental investigation of partitioning between majoritic garnet and ordinary chondrite liquid. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013HyInt.218..107L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013HyInt.218..107L"><span>Mössbauer <span class="hlt">study</span> of Slovak <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lipka, J.; Sitek, J.; Dekan, J.; Degmová, J.; Porubčan, V.</p> <p>2013-04-01</p> <p>57Fe Mössbauer spectroscopy was used as an analytical tool in the investigation of iron containing compounds of two <span class="hlt">meteorites</span> (Rumanová and Košice) out of total of six which had fallen on Slovak territory. In the magnetic fraction of the iron bearing compounds in the Rumanová <span class="hlt">meteorite</span>, maghemite, troilite and Fe-Ni alloy were identified. In the non-magnetic fraction silicate phases were found, such as olivine and pyroxene. The paramagnetic component containing Fe3 + ions corresponds probably to small superparamagnetic particles. The Košice <span class="hlt">meteorite</span> was found near the town of Košice in February 2010. Its magnetic fraction consists of a Fe-Ni alloy with the Mössbauer parameters of the magnetic field corresponding to kamacite α-Fe(Ni, Co) and troilite. The non-magnetic part consists of Fe2 + phases such as olivine and pyroxene and traces of a Fe3 + phase. The main difference between these <span class="hlt">meteorites</span> is their iron oxide content. These kinds of analyses can bring important knowledge about phases and compounds formed in extraterrestrial conditions, which have other features than their terrestrial analogues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1036318-laboratory-shock-experiments-basalt-iron-sulfate-mixes-gpa-relevance-martian-reolith-component-present-shergotties','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1036318-laboratory-shock-experiments-basalt-iron-sulfate-mixes-gpa-relevance-martian-reolith-component-present-shergotties"><span>Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at ~ 40 - 50 GPa and their Relevance to the <span class="hlt">Martian</span> Reolith Component Present in Shergotties</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rao, M N; Nyquist, L E; Ross, D K</p> <p>2012-03-14</p> <p>Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in <span class="hlt">Martian</span> atmospheric gases and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a <span class="hlt">Martian</span> regolith component based on Sm and Kr isotopic <span class="hlt">studies</span>. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The material comprising these glasses arises from the highly oxidizing <span class="hlt">Martian</span> surfacemore » and sulfur is unlikely to occur as sulfide in the <span class="hlt">Martian</span> regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> into space. As a result of high energy deposition by shock (~ 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H 2 and CO which were shock-implanted from the <span class="hlt">Martian</span> atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to shock pressures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992EOSTr..73...52S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992EOSTr..73...52S"><span><span class="hlt">Martian</span> Surface and Atmosphere Workshop</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schuraytz, Benjamin C.</p> <p></p> <p>The NASA-sponsored <span class="hlt">Martian</span> Surface and Atmosphere Through Time <span class="hlt">Study</span> Project convened its first major meeting at the University of Colorado in Boulder, September 23-25, 1991. The workshop, co-sponsored by the Lunar and Planetary Institute (LPI) and the Laboratory for Atmospheric and Space Physics at the University of Colorado, brought together an international group of 125 scientists to discuss a variety of issues relevant to the goals of the MSATT Program. The workshop program committee included co-convenors Robert Haberle, MSATT Steering Committee Chairman NASA Ames Research Center) and Bruce Jakosky (University of Colorado), and committee members Amos Banin (NASA Ames Research Center and Hebrew University), Benjamin Schuraytz (LPI), and Kenneth Tanaka (U.S. Geological Survey, Flagstaff, Ariz.).The purpose of the workshop was to begin exploring and defining the relationships between different aspects of Mars science—the evolution of the surface, the atmosphere, upper atmosphere, volatiles, and climate. Specific topics addressed in the 88 contributed abstracts included the current nature of the surface with respect to physical properties and photometric observations and interpretations; the history of geological processes, comprising water and ice-related geomorphology, impact cratering, and volcanism; and the geochemistry and mineralogy of the surface with emphasis on compositional and spectroscopic <span class="hlt">studies</span> and weathering processes. Also addressed were the present atmosphere, focusing on structure and dynamics, volatile and dust distribution, and the upper atmosphere; long-term volatile evolution based on volatiles in SNC <span class="hlt">meteorites</span> (certain <span class="hlt">meteorites</span> thought to have come from Mars) and atmospheric evolution processes; climate history and volatile cycles in relation to early climate and the polar caps, ground ice, and regolith; and future mission concepts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001831','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001831"><span>Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at Approximately 40-50 GPa and Their Relevance to the <span class="hlt">Martian</span> Regolith Component Present in Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Nyquist, L. E.; Ross, D. K.; Asimow, P. D.; See, T.; Sutton, S.; Cardernas, F.; Montes, R.; Cintala, M.</p> <p>2012-01-01</p> <p>Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in <span class="hlt">Martian</span> atmospheric gases [1] and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a <span class="hlt">Martian</span> regolith component based on Sm and Kr isotopic <span class="hlt">studies</span> [2]. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles [3, 4]. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The material comprising these glasses arises from the highly oxidizing <span class="hlt">Martian</span> surface and sulfur is unlikely to occur as sulfide in the <span class="hlt">Martian</span> regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev [5]. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> into space [6]. As a result of high energy deposition by shock (approx. 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H2 and CO which were shock-implanted from the <span class="hlt">Martian</span> atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P13A1917A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P13A1917A"><span>Lunar and <span class="hlt">Meteorite</span> Thin Sections for Undergraduate and Graduate <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allen, J.; Allen, C.</p> <p>2012-12-01</p> <p>The Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation, and distribution of samples for research, education, and public outreach. <span class="hlt">Studies</span> of rock and soil samples from the Moon and <span class="hlt">meteorites</span> continue to yield useful information about the early history of the Moon, the Earth, and the inner solar system. Petrographic Thin Section Packages containing polished thin sections of samples from either the Lunar or <span class="hlt">Meteorite</span> collections have been prepared. Each set of twelve sections of Apollo lunar samples or twelve sections of <span class="hlt">meteorites</span> is available for loan from JSC. The thin sections sets are designed for use in domestic college and university courses in petrology. The loan period is very strict and limited to two weeks. Contact Ms. Mary Luckey, Education Sample Curator. Email address: mary.k.luckey@nasa.gov Each set of slides is accompanied by teaching materials and a sample disk of representative lunar or <span class="hlt">meteorite</span> samples. It is important to note that the samples in these sets are not exactly the same as the ones listed here. This list represents one set of samples. A key education resource available on the Curation website is Antarctic <span class="hlt">Meteorite</span> Teaching Collection: Educational <span class="hlt">Meteorite</span> Thin Sections, originally compiled by Bevan French, Glenn McPherson, and Roy Clarke and revised by Kevin Righter in 2010. Curation Websites College and university staff and students are encouraged to access the Lunar Petrographic Thin Section Set Publication and the <span class="hlt">Meteorite</span> Petrographic Thin Section Package Resource which feature many thin section images and detailed descriptions of the samples, research results. http://curator.jsc.nasa.gov/Education/index.cfm Request research samples: http://curator.jsc.nasa.gov/ JSC-CURATION-EDUCATION-DISKS@mail.nasa.govLunar Thin Sections; <span class="hlt">Meteorite</span> Thin Sections;</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000064709&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dlindstrom','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000064709&hterms=lindstrom&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D30%26Ntt%3Dlindstrom"><span>Noble Gases in Iddingsite from the Lafayette <span class="hlt">Meteorite</span>: Evidence for Liquid Water on Mars in the Last Few Hundred Million Years</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Swindle, T. D.; Treiman, A. H.; Lindstrom, D. J.; Brkland, M. K.; Cohen, B. A.; Grier, J. A.; Li, B.; Olson, E. K.</p> <p>2000-01-01</p> <p>We analyzed noble gases from 18 samples of weathering products ("iddingsite") from the Lafayette <span class="hlt">meteorite</span>. Potassium-argon ages of 12 samples range from near zero to 670 +/- 91 Ma. These ages confirm the <span class="hlt">martian</span> origin of the iddingsite, but it is not clear whether any or all of the ages represent iddingsite formation as opposed to later alteration or incorporation of <span class="hlt">martian</span> atmospheric Ar-40. In any case, because iddingsite formation requires liquid water, this data requires the presence of liquid water near the surface of Mars at least as recently as 1300 Ma ago, and probably as recently as 650 Ma ago. Krypton and Xe analysis of a single 34 microg sample indicates the presence of fractionated <span class="hlt">martian</span> atmosphere within the iddingsite. This also confirms the <span class="hlt">martian</span> origin of the iddingsite. The mechanism of incorporation could either be through interaction with liquid water during iddingsite formation or a result of shock implantation of adsorbed atmospheric gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5287701','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5287701"><span>Two billion years of magmatism recorded from a single Mars <span class="hlt">meteorite</span> ejection site</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lapen, Thomas J.; Righter, Minako; Andreasen, Rasmus; Irving, Anthony J.; Satkoski, Aaron M.; Beard, Brian L.; Nishiizumi, Kunihiko; Jull, A. J. Timothy; Caffee, Marc W.</p> <p>2017-01-01</p> <p>The timing and nature of igneous activity recorded at a single Mars ejection site can be determined from the isotope analyses of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Northwest Africa (NWA) 7635 has an Sm-Nd crystallization age of 2.403 ± 0.140 billion years, and isotope data indicate that it is derived from an incompatible trace element–depleted mantle source similar to that which produced a geochemically distinct group of 327- to 574-million-year-old “depleted” shergottites. Cosmogenic nuclide data demonstrate that NWA 7635 was ejected from Mars 1.1 million years ago (Ma), as were at least 10 other depleted shergottites. The shared ejection age is consistent with a common ejection site for these <span class="hlt">meteorites</span>. The spatial association of 327- to 2403-Ma depleted shergottites indicates >2 billion years of magmatism from a long-lived and geochemically distinct volcanic center near the ejection site. PMID:28164153</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003093','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003093"><span>Oxygen Isotope Compositions of the Kaidun <span class="hlt">Meteorite</span> - Indications for Aqeuous Alteration of E-Chondrites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ziegler, K.; Zolensky, M.; Young, E. D.; Ivanov, A.</p> <p>2012-01-01</p> <p>The Kaidun microbreccia is a unique <span class="hlt">meteorite</span> due to the diversity of its constituent clasts. Fragments of various types of carbonaceous (CI, CM, CV, CR), enstatite (EH, EL), and ordinary chondrites, basaltic achondrites, and impact melt products have been described, and also several unknown clasts [1, and references therein]. The small mm-sized clasts represent material from different places and times in the early solar system, involving a large variety of parent bodies [2]; <span class="hlt">meteorites</span> are of key importance to the <span class="hlt">study</span> of the origin and evolution of the solar system, and Kaidun is a collection of a range of bodies evidently representing samples from across the asteroid belt. The parent-body on which Kaidun was assembled is believed to be a C-type asteroid, and 1-Ceres and the <span class="hlt">martian</span> moon Phobos have been proposed [1-4]. Both carbonaceous (most oxidized) and enstatite (most reduced) chondrite clasts in Kaidun show signs of aqueous alterations that vary in type and degree and are most likely of pre-Kaidun origin [1, 4].</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...106.1401M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...106.1401M"><span>Early evolution of <span class="hlt">Martian</span> volatiles: Nitrogen and noble gas components in ALH84001 and Chassigny</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mathew, K. J.; Marti, K.</p> <p>2001-01-01</p> <p><span class="hlt">Studies</span> on SNC <span class="hlt">meteorites</span> have permitted the characterization of modern <span class="hlt">Martian</span> atmospheric components as well as indigenous <span class="hlt">Martian</span> nitrogen and solar-type xenon. New isotopic and elemental abundances of noble gases and nitrogen in ALH84001 and Chassigny provide important constraints on the early evolution of the planet. A primitive solar Xe component (Chass-S) and an evolved Xe component (Chass-E), augmented with fission Xe are identified in Chassigny. Both components represent interior reservoirs of Mars and are characterized by low 129Xe/132Xe (<1.07) and by distinct elemental ratios 36Ar/132Xe<5 and >130, respectively. Light nitrogen (δ15N=-30‰) is associated with the Chass-S component and is enriched in melt inclusions in olivine. An ancient (presumably incorporated ~4 Gyr ago) evolved <span class="hlt">Martian</span> atmospheric component is identified in ALH84001 and has the following signatures: 129Xe/132Xe=2.16, 36Ar/38Ar>=5.0, 36Ar/132Xe=~50, 84Kr/132Xe=~6, and δ15N=7‰. The trapped Xe component in ALH84001 is not isotopically fractionated. We observe major shifts in nitrogen signatures due to cosmogenic N component in both Chassigny and ALH84001. A heavy nitrogen component of comparable magnitude (δ15N>150‰) has previously been interpreted as (heavy) <span class="hlt">Martian</span> atmospheric N. In situ produced fission Xe components, due to 244Pu in ALH84001 and due to 238U in Chassigny, are identified. The ALH84001 data strongly constrain exchanges of <span class="hlt">Martian</span> atmospheric and interior reservoirs. Mars retained abundant fission Xe components, and this may account for the low observed fission Xe component in the modern <span class="hlt">Martian</span> atmosphere. Chronometric information regarding the evolution of the early <span class="hlt">Martian</span> atmosphere can be secured from the relative abundances of radiogenic and fission Xe, as ~80% of the <span class="hlt">Martian</span> 129Xer is observed in the atmospheric 129Xe/132Xe ratio ~ 4 Gyr ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009148"><span>The Search for Ammonia in <span class="hlt">Martian</span> Soils with Curiosity's SAM Instrument</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wray, James J.; Archer, P. D.; Brinckerhoff, W. B.; Eigenbrode, J. L.; Franz, H. B.; Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; McKay, C. P.; Navarro-Gonzalez, R.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20130009148'); toggleEditAbsImage('author_20130009148_show'); toggleEditAbsImage('author_20130009148_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20130009148_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20130009148_hide"></p> <p>2013-01-01</p> <p>Nitrogen is the second or third most abundant constituent of the <span class="hlt">Martian</span> atmosphere [1,2]. It is a bioessential element, a component of all amino acids and nucleic acids that make up proteins, DNA and RNA, so assessing its availability is a key part of Curiosity's mission to characterize <span class="hlt">Martian</span> habitability. In oxidizing desert environments it is found in nitrate salts that co-occur with perchlorates [e.g., 3], inferred to be widespread in Mars soils [4-6]. A Mars nitrogen cycle has been proposed [7], yet prior missions have not constrained the state of surface N. Here we explore Curiosity's ability to detect N compounds using data from the rover's first solid sample. Companion abstracts describe evidence for nitrates [8] and for nitriles (C(triple bond)N) [9]; we focus here on nonnitrile, reduced-N compounds as inferred from bonded N-H. The simplest such compound is ammonia (NH3), found in many carbonaceous chondrite <span class="hlt">meteorites</span> in NH4(+) salts and organic compounds [e.g., 10].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Humans+AND+mars&pg=2&id=ED248165','ERIC'); return false;" href="https://eric.ed.gov/?q=Humans+AND+mars&pg=2&id=ED248165"><span>The <span class="hlt">Martian</span> Chronicles. A Sound Filmstrip Program. <span class="hlt">Study</span> Guide.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Christesen, Barbara</p> <p></p> <p>This filmstrip <span class="hlt">study</span> guide dramatizes several stories from Ray Bradbury's "The <span class="hlt">Martian</span> Chronicles" concerning basic issues of human nature: the need to respect cultural differences and the importance of preserving the environment. A collection of 26 short stories, "The <span class="hlt">Martian</span> Chronicles" describes the colonization of Mars. The…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatAs...1E.179P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatAs...1E.179P"><span>A <span class="hlt">Martian</span> origin for the Mars Trojan asteroids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Polishook, D.; Jacobson, S. A.; Morbidelli, A.; Aharonson, O.</p> <p>2017-08-01</p> <p>Seven of the nine known Mars Trojan asteroids belong to an orbital cluster1,2 named after its largest member, (5261) Eureka. Eureka is probably the progenitor of the whole cluster, which formed at least 1 Gyr ago3. It has been suggested3 that the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect spun up Eureka, resulting in fragments being ejected by the rotational-fission mechanism. Eureka's spectrum exhibits a broad and deep absorption band around 1 μm, indicating an olivine-rich composition4. Here we show evidence that the Trojan Eureka cluster progenitor could have originated as impact debris excavated from the <span class="hlt">Martian</span> mantle. We present new near-infrared observations of two Trojans ((311999) 2007 NS2 and (385250) 2001 DH47) and find that both exhibit an olivine-rich reflectance spectrum similar to Eureka's. These measurements confirm that the progenitor of the cluster has an achondritic composition4. Olivine-rich reflectance spectra are rare amongst asteroids5 but are seen around the largest basins on Mars6. They are also consistent with some <span class="hlt">Martian</span> <span class="hlt">meteorites</span> (for example, Chassigny7) and with the material comprising much of the <span class="hlt">Martian</span> mantle8,9. Using numerical simulations, we show that the Mars Trojans are more likely to be impact ejecta from Mars than captured olivine-rich asteroids transported from the main belt. This result directly links specific asteroids to debris from the forming planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170008100','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170008100"><span>Kinetic Damage from <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooke, William; Brown, Peter; Matney, Mark</p> <p>2017-01-01</p> <p>A Near Earth object impacting into Earth's atmosphere may produce damaging effects at the surface due to airblast, thermal pulse, or kinetic impact in the form of <span class="hlt">meteorites</span>. At large sizes (>many tens of meters), the damage is amplified by the hypersonic impact of these large projectiles moving with cosmic velocity, leaving explosively produced craters. However, much more common is simple "kinetic" damage caused by the impact of smaller <span class="hlt">meteorites</span> moving at terminal speeds. As of this date a handful of instances are definitively known of people or structures being directly hit and/or damaged by the kinetic impact of <span class="hlt">meteorites</span>. <span class="hlt">Meteorites</span> known to have struck humans include the Sylacauga, Alabama fall (1954) and the Mbale <span class="hlt">meteorite</span> fall (1992). Much more common is kinetic <span class="hlt">meteorite</span> damage to cars, buildings, and even a post box (Claxton, Georgia - 1984). Historical accounts indicate that direct kinetic damage by <span class="hlt">meteorites</span> may be more common than recent accounts suggest (Yau et al., 1994). In this talk we will examine the contemporary <span class="hlt">meteorite</span> flux and estimate the frequency of kinetic damage to various structures, as well as how the <span class="hlt">meteorite</span> flux might affect the rate of human casualties. This will update an earlier <span class="hlt">study</span> by Halliday et al (1985), adding variations expected in <span class="hlt">meteorite</span> flux with latitude (Le Feuvre and Wieczorek, 2008) and validating these model predictions of speed and entry angle with observations from the NASA and SOMN fireball networks. In particular, we explore the physical characteristics of bright meteors which may be used as a diagnostic for estimating which fireballs produce <span class="hlt">meteorites</span> and hence how early warning of such kinetic damage may be estimated in advance through observations and modelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170005389','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170005389"><span>Kinetic Damage from <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooke, William; Brown, Peter; Matney, Mark</p> <p>2017-01-01</p> <p>A Near Earth object impacting into Earth's atmosphere may produce damaging effects at the surface due to airblast, thermal pulse, or kinetic impact in the form of <span class="hlt">meteorites</span>. At large sizes (greater than many tens of meters), the damage is amplified by the hypersonic impact of these large projectiles moving with cosmic velocity, leaving explosively produced craters. However, much more common is simple "kinetic" damage caused by the impact of smaller <span class="hlt">meteorites</span> moving at terminal speeds. As of this date a handful of instances are definitively known of people or structures being directly hit and/or damaged by the kinetic impact of <span class="hlt">meteorites</span>. <span class="hlt">Meteorites</span> known to have struck humans include the Sylacauga, Alabama fall (1954) and the Mbale <span class="hlt">meteorite</span> fall (1992). Much more common is kinetic <span class="hlt">meteorite</span> damage to cars, buildings, and even a post box (Claxton, Georgia - 1984). Historical accounts indicate that direct kinetic damage by <span class="hlt">meteorites</span> may be more common than recent accounts suggest (Yau et al., 1994). In this talk we will examine the contemporary <span class="hlt">meteorite</span> flux and estimate the frequency of kinetic damage to various structures, as well as how the <span class="hlt">meteorite</span> flux might affect the rate of human casualties. This will update an earlier <span class="hlt">study</span> by Halliday et al (1985), adding variations expected in <span class="hlt">meteorite</span> flux with latitude (Le Feuvre and Wieczorek, 2008) and validating these model predictions of speed and entry angle with observations from the NASA and SOMN fireball networks. In particular, we explore the physical characteristics of bright meteors which may be used as a diagnostic for estimating which fireballs produce <span class="hlt">meteorites</span> and hence how early warning of such kinetic damage may be estimated in advance through observations and modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1800.5243H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1800.5243H"><span>Cosmogenic Nuclides <span class="hlt">Study</span> of Large Iron <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hutzler, A.; Smith, T.; Rochette, P.; Bourles, D. L.; Leya, I.; Gattacceca, J.</p> <p>2014-09-01</p> <p>Six large iron <span class="hlt">meteorites</span> were selected (Saint-Aubin, Mont-Dieu, Caille, Morasko, Agoudal, and Gebel Kamil). We measured stable and radiogenic cosmogenic nuclides, to <span class="hlt">study</span> pre-atmospheric size, cosmic-ray exposure ages and terrestrial ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AcSpe..62.1606D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AcSpe..62.1606D"><span>Laser induced breakdown spectroscopy on <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Giacomo, A.; Dell'Aglio, M.; de Pascale, O.; Longo, S.; Capitelli, M.</p> <p>2007-12-01</p> <p>The classification of <span class="hlt">meteorites</span> when geological analysis is unfeasible is generally made by the spectral line emission ratio of some characteristic elements. Indeed when a <span class="hlt">meteorite</span> impacts Earth's atmosphere, hot plasma is generated, as a consequence of the braking effect of air, with the consequent ablation of the falling body. Usually, by the plasma emission spectrum, the <span class="hlt">meteorite</span> composition is determined, assuming the Boltzmann equilibrium. The plasma generated during Laser Induced Breakdown Spectroscopy (LIBS) experiment shows similar characteristics and allows one to verify the mentioned method with higher accuracy. On the other hand the <span class="hlt">study</span> of Laser Induced Breakdown Spectroscopy on <span class="hlt">meteorite</span> can be useful for both improving <span class="hlt">meteorite</span> classification methods and developing on-flight techniques for asteroid investigation. In this paper certified <span class="hlt">meteorites</span> belonging to different typologies have been investigated by LIBS: Dofhar 461 (lunar <span class="hlt">meteorite</span>), Chondrite L6 (stony <span class="hlt">meteorite</span>), Dofhar 019 (Mars <span class="hlt">meteorite</span>) and Sikhote Alin (irony <span class="hlt">meteorite</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035620','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035620"><span><span class="hlt">Meteorites</span> at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fairen, A.G.; Dohm, J.M.; Baker, V.R.; Thompson, S.D.; Mahaney, W.C.; Herkenhoff, K. E.; Rodriguez, J.A.P.; Davila, A.F.; Schulze-Makuch, D.; El Maarry, M.R.; Uceda, E.R.; Amils, R.; Miyamoto, H.; Kim, K.J.; Anderson, R.C.; McKay, C.P.</p> <p>2011-01-01</p> <p>Six large iron <span class="hlt">meteorites</span> have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six <span class="hlt">meteorites</span> could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the <span class="hlt">Martian</span> surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. <span class="hlt">Meteorites</span> could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The <span class="hlt">meteorites</span> apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10-80m of deflation in the last 3-3.5Gy, would have exposed the buried <span class="hlt">meteorites</span>. We conclude that the iron <span class="hlt">meteorites</span> support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface. ?? The <span class="hlt">Meteoritical</span> Society, 2011.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27623199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27623199"><span>Supercritical Carbon Dioxide Extraction of Coronene in the Presence of Perchlorate for In Situ Chemical Analysis of <span class="hlt">Martian</span> Regolith.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCaig, Heather C; Stockton, Amanda; Crilly, Candice; Chung, Shirley; Kanik, Isik; Lin, Ying; Zhong, Fang</p> <p>2016-09-01</p> <p>The analysis of the organic compounds present in the <span class="hlt">martian</span> regolith is essential for understanding the history and habitability of Mars, as well as <span class="hlt">studying</span> the signs of possible extant or extinct life. To date, pyrolysis, the only technique that has been used to extract organic compounds from the <span class="hlt">martian</span> regolith, has not enabled the detection of unaltered native <span class="hlt">martian</span> organics. The elevated temperatures required for pyrolysis extraction can cause native <span class="hlt">martian</span> organics to react with perchlorate salts in the regolith and possibly result in the chlorohydrocarbons that have been detected by in situ instruments. Supercritical carbon dioxide (SCCO2) extraction is an alternative to pyrolysis that may be capable of delivering unaltered native organic species to an in situ detector. In this <span class="hlt">study</span>, we report the SCCO2 extraction of unaltered coronene, a representative polycyclic aromatic hydrocarbon (PAH), from <span class="hlt">martian</span> regolith simulants, in the presence of 3 parts per thousand (ppth) sodium perchlorate. PAHs are a class of nonpolar molecules of astrobiological interest and are delivered to the <span class="hlt">martian</span> surface by <span class="hlt">meteoritic</span> infall. We also determined that the extraction efficiency of coronene was unaffected by the presence of perchlorate on the regolith simulant, and that no sodium perchlorate was extracted by SCCO2. This indicates that SCCO2 extraction can provide de-salted samples that could be directly delivered to a variety of in situ detectors. SCCO2 was also used to extract trace native fluorescent organic compounds from the <span class="hlt">martian</span> regolith simulant JSC Mars-1, providing further evidence that SCCO2 extraction may provide an alternative to pyrolysis to enable the delivery of unaltered native organic compounds to an in situ detector on a future Mars rover. Biomarkers-Carbon dioxide-In situ measurement-Mars-Search for Mars' organics. Astrobiology 16, 703-714.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002644','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002644"><span>Hydrogen Isotopic Composition of Apatite in Northwest Africa 7034: A Record of the "Intermediate" H-Isotopic Reservoir in the <span class="hlt">Martian</span> Crust?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCubbin, F. M.; Barnes, J. J.; Santos, A. R.; Boyce, J. W.; Anand, M.; Franchi, I. A.; Agee, C. B.</p> <p>2016-01-01</p> <p>Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other <span class="hlt">martian</span> <span class="hlt">meteorite</span> to visible-infrared reflectance spectra of the <span class="hlt">martian</span> surface measured from orbit [2]. The composition of the fine-grained matrix within NWA 7034 bears a striking resemblance to the major element composition estimated for the <span class="hlt">martian</span> crust, with several exceptions. The NWA 7034 matrix is depleted in Fe, Ti, and Cr and enriched in Al, Na, and P [3]. The differences in Al and Fe are the most substantial, but the Fe content of NWA 7034 matrix falls within the range reported for the southern highlands crust [6]. It was previously suggested by [4] that NWA 7034 was sourced from the southern highlands based on the ancient 4.4 Ga ages recorded in NWA 7034/7533 zircons [4, 5]. In addition, the NWA 7034 matrix material is enriched in incompatible trace elements by a factor of 1.2-1.5 [7] relative to estimates of the bulk <span class="hlt">martian</span> crust. The La/Yb ratio of the bulk <span class="hlt">martian</span> crust is estimated to be approximately 3 [7], and the La/Yb of the NWA 7034 matrix materials ranges from approximately 3.9 to 4.4 [3, 8], indicating a higher degree of LREE enrichment in the NWA 7034 matrix materials. This elevated La/Yb ratio and enrichment in incompatible lithophile trace elements is consistent with NWA 7034 representing a more geochemically enriched crustal terrain than is represented by the bulk <span class="hlt">martian</span> crust, which would be expected if NWA 7034 represents the bulk crust from the southern highlands. Given the similarities between NWA 7034 and the <span class="hlt">martian</span> crust, NWA 7034 may represent an important sample for constraining the composition of the <span class="hlt">martian</span> crust, particularly the ancient highlands. In the present <span class="hlt">study</span>, we seek to constrain the H isotopic composition of the <span class="hlt">martian</span> crust using Cl-rich apatite in NWA 7034. Usui et al., [9] recently proposed that a H isotopic reservoir exists within the <span class="hlt">martian</span> crust that has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160011250','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160011250"><span>Evidence for a Heterogeneous Distribution of Water in the <span class="hlt">Martian</span> Interior</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCubbin, Francis; Boyce, Jeremy W.; Srinvasan, Poorna; Santos, Alison R.; Elardo, Stephen M.; Filiberto, Justin; Steele, Andrew; Shearer, Charles K.</p> <p>2016-01-01</p> <p>The abundance and distribution of H2O within the terrestrial planets, as well as its timing of delivery, is a topic of vital importance for understanding the chemical and physical evolution of planets and their potential for hosting habitable environments. Analysis of planetary materials from Mars, the Moon, and the eucrite parent body (i.e., asteroid 4Vesta) have confirmed the presence of H2O within their interiors. Moreover, H and N isotopic data from these planetary materials suggests H2O was delivered to the inner solar system very early from a common source, similar in composition to the carbonaceous chondrites. Despite the ubiquity of H2O in the inner Solar System, the only destination with any prospects for past or present habitable environments at this time, outside of the Earth, is Mars. Although the presence of H2O within the <span class="hlt">martian</span> interior has been confirmed, very little is known regarding its abundance and distribution within the <span class="hlt">martian</span> interior and how the <span class="hlt">martian</span> water inventory has changed over time. By combining new analyses of <span class="hlt">martian</span> apatites within a large number of <span class="hlt">martian</span> <span class="hlt">meteorite</span> types with previously published volatile data and recently determined mineral-melt partition coefficients for apatite, we report new insights into the abundance and distribution of volatiles in the <span class="hlt">martian</span> crust and mantle. Using the subset of samples that did not exhibit crustal contamination, we determined that the enriched shergottite mantle source has 36-73 ppm H2O and the depleted shergottite mantle source has 14-23 ppm H2O. This result is consistent with other observed geochemical differences between enriched and depleted shergottites and supports the idea that there are at least two geochemically distinct reservoirs in the <span class="hlt">martian</span> mantle. We also estimated the H2O content of the <span class="hlt">martian</span> crust using the revised mantle H2O abundances and known crust-mantle distributions of incompatible lithophile elements. We determined that the bulk <span class="hlt">martian</span> crust has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGP42A..06U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGP42A..06U"><span>Magnetic <span class="hlt">study</span> of <span class="hlt">meteorites</span> recovered in the Atacama desert (Chile): implications for <span class="hlt">meteorite</span> paleomagnetism and the stability of hot desert surfaces (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uehara, M.; Gattacceca, J.; Valenzuela, M.; Demory, F.; Rochette, P.</p> <p>2010-12-01</p> <p>Hot deserts are one of the large reservoirs of <span class="hlt">meteorites</span> on Earth (about 25% of total <span class="hlt">meteorites</span>), and some groups of rare <span class="hlt">meteorites</span> (Rumuruti chondrites or lunar <span class="hlt">meteorites</span> for instance). Therefore, the paleomagnetic record of hot desert <span class="hlt">meteorites</span> is potentially a good source of information about the ancient extraterrestrial magnetic fields. However, <span class="hlt">meteorites</span> recovered in hot deserts have typical terrestrial residence times (their so-called terrestrial ages) in the order of a few to several tens of kyr. During that time, a desert <span class="hlt">meteorite</span> is exposed to the geomagnetic field, and is likely to acquire a Viscous Remanent Magnetization (VRM) whose intensity is controlled, among other things, by the stability of the desert surface. Moreover, with increasing terrestrial age, metallic and sulphide phases that are the dominant magnetic minerals in <span class="hlt">meteorites</span> are oxidized and form potentially magnetic weathering minerals, resulting in the possible destruction of the primary remanence and acquisition of secondary terrestrial chemical remanence (CRM). Therefore, the paleomagnetic <span class="hlt">study</span> of desert <span class="hlt">meteorites</span> must take into account these terrestrial processes, in order to isolate the extraterrestrial magnetic record. We report here the paleomagnetic data obtained from 8 ordinary chondrites (3 H- and 5 L-chondrites) collected by our group in the Atacama desert (Chile) and oriented in situ with respect to the geographic north. Optical microscopy found that their weathering grades are W3 (60 - 95 % of metal is replaced by oxi-/hydroxides, 4 samples), W2 (moderate oxidation of metal, 20 - 60 % replaced; 2 samples), and W1 (only minor oxidation, 2 samples). Alternating field demagnetization experiments up to 100 mT found that W1 and W2 samples have a very low coercivity component (< 5 mT) and show unstable demagnetization paths above 10 mT, a behavior similar to that of freshly fallen ordinary chondrites. On the other hand, the more weathered samples (weathering stage W3) have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25641494','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25641494"><span>Dating the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J</p> <p>2015-01-30</p> <p>The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami <span class="hlt">meteorite</span> represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3193235','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3193235"><span>Carbonates in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Allan Hills 84001 formed at 18 ± 4 °C in a near-surface aqueous environment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Halevy, Itay; Fischer, Woodward W.; Eiler, John M.</p> <p>2011-01-01</p> <p>Despite evidence for liquid water at the surface of Mars during the Noachian epoch, the temperature of early aqueous environments has been impossible to establish, raising questions of whether the surface of Mars was ever warmer than today. We address this problem by determining the precipitation temperature of secondary carbonate minerals preserved in the oldest known sample of Mars’ crust—the approximately 4.1 billion-year-old <span class="hlt">meteorite</span> Allan Hills 84001 (ALH84001). The formation environment of these carbonates, which are constrained to be slightly younger than the crystallization age of the rock (i.e., 3.9 to 4.0 billion years), has been poorly understood, hindering insight into the hydrologic and carbon cycles of earliest Mars. Using “clumped” isotope thermometry we find that the carbonates in ALH84001 precipitated at a temperature of approximately 18 °C, with water and carbon dioxide derived from the ancient <span class="hlt">Martian</span> atmosphere. Furthermore, covarying carbonate carbon and oxygen isotope ratios are constrained to have formed at constant, low temperatures, pointing to deposition from a gradually evaporating, subsurface water body—likely a shallow aquifer (meters to tens of meters below the surface). Despite the mild temperatures, the apparently ephemeral nature of water in this environment leaves open the question of its habitability. PMID:21969543</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000057048','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000057048"><span>Mineralogy of the <span class="hlt">Martian</span> Surface: Crustal Composition to Surface Processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mustard, John F.</p> <p>1999-01-01</p> <p>Over the course of this award we have: 1) Completed and published the results of a <span class="hlt">study</span> of the effects of hyperfine particles on reflectance spectra of olivine and quartz, which included the development of scattering codes. Research has also progressed in the analysis of the effects of fine particle sizes on clay spectra. 2) Completed the analysis of the mineralogy of dark regions, showed the insitu compositions are highly correlated to the SNC <span class="hlt">meteorites</span>, and determined that the <span class="hlt">martian</span> mantle was depleted in aluminum prior to 2-3 GA ago; <span class="hlt">Studies</span> of the mineralogic heterogeneity of surficial materials on Mars have also been conducted. and 3) Performed initial work on the <span class="hlt">study</span> of the physical and chemical processes likely to form and modify duricrust. This includes assessments of erosion rates, solubility and transport of iron in soil environments, and models of pedogenic crust formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830012611','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830012611"><span>The 45th Annual <span class="hlt">Meteoritical</span> Society Meeting</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, P. (Compiler); Turner, L. (Compiler)</p> <p>1982-01-01</p> <p>Impact craters and shock effects, chondrite formation and evolution, <span class="hlt">meteorites</span>, chondrules, irons, nebular processes and <span class="hlt">meteorite</span> parent bodies, regoliths and breccias, antarctic <span class="hlt">meteorite</span> curation, isotopic <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and lunar samples, organics and terrestrial weathering, refractory inclusions, cosmic dust, particle irradiations before and after compaction, and mineralogic <span class="hlt">studies</span> and analytical techniques are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23869013','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23869013"><span>Isotope ratios of H, C, and O in CO2 and H2O of the <span class="hlt">martian</span> atmosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Webster, Chris R; Mahaffy, Paul R; Flesch, Gregory J; Niles, Paul B; Jones, John H; Leshin, Laurie A; Atreya, Sushil K; Stern, Jennifer C; Christensen, Lance E; Owen, Tobias; Franz, Heather; Pepin, Robert O; Steele, Andrew; Achilles, Cherie; Agard, Christophe; Alves Verdasca, José Alexandre; Anderson, Robert; Anderson, Ryan; Archer, Doug; Armiens-Aparicio, Carlos; Arvidson, Ray; Atlaskin, Evgeny; Aubrey, Andrew; Baker, Burt; Baker, Michael; Balic-Zunic, Tonci; Baratoux, David; Baroukh, Julien; Barraclough, Bruce; Bean, Keri; Beegle, Luther; Behar, Alberto; Bell, James; Bender, Steve; Benna, Mehdi; Bentz, Jennifer; Berger, Gilles; Berger, Jeff; Berman, Daniel; Bish, David; Blake, David F; Blanco Avalos, Juan J; Blaney, Diana; Blank, Jen; Blau, Hannah; Bleacher, Lora; Boehm, Eckart; Botta, Oliver; Böttcher, Stephan; Boucher, Thomas; Bower, Hannah; Boyd, Nick; Boynton, Bill; Breves, Elly; Bridges, John; Bridges, Nathan; Brinckerhoff, William; Brinza, David; Bristow, Thomas; Brunet, Claude; Brunner, Anna; Brunner, Will; Buch, Arnaud; Bullock, Mark; Burmeister, Sönke; Cabane, Michel; Calef, Fred; Cameron, James; Campbell, John; Cantor, Bruce; Caplinger, Michael; Caride Rodríguez, Javier; Carmosino, Marco; Carrasco Blázquez, Isaías; Charpentier, Antoine; Chipera, Steve; Choi, David; Clark, Benton; Clegg, Sam; Cleghorn, Timothy; Cloutis, Ed; Cody, George; Coll, Patrice; Conrad, Pamela; Coscia, David; Cousin, Agnès; Cremers, David; Crisp, Joy; Cros, Alain; Cucinotta, Frank; d'Uston, Claude; Davis, Scott; Day, Mackenzie; de la Torre Juarez, Manuel; DeFlores, Lauren; DeLapp, Dorothea; DeMarines, Julia; DesMarais, David; Dietrich, William; Dingler, Robert; Donny, Christophe; Downs, Bob; Drake, Darrell; Dromart, Gilles; Dupont, Audrey; Duston, Brian; Dworkin, Jason; Dyar, M Darby; Edgar, Lauren; Edgett, Kenneth; Edwards, Christopher; Edwards, Laurence; Ehlmann, Bethany; Ehresmann, Bent; Eigenbrode, Jen; Elliott, Beverley; Elliott, Harvey; Ewing, Ryan; Fabre, Cécile; Fairén, Alberto; Farley, Ken; Farmer, Jack; Fassett, Caleb; Favot, Laurent; Fay, Donald; Fedosov, Fedor; Feldman, Jason; Feldman, Sabrina; Fisk, Marty; Fitzgibbon, Mike; Floyd, Melissa; Flückiger, Lorenzo; Forni, Olivier; Fraeman, Abby; Francis, Raymond; François, Pascaline; Freissinet, Caroline; French, Katherine Louise; Frydenvang, Jens; Gaboriaud, Alain; Gailhanou, Marc; Garvin, James; Gasnault, Olivier; Geffroy, Claude; Gellert, Ralf; Genzer, Maria; Glavin, Daniel; Godber, Austin; Goesmann, Fred; Goetz, Walter; Golovin, Dmitry; Gómez Gómez, Felipe; Gómez-Elvira, Javier; Gondet, Brigitte; Gordon, Suzanne; Gorevan, Stephen; Grant, John; Griffes, Jennifer; Grinspoon, David; Grotzinger, John; Guillemot, Philippe; Guo, Jingnan; Gupta, Sanjeev; Guzewich, Scott; Haberle, Robert; Halleaux, Douglas; Hallet, Bernard; Hamilton, Vicky; Hardgrove, Craig; Harker, David; Harpold, Daniel; Harri, Ari-Matti; Harshman, Karl; Hassler, Donald; Haukka, Harri; Hayes, Alex; Herkenhoff, Ken; Herrera, Paul; Hettrich, Sebastian; Heydari, Ezat; Hipkin, Victoria; Hoehler, Tori; Hollingsworth, Jeff; Hudgins, Judy; Huntress, Wesley; Hurowitz, Joel; Hviid, Stubbe; Iagnemma, Karl; Indyk, Steve; Israël, Guy; Jackson, Ryan; Jacob, Samantha; Jakosky, Bruce; Jensen, Elsa; Jensen, Jaqueline Kløvgaard; Johnson, Jeffrey; Johnson, Micah; Johnstone, Steve; Jones, Andrea; Joseph, Jonathan; Jun, Insoo; Kah, Linda; Kahanpää, Henrik; Kahre, Melinda; Karpushkina, Natalya; Kasprzak, Wayne; Kauhanen, Janne; Keely, Leslie; Kemppinen, Osku; Keymeulen, Didier; Kim, Myung-Hee; Kinch, Kjartan; King, Penny; Kirkland, Laurel; Kocurek, Gary; Koefoed, Asmus; Köhler, Jan; Kortmann, Onno; Kozyrev, Alexander; Krezoski, Jill; Krysak, Daniel; Kuzmin, Ruslan; Lacour, Jean Luc; Lafaille, Vivian; Langevin, Yves; Lanza, Nina; Lasue, Jeremie; Le Mouélic, Stéphane; Lee, Ella Mae; Lee, Qiu-Mei; Lees, David; Lefavor, Matthew; Lemmon, Mark; Lepinette Malvitte, Alain; Léveillé, Richard; Lewin-Carpintier, Éric; Lewis, Kevin; Li, Shuai; Lipkaman, Leslie; Little, Cynthia; Litvak, Maxim; Lorigny, Eric; Lugmair, Guenter; Lundberg, Angela; Lyness, Eric; Madsen, Morten; Maki, Justin; Malakhov, Alexey; Malespin, Charles; Malin, Michael; Mangold, Nicolas; Manhes, Gérard; Manning, Heidi; Marchand, Geneviève; Marín Jiménez, Mercedes; Martín García, César; Martin, Dave; Martin, Mildred; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F Javier; Mauchien, Patrick; Maurice, Sylvestre; McAdam, Amy; McCartney, Elaina; McConnochie, Timothy; McCullough, Emily; McEwan, Ian; McKay, Christopher; McLennan, Scott; McNair, Sean; Melikechi, Noureddine; Meslin, Pierre-Yves; Meyer, Michael; Mezzacappa, Alissa; Miller, Hayden; Miller, Kristen; Milliken, Ralph; Ming, Douglas; Minitti, Michelle; Mischna, Michael; Mitrofanov, Igor; Moersch, Jeff; Mokrousov, Maxim; Molina Jurado, Antonio; Moores, John; Mora-Sotomayor, Luis; Morookian, John Michael; Morris, Richard; Morrison, Shaunna; Mueller-Mellin, Reinhold; Muller, Jan-Peter; Muñoz Caro, Guillermo; Nachon, Marion; Navarro López, Sara; Navarro-González, Rafael; Nealson, Kenneth; Nefian, Ara; Nelson, Tony; Newcombe, Megan; Newman, Claire; Newsom, Horton; Nikiforov, Sergey; Nixon, Brian; Noe Dobrea, Eldar; Nolan, Thomas; Oehler, Dorothy; Ollila, Ann; Olson, Timothy; de Pablo Hernández, Miguel Ángel; Paillet, Alexis; Pallier, Etienne; Palucis, Marisa; Parker, Timothy; Parot, Yann; Patel, Kiran; Paton, Mark; Paulsen, Gale; Pavlov, Alex; Pavri, Betina; Peinado-González, Verónica; Peret, Laurent; Perez, Rene; Perrett, Glynis; Peterson, Joe; Pilorget, Cedric; Pinet, Patrick; Pla-García, Jorge; Plante, Ianik; Poitrasson, Franck; Polkko, Jouni; Popa, Radu; Posiolova, Liliya; Posner, Arik; Pradler, Irina; Prats, Benito; Prokhorov, Vasily; Purdy, Sharon Wilson; Raaen, Eric; Radziemski, Leon; Rafkin, Scot; Ramos, Miguel; Rampe, Elizabeth; Raulin, François; Ravine, Michael; Reitz, Günther; Rennó, Nilton; Rice, Melissa; Richardson, Mark; Robert, François; Robertson, Kevin; Rodriguez Manfredi, José Antonio; Romeral-Planelló, Julio J; Rowland, Scott; Rubin, David; Saccoccio, Muriel; Salamon, Andrew; Sandoval, Jennifer; Sanin, Anton; Sans Fuentes, Sara Alejandra; Saper, Lee; Sarrazin, Philippe; Sautter, Violaine; Savijärvi, Hannu; Schieber, Juergen; Schmidt, Mariek; Schmidt, Walter; Scholes, Daniel; Schoppers, Marcel; Schröder, Susanne; Schwenzer, Susanne; Sebastian Martinez, Eduardo; Sengstacken, Aaron; Shterts, Ruslan; Siebach, Kirsten; Siili, Tero; Simmonds, Jeff; Sirven, Jean-Baptiste; Slavney, Susie; Sletten, Ronald; Smith, Michael; Sobrón Sánchez, Pablo; Spanovich, Nicole; Spray, John; Squyres, Steven; Stack, Katie; Stalport, Fabien; Stein, Thomas; Stewart, Noel; Stipp, Susan Louise Svane; Stoiber, Kevin; Stolper, Ed; Sucharski, Bob; Sullivan, Rob; Summons, Roger; Sumner, Dawn; Sun, Vivian; Supulver, Kimberley; Sutter, Brad; Szopa, Cyril; Tan, Florence; Tate, Christopher; Teinturier, Samuel; ten Kate, Inge; Thomas, Peter; Thompson, Lucy; Tokar, Robert; Toplis, Mike; Torres Redondo, Josefina; Trainer, Melissa; Treiman, Allan; Tretyakov, Vladislav; Urqui-O'Callaghan, Roser; Van Beek, Jason; Van Beek, Tessa; VanBommel, Scott; Vaniman, David; Varenikov, Alexey; Vasavada, Ashwin; Vasconcelos, Paulo; Vicenzi, Edward; Vostrukhin, Andrey; Voytek, Mary; Wadhwa, Meenakshi; Ward, Jennifer; Weigle, Eddie; Wellington, Danika; Westall, Frances; Wiens, Roger Craig; Wilhelm, Mary Beth; Williams, Amy; Williams, Joshua; Williams, Rebecca; Williams, Richard B; Wilson, Mike; Wimmer-Schweingruber, Robert; Wolff, Mike; Wong, Mike; Wray, James; Wu, Megan; Yana, Charles; Yen, Albert; Yingst, Aileen; Zeitlin, Cary; Zimdar, Robert; Zorzano Mier, María-Paz</p> <p>2013-07-19</p> <p>Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the <span class="hlt">martian</span> atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of <span class="hlt">martian</span> <span class="hlt">meteorites</span> such as ALH 84001 implies that the <span class="hlt">martian</span> reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P23C1942A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P23C1942A"><span>Micro-mapping <span class="hlt">Meteorite</span> Surfaces on Mars using Microscopic Imager Mosaics — A Tool for Unraveling Weathering History at Meridiani Planum</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashley, J. W.; Herkenhoff, K. E.; Golombek, M. P.; Johnson, J. R.</p> <p>2012-12-01</p> <p><span class="hlt">Meteorites</span> found on Mars provide valuable insights into <span class="hlt">martian</span> surface processes. During the course of Mars Exploration Rover (MER) extended missions, Spirit and Opportunity have identified 17 confirmed and candidate <span class="hlt">meteorites</span> on Mars, most of which are irons. The iron <span class="hlt">meteorites</span> exhibit morphologies and coatings that communicate complex post-fall exposure histories relevant to an understanding of climate near the <span class="hlt">martian</span> equator [1-4]. Both chemical and mechanical weathering effects are represented. Among the more significant of these are: 1) cm-scale hollowing, 2) surficial rounding, 3) mass excavation/dissolution and removal, 4) differential etching of kamacite plates and taenite lamellae, revealing Widmanstätten patterns, 5) discontinuous iron oxide coatings, and 6) the effects of cavernous weathering, which often penetrate to rock interiors. Determining the nature, magnitude, and timing of each process and its associated features is a complex problem that will be aided by laboratory experiments, image processing, and careful surface evaluation. Because some features appear to superpose others in ways analogous to stratigraphic relationships, Microscopic Imager (MI) mosaics are useful for sketching "geologic maps" of <span class="hlt">meteorite</span> surfaces. Employing the techniques of conventional planetary mapping [5], each map was drafted manually using full-resolution MI mosaics and Adobe Photoshop software. Units were selected to represent the oxide coating, dust-coated surfaces, sand-coated surfaces, taenite lamellae, and uncoated metal. Also included are areas in shadow, and regions of blooming caused by specular reflection of metal. Regmaglypt rim crests are presented as lineations. As with stratigraphic relationships, noting embayments and other cross-cutting relationships assists with establishing the relative timing for observed weathering effects. In addition to suggesting alternating sequences of wind and water exposure [1], patterns in oxide coating occurrence show</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970019937','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970019937"><span>Constraints on <span class="hlt">Martian</span> Differentiation Processes from Rb-Sr and Sm-Nd Isotopic Analyses of the Basaltic Shergottite QUE 94201</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Borg, Lars E.; Nyquist, Larry E.; Taylor, Larry A.; Wiesmann, Henry; Shih, Chi-Y.</p> <p>1997-01-01</p> <p>Isotopic analyses of mineral, leachate, and whole rock fractions from the <span class="hlt">Martian</span> shergottite <span class="hlt">meteorite</span> QUE 94201 yield Rb-Sr and Sm-Nd crystallization ages of 327 +/- 12 and 327 +/- 19 Ma, respectively. These ages are concordant, although the isochrons are defined by different fractions within the <span class="hlt">meteorite</span>. Comparison of isotope dilution Sm and Nd data for the various QUE 94201 fractions with in situ ion microprobe data for QUE 94201 minerals from the literature demonstrate the presence of a leachable crustal component in the <span class="hlt">meteorite</span>. This component is likely to have been added to QUE 94201 by secondary alteration processes on Mars, and can affect the isochrons by selectively altering the isotopic systematics of the leachates and some of the mineral fractions. The absence of crustal recycling processes on Mars may preserve the geochemical evidence for early differentiation and the decoupling of the Rb-Sr and Sm-Nd isotopic systems, underscoring one of the fundamental differences between geologic processes on Mars and the Earth.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814173L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814173L"><span>Evaporites on Ice: Experimental Assessment of Evaporites Formation on Antarctica (and on <span class="hlt">Martian</span> North Polar Residual Cap)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losiak, Anna; Derkowski, Arkadiusz; Skala, Aleksander; Trzcinski, Jerzy</p> <p>2016-04-01</p> <p>Evaporites are highly water soluble minerals, formed as a result of the evaporation or freezing of bodies of water. They are common weathering minerals found on rocks (including <span class="hlt">meteorites</span>) on Antarctic ice sheet [1,2,3,4]. The water necessary for the reaction is produced by melting of ice below the dark-colored <span class="hlt">meteorites</span> which can heat up to a few degrees above 0 °C due to insolation heating during wind-free summer days [5,6]. The <span class="hlt">Martian</span> North Polar Residual Cap is surrounded by a young [7] dune field that is rich in evaporitic mineral: gypsum [8]. Its existence implies that relatively recently in the <span class="hlt">Martian</span> history (in late Amazonian, when surface conditions were comparable to the current ones) there was a significant amount of liquid water present on the Mars surface. One of the proposed solutions to this problem is that gypsum is formed by weathering on/in ice [9,10,11,12,13], similarly to the process occurring on the Antarctic ice sheet. Recently, Losiak et al. 2015 showed that that during the warmest days of the <span class="hlt">Martian</span> summer, solar irradiation may be sufficient to melt pure water ice located below a layer of dark dust particles lying on the steepest sections of the equator-facing slopes of the spiral troughs within <span class="hlt">Martian</span> NPRC. Under the current irradiation conditions, melting is possible in very restricted areas of the NPRC and it lasts for up to couple of hours, but during the times of high irradiance at the north pole [15] this process could have been much more pronounced. Liquid water can be metastable at the NPRC because the pressure during the summer season is ~760-650 Pa [16] which is above the triple point of water. The rate of free-surface "clean" liquid water evaporation under average <span class="hlt">Martian</span> conditions determined experimentally by [17] is comparable to the rate of melting determined by [21] (if there is no wind at the surface). In the current <span class="hlt">study</span> we attempt to determine experimentally how many melting-freezing cycles are required to form</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019339','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019339"><span>International Workshop on Antarctic <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Annexstad, J. O.; Schultz, L.; Waenke, H.</p> <p>1986-01-01</p> <p>Topics addressed include: <span class="hlt">meteorite</span> concentration mechanisms; <span class="hlt">meteorites</span> and the Antarctic ice sheet; iron <span class="hlt">meteorites</span>; iodine overabundance in <span class="hlt">meteorites</span>; entrainment, transport, and concentration of <span class="hlt">meteorites</span> in polar ice sheets; weathering of stony <span class="hlt">meteorites</span>; cosmic ray records; radiocarbon dating; element distribution and noble gas isotopic abundances in lunar <span class="hlt">meteorites</span>; thermoanalytical characterization; trace elements; thermoluminescence; parent sources; and <span class="hlt">meteorite</span> ablation and fusion spherules in Antarctic ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8521E..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8521E..05P"><span>Microbiological <span class="hlt">study</span> of the Murchison CM2 <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pikuta, Elena V.; Hoover, Richard B.</p> <p>2012-10-01</p> <p>In 1864, Louis Pasteur attempted to cultivate living microorganisms from pristine samples of the Orgueil CI1 carbonaceous <span class="hlt">meteorite</span>. His results were negative and never published, but recorded it in his laboratory notebooks. At that time, only aerobic liquid or agar-based organic reach media were used, as his research on anaerobes had just started. In our laboratory the Murchison CM2 carbonaceous <span class="hlt">meteorite</span> was selected to expand on these <span class="hlt">studies</span> for microbiological <span class="hlt">study</span> by cultivation on anaerobic mineral media. Since the surface could have been more easily contaminated, interior fragments of a sample of the Murchison <span class="hlt">meteorite</span> were extracted and crushed under sterile conditions. The resulting powder was then mixed in anoxic medium and injected into Hungate tubes containing anaerobic media with various growth substrates at different pH and salinity and incubated at different temperatures. The goal of the experiments was to determine if living cells would grow from the material of freshly fractured interior fragments of the stone. If any growth occurred, work could then be carried out to assess the nature of the environmental contamination by observations of the culture growth (rates of speed and biodiversity); live/dead fluorescent staining to determine contamination level and DNA analysis to establish the microbial species present. In this paper we report the results of that <span class="hlt">study</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100010148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100010148"><span>Sm-Nd Isotopic <span class="hlt">Studies</span> of Two Nakhlites, NWA 5790 and Nakhla</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>C.-Y. Shih; Nyquist, L. E.; Reese, Y.; Jambon, A.</p> <p>2010-01-01</p> <p>NWA 5790 is a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> recently found in the Mauritania part of the Saharan desert and is classified as a nakhlite, containing a small amount of interstitial plagioclase. Unlike other <span class="hlt">Martian</span> <span class="hlt">meteorites</span> ( e.g., shergottites), nakhlites have been only moderately shocked and their original igneous textures are still well-preserved. In this report, we present Sm-Nd isotopic data for NWA 5790 and Nakhla, a rare "fall" nakhlite, correlate their ages with those of other nakhlites and discuss their petrogenesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780004992','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780004992"><span>Comparison of lunar rocks and <span class="hlt">meteorites</span>: Implications to histories of the moon and parent <span class="hlt">meteorite</span> bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prinz, M.; Fodor, R. V.; Keil, K.</p> <p>1977-01-01</p> <p>There are many similarities between lunar samples and stone <span class="hlt">meteorites</span>. Lunar samples, especially from the highlands, indicate that they have been affected by complex and repeated impact processes. Similar complex and repeated impact processes have also been operative on the achondritic and chondritic <span class="hlt">meteorites</span>. Similarities between lunar and <span class="hlt">meteoritic</span> rocks are discussed as follows: (1) Monomict and polymict breccias occur in lunar rocks, as well as in achondritic and chondritic <span class="hlt">meteorites</span>, having resulted from complex and repeated impact processes; (2) Chondrules are present in lunar <span class="hlt">meteorites</span>, as well as in a few achondritic and most chondritic <span class="hlt">meteorites</span>. They apparently crystallized spontaneously from molten highly supercooled droplets which may have formed from impact melts or, perhaps, volcanic processes (as well as from the solar nebula, in the case of <span class="hlt">meteoritic</span> chondrites); (3) Lithic fragments vary from little modified (relative to the apparent original texture) to partly or completely melted and recrystallized lithic fragments. Their detailed <span class="hlt">study</span> allows conclusions to be drawn about their parent rock types and their origin, thereby gaining insight into preimpact histories of lunar and <span class="hlt">meteoritic</span> breccias. There is evidence that cumulate rocks were involved in the early history of both moon and parent <span class="hlt">meteorite</span> bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PSA..75.5339I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PSA..75.5339I"><span>Complexities of Focused Ion Beam Preparation of Electron-Transparent Sections for <span class="hlt">Meteorite</span> <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishii, H. A.; Bradley, J. P.; Teslich, N.</p> <p>2012-09-01</p> <p>Focused Ion Beam is increasingly used to prepare site-specific, electron-transparent sections for <span class="hlt">meteorite</span> micro-texture and -chemistry <span class="hlt">studies</span>. We discuss technical challenges and frequently-overlooked FIB artifacts relevant to <span class="hlt">meteorite</span> analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70004674','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70004674"><span><span class="hlt">Meteorites</span> at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fairen, Alberto G.; Dohm, James M.; Baker, Victor R.; Thompson, Shane D.; Mahaney, William C.; Herkenhoff, Kenneth E.; Rodriguez, J. Alexis P.; Davila, Alfonso F.; Schulze-Makuch, Dirk; El Maarry, M. Ramy; Uceda, Esther R.; Amils, Ricardo; Miyamoto, Hirdy; Kim, Kyeong J.; Anderson, Robert C.; McKay, Christopher P.</p> <p>2011-01-01</p> <p>Six large iron <span class="hlt">meteorites</span> have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25 km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six <span class="hlt">meteorites</span> could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the <span class="hlt">Martian</span> surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. <span class="hlt">Meteorites</span> could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The <span class="hlt">meteorites</span> apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10–80 m of deflation in the last 3–3.5 Gy, would have exposed the buried <span class="hlt">meteorites</span>. We conclude that the iron <span class="hlt">meteorites</span> support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019344','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019344"><span>Mysterious iodine-overabundance in Antarctic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dreibus, G.; Waenke, H.; Schultz, L.</p> <p>1986-01-01</p> <p>Halogen as well as other trace element concentrations in <span class="hlt">meteorite</span> finds can be influenced by alteration processes on the Earth's surface. The discovery of Antarctic <span class="hlt">meteorites</span> offered the opportunity to <span class="hlt">study</span> <span class="hlt">meteorites</span> which were kept in one of the most sterile environment of the Earth. Halogen determination in Antartic <span class="hlt">meteorites</span> was compared with non-Antarctic <span class="hlt">meteorites</span>. No correlation was found between iodine concentration and the weathering index, or terrestrial age. The halogen measurements indicate a contaminating phase rich in iodine and also containing chlorine. Possible sources for this contamination are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27R.298T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27R.298T"><span>Foundations of Forensic <span class="hlt">Meteoritics</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treiman, A. H.</p> <p>1992-07-01</p> <p>, soil) adhering to a <span class="hlt">meteorite</span> are samples of the actual physical environment in which the <span class="hlt">meteorite</span> rested. Adhesion may derive from chemical cementation (incl. rust from the <span class="hlt">meteorite</span>), biologic activity (incl. desert varnish?), or impact processes [2]. Given the wide diversity of geological materials and processes on the Earth, adhering geological materials may be useful forensic tools. For instance, fall in a volcanic terrane may be inconsistent with adhering sediments of clean quartz sand. Biologic matter on <span class="hlt">meteorites</span> includes animal and vegetable matter mixed with the adhering geological materials, lichens and other plants growing in place, and purposefully attached animal matter (e.g. insect eggs). The most useful biological data may be provided by pollen, which can often be referred unambiguously to genera and species of plants. For example, sediments adhering to <span class="hlt">meteorites</span> from the central Nullabor Plain (W. Australia) are different from sediments from the Plain's margin in S. Australia. Sediment on <span class="hlt">meteorites</span> from the central Nullabor (e.g. Mundrabilla) lacks quartz sand and consists almost entirely of clay-sized particles, consistent with derivation from the local saprolitic soil. Sediment on <span class="hlt">meteorites</span> from the eastern Nullabor (e.g. Hughes and Cook, S.A.) contains a significant fraction of quartz sand, 1/4- to 1/2-mm grains, probably blown from the Great Victoria Desert to the north and northwest. However, sedimentologic data alone may be misleading. For instance, sediments adhering to Nuevo Mercurio stones (H5; Zacatecas, Mexico) are clay-sized and lack coarser material. But sediment on Nuevo Mercurio (b), a ureilite found in the Nuevo Mercurio strewn field, consists of quartz sand and clay pellets, 1/4 to 1/2 mm diameter. Clearly, local environments may affect the character of sediment adhering to a <span class="hlt">meteorite</span>, and careful detailed <span class="hlt">study</span> may be required to determine whether a <span class="hlt">meteorite</span> has been transported. I am grateful to R. Farrell and D. New for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004cosp...35.2156T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004cosp...35.2156T"><span>Remote Sensing <span class="hlt">Studies</span> Of The Current <span class="hlt">Martian</span> Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, F. W.; McCleese, D. J.; Schofield, J. T.; Calcutt, S. B.; Moroz, V. I.</p> <p></p> <p>A systematic and detailed experimental <span class="hlt">study</span> of the <span class="hlt">Martian</span> atmosphere remains to be carried out, despite many decades of intense interest in the nature of the <span class="hlt">Martian</span> climate system, its interactions, variability and long-term stability. Such a <span class="hlt">study</span> is planned by the 2005 Mars Reconnaissance Orbiter, using limb-scanning infrared radiometric techniques similar to those used to <span class="hlt">study</span> trace species in the terrestrial stratosphere. For Mars, the objectives are temperature, humidity, dust and condensate abundances with high vertical resolution and global coverage in the 0 to 80 km height range. The paper will discuss the experiment and its methodology and expectations for the results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14577885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14577885"><span>Submicron magnetite grains and carbon compounds in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001: inorganic, abiotic formation by shock and thermal metamorphism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Treiman, Allan H</p> <p>2003-01-01</p> <p>Purported biogenic features of the ALH84001 <span class="hlt">Martian</span> <span class="hlt">meteorite</span> (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive hypothesis is offered here. The carbonate globules were deposited from hydrothermal water, without biological mediation. Thereafter, ALH84001 was affected by an impact shock event, which raised its temperature nearly instantaneously to 500-700K, and induced iron-rich carbonate in the globules to decompose to magnetite and other minerals. The rapidity of the temperature increase caused magnetite grains to nucleate in abundance; hence individual crystals were very small. Nucleation and growth of magnetite crystals were fastest along edges and faces of the precursor carbonate grains, forcing the magnetite grains to be platy or elongated, including the "truncated hexa-octahedra" shape. ALH84001 had formed at some depth within Mars where the lithostatic pressure was significantly above that of Mars' surface. Also, because the rock was at depth, the impact heat dissipated slowly. During this interval, magnetite crystals approached chemical equilibria with surrounding minerals and gas. Their composition, nearly pure Fe(3)O(4), reflects those of equilibria; elements that substitute into magnetite are either absent from iron-rich carbonate (e.g., Ti, Al, Cr), or partitioned into other minerals during magnetite formation (Mg, Mn). Many microstructural imperfections in the magnetite grains would have annealed out as the rock cooled. In this post-shock thermal regime, carbon-bearing gas from the decomposition of iron carbonates reacted with water in the rock (or from its surroundings) to produce organic matter via Fischer-Tropschlike reactions. Formation of such organic compounds like polycyclic aromatic hydrocarbons would have been catalyzed by the magnetite (formation of graphite, the thermochemically stable phase, would be kinetically hindered).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160005747&hterms=Steele&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3DSteele','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160005747&hterms=Steele&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3DSteele"><span>Alteration of the Carbon and Nitrogen Isotopic Composition in the <span class="hlt">Martian</span> Surface Rocks Due to Cosmic Ray Exposure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.</p> <p>2014-01-01</p> <p>C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the <span class="hlt">Martian</span> carbon cycle, history of the <span class="hlt">Martian</span> atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of <span class="hlt">Martian</span> surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various <span class="hlt">Martian</span> rocks. We calculate that in the top meter of the <span class="hlt">Martian</span> rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the <span class="hlt">Martian</span> rocks. We demonstrate that if the total carbon content in a surface <span class="hlt">Martian</span> rock is <10 ppm, then the "light," potentially "biological" C-13/C-12 ratio would be effectively erased by cosmic rays over 3.5 billion years of exposure. We found that for the rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and the current Mars Science Laboratory mission are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2017N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2017N"><span>Mid-infrared <span class="hlt">study</span> of stones from the Sutter's Mill <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nuevo, Michel; Sandford, Scott A.; Flynn, George J.; Wirick, Susan</p> <p>2014-11-01</p> <p>The Sutter's Mill <span class="hlt">meteorite</span> fell in northern California on April 22, 2012. Several fragments of the <span class="hlt">meteorite</span> were recovered, some of them shortly after the fall, others several days later after a heavy rainstorm. In this work, we analyzed several samples of four fragments―SM2, SM12, SM20, and SM30―from the Sutter's Mill <span class="hlt">meteorite</span> with two infrared (IR) microscopes operating in the 4000-650 cm-1 (2.5-15.4 μm) range. Spectra show absorption features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics. Spectra of specific minerals vary from one particle to another within a given stone, and even within a single particle, indicating a nonuniform mineral composition. Infrared features associated with aliphatic CH2 and CH3 groups associated with organics are also seen in several spectra. However, the presence of organics in the samples <span class="hlt">studied</span> is not clear because these features overlap with carbonate overtone bands. Finally, other samples collected within days after the rainstorm show evidence for bacterial terrestrial contamination, which indicates how quickly <span class="hlt">meteorites</span> can be contaminated on such small scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028733','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028733"><span>Carbonates, surfates, phosphates, nitrates, and organic materials: Their association in a <span class="hlt">Martian</span> <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, I. P.; Grady, M. M.; Pillinger, C. T.</p> <p>1993-01-01</p> <p>The debate concerning the evolution of CO2 on Mars continues. It would appear that in order to explain the valley networks and other relict fluvial landforms it is necessary to accept that liquid water was once present at the surface of Mars. This in turn requires, at some point in the planet's history, a higher surface temperature than exists today, proposition explained traditionally by an early dense CO2, atmosphere. However, there are a number of problems with this notion: for instance, CO2 alone is not an efficient greenhouse gas because of its tendency to form clouds. Moreover, if there was an early dense CO2 atmosphere, it is necessary to explain where the elemental constituents now reside. There are two possibilities for the latter, namely loss to outer space of atmospheric CO2 or the formation of vast carbonate deposits. While some models of atmospheric loss predict that up to 0.4 bar of CO2 could be removed from the <span class="hlt">Martian</span> surface, this is still not enough to account for the original atmospheric inventory, usually considered to have been in the range of 1-5 bar. Thus, most models of the evolution of the <span class="hlt">Martian</span> surface require removal of CO2 from the atmosphere and into carbonate deposits. However, as yet, the evidence for the existence of carbonates on Mars is fairly scant. This is an issue that would have been resolved by results obtained from Mars Observer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130003564','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130003564"><span>Water in Nominally Anhydrous Minerals from Nakhlites and Shergottites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peslier, Anne H.</p> <p>2013-01-01</p> <p>Estimating the amount of water in the interior of terrestrial planets has tremendous implications on our understanding of solar nebula evolution, planet formation and geological history, and extraterrestrial volcanism. Mars has been a recent focus of such enquiry with complementary datasets from spacecrafts, rovers and <span class="hlt">martian</span> <span class="hlt">meteorite</span> <span class="hlt">studies</span>. In planetary interiors, water can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) such as olivine, pyroxene, or feldspar [1-3]. Measuring water in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> NAM is challenging because the minerals are fragile and riddled with fractures from impact processes that makes them break apart during sample processing. Moreover, curing the sample in epoxy causes problems for the two main water analysis techniques, Fourier transform infrared spectrometry (FTIR) and secondary ionization mass spectrometry (SIMS). Measurements to date have resulted in a heated debate on how much water the mantle of Mars contains. SIMS <span class="hlt">studies</span> of NAM [4], amphiboles [5], and apatites [6-8] from <span class="hlt">Martian</span> <span class="hlt">meteorites</span> report finding enough water in these phases to infer that the <span class="hlt">martian</span> mantle is as hydrous as that of the Earth. On the other hand, a SIMS <span class="hlt">study</span> of glass in olivine melt inclusions from shergottites concludes that the <span class="hlt">Martian</span> mantle is much drier [9]. The latter interpretation is also supported by the fact that most <span class="hlt">martian</span> hydrous minerals generally have the relevant sites filled with Cl and F instead of H [10,11]. As for experimental results, <span class="hlt">martian</span> basalt compositions can be reproduced using water as well as Cl in the parent melts [12,13]. Here FTIR is used to measure water in <span class="hlt">martian</span> <span class="hlt">meteorite</span> minerals in order to constrain the origin of the distribution of water in <span class="hlt">martian</span> <span class="hlt">meteorite</span> phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA276988','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA276988"><span><span class="hlt">Meteoritics</span>, Number 19</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1964-06-01</p> <p>of the Migeya <span class="hlt">meteorite</span>, which contains volatile organic compounds (a feature which proves the absence of overheating during its life), is 4.3...pattern in their discovery of gallium and germanium in iron <span class="hlt">meteorites</span> as small ad- mixtures. Iron <span class="hlt">meteorites</span> are divided into four groups by their content...as a basis for the classification of <span class="hlt">meteorites</span> by their composition that we have suggested- By comparing the data they obtained on gallium and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016pimo.conf..298T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016pimo.conf..298T"><span>Rediscovery of Polish <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tymiński, Z.; Stolarz, M.; Żołądek, P.; Wiśniewski, M.; Olech, A.</p> <p>2016-01-01</p> <p>The total number of Polish registered <span class="hlt">meteorites</span> (by July 2016) including the <span class="hlt">meteoritical</span> artifacts as Czestochowa Raków I and II is 22. Most of them are described by the pioneer of Polish <span class="hlt">Meteoritics</span> Jerzy Pokrzywnicki who also identified the <span class="hlt">meteorite</span> fall locations. In recent years prospectors found impressive specimens of known Polish <span class="hlt">meteorites</span> such as Morasko: 34 kg, 50 kg, 164 kg, 174 kg and 261 kg or Pultusk: 1578 g, 1576 g, 1510 g, 610 g and 580 g expanding and determining precisely the known <span class="hlt">meteorite</span> strewn fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P31F..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P31F..02P"><span>A massive hydrogen-rich <span class="hlt">Martian</span> greenhouse recorded in D/H</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pahlevan, K.; Schaefer, L. K.; Desch, S. J.; Elkins-Tanton, L. T.</p> <p>2017-12-01</p> <p>The deuterium-to-hydrogen (D/H) ratio in <span class="hlt">Martian</span> atmospheric water ( 6x standard mean ocean water, SMOW) [1,2] is higher than that of known sources [3,4] alluding to a planetary enrichment process. A recent measurement by the Curiosity rover of Hesperian clays yields a D/H value 3x higher than SMOW [5], demonstrating that most enrichment occurred early in planetary history, buttressing the conclusions of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> <span class="hlt">studies</span> [6,7]. Extant models of the isotopic evolution of the <span class="hlt">Martian</span> hydrosphere have not incorporated primordial H2, despite its likely abundance on early Mars. Here, we report the first 1D climate calculations with an atmospheric composition determined via degassing from a reducing magma ocean to <span class="hlt">study</span> <span class="hlt">Martian</span> climate during an early water ocean stage. A reducing <span class="hlt">Martian</span> magma ocean is expected based on experimental petrology [8], the degassing of which gives rise to an H2-rich steam atmosphere [9] with strong attendant greenhouse warming [10,11] even after the removal of steam via condensation. At the pressures and temperatures prevailing in such a degassed greenhouse, we find that isotopic exchange in the fluid envelope is rapid, strongly concentrating deuterium in water molecules over molecular hydrogen [12]. The subsequent loss of the isotopically light H2-rich atmosphere results in a 2x D/H enrichment in the oceans via isotopic equilibration alone. These calculations suggest that most of the D/H enrichment observed in the first billion years of <span class="hlt">Martian</span> history is produced by the evolution of a massive ( 100 bar) H2-rich greenhouse in the aftermath of magma ocean crystallization. The proposed link between early planetary process and modern isotopic observable opens a new window into the earliest history of Mars. [1] Owen, T. et al. Science 240, 1767-1770 (1988). [2] Webster, C. R. et al. Science 341, 260-263 (2013). [3] Lunine, J. I. et al. Icarus 165, 1-8, (2003). [4] Marty, B. et al. EPSL 441, 91-102, (2016). [5] Mahaffy, P. et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17008212','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17008212"><span>Searching for signatures of life on Mars: an Fe-isotope perspective.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anand, M; Russell, S S; Blackhurst, R L; Grady, M M</p> <p>2006-10-29</p> <p>Recent spacecraft and lander missions to Mars have reinforced previous interpretations that Mars was a wet and warm planet in the geological past. The role of liquid water in shaping many of the surface features on Mars has long been recognized. Since the presence of liquid water is essential for survival of life, conditions on early Mars might have been more favourable for the emergence and evolution of life. Until a sample return mission to Mars, one of the ways of <span class="hlt">studying</span> the past environmental conditions on Mars is through chemical and isotopic <span class="hlt">studies</span> of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Over 35 individual <span class="hlt">meteorite</span> samples, believed to have originated on Mars, are now available for lab-based <span class="hlt">studies</span>. Fe is a key element that is present in both primary and secondary minerals in the <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Fe-isotope ratios can be fractionated by low-temperature processes which includes biological activity. Experimental investigations of Fe reduction and oxidation by bacteria have produced large fractionation in Fe-isotope ratios. Hence, it is considered likely that if there is/were any form of life present on Mars then it might be possible to detect its signature by Fe-isotope <span class="hlt">studies</span> of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. In the present <span class="hlt">study</span>, we have analysed a number of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> for their bulk-Fe-isotope composition. In addition, a set of terrestrial analogue material has also been analysed to compare the results and draw inferences. So far, our <span class="hlt">studies</span> have not found any measurable Fe-isotopic fractionation in bulk <span class="hlt">Martian</span> <span class="hlt">meteorites</span> that can be ascribed to any low-temperature process operative on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1569..492Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1569..492Z"><span>Classification of an unidentified <span class="hlt">meteorite</span> through TXRF technique and the chemical comparison with a known <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaki, Wafaa</p> <p>2013-12-01</p> <p><span class="hlt">Meteorites</span>, space rocks, are characterized by several distinctive properties that distinguish them from terrestrial (Earth) rocks. <span class="hlt">Meteorites</span> may have all or most of such properties. Sometimes, <span class="hlt">meteorite</span> characterization requires detailed chemical analyses. Two types of <span class="hlt">meteorites</span> were <span class="hlt">studied</span> and chemically analyzed. One, had already been located and listed internationally (AL-Taamem <span class="hlt">Meteorite</span>77). The other one is not listed yet as it fell in 1993 at the northern Kurdistan region of Iraq. The chemical analysis of grinded <span class="hlt">meteorite</span> was conducted using TXRF technique. The analysis involved the utilization of one type of carrier and one type of disks (quartz). High purity silicon was used for fixing the <span class="hlt">meteorite</span> powder onto the quartz glass disks for vacuum uses. Each sample test was carried out twice using the Bruker S2 Picofox TXRF instrument (for 600s). The spectra were investigated and several indicative characteristics were concluded. The samples were identified as <span class="hlt">meteorite</span>, particularly for the appearance of the typical nickel peak near the iron peak in the spectra. This is in accordance with the method of classification of <span class="hlt">meteorites</span> and by comparison between the listed and unlisted samples. All these analyses were conducted in the laboratories of Chemistry for Technologies in Brescia University, Italy).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51..483N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..483N"><span>Rb-Sr and Sm-Nd isotopic and REE <span class="hlt">studies</span> of igneous components in the bulk matrix domain of <span class="hlt">Martian</span> breccia Northwest Africa 7034</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyquist, Laurence E.; Shih, Chi-Yu; McCubbin, Francis M.; Santos, Alison R.; Shearer, Charles K.; Peng, Zhan X.; Burger, Paul V.; Agee, Carl B.</p> <p>2016-03-01</p> <p>The bulk matrix domain of the <span class="hlt">Martian</span> breccia NWA 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia. Both 147Sm-143Nd and 146Sm-142Nd age results for mineral separates from the bulk matrix portion of breccia NWA 7034 suggest that various lithological components in the breccia probably formed contemporaneously ~4.44 Ga ago. This old age is in excellent agreement with the upper intersection ages (4.35-4.45 Ga) for U-Pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous-textured clasts. Consequently, we confirm an ancient age for the igneous components that make up the NWA 7034 breccia. Substantial disturbance in the Rb-Sr system was detected, and no age significance could be gleaned from our Rb-Sr data. The disturbance to the Rb-Sr system may be due to a thermal event recorded by bulk-rock K-Ar ages of 1.56 Ga and U-Pb ages of phosphates at about 1.35-1.5 Ga, which suggest partial resetting from an unknown thermal event(s), possibly accompanying breccia formation. The NWA 7034 bulk rock is LREE enriched and similar to KREEP-rich lunar rocks, which indicates that the earliest <span class="hlt">Martian</span> crust was geochemically enriched. This enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on Mars that have been detected in <span class="hlt">studies</span> of other <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000034786&hterms=elephants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delephants','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000034786&hterms=elephants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delephants"><span>Terrestrial Ages of Antarctic <span class="hlt">Meteorites</span>- Update 1999</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishiizumi, Kunihiko; Welten, K. C.; Caffee, Marc W.</p> <p>1999-01-01</p> <p>We are continuing our ongoing <span class="hlt">study</span> of cosmogenic nuclides in Antarctic <span class="hlt">meteorites</span>. In addition to the <span class="hlt">studies</span> of exposure histories of <span class="hlt">meteorites</span>, we <span class="hlt">study</span> terrestrial ages and pairing of Antarctic <span class="hlt">meteorites</span> and desert <span class="hlt">meteorites</span>. Terrestrial ages of Antarctic <span class="hlt">meteorites</span> provide information on <span class="hlt">meteorite</span> accumulation mechanisms, mean weathering lifetimes, and influx rates. The determination of Cl-36(half-life=3.01 x 10(exp 5) y) terrestrial ages is one of our long-term on-going projects, however, in many instances neither Cl-36 or C-14 (5,730 y) yields an accurate terrestrial age. Using Ca-14 (1.04 x 10(exp 5) y) for terrestrial age determinations solves this problem by filling the c,ap in half-life between 14-C and Cl-36 ages. We are now applying the new Ca-41- Cl-36 terrestrial age method as well as the Cl-36-Be-10 method to Antarctic <span class="hlt">meteorites</span>. Our measurements and C-14 terrestrial age determinations by the University of Arizona group are always complementary. We have measured Cl-36 in over 270 Antarctic <span class="hlt">meteorites</span> since our previous compilation of terrestrial ages. Since a large number of <span class="hlt">meteorites</span> have been recovered from many different icefields in Antarctica, we continue to survey the trends of terrestrial ages for different icefields. We have also measured detailed terrestrial ages vs. sample locations for Allan Hills, Elephant Moraine, and Lewis Cliff Icefields, where <span class="hlt">meteorites</span> have been found with very long ages. The updated histograms of terrestrial ages of <span class="hlt">meteorites</span> from the Allan Hills Main Icefield and Lewis Cliff Icefield are shown. These figures include C-14 ages obtained by the University of Arizona group. Pairs of <span class="hlt">meteorites</span> are shown as one object for which the age is the average of all members of the same fall. The width of the bars represents 70,000 years, which was a typical uncertainty for Cl-36 ages. We reduced the uncertainty of terrestrial age determinations to approx. 40,000 years by using pairs of nuclides such as Ca-41-Cl-36 or Cl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991rnes.nasa...14D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991rnes.nasa...14D"><span>Asteroid/<span class="hlt">meteorite</span> streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drummond, J.</p> <p></p> <p>The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 <span class="hlt">meteorite</span> producing fireballs presents the possibility of matching specific <span class="hlt">meteorites</span> to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three <span class="hlt">meteorites</span> with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant <span class="hlt">meteorite</span> types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram <span class="hlt">meteorite</span> and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree <span class="hlt">meteorite</span> is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five <span class="hlt">meteorite</span>-dropping fireballs and this one asteroid. The H5 Lost City <span class="hlt">meteorite</span> is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four <span class="hlt">meteorite</span>-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no <span class="hlt">meteorites</span> have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated <span class="hlt">meteorites</span> would provide an opportunity for in-hand analysis of a potential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910016724&hterms=innisfree&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dinnisfree','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910016724&hterms=innisfree&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dinnisfree"><span>Asteroid/<span class="hlt">meteorite</span> streams</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Drummond, J.</p> <p>1991-01-01</p> <p>The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 <span class="hlt">meteorite</span> producing fireballs presents the possibility of matching specific <span class="hlt">meteorites</span> to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three <span class="hlt">meteorites</span> with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant <span class="hlt">meteorite</span> types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram <span class="hlt">meteorite</span> and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree <span class="hlt">meteorite</span> is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five <span class="hlt">meteorite</span>-dropping fireballs and this one asteroid. The H5 Lost City <span class="hlt">meteorite</span> is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four <span class="hlt">meteorite</span>-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no <span class="hlt">meteorites</span> have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated <span class="hlt">meteorites</span> would provide an opportunity for in-hand analysis of a potential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990pmce.conf...67G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990pmce.conf...67G"><span>Invar alloys: information from the <span class="hlt">study</span> of iron <span class="hlt">meteorites</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldstein, J. I.; Williams, D. B.; Zhang, J.; Clarke, R.</p> <p></p> <p>The iron <span class="hlt">meteorites</span> were slow cooled (<108years) in their asteroidal bodies and are useful as indicators of the phase transformations which occur in Fe-Ni alloys. In the invar composition range, the iron <span class="hlt">meteorites</span> contain a cloudy zone structure composed of an ordered tetrataenite phase and a surrounding honeycomb phase either of gamma or alpha phase. This structure is the result of a spinodal reaction below 350°C. The Santa Catharina iron <span class="hlt">meteorite</span> has the typical invar composition of 36 wt% Ni and its structure is entirely cloudy zone although some of the honeycomb phase has been oxidized by terrestrial corrosion. Invar alloys would contain such a cloudy zone structure if more time was available for cooling. A higher temperature spinodal in the Fe-Ni phase diagram may be operative in invar alloys but has not been observed in the structure of the iron <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P52A..04U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P52A..04U"><span>The Evolution of Water in <span class="hlt">Martian</span> Atmosphere, Hydrosphere, and Cryosphere: Insights from Hydrogen Isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Usui, T.; Kurokawa, H.; Alexander, C.; Simon, J. I.; Wang, J.; Jones, J. H.</p> <p>2016-12-01</p> <p>Mars exploration missions provide compelling evidence for the presence of liquid water during the earliest geologic era (Noachian: > 3.9 Ga) of Mars. The amount and stability of liquid water on the surface is strongly influenced by the composition and pressure of the atmosphere. However, the evolution of Noachian atmosphere has been poorly constrained due to uncertainties of atmospheric loss regimes and internal/external factors such as impact flux and volcanic degassing. We can trace the evolution of the early <span class="hlt">Martian</span> atmosphere and its interaction with the hydrosphere and cryosphere with hydrogen isotope ratios (D/H) because they fractionate during atmospheric escape and during hydrological cycling between the atmosphere, surface waters, and the polar ice caps. This <span class="hlt">study</span> reports D/H ratios of primordial and 4 Ga-old atmosphere by ion microprobe analyses of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Analyses of olivine-hosted glass inclusions in the most primitive shergottite (Yamato 980459) provide a near-chondritic D/H ratio (1.3×SMOW) for the 4.5 Ga primordial water preserved in the mantle. On the other hand, carbonates in Allan Hills 84001 provide a D/H range (1.5-2.0×SMOW) for the Noachian surface water that was isotopically equilibrated with the 4 Ga atmosphere. The latter observation requires that even after the Noachian period the hydrogen isotopes were fractionated significantly to reach the present-day value of 6×SMOW. Using the one-reservoir model of Kurokawa et al. (2014) we can provide minimum estimates on the amounts of hydrogen loss before and after 4 Ga based on the D/H data from the <span class="hlt">meteorites</span> (1.3×SMOW at 4.5 Ga and 1.5-2.0×SMOW at 4 Ga) assuming the volume of polar surface-ice (20-30 m global equivalent layers, GEL). The model indicates that the hydrogen loss during the first 0.5 billion years (16-54 m GEL) was comparable to those (42-93 mGEL) in the remaining <span class="hlt">Martian</span> history. These values are distinctly lower than the geological estimates on the volumes of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P23B0196B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P23B0196B"><span>The <span class="hlt">Martian</span> Surface is old and so are Shergottites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouvier, A.; Blichert-Toft, J.; Vervoort, J. D.; Albarede, F.</p> <p>2005-12-01</p> <p>We report new Sm-Nd, Lu-Hf, and Pb-Pb mineral and whole-rock (WR) isotope data for the basaltic shergottite (BS) Zagami (Zag), as well as Pb-Pb WR isotope data for the BS Los Angeles (LA). The isotopic analyses were carried out by MC-ICP-MS at ENSL. The Sm-Nd and Lu-Hf data for Zag yield internal isochron ages of 155±9 Ma (MSWD=0.45) and 185±36 Ma (MSWD=1.2), respectively. While these young ages overlap with earlier Rb-Sr, Sm-Nd, and U-Pb ages (2), the Pb-Pb age does not. Our Pb isotope data on Zag and LA lie on the same Pb-Pb array as previous analyses of BS by (1), which, if interpreted as an isochron, indicate an age of ~4 Ga. The range of δ18O (3.9-5.2 permil) observed in shergottites (3, 4) is too broad to be accounted for by igneous processes only and attests to low-T interaction with fluids. The <span class="hlt">Martian</span> surface appears to be covered with sulfates, while essentially lacking carbonates (5, 6), implying that the surface of Mars was once covered with acidic water bodies of unknown depths (7). An important observation is that apatite is a common phase in Zag and LA, as in all the shergottites (8), and explains why most of the REE, Th, U, and some fraction of Pb can be removed by leaching (9). The main inventory of Pb, however, resides in maskelynite. The Pb isotope data on shergottites, in conjunction with the existing body of geochemical and geophysical evidence, have important implications for the history of the <span class="hlt">Martian</span> surface and lithosphere. A fundamental problem with the young crystallization ages for the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been that these ages are difficult to reconcile with the large 182W and 142Nd isotopic anomalies present in these <span class="hlt">meteorites</span>. On one hand, the anomalies from the extinct radionuclides appear to require a static, non-convecting mantle, whereas widespread volcanism on Mars as young as 150 Ma seems to require an actively convecting mantle. We suggest, based on the Pb isotope systematics of shergottites, that the <span class="hlt">Martian</span> surface is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeCoA..74.4829W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeCoA..74.4829W"><span><span class="hlt">Martian</span> regolith in Elephant Moraine 79001 shock melts? Evidence from major element composition and sulfur speciation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walton, E. L.; Jugo, P. J.; Herd, C. D. K.; Wilke, M.</p> <p>2010-08-01</p> <p>Shock veins and melt pockets in Lithology A of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Elephant Moraine (EETA) 79001 have been investigated using electron microprobe (EM) analysis, petrography and X-ray Absorption Near Edge Structure (XANES) spectroscopy to determine elemental abundances and sulfur speciation (S 2- versus S 6+). The results constrain the materials that melted to form the shock glasses and identify the source of their high sulfur abundances. The XANES spectra for EETA79001 glasses show a sharp peak at 2.471 keV characteristic of crystalline sulfides and a broad peak centered at 2.477 keV similar to that obtained for sulfide-saturated glass standards analyzed in this <span class="hlt">study</span>. Sulfate peaks at 2.482 keV were not observed. Bulk compositions of EETA79001 shock melts were estimated by averaging defocused EM analyses. Vein and melt pocket glasses are enriched in Al, Ca, Na and S, and depleted in Fe, Mg and Cr compared to the whole rock. Petrographic observations show preferential melting and mobilization of plagioclase and pyrrhotite associated with melt pocket and vein margins, contributing to the enrichments. Estimates of shock melt bulk compositions obtained from glass analyses are biased towards Fe- and Mg- depletions because, in general, basaltic melts produced from groundmass minerals (plagioclase and clinopyroxene) will quench to a glass, whereas ultramafic melts produced from olivine and low-Ca pyroxene megacrysts crystallize during the quench. We also note that the bulk composition of the shock melt pocket cannot be determined from the average composition of the glass but must also include the crystals that grew from the melt - pyroxene (En 72-75Fs 20-21Wo 5-7) and olivine (Fo 75-80). Reconstruction of glass + crystal analyses gives a bulk composition for the melt pocket that approaches that of lithology A of the <span class="hlt">meteorite</span>, reflecting bulk melting of everything except xenolith chromite. Our results show that EETA79001 shock veins and melt pockets represent local mineral</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52..493H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52..493H"><span><span class="hlt">Martian</span> cratering 11. Utilizing decameter scale crater populations to <span class="hlt">study</span> <span class="hlt">Martian</span> history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartmann, W. K.; Daubar, I. J.</p> <p>2017-03-01</p> <p>New information has been obtained in recent years regarding formation rates and the production size-frequency distribution (PSFD) of decameter-scale primary <span class="hlt">Martian</span> craters formed during recent orbiter missions. Here we compare the PSFD of the currently forming small primaries (P) with new data on the PSFD of the total small crater population that includes primaries and field secondaries (P + fS), which represents an average over longer time periods. The two data sets, if used in a combined manner, have extraordinary potential for clarifying not only the evolutionary history and resurfacing episodes of small <span class="hlt">Martian</span> geological formations (as small as one or few km2) but also possible episodes of recent climatic change. In response to recent discussions of statistical methodologies, we point out that crater counts do not produce idealized statistics, and that inherent uncertainties limit improvements that can be made by more sophisticated statistical analyses. We propose three mutually supportive procedures for interpreting crater counts of small craters in this context. Applications of these procedures support suggestions that topographic features in upper meters of mid-latitude ice-rich areas date only from the last few periods of extreme <span class="hlt">Martian</span> obliquity, and associated predicted climate excursions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1664681','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1664681"><span>Searching for signatures of life on Mars: an Fe-isotope perspective</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Anand, M; Russell, S.S; Blackhurst, R.L; Grady, M.M</p> <p>2006-01-01</p> <p>Recent spacecraft and lander missions to Mars have reinforced previous interpretations that Mars was a wet and warm planet in the geological past. The role of liquid water in shaping many of the surface features on Mars has long been recognized. Since the presence of liquid water is essential for survival of life, conditions on early Mars might have been more favourable for the emergence and evolution of life. Until a sample return mission to Mars, one of the ways of <span class="hlt">studying</span> the past environmental conditions on Mars is through chemical and isotopic <span class="hlt">studies</span> of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Over 35 individual <span class="hlt">meteorite</span> samples, believed to have originated on Mars, are now available for lab-based <span class="hlt">studies</span>. Fe is a key element that is present in both primary and secondary minerals in the <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Fe-isotope ratios can be fractionated by low-temperature processes which includes biological activity. Experimental investigations of Fe reduction and oxidation by bacteria have produced large fractionation in Fe-isotope ratios. Hence, it is considered likely that if there is/were any form of life present on Mars then it might be possible to detect its signature by Fe-isotope <span class="hlt">studies</span> of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. In the present <span class="hlt">study</span>, we have analysed a number of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> for their bulk-Fe-isotope composition. In addition, a set of terrestrial analogue material has also been analysed to compare the results and draw inferences. So far, our <span class="hlt">studies</span> have not found any measurable Fe-isotopic fractionation in bulk <span class="hlt">Martian</span> <span class="hlt">meteorites</span> that can be ascribed to any low-temperature process operative on Mars. PMID:17008212</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003TrGeo...1..347H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...1..347H"><span>Cosmic-ray Exposure Ages of <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herzog, G. F.</p> <p>2003-12-01</p> <p> hundreds of <span class="hlt">meteorites</span> had been estimated from noble gas measurements. Histograms of the CRE age distributions pointed to several important observations.(i) The CRE ages of <span class="hlt">meteorites</span> increase in the order stones <stony irons <irons.(ii) The CRE ages of stones rarely exceed 100 Myr; the average ages of stony irons are typically between 50 Myr and 200 Myr; the CRE ages of irons vary with group but more often than not exceed 200 Myr.(iii) The CRE ages of stones and of irons are neither uniformly distributed nor tightly clustered.These early conclusions imply first that meteoroid production does not take place uniformly through time, for if it did, then we ought to see a distribution of CRE ages without peaks. Second, they imply that mechanical toughness contributes to the survival ability of meteoroids, a hypothesis that helps explain the greater fraction of irons with high CRE ages and the much shorter CRE ages of, e.g., the relatively fragile carbonaceous chondrites. Third, comparisons of the CRE age distributions of different types of stones point to the importance of orbits. Although aubrites and CI carbonaceous chondrites, e.g., are both fairly fragile, aubrites have much larger CRE ages. This difference (along with dynamical calculations) suggested early on that the original orbit of the parent body affects CRE ages.Since the early 1970s, several developments have brought the landscape of CRE ages into sharper focus. The number of <span class="hlt">meteorites</span> available for analyses has increased greatly, by a factor of ˜10, thanks to abundant finds in the Antarctic, northern Africa/Arabia, and Australia. With increased sampling, the statistical properties of CRE age distributions have become more convincing. Further, the worlds collection of <span class="hlt">meteorites</span> collection has become more diverse. In this respect, the lunar and the <span class="hlt">martian</span> <span class="hlt">meteorites</span> take pride of place but leave ample room for R, CH, and CB chondrites, new angrites, and other unusual specimens. At the same time, better</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E"><span>Partitioning of light lithophile elements during basalt eruptions on Earth and application to <span class="hlt">Martian</span> shergottites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edmonds, Marie</p> <p>2015-02-01</p> <p>An enigmatic record of light lithophile element (LLE) zoning in pyroxenes in basaltic shergottite <span class="hlt">meteorites</span>, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that <span class="hlt">Martian</span> basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile elements (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of Earth and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the shergottite <span class="hlt">meteorites</span>. Through a geochemical <span class="hlt">study</span> of LLE, volatile and trace elements in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare Earth elements during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients <0.1. Degassing of LLE is further inhibited at high temperatures. Pyroxene and associated melt inclusion LLE concentrations from a range of volcanoes are used to quantify lithium pyroxene-melt partition coefficients, which correlate negatively with melt H2O content, ranging from 0.13 at low water contents to <0.08 at H2O contents >4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to <span class="hlt">Martian</span> primitive melts through modeling. The zoning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002360','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002360"><span>Searching for Extraterrestrial Amino Acids in a Contaminated <span class="hlt">Meteorite</span>: Amino Acid Analyses of the Canakkale L6 Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burton, A. S.; Elsila, J. E.; Glavin, D. P.; Dworkin, J. P.; Ornek, C. Y.; Esenoglu, H. H.; Unsalan, O.; Ozturk, B.</p> <p>2016-01-01</p> <p>Amino acids can serve as important markers of cosmochemistry, as their abundances and isomeric and isotopic compositions have been found to vary predictably with changes in parent body chemistry and alteration processes. Amino acids are also of astrobiological interest because they are essential for life on Earth. Analyses of a range of <span class="hlt">meteorites</span>, including all groups of carbonaceous chondrites, along with H, R, and LL chondrites, ureilites, and a <span class="hlt">martian</span> shergottite, have revealed that amino acids of plausible extraterrestrial origin can be formed in and persist after a wide range of parent body conditions. However, amino acid analyses of L6 chondrites to date have not provided evidence for indigenous amino acids. In the present <span class="hlt">study</span>, we performed amino acid analysis on larger samples of a different L6 chondite, Canakkale, to determine whether or not trace levels of indigenous amino acids could be found. The Canakkale meteor was an observed fall in late July, 1964, near Canakkale, Turkey. The <span class="hlt">meteorite</span> samples (1.36 and 1.09 g) analyzed in this <span class="hlt">study</span> were allocated by C. Y. Ornek, along with a soil sample (1.5 g) collected near the Canakkale recovery site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1037K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1037K"><span>Annual Occurrence of <span class="hlt">Meteorite</span>-Dropping Fireballs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konovalova, Natalia; Jopek, Tadeusz J.</p> <p>2016-07-01</p> <p>The event of Chelyabinsk <span class="hlt">meteorite</span> has brought about change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the <span class="hlt">meteorite</span>. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of <span class="hlt">meteorites</span> with the known fall dates and of the <span class="hlt">meteorite</span>-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of <span class="hlt">meteorites</span> and <span class="hlt">meteorite</span>-dropping fireballs shows several periods of increased activity in the course of the year. The analysis of the atmospheric trajectories and physical properties of sporadic <span class="hlt">meteorite</span>-dropping fireballs observed in Tajikistan by instrumental methods in the summer‒autumn periods of increased fireballs activity has been made. As a result the structural strength, the bulk density and terminal mass of the <span class="hlt">studied</span> fireballs that can survive in the Earth atmosphere and became <span class="hlt">meteorites</span> was obtained. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by D-criterion of Southworth and Hawkins the fireballs that could be the members of group of <span class="hlt">meteorite</span>-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for <span class="hlt">meteorite</span>-dropping fireballs was made and the evolution of orbits of these objects in the past on a long interval of time was investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960017269','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960017269"><span>Numerical Model <span class="hlt">Studies</span> of the <span class="hlt">Martian</span> Mesoscale Circulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Segal, M.; Arritt, R. W.</p> <p>1996-01-01</p> <p><span class="hlt">Studies</span> concerning mesoscale topographical effects on <span class="hlt">Martian</span> flows examined low-level jets in the near equatorial latitudes and the dynamical intensification of flow by steep terrain. Continuation of work from previous years included evaluating the dissipation of cold air mass outbreaks due to enhanced sensible heat flux, further sensitivity and scaling evaluations for generalization of the characteristics of <span class="hlt">Martian</span> mesoscale circulation caused by horizontal sensible heat-flux gradients, and evaluations of the significance that non-uniform surface would have on enhancing the polar CO2 ice sublimation during the spring. The sensitivity of maximum and minimum atmospheric temperatures to changes in wind speed, surface albedo, and deep soil temperature was investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17779983','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17779983"><span>The <span class="hlt">martian</span> surface.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Opik, E J</p> <p>1966-07-15</p> <p> could depend on the low night-time temperature and deposition of hoarfrost, which could melt into droplets after sunrise, before evaporating. If not vegetation, it must be something thing specifically <span class="hlt">Martian</span>; no other hypothesis hitherto proposed is able to account for the facts. However, the infrared bands which at one time were thought to be associated with the presence of organic matter, belong to heavy water in the terrestrial atmosphere. The conversion of a former bright area into a dark one in 1954, over some 1 million square kilometers, is the largest recorded change of this kind. Even on the vegetation hypothesis, it eludes satisfactory explanation. Relatively bright areas observed in the blue and violet in polar regions and elsewhere on the limb can be explained by a greater transparency of the atmosphere,its dust content being decreased by a downward (anticyclonic) current. The surface, of a greater reflecting power than the atmospheric smoke, then becomes visible. The sudden explosion-like occurrence of yellow or gray clouds, reducing atmospheric transparency and surface contrast, could be due to impacts of asteroids; in such a case, however, the number of unobservable small asteroids, down to 30 to 40 meters in diameter, should greatly exceed the number extrapolated from the larger members of the group. A "<span class="hlt">meteoritic</span>" increment in numbers, instead of the asteroidal one, would be required. special observations with large Schmidt telescopes could settle this crucial question. The <span class="hlt">Martian</span> "oases," centers of "canal" systems, could be impact creters. The canals may be real formations, without sharp borders and 100 to 200 kilometers wide, due to a systematic alignment. of the dark surface elements. They may indicate cracks in the planet's crust, radiating from the point of impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930022751&hterms=groundwater&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgroundwater','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022751&hterms=groundwater&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgroundwater"><span>Calculated mineral precipitation upon evaporation of a model <span class="hlt">Martian</span> groundwater near 0 C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Debraal, J. D.; Reed, M. H.; Plumlee, G. S.</p> <p>1992-01-01</p> <p>Previously, the effect of weathering a basalt of Shergotty <span class="hlt">meteorite</span> composition with pure water buffered at <span class="hlt">martian</span> atmospheric values of CO2 and O2, to place constraints upon the composition of <span class="hlt">martian</span> groundwater, and to determine possible equilibrium mineral assemblages was calculated. A revised calculation of the composition of the aqueous phase in the weathering reaction as a function of the amount of basalt titrated into the solution is shown. The concentrations of sulfate and chloride ions increase in the solution from high water/rock ratios (w/r) on the left to low water/rock ratios on the right, until at w/r = 1, where 1 kg of basalt has been titrated, sulfate concentration is 1564 ppm and chloride is 104 ppm. This resulting fluid is dominated by sulfate and sodium, with bicarbonate and chloride at about the same concentration. This solution was evaporated in an attempt to determine if the resulting evaporite can explain the Viking XRF data. The program CHILLER was used to evaporate this solution at 0.1 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000688"><span>Consortium <span class="hlt">Study</span> of the Chelyabinsk <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, K.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Keller, L. P.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20140000688'); toggleEditAbsImage('author_20140000688_show'); toggleEditAbsImage('author_20140000688_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20140000688_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20140000688_hide"></p> <p>2013-01-01</p> <p>On February 15, 2013 approximately 17 m asteroid hit Earth, causing shock waves and air blasts over a portion of Russia. A significant amount of material has been recovered from this <span class="hlt">meteorite</span> fall, officially named Chelyabinsk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860027626&hterms=taxonomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtaxonomy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860027626&hterms=taxonomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtaxonomy"><span>Chemical compositional <span class="hlt">study</span> of 35 iron <span class="hlt">meteorites</span> and its application in taxonomy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wang, D.; Malvin, D. J.; Wasson, J. T.</p> <p>1985-01-01</p> <p>Structural and compositional data are reported as a guide to the classification of 35 iron <span class="hlt">meteorites</span>. The Xinjiang iron <span class="hlt">meteorite</span>, previously classified as III AB, is reclassified as III E on the basis of its lower Ga/Ni and Ge/Ni ratios, its wider, swollen kamacite bands, and the ubiquitous presence of haxonite, (Fe,Ni)22C. The Dongling (III CD) appears not to be a new <span class="hlt">meteorite</span>, but to be paired with the Nantan. Four Antarctic iron <span class="hlt">meteorites</span>, IAB Allan Hills A77250, A77263, A77289, and A77290, are classified as a paired <span class="hlt">meteorite</span> because of their similarities in structure and in concentrations of various elements. It is shown that Cu shares certain properties with Ga and Ge, which makes them excellent taxonomic parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000040793','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000040793"><span>Antarctic <span class="hlt">Meteorite</span> Newsletter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lindstrom, Marilyn</p> <p>2000-01-01</p> <p>This newsletter contains something for everyone! It lists classifications of about 440 <span class="hlt">meteorites</span> mostly from the 1997 and 1998 ANSMET (Antarctic Search for <span class="hlt">Meteorites</span>) seasons. It also gives descriptions of about 45 <span class="hlt">meteorites</span> of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130010925','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130010925"><span>A New Spinel-Olivine Oxybarometer: Near-Liquidus Partitioning of V between Olivine-Melt, Spinel-Melt, and Spinel-Olivine in <span class="hlt">Martian</span> Basalt Composition Y980459 as a Function of Oxygen Fugacity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Papike, J. J.; Le, L.; Burger, P. V.; Shearer, C. K.; Bell, A. S.; Jones, J.</p> <p>2013-01-01</p> <p>Our research on valence state partitioning began in 2005 with a review of Cr, Fe, Ti, and V partitioning among crystallographic sites in olivine, pyroxene, and spinel [1]. That paper was followed by several on QUE94201 melt composition and specifically on Cr, V, and Eu partitioning between pyroxene and melt [2-5]. This paper represents the continuation of our examination of the partitioning of multivalent V between olivine, spinel, and melt in <span class="hlt">martian</span> olivine-phyric basalts of Y980459 composition [6, 7]. Here we introduce a new, potentially powerful oxybarometer, V partitioning between spinel and olivine, which can be used when no melt is preserved in the <span class="hlt">meteorite</span>. The bulk composition of QUE94201 was ideal for our <span class="hlt">study</span> of <span class="hlt">martian</span> pyroxene-phyric basalts and specifically the partitioning between pyroxene-melt for Cr, V, and Eu. Likewise, bulk composition Y980459 is ideal for the <span class="hlt">study</span> of <span class="hlt">martian</span> olivine-phyric basalts and specifically for olivine-melt, spinel-melt, and spinel-olivine partitioning of V as a function of oxygen fugacity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010048879&hterms=organic+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dorganic%2Bchemistry','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010048879&hterms=organic+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dorganic%2Bchemistry"><span>Organic Chemistry of <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chang, S.; Morrison, David (Technical Monitor)</p> <p>1994-01-01</p> <p><span class="hlt">Studies</span> of the molecular structures and C,N,H-isotopic compositions of organic matter in <span class="hlt">meteorites</span> reveal a complex history beginning in the parent interstellar cloud which spawned the solar system. Incorporation of interstellar dust and gas in the protosolar nebula followed by further thermal and aqueous processing on primordial parent bodies of carbonaceous, <span class="hlt">meteorites</span> have produced an inventory of diverse organic compounds including classes now utilized in biochemistry. This inventory represents one possible set of reactants for chemical models for the origin of living systems on the early Earth. Evidence bearing on the history of <span class="hlt">meteoritic</span> organic matter from astronomical observations and laboratory investigations will be reviewed and future research directions discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020048255&hterms=enrichment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Denrichment','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020048255&hterms=enrichment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Denrichment"><span>Sublimation: A Mechanism for the Enrichment of Organics in Antarctic Ice</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, Luann; McDonald, Gene D.; Glavin, Daniel P.; Bada, Jeffrey L.; Bunch, Theodore E.; Chang, Sherwood (Technical Monitor)</p> <p>1997-01-01</p> <p>Recent analyses of the carbonate globules present in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level. The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the <span class="hlt">meteorite</span>, perhaps derived from an ancient <span class="hlt">Martian</span> biota. However, Becker et al., have examined PAHs in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> EETA79001, in several Antarctic carbonaceous chondrites and Antarctic Allan Hills Ice and detected many of the same PAHs found in ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material, suggests that this <span class="hlt">meteorite</span> is contaminated with terrestrial/extraterrestrial organics probably derived from Antarctic ice meltwater that had percolated through the <span class="hlt">meteorite</span>. The detection of PAHs and L-amino acids in these <span class="hlt">Martian</span> <span class="hlt">meteorites</span> suggests that despite storage in the Antarctic ice, selective changes of certain chemical and mineralogical phases has occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890017427','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890017427"><span>Antarctic <span class="hlt">Meteorite</span> Location Map Series</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schutt, John (Editor); Fessler, Brian (Editor); Cassidy, William (Editor)</p> <p>1989-01-01</p> <p>Antarctica has been a prolific source of <span class="hlt">meteorites</span> since <span class="hlt">meteorite</span> concentrations were discovered in 1969. The Antarctic Search For <span class="hlt">Meteorites</span> (ANSMET) project has been active over much of the Trans-Antarctic Mountain Range. The first ANSMET expedition (a joint U.S.-Japanese effort) discovered what turned out to be a significant concentration of <span class="hlt">meteorites</span> at the Allan Hills in Victoria Land. Later reconnaissance in this region resulted in the discovery of <span class="hlt">meteorite</span> concentrations on icefields to the west of the Allan Hills, at Reckling Moraine, and Elephant Moraine. Antarctic <span class="hlt">meteorite</span> location maps (reduced versions) of the Allan Hills main, near western, middle western, and far western icefields and the Elephant Moraine icefield are presented. Other Antarctic <span class="hlt">meteorite</span> location maps for the specimens found by the ANSMET project are being prepared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=How+soil+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bsoil%2Bform','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=How+soil+form&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bsoil%2Bform"><span>JSC Mars-1 <span class="hlt">Martian</span> Soil Simulant: Melting Experiments and Electron Microprobe <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carpenter, P.; Sebille, L.; Boles, W.; Chadwell, M.; Schwarz, L.</p> <p>2003-01-01</p> <p>JSC Mars-1 has been developed as a <span class="hlt">Martian</span> regolith simulant, and is the <1 mm size fraction of a palagonitic tephra (a glassy volcanic ash altered at low temperatures) from Pu'u Nene cinder cone on the Island of Hawaii. The Mars-1 simulant forms the basis for numerous terrestrial <span class="hlt">studies</span> which aim to evaluate the suitability of <span class="hlt">Martian</span> soil for materials processing. <span class="hlt">Martian</span> soil may be sintered to form building materials for construction, and also melted or reacted to extract metals for various uses, as well as oxygen for life support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019348','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019348"><span>Radiocarbon datings of Yamato <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kigoshi, K.; Matsuda, E.</p> <p>1986-01-01</p> <p>The terrestrial ages of five Yamato <span class="hlt">Meteorites</span> were measured by the content of cosmic-ray-produced carbon-14. Three Yamato <span class="hlt">Meteorites</span> Y-74013, Y-74097, and Y-74136, which are all diogenites, were found at sites from one to two kilometers apart from each other. Evidence is presented for these three <span class="hlt">meteorites</span> being a single <span class="hlt">meteorite</span>. Also presented is a method adopted in the experimental procedure which includes a check for modern carbon contamination in the <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023014','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023014"><span>Wind tunnel <span class="hlt">studies</span> of <span class="hlt">Martian</span> aeolian processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, R.; Iversen, J. D.; Pollack, J. B.; Udovich, N.; White, B.</p> <p>1973-01-01</p> <p>Preliminary results are reported of an investigation which involves wind tunnel simulations, geologic field <span class="hlt">studies</span>, theoretical model <span class="hlt">studies</span>, and analyses of Mariner 9 imagery. Threshold speed experiments were conducted for particles ranging in specific gravity from 1.3 to 11.35 and diameter from 10.2 micron to 1290 micron to verify and better define Bagnold's (1941) expressions for grain movement, particularly for low particle Reynolds numbers and to <span class="hlt">study</span> the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some <span class="hlt">martian</span> craters and which indicates that some dark zones around <span class="hlt">Martian</span> craters are erosional and some light zones are depositional.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003248','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003248"><span>Lunar and <span class="hlt">Meteorite</span> Thin Sections for Undergraduate and Graduate <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen, J.; Galindo, C.; Luckey, M.; Reustle, J.; Todd, N.; Allen, C.</p> <p>2012-01-01</p> <p>The Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation, and distribution of samples for research, education, and public outreach. Between 1969 and 1972 six Apollo missions brought back 382 kilograms of lunar rocks, core samples, pebbles, sand and dust from the lunar surface. JSC also curates <span class="hlt">meteorites</span> collected on US expeditions to Antarctica including rocks from Moon, Mars, and many asteroids including Vesta. <span class="hlt">Studies</span> of rock and soil samples from the Moon and <span class="hlt">meteorites</span> continue to yield useful information about the early history of the Moon, the Earth, and the inner solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009psrd.reptE.133T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009psrd.reptE.133T"><span>Mars Crust: Made of Basalt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, G. J.</p> <p>2009-05-01</p> <p>By combining data from several sources, Harry Y. (Hap) McSween (University of Tennessee), G. Jeffrey Taylor (University of Hawaii) and Michael B. Wyatt (Brown University) show that the surface of Mars is composed mostly of basalt not unlike those that make up the Earth's oceanic crust. McSween and his colleagues used data from <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, analyses of soils and rocks at robotic landing sites, and chemical and mineralogical information from orbiting spacecraft. The data show that Mars is composed mostly of rocks similar to terrestrial basalts called tholeiites, which make up most oceanic islands, mid-ocean ridges, and the seafloor beneath sediments. The <span class="hlt">Martian</span> samples differ in some respects that reflect differences in the compositions of the <span class="hlt">Martian</span> and terrestrial interiors, but in general are a lot like Earth basalts. Cosmochemistst have used the compositions of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> to discriminate bulk properties of Mars and Earth, but McSween and coworkers' synthesis shows that the <span class="hlt">meteorites</span> differ from most of the <span class="hlt">Martian</span> crust (the <span class="hlt">meteorites</span> have lower aluminum, for example), calling into question how diagnostic the <span class="hlt">meteorites</span> are for understanding the <span class="hlt">Martian</span> interior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002923','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002923"><span>Formation and Preservation of the Depleted and Enriched Shergottite Isotopic Reservoirs in a Convecting <span class="hlt">Martian</span> Mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kiefer, Walter S.; Jones, John H.</p> <p>2015-01-01</p> <p>There is compelling isotopic and crater density evidence for geologically recent volcanism on Mars, in the last 100-200 million years and possibly in the last 50 million years. This volcanism is due to adiabatic decompression melting and thus requires some type of present-day convective upwelling in the <span class="hlt">martian</span> mantle. On the other hand, <span class="hlt">martian</span> <span class="hlt">meteorites</span> preserve evidence for at least 3 distinct radiogenic isotopic reservoirs. Anomalies in short-lived isotopic systems (Sm-146, Nd-142, Hf-182, W-182) require that these reservoirs must have developed in the first 50 to 100 million years of Solar System history. The long-term preservation of chemically distinct reservoirs has sometimes been interpreted as evidence for the absence of mantle convection and convective mixing on Mars for most of <span class="hlt">martian</span> history, a conclusion which is at odds with the evidence for young volcanism. This apparent paradox can be resolved by recognizing that a variety of processes, including both inefficient mantle mixing and geographic separation of isotopic reservoirs, may preserve isotopic heterogeneity on Mars in an actively convecting mantle. Here, we focus on the formation and preservation of the depleted and enriched isotopic and trace element reservoirs in the shergottites. In particular, we explore the possible roles of processes such as chemical diffusion and metasomatism in dikes and magma chambers for creating the isotopically enriched shergottites. We also consider processes that may preserve the enriched reservoir against convective mixing for most of <span class="hlt">martian</span> history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090034382&hterms=cyanobacteria&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dcyanobacteria','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090034382&hterms=cyanobacteria&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dcyanobacteria"><span>Microfossils in Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.</p> <p>2009-01-01</p> <p>Microfossils of large filamentous trichomic prokaryotes have been detected during in-situ investigations of carbonaceous <span class="hlt">meteorites</span>. This research has been carried out using the Field Emission Scanning Electron Microscope (FESEM) to examine freshly fractured interior surfaces of the <span class="hlt">meteorites</span>. The images obtained reveal that many of these remains are embedded in the <span class="hlt">meteorite</span> rock matrix. Energy Dispersive X-Ray Spectroscopy (EDS) <span class="hlt">studies</span> establish that the filamentous microstructures have elemental compositions consistent with the <span class="hlt">meteorite</span> matrix, but are often encased within carbon-rich electron transparent sheath-like structures infilled with magnesium sulfate. This is consistent with the taphonomic modes of fossilization of cyanobacteria and sulphur bacteria, since the life habits and processes of these microorganisms frequently result in distinctive chemical biosignatures associated with the properties of their cell-walls, trichomes, and the extracellular polymeric substances (EPS) of the sheath. In this paper the evidence for biogenicity presented includes detailed morphological and morphometric data consistent with known characteristics of uniseriate and multiseriate cyanobacteria. Evidence for indigeneity includes the embedded nature of the fossils and elemental compositions inconsistent with modern biocontaminants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=FeTiO3&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DFeTiO3','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=FeTiO3&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DFeTiO3"><span>An ion microprobe <span class="hlt">study</span> of CAIs from CO3 <span class="hlt">meteorites</span>. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, S. S.; Greenwood, R. C.; Fahey, A. J.; Huss, G. R.; Wasserburg, G. J.</p> <p>1994-01-01</p> <p>When attempting to interpret the history of Ca, Al-rich inclusions (CAIs) it is often difficult to distinguish between primary features inherited from the nebula and those produced during secondary processing on the parent body. We have undertaken a systematic <span class="hlt">study</span> of CAIs from 10 CO chondrites, believed to represent a metamorphic sequence with the goal of distinguishing primary and secondary features. ALHA 77307 (3.0), Colony (3.0), Kainsaz (3.1), Felix (3.2), ALH 82101 (3.3), Ornans (3.3), Lance (3.4), ALHA 77003 (3.5), Warrenton (3.6), and Isna (3.7) were examined by Scanning Electron Microscopy (SEM) and optical microscopy. We have identified 141 CAIs within these samples, and <span class="hlt">studied</span> in detail the petrology of 34 inclusions. The primary phases in the lower petrologic types are spinel, melilite, and hibonite. Perovskite, FeS, ilmenite, anorthite, kirschsteinite, and metallic Fe are present as minor phases. Melilite becomes less abundant in higher petrologic types and was not detected in chondrites of type 3.5 and above, confirming previous reports that this mineral easily breaks down during heating. Iron, an element that would not be expected to condense at high temperatures, has a lower abundance in spinel from low-petrologic-type <span class="hlt">meteorites</span> than those of higher grade, and CaTiO3 is replaced by FeTiO3 in <span class="hlt">meteorites</span> of higher petrologic type. The abundance of CAIs is similar in each <span class="hlt">meteorite</span>. Eight inclusions have been analyzed by ion probe. The results are summarized. The results obtained to date show that CAIs in CO <span class="hlt">meteorites</span>, like those from other <span class="hlt">meteorite</span> classes, contain Mg* and that Mg in some inclusions has been redistributed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23869014','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23869014"><span>Abundance and isotopic composition of gases in the <span class="hlt">martian</span> atmosphere from the Curiosity rover.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mahaffy, Paul R; Webster, Christopher R; Atreya, Sushil K; Franz, Heather; Wong, Michael; Conrad, Pamela G; Harpold, Dan; Jones, John J; Leshin, Laurie A; Manning, Heidi; Owen, Tobias; Pepin, Robert O; Squyres, Steven; Trainer, Melissa</p> <p>2013-07-19</p> <p>Volume mixing and isotope ratios secured with repeated atmospheric measurements taken with the Sample Analysis at Mars instrument suite on the Curiosity rover are: carbon dioxide (CO2), 0.960(±0.007); argon-40 ((40)Ar), 0.0193(±0.0001); nitrogen (N2), 0.0189(±0.0003); oxygen, 1.45(±0.09) × 10(-3); carbon monoxide, < 1.0 × 10(-3); and (40)Ar/(36)Ar, 1.9(±0.3) × 10(3). The (40)Ar/N2 ratio is 1.7 times greater and the (40)Ar/(36)Ar ratio 1.6 times lower than values reported by the Viking Lander mass spectrometer in 1976, whereas other values are generally consistent with Viking and remote sensing observations. The (40)Ar/(36)Ar ratio is consistent with <span class="hlt">martian</span> <span class="hlt">meteoritic</span> values, which provides additional strong support for a <span class="hlt">martian</span> origin of these rocks. The isotopic signature δ(13)C from CO2 of ~45 per mil is independently measured with two instruments. This heavy isotope enrichment in carbon supports the hypothesis of substantial atmospheric loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002834','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002834"><span>Halite as a Methane Sequestration Host: A Possible Explanation for Periodic Methane Release on Mars, and a Surface-accessible Source of Ancient <span class="hlt">Martian</span> Carbon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fries, M. D.; Steele, Andrew; Hynek, B. M.</p> <p>2015-01-01</p> <p>We present the hypothesis that halite may play a role in methane sequestration on the <span class="hlt">martian</span> surface. In terrestrial examples, halite deposits sequester large volumes of methane and chloromethane. Also, examples of chloromethane-bearing, approximately 4.5 Ga old halite from the Monahans <span class="hlt">meteorite</span> show that this system is very stable unless the halite is damaged. On Mars, methane may be generated from carbonaceous material trapped in ancient halite deposits and sequestered. The methane may be released by damaging its halite host; either by aqueous alteration, aeolian abrasion, heating, or impact shock. Such a scenario may help to explain the appearance of short-lived releases of methane on the <span class="hlt">martian</span> surface. The methane may be of either biogenic or abiogenic origin. If this scenario plays a significant role on Mars, then <span class="hlt">martian</span> halite deposits may contain samples of organic compounds dating to the ancient desiccation of the planet, accessible at the surface for future sample return missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P21A2071K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P21A2071K"><span>Water-rich <span class="hlt">Martian</span> mantle can account for the elastic thickness in Amazonian era</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Katayama, I.; Matsuoka, Y.; Azuma, S.</p> <p>2016-12-01</p> <p>Although high water content in the <span class="hlt">Martian</span> mantle is inferred from cosmochemistry, the direct measurements of water in the SNC <span class="hlt">meteorites</span> are controversial, because hydrogen is a highly mobile element and the later terrestrial alteration can modify the primarily concentration in the Mars. On the one hand, water has a significant effect on the rock strength in both brittle and ductile fields; consequently, the presence of water can influence the elastic thickness that is primary controlled by stress distribution in the lithosphere. The <span class="hlt">Martian</span> elastic lithosphere estimated from gravity and topography data indicates different thickness at the time of loading (e.g. McGovern et al. 2002). The increase of elastic thickness from Noachian to Hesperian is most likely related to the secular cooling in the Mars; however, the nearly constant elastic lithosphere in Amazonian cannot be explained by the thermal evolution alone. In this <span class="hlt">study</span>, we applied recent rheological data to the <span class="hlt">Martian</span> lithosphere and tested whether water can account for the elastic thickness seen in the Amazonian era. We incorporated the effect of pore fluid pressure in the brittle regime and Peierls mechanism in the ductile regime in the rheological model, which are not applied in the most previous calculation (e.g. Grott and Breuer 2008) but have a significant influence on the stress distribution in the lithosphere. Since the pore pressure reduces the effective normal stress on the fault plane, the maximum stress in the brittle regime is markedly decreased by the presence of pore fluid. The estimate of elastic lithosphere is dependent on thermal structure, and we used the heat production rate obtained from the Mars Odyssey spectrometry as thermal model (Hahn et al. 2011). Our results indicate the elastic thickness in Amazonian era of 120-170 km for dry condition and 80-110 km for wet condition. The thin elastic thickness calculated under wet environments is a result of significant reduction of flexure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050167193','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050167193"><span>Keto-acids in Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooper, G.; Chang, P. M.; Dugas, A.; Byrd, A.; Chang, P. M.; Washington, N.</p> <p>2005-01-01</p> <p>The Murchison and Murray <span class="hlt">meteorites</span> are the best-characterized carbonaceous <span class="hlt">meteorites</span> with respect to organic chemistry and are generally used as references for organic compounds in extraterrestrial material. Among the classes of organic compounds found in these <span class="hlt">meteorites</span> are amino acids, carboxylic acids, hydroxy acids, purines, and pyrimidines. Such compounds, important in contemporary biochemistry, are thought to have been delivered to the early Earth in asteroids and comets and may have played a role in early life and/or the origin of life. Absent among (today's) critically important biological compounds reported in carbonaceous <span class="hlt">meteorites</span> are keto acids, i.e., pyruvic acid, acetoacetic acid, and higher homologs. These compounds are key intermediates in such critical processes as glycolysis and the citric acid cycle. In this <span class="hlt">study</span> several individual <span class="hlt">meteoritic</span> keto acids were identified by gas chromatography-mass spectrometry (GC-MS) (see figure below). All compounds were identified as their trimethylsilyl (TMS), isopropyl ester (ISP), and tert-butyldimethylsilyl (tBDMS) derivatives. In general, the compounds follow the abiotic synthesis pattern of other known <span class="hlt">meteorite</span> classes of organic compounds [1,2]: a general decrease in abundance with increasing carbon number within a class of compounds and many, if not all, possible isomers present at a given carbon number. The majority of the shown compounds was positively identified by comparison of their mass spectra to commercially available standards or synthesized standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002iaf..confE.187P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002iaf..confE.187P"><span>Simulation of <span class="hlt">Martian</span> EVA at the Mars Society Arctic Research Station</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pletser, V.; Zubrin, R.; Quinn, K.</p> <p></p> <p>The Mars Society has established a Mars Arctic Research Station (M.A.R.S.) on Devon Island, North of Canada, in the middle of the Haughton crater formed by the impact of a large <span class="hlt">meteorite</span> several million years ago. The site was selected for its similarities with the surface of the Mars planet. During the Summer 2001, the MARS Flashline Research Station supported an extended international simulation campaign of human Mars exploration operations. Six rotations of six person crews spent up to ten days each at the MARS Flashline Research Station. International crews, of mixed gender and professional qualifications, conducted various tasks as a <span class="hlt">Martian</span> crew would do and performed scientific experiments in several fields (Geophysics, Biology, Psychology). One of the goals of this simulation campaign was to assess the operational and technical feasibility of sustaining a crew in an autonomous habitat, conducting a field scientific research program. Operations were conducted as they would be during a <span class="hlt">Martian</span> mission, including Extra-Vehicular Activities (EVA) with specially designed unpressurized suits. The second rotation crew conducted seven simulated EVAs for a total of 17 hours, including motorized EVAs with All Terrain Vehicles, to perform field scientific experiments in Biology and Geophysics. Some EVAs were highly successful. For some others, several problems were encountered related to hardware technical failures and to bad weather conditions. The paper will present the experiment programme conducted at the Mars Flashline Research Station, the problems encountered and the lessons learned from an EVA operational point of view. Suggestions to improve foreseen <span class="hlt">Martian</span> EVA operations will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..604C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..604C"><span>Vigie Ciel a collaborative project to <span class="hlt">study</span> fireballs and organise <span class="hlt">meteorite</span> recoveries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colas, F.; Zanda, B.; Bouley, S.; Lewin, E.; Vaubaillon, J.; Marmo, C.; Rotaru, M.; Labenne, L.; Julien, J. F.; Linares, M.; Steinhausser, A.; Rault, J. L.; Vernazza, P.</p> <p>2015-10-01</p> <p>Research on fireballs and <span class="hlt">meteorites</span> has always been of interest to the public, due to the beauty of shooting stars in the night sky and to the extraterrestrial origin of <span class="hlt">meteorites</span>. A fireball observation network called FRIPON [1] (Colas et al, 2015) is currently being setup, funded by ANR (Agence Nationale pour la Recherche). It will cover France with 100 cameras and is expected to be operational for the end of 2015. FRIPON will detect fireballs and hence allow us to define <span class="hlt">meteorite</span> strewn fields within 24h, so that <span class="hlt">meteorite</span> searches can be launched very early on. Because of the need to search all over France, including in private land, it is important that the general public be aware of our project and be willing to help or participate. Indeed, as the main goal of FRIPON is to recover fresh <span class="hlt">meteorites</span> (within a few days), our aim is to be able to organize a search with at least 50 persons to scan an area of a few km2 within a week. Help from the public would hence be most helpful but it is also important to have an operational and trained research team. This project thus appears as a unique occasion to involve the public in a scientific project while promoting informal scientific education. This prompted us to set up Vigie-Ciel, a citizen science network centered on <span class="hlt">meteorite</span> recovery. FRIPON is an open network based on open-source software, it will accept citizenrun cameras. In addition to fireballs, it will allow scientists and Vigie-Ciel participants to <span class="hlt">study</span> anything that can be observed by all-sky cameras: bird migrations, bats, clouds, lightning, etc. The data will be freely available to all.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20180002011','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20180002011"><span>Indigenous Amino Acids in Iron <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elsila, J. E.; Dworkin, J. P.; Glavin, D. P.; Johnson, N. M.</p> <p>2018-01-01</p> <p>Understanding the organic content of <span class="hlt">meteorites</span> and the potential delivery of molecules relevant to the origin of life on Earth is an important area of <span class="hlt">study</span> in astrobiology. There have been many <span class="hlt">studies</span> of <span class="hlt">meteoritic</span> organics, with much focus on amino acids as monomers of proteins and enzymes essential to terrestrial life. The majority of these <span class="hlt">studies</span> have involved analysis of carbonaceous chondrites, primitive <span class="hlt">meteorites</span> containing approx. 3-5 wt% carbon. Amino acids have been observed in varying abundances and distributions in representatives of all eight carbonaceous chondrite groups, as well as in ungrouped carbonaceous chondrites, ordinary and R chondrites, ureilites, and planetary achondrites [1 and references therein].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170002069','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170002069"><span>Lunar <span class="hlt">Meteorites</span>: A Global Geochemical Dataset</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zeigler, R. A.; Joy, K. H.; Arai, T.; Gross, J.; Korotev, R. L.; McCubbin, F. M.</p> <p>2017-01-01</p> <p>To date, the world's <span class="hlt">meteorite</span> collections contain over 260 lunar <span class="hlt">meteorite</span> stones representing at least 120 different lunar <span class="hlt">meteorites</span>. Additionally, there are 20-30 as yet unnamed stones currently in the process of being classified. Collectively these lunar <span class="hlt">meteorites</span> likely represent 40-50 distinct sampling locations from random locations on the Moon. Although the exact provenance of each individual lunar <span class="hlt">meteorite</span> is unknown, collectively the lunar <span class="hlt">meteorites</span> represent the best global average of the lunar crust. The Apollo sites are all within or near the Procellarum KREEP Terrane (PKT), thus lithologies from the PKT are overrepresented in the Apollo sample suite. Nearly all of the lithologies present in the Apollo sample suite are found within the lunar <span class="hlt">meteorites</span> (high-Ti basalts are a notable exception), and the lunar <span class="hlt">meteorites</span> contain several lithologies not present in the Apollo sample suite (e.g., magnesian anorthosite). This chapter will not be a sample-by-sample summary of each individual lunar <span class="hlt">meteorite</span>. Rather, the chapter will summarize the different types of lunar <span class="hlt">meteorites</span> and their relative abundances, comparing and contrasting the lunar <span class="hlt">meteorite</span> sample suite with the Apollo sample suite. This chapter will act as one of the introductory chapters to the volume, introducing lunar samples in general and setting the stage for more detailed discussions in later more specialized chapters. The chapter will begin with a description of how lunar <span class="hlt">meteorites</span> are ejected from the Moon, how deep samples are being excavated from, what the likely pairing relationships are among the lunar <span class="hlt">meteorite</span> samples, and how the lunar <span class="hlt">meteorites</span> can help to constrain the impactor flux in the inner solar system. There will be a discussion of the biases inherent to the lunar <span class="hlt">meteorite</span> sample suite in terms of underrepresented lithologies or regions of the Moon, and an examination of the contamination and limitations of lunar <span class="hlt">meteorites</span> due to terrestrial weathering. The</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870014029','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870014029"><span>Fluvial valleys on <span class="hlt">Martian</span> volcanoes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baker, Victor R.; Gulick, Virginia C.</p> <p>1987-01-01</p> <p>Channels and valleys were known on the <span class="hlt">Martian</span> volcanoes since their discovery by the Mariner 9 mission. Their analysis has generally centered on interpretation of possible origins by fluvial, lava, or viscous flows. The possible fluvial dissection of <span class="hlt">Martian</span> volcanoes has received scant attention in comparison to that afforded outflow, runoff, and fretted channels. Photointerpretative, mapping, and morphometric <span class="hlt">studies</span> of three <span class="hlt">Martian</span> volcanoes were initiated: Ceraunius Tholus, Hecate Tholus, and Alba Patera. Preliminary morphometric results indicate that, for these three volcanoes, valley junction angles increase with decreasing slope. Drainage densities are quite variable, apparently reflecting complex interactions in the landscape-forming factors described. Ages of the <span class="hlt">Martian</span> volcanoes were recently reinterpreted. This refined dating provides a time sequence in which to evaluate the degradational forms. An anomaly has appeared from the initial <span class="hlt">study</span>: fluvial valleys seem to be present on some <span class="hlt">Martian</span> volcanoes, but not on others of the same age. Volcanic surfaces characterized only by high permeability lava flows may have persisted without fluvial dissection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMED51D..05B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMED51D..05B"><span>Vigie-Ciel : a french citizen network to <span class="hlt">study</span> meteors and <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouley, S.; Zanda, B.; Colas, F.; Vaubaillon, J.; Marmo, C.; Vernazza, P.; Gattacceca, J.</p> <p>2013-12-01</p> <p>Vigie Ciel is a french citizen network supported by the Muséum National d'Histoire Naturelle (MNHN) and the Université Paris-Sud (UPsud). It is based on the scientific FRIPON program developed by Paris Observatory (Fireball Recovery and Planetary Inter Observation Network) which has for main goal to (i) determine the source region(s) of the various <span class="hlt">meteorite</span> classes, (ii) collect both fresh and rare <span class="hlt">meteorite</span> types and (iii) perform scientific outreach. This will be achieved by building the densest camera network in the world, based on state of the art technologies and associated with a participative network for <span class="hlt">meteorite</span> recovery. We propose to install a network of 100 digital cameras covering the entire French territory to compute impact locations with accuracy of the order of one kilometer. Considering that there are 5 to 25 falls over France per year (~15 on average), during the same time, we will observe ~50 falls out of which we realistically expect to find 10 <span class="hlt">meteorites</span>. Our project is original in several ways. (i) It is inter-disciplinary, involving experts in <span class="hlt">meteoritics</span>, asteroidal science as well as fireball observation and dynamics. It will thus create new synergies between prominent institutions and/or laboratories, namely between MNHN, Paris Observatory and Université Paris-Sud in the Parisian region; and between CEREGE and LAM in the Provence region. Overall, scientists from over 25 laboratories will be involved, covering a mix of scientific disciplines and all the regions of France. (ii) It will generate a large body of data, feeding databases of interest to several disciplines (e.g. bird migration, variations of the luminosity of the brightest stars, observation of space debris, meteorology...). (iii) It will for the first time involve the general public (including schools) in the search for the <span class="hlt">meteorite</span> falls, thus boosting the interest in <span class="hlt">meteorite</span> and asteroid related science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P11B1822S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P11B1822S"><span>Mantle evolution on Mars: Constraints from Lu-Hf and Sm-Nd isotope systematics of SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scherer, E. E.; Kurahashi, E.; Mezger, K.</p> <p>2012-12-01</p> <p>The long-lived 176Lu-176Hf and 147Sm-143Nd isotope systems are commonly employed to track the evolution of complementary mantle and crust reservoirs. The four elements involved are refractory and lithophile, and thus their relative abundances are not expected to have been changed by accretion or core formation. Subsequent silicate differentiation processes, however, e.g., the formation of crust by extraction of melts from the mantle, will fractionate Lu/Hf and Sm/Nd. This typically leaves a depleted mantle with higher Lu/Hf and Sm/Nd values than those of the undifferentiated, presumably chondritic parental reservoir. On the other hand, these same values in crustal rocks tend to be lower than those of their source. (Apparent exceptions are the <span class="hlt">Martian</span> shergottites, which tend to have lower Lu/Hf as expected, but Sm/Nd higher than their presumed sources. Such decoupling of the two isotope systems may be explained by two-stage melting [e.g., 1, 5].) The ensuing chemical variability among secondary and later generation silicate reservoirs causes their isotopic compositions (e.g., 176Hf/177Hf and 143Nd/144Nd) to diverge from that of the bulk silicate planet over hundreds of millions of years. The resulting isotopic diversity preserved (SNC) <span class="hlt">meteorites</span> is being used to constrain the differentiation history, melting mineralogy, and dynamics of the <span class="hlt">Martian</span> mantle [e.g., 1-8]. However, interpretations based on the initial isotope compositions of Hf and Nd strongly depend on the accuracy of crystallization ages. The ages of shergottites in particular are debated (e.g., [3,4,7]). To resolve this issue and gain a better understanding of <span class="hlt">Martian</span> mantle evolution, we are investigating the Lu-Hf and Sm-Nd systematics of bulk SNC <span class="hlt">meteorites</span> and constructing internal (mineral) isochrons. Eleven bulk <span class="hlt">Martian</span> <span class="hlt">meteorites</span> (5 shergottites, 4 nakhlites, and 2 chassignites) were digested without prior leaching in high-pressure autoclaves for 5 days. Initial ɛ176Hf and ɛ143Nd values</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P21C2145E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P21C2145E"><span>Stepped Acid Extractions of CO2 from Ancient Carbonates in <span class="hlt">Martian</span> Nakhlites (MIL 03346, 090030, 090032, 090036) Show Distinct δ18O and δ13C Isotopic Values Compared to Secondary Terrestrial Carbonates Formed on Ordinary Chondrites (OC) Collected from Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, M. E.; Niles, P. B.</p> <p>2016-12-01</p> <p>This <span class="hlt">study</span> finds that 1) <span class="hlt">Martian</span> Nakhlite <span class="hlt">meteorites</span> contain insitu carbonates with distinctive δ13C from terrestrial carbonates formed on Antarctic Ordinary Chondrites (OCs), and 2) <span class="hlt">Martian</span> carbonate formation δ18O values for atmospheric CO2 and meteoric water can be predicted with a mixing model created from Antarctic OC carbonate data. Nakhlite and OC <span class="hlt">meteorites</span> collected in Antarctica contain both calcites and non-calcite carbonates. Rock samples were crushed, dissolved in pure phosphoric acid, and allowed to react at the following conditions: 1 hr@30°C (Rx0, fine calcite), 18 hr@30°C (Rx1, course calcite), and 3 hr@150°C (Rx2, siderite and/or magnesite). The collected CO2 was purified with a Thermo Trace GC and analyzed on a Thermo MAT 253 IRMS in dual inlet mode. Ten OC <span class="hlt">meteorite</span> samples collected from three different Antarctic regions (RBT, ALH, MIL) were analyzed. These samples had no pre-terrestrial aqueous alterations, yet evaporite minerals were visible on the fusion crust. It is deduced these OC carbonates were completely terrestrial. These calcites have δ13C=+6‰ and are consistent with equilibrium formation to Earth atmospheric CO2 δ13C=-7‰ at 0°C to 10°C. Siderite or magnesite fractionation may create slightly heavier δ13C as seen in the Rx2 results. The range of δ18O from +3‰ to +30‰ is heavier than expected if carbonate forms in equilibrium with only meteoric water. A δ18O mixing model is created with Earth atmospheric CO2 and meteoric water as end members. This model predicts the OC calcites form with 60%-90% contribution from atmospheric CO2 at 0°C, and the non-calcites form with 40-60% contribution from atmospheric CO2. Four <span class="hlt">martian</span> Nakhlites collected from the Antarctic Miller Range were analyzed. These samples contain low carbonate concentrations (avg. 0.007% by weight) with distinctly heavier δ13C = +7‰ to +59‰. In general, these carbonates are lighter than expected if formed in equilibrium with the modern <span class="hlt">martian</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990087893&hterms=onion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Donion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990087893&hterms=onion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Donion"><span>Fullerenes in Allende <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, L.; Bada, J. L.; Winans, R. E.; Bunch, T. E.</p> <p>1994-01-01</p> <p>The detection of fullerenes in deposits from meteor impacts has led to renewed interest in the possibility that fullerenes are present in <span class="hlt">meteorites</span>. Although fullerenes have not previously been detected in the Murchison and Allende <span class="hlt">meteorites</span>, the Allende <span class="hlt">meteorite</span> is known to contain several well-ordered graphite particles which are remarkably similar in size and appearance to the fullerene-related structures carbon onions and nanotubes. We report that fullerenes are in fact present in trace amounts in the Allende <span class="hlt">meteorite</span>. In addition to fullerenes, we detected many polycyclic aromatic hydrocarbons (PAHs) in the Allende <span class="hlt">meteorite</span>, consistent with previous reports. In particular, we detected benzofluoranthene and corannulene (C20H10), five-membered ring structures which have been proposed as precursors to the formation of fullerene synthesis, perhaps within circumstellar envelopes or other sites in the interstellar medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006DPS....38.4602L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006DPS....38.4602L"><span><span class="hlt">Meteorite</span> Magazine: Promoting Science, Discovery, And Education</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lebofsky, Larry A.; Lebofsky, N. R.; Sears, H.; Sears, D.</p> <p>2006-09-01</p> <p>In late 2005, Larry and Nancy Lebofsky and Derek and Hazel Sears took over the editing and publishing of <span class="hlt">Meteorite</span> magazine. We saw a great educational potential for the magazine. With a circulation over 600, the magazine reaches a broad readership: <span class="hlt">meteorite</span> scientists, hunters, collectors, and enthusiasts. Unlike the professional journal of the <span class="hlt">Meteoritical</span> Society, <span class="hlt">Meteoritics</span> and Planetary Sciences, the articles in <span class="hlt">Meteorite</span> range from scientific articles, reports from <span class="hlt">meteorite</span> shows, and how to preserve <span class="hlt">meteorites</span> to stories about searching for <span class="hlt">meteorites</span> around the world. <span class="hlt">Meteorites</span> are of interest to people. Asteroids, meteoroids, meteors, and <span class="hlt">meteorites</span> are in many states' science standards. Yet, how many museums have <span class="hlt">meteorite</span> collections with staff who know little about them? How many amateur astronomers, when seeing meteors or meteor showers, can explain how asteroids, comets, meteors, and <span class="hlt">meteorites</span> are related and what they tell us about the formation of our Solar System? How many <span class="hlt">meteorite</span> collectors are knowledgeable about how these objects are related to each other? How do we reach the broader community? Unlike the hundreds of amateur and school astronomy clubs, there are no <span class="hlt">meteorite</span> clubs. While one can point out the wonders of the night sky and what can be seen through a telescope at star parties, there is no such thing as school <span class="hlt">meteorite</span> hunting parties. The <span class="hlt">meteorite</span> and planetary sciences communities working together can bring the excitement of <span class="hlt">meteorites</span> and the science behind these fascinating objects to teachers, students, and museum and planetarium staff. We will present ideas for accomplishing this.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000409','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000409"><span>Ar-Ar and Rb-Sr Ages of the Tissint Olivine-phyric <span class="hlt">Martian</span> Shergottite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Herzog, G. F.; Nyquist, L. E.; Shih, C.-Y.; Turin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Agee, C.</p> <p>2013-01-01</p> <p>The fifth <span class="hlt">martian</span> <span class="hlt">meteorite</span> fall, Tissint, is an olivine-phyric shergottite that contains olivine macrocrysts (approximately 1.5 mm) [1]. [2] reported the Sm-Nd age of Tissint as 596 plus or minus 23 Ma along with Rb-Sr data that defined no isochron. [3] reported Lu-Hf and Sm-Nd ages of 583 plus or minus 86 Ma and 616 plus or minus 67 Ma, respectively. The cosmic-ray exposure ages of Tissint are 1.10 plus or minus 0.15 Ma based on 10Be [4], and 1.0-1.1 Ma, based on 3He, 21Ne, and 38Ar [5,6].We report Ar-Ar ages and Rb-Sr data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140004205','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140004205"><span>Detection and Quantification of Nitrogen Compounds in <span class="hlt">Martian</span> Solid Samples by the Sample Analysis at Mars (SAM) Instrument Suite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stern, Jennifer C.; Navarro-Gonzalez, Rafael; Freissinet, Caroline; McKay, Christopher P.; Archer, Paul Douglas; Buch, Arnaud; Eigenbrode, Jennifer L.; Franz, Heather; Glavin, Daniel Patrick; Ming, Douglas W/; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20140004205'); toggleEditAbsImage('author_20140004205_show'); toggleEditAbsImage('author_20140004205_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20140004205_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20140004205_hide"></p> <p>2013-01-01</p> <p>The Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity Rover detected both reduced and oxidized nitrogen-bearing compounds during the pyrolysis of surface materials from three sites at Gale Crater. Preliminary detections of nitrogen species include NO, HCN, ClCN, CH3CN, and TFMA (trifluoro-Nmethyl-acetamide). On Earth, nitrogen is a crucial bio-element, and nitrogen availability controls productivity in many environments. Nitrogen has also recently been detected in the form of CN in inclusions in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Tissint, and isotopically heavy nitrogen (delta N-15 approx +100per mille) has been measured during stepped combustion experiments in several SNC <span class="hlt">meteorites</span>. The detection of nitrogen-bearing compounds in <span class="hlt">Martian</span> regolith would have important implications for the habitability of ancient Mars. However, confirmation of indigenous <span class="hlt">Martian</span> nitrogen bearing compounds will require ruling out their formation from the terrestrial derivatization reagents (e.g. N-methyl-N-tert-butyldimethylsilyl-trifluoroacetamide, MTBSTFA and dimethylformamide, DMF) carried for SAM's wet chemistry experiment that contribute to the SAM background. The nitrogen species we detect in the SAM solid sample analyses can also be produced during laboratory pyrolysis experiments where these reagents are heated in the presence of perchlorate, a compound that has also been identified by SAM in Mars solid samples. However, this does not preclude a <span class="hlt">Martian</span> origin for some of these compounds, which are present in nanomolar concentrations in SAM evolved gas analyses. Analysis of SAM data and laboratory breadboard tests are underway to determine whether nitrogen species are present at higher concentrations than can be accounted for by maximum estimates of nitrogen contribution from MTBSTFA and DMF. In addition, methods are currently being developed to use GC Column 6, (functionally similar to a commercial Q-Bond column), to separate and identify</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110014367','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110014367"><span>Antarctic <span class="hlt">Meteorite</span> Classification and Petrographic Database</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Todd, Nancy S.; Satterwhite, C. E.; Righter, Kevin</p> <p>2011-01-01</p> <p>The Antarctic <span class="hlt">Meteorite</span> collection, which is comprised of over 18,700 <span class="hlt">meteorites</span>, is one of the largest collections of <span class="hlt">meteorites</span> in the world. These <span class="hlt">meteorites</span> have been collected since the late 1970's as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s <span class="hlt">Meteorite</span> Lab and the Smithsonian Institution and results are published twice a year in the Antarctic <span class="hlt">Meteorite</span> Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these <span class="hlt">meteorites</span> is also published on the NASA Curation website [2] and made available through the <span class="hlt">Meteorite</span> Classification Database allowing scientists to search by a variety of parameters</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P51E3986O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P51E3986O"><span>What Can Spectral Properties of <span class="hlt">Martian</span> Surface and Snc Can Tell Us about the <span class="hlt">Martian</span> Crust Composition and Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ody, A.; Poulet, F.; Baratoux, D.; Quantin, C.; Bibring, J. P.</p> <p>2014-12-01</p> <p>While the <span class="hlt">study</span> of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> can provide detailed information about the crust and mantle composition and evolution, remote-sensing observations, through the merging of compositional and geological data, allow highlighting planetary-scale trends of the <span class="hlt">Martian</span> crustal evolution [1,2]. Recently, the analysis of the global distribution of mafic minerals [3] has put new constraints on the <span class="hlt">Martian</span> crust formation and evolution. One of the major results is a past global event of olivine-bearing fissural volcanism that has filled craters and low depressions in the southern highlands and a large part of the Northern plains during the late Noachian/early Hesperian. Petrologic models show that this sudden increase of the olivine content at the Noachian-Hesperian boundary could be the result of a rapid thickening of the lithosphere at the end of the Noachian era [4]. A recent <span class="hlt">study</span> based on the OMEGA/MEx data has shown that the spectral properties of the shergottites are similar to those of some Noachian and Hesperian terrains [5]. To contrary, the Nakhla spectral properties are very different from those of the observable surface and could be representative of Amazonian terrains buried under dust. These results are best explained with an old age of the shergottites [6] and with the present understanding of the evolution of magma composition at a planetary scale [7]. On the other hand, if shergottites are young [8], the similarities between the shergottites and ancient terrains implies that exceptional conditions of melting with respect to the ambient mantle (e.g., hot spots or water-rich mantle source) were responsible for the formation of these samples [9]. References: [1] McSween et al., 2009, Science, 324. [2] Ehlmann & Edwards 2014, AREPS, vol. 42. [3] Ody et al., 2013, JGR,117,E00J14. [4] Ody et al., 2014, 8th Inter. Conf. on Mars,#1190. [5] Ody et al., 2013, 44th LPSC, #1719. [6] Bouvier et al., 2009, EPSL, 280. [7] Baratoux et al., 2013, JGR, 118. [8] Nyquist</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040059920&hterms=crystallization&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcrystallization','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040059920&hterms=crystallization&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcrystallization"><span>Rb-Sr and Sm-Nd Isotope Systematics of Shergottite NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brandon, A. D.; Nyquist, L. E.; Shih, C.-Y.; Wiesmann, H.</p> <p>2004-01-01</p> <p>Nakhlite NWA 998 was discovered in Algeria in 2001, and is unique among the six known members of this group of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> in containing significant modal orthopyroxene. Initial petrologic and isotopic data were reported by Irving et al. This 456 gram stone consists mainly of sub-calcic augite with subordinate olivine and minor orthopyroxene, titanomagnetite, pyrrhotite, chlorapatite, and intercumulus An(sub 35) plagioclase. We report here preliminary results of radiogenic isotopic analyses conducted on fragmental material from the main mass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IAUGA..2253637M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2253637M"><span>Organic Molecules in <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martins, Zita</p> <p>2015-08-01</p> <p>Carbonaceous <span class="hlt">meteorites</span> are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous <span class="hlt">meteorites</span> may have contributed to the organic inventory of the early Earth. The majority (>70%) of the <span class="hlt">meteoritic</span> organic material consist of insoluble organic matter (IOM) [1]. The remaining <span class="hlt">meteoritic</span> organic material (<30%) consists of a rich organic inventory of soluble organic compounds, including key compounds important in terrestrial biochemistry [2-4]. Different carbonaceous <span class="hlt">meteorites</span> contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the <span class="hlt">meteorite</span> parent bodies. Extensive aqueous alteration on the <span class="hlt">meteorite</span> parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous <span class="hlt">meteorites</span> may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the <span class="hlt">meteorite</span> parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in <span class="hlt">meteorites</span> helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930000955','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930000955"><span>Simulated <span class="hlt">meteorite</span> impacts and volcanic explosions: Ejecta analyses and planetary implications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gratz, A. J.; Nellis, W. J.</p> <p>1992-01-01</p> <p>Past cratering <span class="hlt">studies</span> have focused primarily on crater morphology. However, important questions remain about the nature of crater deposits. Phenomena that need to be <span class="hlt">studied</span> include the distribution of shock effects in crater deposits and crater walls; the origin of mono- and polymict breccia; differences between local and distal ejecta; deformation induced by explosive volcanism; and the production of unshocked, high-speed ejecta that could form the lunar and <span class="hlt">martian</span> <span class="hlt">meteorites</span> found on the Earth. To <span class="hlt">study</span> these phenomena, one must characterize ejecta and crater wall materials from impacts produced under controlled conditions. New efforts at LLNL simulate impacts and volcanism and <span class="hlt">study</span> resultant deformation. All experiments use the two-stage light-gas gun facility at LLNL to accelerate projectiles to velocities of 0.2 to 4.3 km/s, including shock pressures of 0.9 to 50 GPa. We use granite targets and novel experimental geometries to unravel cratering processes in crystalline rocks. We have thus far conducted three types of simulations: soft recovery of ejecta, 'frozen crater' experiments, and an 'artificial volcano. Our ejecta recovery experiments produced a useful separation of impactites. Material originally below the projectile remained trapped there, embedded in the soft metal of the flyer plate. In contrast, material directly adjacent to the projectile was jetted away from the impact, producing an ejecta cone that was trapped in the foam recovery fixture. We find that a significant component of crater ejecta shows no signs of strong shock; this material comes from the near-surface 'interference zone' surrounding the impact site. This phenomenon explains the existence of unshocked <span class="hlt">meteorites</span> on the Earth of lunar and <span class="hlt">martian</span> origin. Impact of a large bolide on neighboring planets will produce high-speed, weakly shocked ejecta, which may be trapped by the Earth's gravitational field. 'Frozen crater' experiments show that the interference zone is highly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992lmip.conf...31G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992lmip.conf...31G"><span>Simulated <span class="hlt">meteorite</span> impacts and volcanic explosions: Ejecta analyses and planetary implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gratz, A. J.; Nellis, W. J.</p> <p>1992-09-01</p> <p>Past cratering <span class="hlt">studies</span> have focused primarily on crater morphology. However, important questions remain about the nature of crater deposits. Phenomena that need to be <span class="hlt">studied</span> include the distribution of shock effects in crater deposits and crater walls; the origin of mono- and polymict breccia; differences between local and distal ejecta; deformation induced by explosive volcanism; and the production of unshocked, high-speed ejecta that could form the lunar and <span class="hlt">martian</span> <span class="hlt">meteorites</span> found on the Earth. To <span class="hlt">study</span> these phenomena, one must characterize ejecta and crater wall materials from impacts produced under controlled conditions. New efforts at LLNL simulate impacts and volcanism and <span class="hlt">study</span> resultant deformation. All experiments use the two-stage light-gas gun facility at LLNL to accelerate projectiles to velocities of 0.2 to 4.3 km/s, including shock pressures of 0.9 to 50 GPa. We use granite targets and novel experimental geometries to unravel cratering processes in crystalline rocks. We have thus far conducted three types of simulations: soft recovery of ejecta, 'frozen crater' experiments, and an 'artificial volcano. Our ejecta recovery experiments produced a useful separation of impactites. Material originally below the projectile remained trapped there, embedded in the soft metal of the flyer plate. In contrast, material directly adjacent to the projectile was jetted away from the impact, producing an ejecta cone that was trapped in the foam recovery fixture. We find that a significant component of crater ejecta shows no signs of strong shock; this material comes from the near-surface 'interference zone' surrounding the impact site. This phenomenon explains the existence of unshocked <span class="hlt">meteorites</span> on the Earth of lunar and <span class="hlt">martian</span> origin. Impact of a large bolide on neighboring planets will produce high-speed, weakly shocked ejecta, which may be trapped by the Earth's gravitational field. 'Frozen crater' experiments show that the interference zone is highly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003704','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003704"><span>Relationships among basaltic lunar <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lindstrom, Marilyn M.</p> <p>1991-01-01</p> <p>During the past two years four <span class="hlt">meteorites</span> of dominantly mare basalt composition were identified in the Japanese and US Antarctic collections. Basalts represent a much higher proportion of the lunar <span class="hlt">meteorites</span> than is expected from photogeologic mapping of mare and highland regions. Also, the basaltic lunar <span class="hlt">meteorites</span> are all described as VLT mare basalt, which is a relatively uncommon type among returned lunar samples. The significance of the basaltic <span class="hlt">meteorites</span> to the understanding of the lunar crust depends on the evaluation of possible relationships among the individual <span class="hlt">meteorites</span>. None of the specimens are paired <span class="hlt">meteorites</span>. They differ from each other in petrography and composition. It is important to determine whether they might be paired ejecta which were ejected from the same mare region by the same impact. The question of paired ejecta must be addressed using a combination of exposure histories and petrographic/compositional characteristics. It is possible that the basaltic lunar <span class="hlt">meteorites</span> are paired ejecta from the same region of the Moon. However, the relationships among them are more complicated than the basaltic breccias being simply brecciated mare gabbros.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150021025','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150021025"><span>Carbon and Oxygen Isotope Measurements of Ordinary Chondrite (OC) <span class="hlt">Meteorites</span> from Antarctica Indicate Distinct Carbonate Species Using a Stepped Acid Extraction Procedure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evans, Michael E.</p> <p>2015-01-01</p> <p>The purpose of this <span class="hlt">study</span> is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from five Ordinary Chondrite (OC) <span class="hlt">meteorites</span> collected in Antarctica. These samples were identified and requested from NASA based upon their size, alteration history, and collection proximity to known <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. They are also assumed to be carbonate-free before falling to Earth. This research addresses two questions involving Mars carbonates: 1) characterize terrestrial, secondary carbonate isotope values to apply to <span class="hlt">Martian</span> <span class="hlt">meteorites</span> for isolating in-situ carbonates, and 2) increase understanding of carbonates formed in cold and arid environments with Antarctica as an analog for Mars. Two samples from each <span class="hlt">meteorite</span>, each approximately 0.5 grams, were crushed and dissolved in pure phosphoric acid for 3 sequential reactions: a) R times 0 for 1 hour at 30 degrees Centigrade (fine calcite extraction), b) R times 1 for 18 hours at 30 degrees Centigrade (course calcite extraction), and c) R times 2 for 3 hours at 150 degrees Centigrade (siderite and/or magnesite extraction). CO (sub 2) was distilled by freezing with liquid nitrogen from each sample tube, then separated from organics and sulfides with a TRACE GC using a Restek HayeSep Q 80/100 6 foot 2 millimeter stainless column, and then analyzed on a Thermo MAT 253 Isotope Ratio Mass Spectrometer (IRMS) in Dual Inlet mode. This system was built at NASA/JSC over the past 3 years and proof-tested with known carbonate standards to develop procedures, assess yield, and quantify expected error bands. Two distinct species of carbonates are found: 1) calcite, and 2) non-calcite carbonate (future testing will attempt to differentiate siderite from magnesite). Preliminary results indicate the terrestrial carbonates are formed at approximately sigma (sup 13) C equal to plus 5 per mille, which is consistent with atmospheric CO (sub 2) sigma (sup 13) C equal to minus 7 per mille and fractionation of plus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750006596','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750006596"><span>The Magnetization of Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Herndon, James Herndon</p> <p>1974-01-01</p> <p>Alternating field demagnetization experiments have been conducted on representative samples of the carbonaceous <span class="hlt">meteorites</span> (carbonaceous chondrites and ureilites). The results indicate that many, if not all, of these <span class="hlt">meteorites</span> possess an intense and stable magnetic moment of extraterrestrial origin. Thermomagnetic analyses have been conducted on samples of all known carbonaceous <span class="hlt">meteorites</span>. In addition to yielding quantitative magnetite estimates, these <span class="hlt">studies</span> indicate the presence of a thermally unstable component, troilite, which reacts with gaseous oxygen to form magnetite. It is proposed that the magnetite found in some carbonaceous chondrites resulted from the oxidation of troilite during the early history of the solar system. The formation of pyrrhotite is expected as a natural consequence of magnetite formation via this reaction. Consideration is given to the implications of magnetite formation on paleointensity <span class="hlt">studies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001926"><span>Mineralogical Comparison of Olivine in Shergottites and A Shocked L Chondrite: Implications for Shock Histories of Brown Olivine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takenouchi, A.; Mikouchi, T.; Yamaguchi, A.; Zolensky, M. E.</p> <p>2015-01-01</p> <p>Most <span class="hlt">Martian</span> <span class="hlt">meteorites</span> are heavily shocked, exhibiting numerous shock features, for example undulatory extinction of olivine and pyroxene, the presence of diaplectic glass ("maskelynite") and the formation of shock melt. Among these shock features, olivine darkening ("brown" olivine) is unique in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> because no other <span class="hlt">meteorite</span> group shows such a feature. Although the presence of brown olivine in shergottites was reported thirty years ago, detailed observation by TEM has not been performed until the NWA 2737 chassignite was discovered, whose olivine is darkened, being completely black in hand specimen. Fe metal nano-particles were found in NWA 2737 olivine which are considered to have been formed by olivine reduction during heavy shock. Subsequently, magnetite nano-particles were also found in other <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and the coexistence of Fe metal and magnetite nano-particles was reported in the NWA 1950 shergottite and some Fe metal nano-particles were mantled by magnetite. Therefore, the formation process of nano-particles seems to be complex. Because "brown" olivine is unique to <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, they have a potential to constrain their shock conditions. In order to better understand the shock history of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, we compared olivine in several shergottites with that in a highly-shocked L chondrite which contains ringwoodite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100009785','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100009785"><span>Enriched Shergottite NWA 5298 As An Evolved Parent Melt: Trace Element Inventory</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hui, Hejiu; Peslier, Anne H.; Lapen, Thomas J.; Shafer, John; Brandon, Alan; Irving, Anthony</p> <p>2010-01-01</p> <p><span class="hlt">Martian</span> <span class="hlt">meteorite</span> Northwest Africa 5298 is a basaltic shergottite that was found near Bir Gandouz (Morocco). Its <span class="hlt">martian</span> origin was confirmed by oxygen isotopes [1], as well as Mn/Fe ratios in the pyroxenes and K/anorthite ratios in the plagioclases [2]. Here we present a petrographic and geochemical <span class="hlt">study</span> of NWA 5298. Comparison of mineralogical and geochemical characteristics of this <span class="hlt">meteorite</span> with other <span class="hlt">Martian</span> rocks shows that NWA 5298 is not likely paired with any other known shergottites, but it has similarities to another basaltic shergottite Dhofar 378.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24740066','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24740066"><span>Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Franz, Heather B; Kim, Sang-Tae; Farquhar, James; Day, James M D; Economos, Rita C; McKeegan, Kevin D; Schmitt, Axel K; Irving, Anthony J; Hoek, Joost; Dottin, James</p> <p>2014-04-17</p> <p>The geochemistry of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> provides a wealth of information about the solid planet and the surface and atmospheric processes that occurred on Mars. The degree to which <span class="hlt">Martian</span> magmas may have assimilated crustal material, thus altering the geochemical signatures acquired from their mantle sources, is unclear. This issue features prominently in efforts to understand whether the source of light rare-earth elements in enriched shergottites lies in crustal material incorporated into melts or in mixing between enriched and depleted mantle reservoirs. Sulphur isotope systematics offer insight into some aspects of crustal assimilation. The presence of igneous sulphides in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> with sulphur isotope signatures indicative of mass-independent fractionation suggests the assimilation of sulphur both during passage of magmas through the crust of Mars and at sites of emplacement. Here we report isotopic analyses of 40 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> that represent more than half of the distinct known <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, including 30 shergottites (28 plus 2 pairs, where pairs are separate fragments of a single <span class="hlt">meteorite</span>), 8 nakhlites (5 plus 3 pairs), Allan Hills 84001 and Chassigny. Our data provide strong evidence that assimilation of sulphur into <span class="hlt">Martian</span> magmas was a common occurrence throughout much of the planet's history. The signature of mass-independent fractionation observed also indicates that the atmospheric imprint of photochemical processing preserved in <span class="hlt">Martian</span> <span class="hlt">meteoritic</span> sulphide and sulphate is distinct from that observed in terrestrial analogues, suggesting fundamental differences between the dominant sulphur chemistry in the atmosphere of Mars and that in the atmosphere of Earth.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.3243M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.3243M"><span>The organic inventory of primitive <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martins, Zita</p> <p></p> <p>Carbonaceous <span class="hlt">meteorites</span> are primitive samples that provide crucial information about the solar system genesis and evolution. This class of <span class="hlt">meteorites</span> has also a rich organic inventory, which may have contributed the first prebiotic building blocks of life to the early Earth. We have <span class="hlt">studied</span> the soluble organic inventory of several CR and CM <span class="hlt">meteorites</span>, using high performance liquid chromatography with UV fluorescence detection (HPLC-FD), gas chromatography-mass spectrometry (GC-MS) and gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Our target organic molecules include amino acids, nucleobases and polycyclic aromatic hydrocarbons (PAHs), among others. CR chondrites contain the highest amino acids concentration ever detected in a <span class="hlt">meteorite</span>. The degree of aqueous alteration amongst this class of <span class="hlt">meteorites</span> seems to be responsible for the amino acid distribution. Pioneering compound-specific carbon isotope measurements of nucleobases present in carbonaceous chondrites show that these compounds have a non-terrestrial origin. This suggests that components of the ge-netic code may have had a crucial role in life's origin. Investigating the abundances, distribution and isotopic composition of organic molecules in primitive <span class="hlt">meteorites</span> significantly improves our knowledge of the chemistry of the early solar system, and the resources available for the first living organisms on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860006697','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860006697"><span>Antarctic <span class="hlt">Meteorite</span> Newsletter, Volume 8, Number 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1985-01-01</p> <p>Requests for samples are welcomed from research scientists of all countries, regardless of their current state of funding for <span class="hlt">meteorite</span> <span class="hlt">studies</span>. All sample requests will be reviewed by the <span class="hlt">Meteorite</span> Working Group (MWG), a peer-review committee that guides the collection, curation, allocation, and distribution of the U.S. Antarctic <span class="hlt">meteorites</span>. Issurance of samples does not imply a commitment by any agency to fund the proposed research. Requests for financial support must be submitted separately to the appropriate funding agencies. As a matter of policy, U.S. Antarctic <span class="hlt">meteorites</span> are the property of the National Science Foundation and all allocations are subject to recall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050170621','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050170621"><span>Compositions of Three Lunar <span class="hlt">Meteorites</span>: <span class="hlt">Meteorite</span> Hills 01210, Northeast Africa 001, and Northwest Africa 3136</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Korotev, R. L.; Irving, A. J.</p> <p>2005-01-01</p> <p>We report on compositions obtained by instrumental neutron activation analysis on three new lunar <span class="hlt">meteorites</span>, MET 01210 (<span class="hlt">Meteorite</span> Hills, Antarctica; 23 g), NEA 001 (Northeast Africa, Sudan; 262 g), and NWA 3136 (Northwest Africa, Algeria or Morocco; 95 g). As in previous similar <span class="hlt">studies</span>, we divided our samples into many (8-9) small (approximately 30 mg) subsamples prior to analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25063942','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25063942"><span>Radioisotope <span class="hlt">studies</span> of the farmville <span class="hlt">meteorite</span> using γγ-coincidence spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Howard, Chris; Ferm, Megan; Cesaratto, John; Daigle, Stephen; Iliadis, Christian</p> <p>2014-12-01</p> <p>Radionuclides are cosmogenically produced in <span class="hlt">meteorites</span> before they fall to the surface of the Earth. Measurement of the radioactive decay of such nuclides provides a wealth of information on the irradiation conditions of the <span class="hlt">meteorite</span> fragment, the intensity of cosmic rays in the inner solar system, and the magnetic activity of the Sun. We report here on the detection of (26)Al using a sophisticated spectrometer consisting of a HPGe detector and a NaI(Tl) annulus. It is shown that modern γ-ray spectrometers represent an interesting alternative to other detection techniques. Data are obtained for a fragment of the Farmville <span class="hlt">meteorite</span> and compared to results from Geant4 simulations. In particular, we report on optimizing the detection sensitivity by using suitable coincidence gates for deposited energy and event multiplicity. We measured an (26)Al activity of 48.5±3.5dpm/kg for the Farmville <span class="hlt">meteorite</span>, in agreement with previously reported values for other H chondrites. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810048189&hterms=deutsche+forschungsgemeinschaft&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddeutsche%2Bforschungsgemeinschaft','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810048189&hterms=deutsche+forschungsgemeinschaft&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddeutsche%2Bforschungsgemeinschaft"><span><span class="hlt">Martian</span> ages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Neukum, G.; Hiller, K.</p> <p>1981-01-01</p> <p>Four discussions are conducted: (1) the methodology of relative age determination by impact crater statistics, (2) a comparison of proposed <span class="hlt">Martian</span> impact chronologies for the determination of absolute ages from crater frequencies, (3) a report on work dating <span class="hlt">Martian</span> volcanoes and erosional features by impact crater statistics, and (4) an attempt to understand the main features of <span class="hlt">Martian</span> history through a synthesis of crater frequency data. Two cratering chronology models are presented and used for inference of absolute ages from crater frequency data, and it is shown that the interpretation of all data available and tractable by the methodology presented leads to a global <span class="hlt">Martian</span> geological history that is characterized by two epochs of activity. It is concluded that Mars is an ancient planet with respect to its surface features.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003250','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003250"><span>Antarctic <span class="hlt">Meteorite</span> Classification and Petrographic Database Enhancements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Todd, N. S.; Satterwhite, C. E.; Righter, K.</p> <p>2012-01-01</p> <p>The Antarctic <span class="hlt">Meteorite</span> collection, which is comprised of over 18,700 <span class="hlt">meteorites</span>, is one of the largest collections of <span class="hlt">meteorites</span> in the world. These <span class="hlt">meteorites</span> have been collected since the late 1970 s as part of a three-agency agreement between NASA, the National Science Foundation, and the Smithsonian Institution [1]. Samples collected each season are analyzed at NASA s <span class="hlt">Meteorite</span> Lab and the Smithsonian Institution and results are published twice a year in the Antarctic <span class="hlt">Meteorite</span> Newsletter, which has been in publication since 1978. Each newsletter lists the samples collected and processed and provides more in-depth details on selected samples of importance to the scientific community. Data about these <span class="hlt">meteorites</span> is also published on the NASA Curation website [2] and made available through the <span class="hlt">Meteorite</span> Classification Database allowing scientists to search by a variety of parameters. This paper describes enhancements that have been made to the database and to the data and photo acquisition process to provide the <span class="hlt">meteorite</span> community with faster access to <span class="hlt">meteorite</span> data concurrent with the publication of the Antarctic <span class="hlt">Meteorite</span> Newsletter twice a year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981Icar...48..308W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981Icar...48..308W"><span>Which fireballs are <span class="hlt">meteorites</span> - A <span class="hlt">study</span> of the Prairie Network photographic meteor data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wetherill, G. W.; Revelle, D. O.</p> <p>1981-11-01</p> <p>With the exception of three recovered <span class="hlt">meteorites</span> with photographic fireball data (Pribram, Lost City, Innisfree), there is generally little information regarding the location of <span class="hlt">meteorites</span> in the solar system prior to their impact on the earth. An investigation is conducted with the objective to identify those fireballs (bright meteor) data from the Prairie Network. The investigation is based on the belief that many small ordinary chondrites must be present among the photographed bright fireballs. Observations of the recovered fireballs are used to identify characteristics of their dynamics while passing through the atmosphere. In this way criteria are established for identifying those fireballs with similar dynamical characteristics. On the basis of the <span class="hlt">studies</span>, a catalog is provided of fireballs which have a high probability of being ordinary chondrites or other strong <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.P33C2135C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.P33C2135C"><span>NWA 7034 <span class="hlt">Martian</span> breccia: Ar/Ar ages of ca. 1.2 to 1.4 Ga</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cohen, B. E.; Mark, D. F.; Cassata, W.; Lee, M. R.; Smith, C. L.</p> <p>2015-12-01</p> <p>NWA 7034 and its paired stones are some of the oldest and most diverse of the <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. They are complex polymict breccias of impact, igneous, and sedimentary clasts set in a dark grey matrix [1; 2]. The rock also contains angular mineral fragments, including K-feldspar, plagioclase feldspar, and pyroxene [1; 2]. Mineral fragments are often > 1 mm wide, and clasts can be > 1 cm. This diverse breccia assemblage indicates formation via repeated impact events, supported by Rb-Sr, Sm-Nd and U-Pb ages ranging from 1.3 to 4.4 Ga [1, 2, and references therein]. In this <span class="hlt">study</span> we investigate the distribution of ages yielded by Ar/Ar, with nine aliquots analyzed to date, and additional analyses planned. In order to analyze only single phases, chips of matrix/clasts were restricted to visibly monomict fragments < 1 mm diameter, while mineral separates were analyzed as single crystals. Cosmogenic Ar corrections are from [3]. Analyses were undertaken at SUERC and Lawrence Livermore National Laboratory, and the results pooled. The bulk of aliquots (n = 8) yielded ages of ca. 1.2-1.4 Ga indicating a major thermal event occurred at around the same time as crystallization of the Nakhlite group of <span class="hlt">meteorites</span>. Select step ages are considerably older (> 2 Ga), supporting results of other chronometers that much older material is present in this sample. These results also demonstrate that some older fragments retained Ar during breccia formation. [1] Wittmann A. et al. (2015) <span class="hlt">Meteoritics</span> & Planet. Sci., 50, 326-352. [2] Santos A. R. et al. (2015) GCA, 157, 56-85. [3] Cassata W. S., and Borg L. E. (2015) 46th LPSC, Abstract #2742.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050172139','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050172139"><span>The <span class="hlt">Martian</span> Soil as a Geochemical Sink for Hydrothermally Altered Crustal Rocks and Mobile Elements: Implications of Early MER Results</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Draper, D. S.</p> <p>2005-01-01</p> <p>Hydrothermal and aqueous alteration can explain some of the exciting results from the MER team s analyses of the <span class="hlt">martian</span> soil, including the major elements, mobile elements, and the nickel enrichment. Published results from the five lander missions lead to the following conclusions: 1) The soil appears to be globally mixed and basaltic with only small local variations in chemistry. Relative to <span class="hlt">martian</span> basaltic <span class="hlt">meteorites</span> and Gusev rocks the soils are depleted in the fluid-mobile element calcium, but only slightly enriched to somewhat depleted in iron oxide. 2) The presence of olivine in the soils based on M ssbauer data argues that the soil is only partly weathered and is more akin to a lunar regolith than a terrestrial soil. 3) The presence of bromine along with sulfur and chlorine in the soils is consistent with addition of a mobile element component to the soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940009382','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940009382"><span><span class="hlt">Martian</span> sedimentary deposits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dehon, Rene</p> <p>1992-01-01</p> <p>The objectives are characterization of flow through outflow channels, sedimentation associated with <span class="hlt">Martian</span> outflow systems, and documentation of <span class="hlt">Martian</span> lakes. Over the period of the grant much, but not all, of the <span class="hlt">study</span> centered on the Maja Valles outflow. Maja served as an example in which the effects of multiple channel routing and ponding could be <span class="hlt">studied</span>. Maja Valles also served as the test case for calculating flow through an outflow system. Applying the lessons learned in Maja Valles and comparisons and contrast required a scrutiny of other channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020041937&hterms=vatican&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dvatican','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020041937&hterms=vatican&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dvatican"><span>Organics In <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chang, Sherwood</p> <p>1996-01-01</p> <p>The variety of classes of organic compounds that occur in carbonaceous <span class="hlt">meteorites</span> suggests a rich pre-planetary chemistry with possible connections to interstellar, solar nebular and parent body processes. Structural diversity prevails within all classes examined in detail. Among amino acids for instance, all possible isomers are found up to species containing 4-6 carbon atoms, with abundances decreasing with increasing molecular weight. Such diversity seems limited to those carbonaceous <span class="hlt">meteorites</span> which show evidence of having been exposed to liquid water; <span class="hlt">meteorites</span> lacking such evidence also show much lower abundances and less structural diversity in their organic contents. This apparent dependency on water suggests a role for cometary ices in the chemical evolution of organic compounds on parent bodies. Measurements of the stable isotope compositions of C, H, N and S in classes of compounds and at the individual compound level show strong deviations from average chondritic values. These deviations are difficult to explain by solar system or parent body processes, and precedents for some of these isotopic anomalies exist in interstellar (e.g., high D/H ratios) and circumstellar chemistry. Therefore, presolar origins for much if not all of the <span class="hlt">meteoritic</span> organic compounds (or their precursors) is a distinct possibility. In contrast, evidence of solar nebular origins is either lacking or suspect. Results from molecular and isotopic analyses of <span class="hlt">meteoritic</span> organics, from laboratory simulations and from a model of interstellar grain reactions will be used to flesh out the hypothesis that this material originated with interstellar chemistry, was distributed within the early solar system as cometary ices, and was subsequently altered on <span class="hlt">meteorite</span> parent bodies to yield the observed compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V21A0959K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V21A0959K"><span>Iron Isotopes in <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kehm, K.; Alexander, C. M.; Hauri, E. H.</p> <p>2001-12-01</p> <p>The recent identification of naturally occurring isotopic mass fractionation of the transition met-als on the Earth has prompted a search for similar variability in <span class="hlt">meteorites</span>. <span class="hlt">Studies</span> of Cu, Zn, and Fe, for example, have revealed per-mil level and larger mass fractionations between different bulk <span class="hlt">meteorites</span>. Such variations can result from temperature-sensitive isotope exchange reactions and kinetic processes, and therefore may reflect conditions in the solar nebula and on <span class="hlt">meteorite</span> parent bodies. Recent advances in ICP-MS have permitted isotope <span class="hlt">studies</span> of transition metals and other elements with similarly small isotopic mass dispersions. Among the transition metals, Fe is perhaps the most difficult to analyze by ICP-MS because plasma sources are copious producers of argide molecules that interfere with the measurement of iron isotopes. However, the stable isotope behavior of Fe is of special interest because it is a non-refractory major element in <span class="hlt">meteorites</span>, present in a variety of mineral associations and redox states. Considerable effort has gone into overcoming the inherent analytical difficulties of measuring Fe using ICP-MS. We recently reported on a technique that achieves argide reduction by operating the plasma source in so-called 'cold' mode. In this presentation, we report results from this ongoing work. To date, analyses of nine different <span class="hlt">meteorites</span>, and eight individual Tieschitz (H3) chondrules have been completed, along with a number of measurements of the Hawaiian basalt sample Kil1919. All of the bulk <span class="hlt">meteorite</span> compositions, which include both chondrites and irons, have identical 56Fe/54Fe to within ~ 0.14 per mil (2 sigma), and are indistinguishable from the composition of the terrestrial basalt. The Tieschitz chondrules, on the other hand, tend to have isotopically light compositions. This could reflect formation from fractionated starting material. Alternatively, Fe condensation, under non-equilibrium conditions can enrich light isotopes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeCoA..74.1122Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeCoA..74.1122Q"><span>Contributors to chromium isotope variation of <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Liping; Alexander, Conel M. O.'D.; Carlson, Richard W.; Horan, Mary F.; Yokoyama, Tetsuya</p> <p>2010-02-01</p> <p>We report the results of a comprehensive, high precision survey of the Cr isotopic compositions of primitive chondrites, along with some differentiated <span class="hlt">meteorites</span>. To ensure complete dissolution of our samples, they were first fused with lithium borate-tetraborate at 1050-1000 °C. Relative to the NIST Cr standard SRM 3112a, carbonaceous chondrites exhibit excesses in 54Cr/ 52Cr from 0.4 to 1.6 ɛ (1 ɛ = 1 part in 10,000), and ordinary chondrites display a common 54Cr/ 52Cr deficit of ˜0.4 ɛ. Analyses of acid-digestion residues of chondrites show that carbonaceous and ordinary chondrites share a common 54Cr-enriched carrier, which is characterized by a large excess in 54Cr/ 52Cr (up to 200 ɛ) associated with a very small deficit in 53Cr/ 52Cr (<2 ɛ). We did not find 54Cr anomalies in either bulk enstatite chondrites or in leachates of their acid-digestion residues. This either requires that the enstatite chondrite parent bodies did not incorporate the 54Cr anomaly carrier phase during their accretion, or the phase was destroyed by parent body metamorphism. Chromium in the terrestrial rocks and lunar samples analyzed here show no deviation from the NIST SRM 3112a Cr standard. The eucrite and <span class="hlt">Martian</span> <span class="hlt">meteorites</span> <span class="hlt">studied</span> exhibit small deficits in 54Cr/ 52Cr. The 54Cr/ 52Cr variations among different <span class="hlt">meteorite</span> classes suggest that there was a spatial and/or temporal heterogeneity in the distribution of a 54Cr-rich component in the inner Solar System. We confirm the correlated excesses in 54Cr/ 52Cr and 53Cr/ 52Cr for bulk carbonaceous chondrites, but the new data yield a steeper slope (˜6.6) than that reported in Shukolyukov and Lugmair (2006). The correlated excesses may affect the use of the Mn-Cr chronometer in carbonaceous chondrites. We could not confirm the bulk carbonaceous chondrite Mn-Cr isochron reported by Shukolyukov and Lugmair (2006) and Moynier et al. (2007), mostly because we find much smaller total variations in ɛ53Cr (˜0.2). All bulk chondrites</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090022361','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090022361"><span>Rb-Sr Isotopic <span class="hlt">Studies</span> Of Antarctic Lherzolitic Shergottite Yamato 984028</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C.-Y.; Nyquist, L. E.; Reese, Y.; Misawa, K.</p> <p>2009-01-01</p> <p>Yamato 984028 is a <span class="hlt">Martian</span> <span class="hlt">meteorite</span> found in the Yamato Mountains of Antarctica. It is classified as a lherzolitic shergottite and petrographically resembles several other lherzolitic shergottites, i.e. ALHA 77005, LEW 88516, Y-793605 and Y-000027/47/97 [e.g. 2-5]. These <span class="hlt">meteorites</span> have similarly young crystallization ages (152-185 Ma) as enriched basaltic shergottites (157-203 Ma), but have very different ejection ages (approximately 4 Ma vs. approximately 2.5 Ma), thus they came from different <span class="hlt">martian</span> target crater areas. Lherzolitic shergottites have mg-values approximately 0.70 and represent the most mafic olivine-pyroxene cumulates. Their parental magmas were melts derived probably from the primitive <span class="hlt">Martian</span> mantle. Here we present Rb-Sr isotopic data for Y-984028 and compare these data with those obtained from other lherzolitic and olivine-phyric basaltic shergottites to better understand the isotopic characteristics of their primitive mantle source regions. Corresponding Sm-Nd analyses for Y-984028 are in progress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002913','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002913"><span>Indigenous Carbonaceous Matter and Boron Associated with Halite Crystals in Nakhla</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas-Keprta, K. L.; Clemett, S. J.; McKay, D. S.; Gibson, E. K.; Wentworth, S. J.</p> <p>2015-01-01</p> <p>We report here the observation of indigenous organic matter spatially associated with, and in several cases embedded within, halite crystals located in alteration veins inside the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Nakhla. Further-more, we have also detected enrichments of boron (B) in these halites far in excess of those previously reported in bulk <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Boron in <span class="hlt">Martian</span> halites has not been detected previously.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900008210','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900008210"><span>Guide to the US collection of antarctic <span class="hlt">meteorites</span> 1976-1988 (everything you wanted to know about the <span class="hlt">meteorite</span> collection). Antarctic <span class="hlt">Meteorite</span> Newsletter, Volume 13, Number 1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Score, Roberta; Lindstrom, Marilyn M.</p> <p>1990-01-01</p> <p>The state of the collection of Antarctic <span class="hlt">Meteorites</span> is summarized. This guide is intended to assist investigators plan their <span class="hlt">meteorite</span> research and select and request samples. Useful information is presented for all classified <span class="hlt">meteorites</span> from 1976 to 1988 collections, as of Sept. 1989. The <span class="hlt">meteorite</span> collection has grown over 13 years to include 4264 samples of which 2754 have been classified. Most of the unclassified <span class="hlt">meteorites</span> are ordinary chondrites because the collections have been culled for specimens of special petrologic type. The guide consists of two large classification tables. They are preceded by a list of sample locations and important notes to make the tables understandable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000101054&hterms=microbiota&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmicrobiota','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000101054&hterms=microbiota&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmicrobiota"><span><span class="hlt">Meteorites</span> and Microbes: <span class="hlt">Meteorite</span> Collection and Ice Sampling at Patriot Hills, Thiel Mountains, and South Pole, Antarctica</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sipiera, Paul P.; Hoover, Richard B.; Rose, M. Franklin (Technical Monitor)</p> <p>2000-01-01</p> <p>During the Antarctica 2000 Expedition, sponsored by the Planetary <span class="hlt">Studies</span> Foundation, <span class="hlt">meteorites</span> and ice microbiota were collected from the Patriot Hills, and Thiel Mountains of Antarctica and snow samples were at the South Pole. Psychrophilic and psychrotrophic microbiota were obtained from blue ice, cryoconite and ice-bubble systems. Twenty frozen <span class="hlt">meteorites</span> were collected using aseptic techniques from the blue ice fields near the Moulton Escarpment of the Thiel Mountains (85 S, 94 W) and from the Morris Moraine of the Patriot Hills (80 S, 81 W) Ellsworth Mountains. These ice and <span class="hlt">meteorite</span> samples are of potential significance to Astrobiology. They may help refine chemical and morphological biomarkers and refine characteristics of microbial life in one of the harshest environments on Earth. We discuss the Antarctica 2000 Expedition and provide preliminary results of the investigation of the <span class="hlt">meteorites</span> and ice microbiota recovered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003NoCe...22...63R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003NoCe...22...63R"><span><span class="hlt">Meteorites</span> from Cluj-Napoca</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Radu, Gelu; Pop, Dana</p> <p>2003-04-01</p> <p>The article represents an interview of the journalist Gelu Radu with the director of the <span class="hlt">Meteorites</span> Museum from the Geological Faculty of the Cluj-Napoca University (Romania) Dana Pop concerning the History, Collection and Actual state of an unique in Romania <span class="hlt">Meteorites</span> Museum, founded in 1882 after the fall of the Mociu <span class="hlt">Meteorit</span> (Cluj County) on 3 february 1882. One discusses about the collection of the Museum and the policy of changes with other similar museums throughout the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000081026&hterms=leaching&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dleaching','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000081026&hterms=leaching&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dleaching"><span>Update on Terrestrial Ages of Antarctic <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Welten, K. C.; Nishiizumi, K.; Caffee, M. W.</p> <p>2000-01-01</p> <p>Terrestial ages are presented for 70 Antarctic <span class="hlt">meteorites</span>, based on cosmogenic Be-10, Al-26 and Cl-36 in the metal phase. Also, results of leaching experiments are discussed to <span class="hlt">study</span> possible contamination of stony <span class="hlt">meteorites</span> with atmospheric Be-10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P53E2678A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P53E2678A"><span><span class="hlt">Martian</span> Chemical and Isotopic Reference Standards in Earth-based Laboratories — An Invitation for Geochemical, Astrobiological, and Engineering Dialog on Considering a Weathered Chondrite for Mars Sample Return.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashley, J. W.; Tait, A. W.; Velbel, M. A.; Boston, P. J.; Carrier, B. L.; Cohen, B. A.; Schröder, C.; Bland, P.</p> <p>2017-12-01</p> <p>Exogenic rocks (<span class="hlt">meteorites</span>) found on Mars 1) have unweathered counterparts on Earth; 2) weather differently than indigenous rocks; and 3) may be ideal habitats for putative microorganisms and subsequent biosignature preservation. These attributes show the potential of <span class="hlt">meteorites</span> for addressing hypothesis-driven science. They raise the question of whether chondritic <span class="hlt">meteorites</span>, of sufficient weathering intensity, might be considered as candidates for sample return in a potential future mission. Pursuant to this discussion are the following questions. A) Is there anything to be learned from the laboratory <span class="hlt">study</span> of a <span class="hlt">martian</span> chondrite that cannot be learned from indigenous materials; and if so, B) is the science value high enough to justify recovery? If both A and B answer affirmatively, then C) what are the engineering constraints for sample collection for Mars 2020 and potential follow-on missions; and finally D) what is the likelihood of finding a favorable sample? Observations relevant to these questions include: i) Since 2005, 24 candidate and confirmed <span class="hlt">meteorites</span> have been identified on Mars at three rover landing sites, demonstrating their ubiquity and setting expectations for future finds. All have been heavily altered by a variety of physical and chemical processes. While the majority of these are irons (not suitable for recovery), several are weathered stony <span class="hlt">meteorites</span>. ii) Exogenic reference materials provide the only chemical/isotope standards on Mars, permitting quantification of alteration rates if residence ages can be attained; and possibly enabling the removal of Late Amazonian weathering overprints from other returned samples. iii) Recent <span class="hlt">studies</span> have established the habitability of chondritic <span class="hlt">meteorites</span> with terrestrial microorganisms, recommending their consideration when exploring astrobiological questions. High reactivity, organic content, and permeability show stony <span class="hlt">meteorites</span> to be more attractive for colonization and subsequent biosignature</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750034440&hterms=fatty+acid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfatty%2Bacid','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750034440&hterms=fatty+acid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfatty%2Bacid"><span>Amino and fatty acids in carbonaceous <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kvenvolden, K. A.</p> <p>1974-01-01</p> <p>Analyses of two carbonaceous <span class="hlt">meteorites</span> have provided much of the latest evidence which seems to support Oparin's theory on the origin of life. The <span class="hlt">meteorites</span> involved are the Murray <span class="hlt">meteorite</span>, which fell in 1950, and the Murchison <span class="hlt">meteorite</span>, which fell in 1969. The amino acids in the two <span class="hlt">meteorites</span> are similar in composition. Eight of the twenty amino acids found belong to amino acids present in proteins. A number of monocarboxylic and dicarboxylic fatty acids were also found in the <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770027125','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770027125"><span><span class="hlt">Martian</span> polar geological <span class="hlt">studies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cutts, J. A. J.</p> <p>1977-01-01</p> <p>Multiple arcs of rugged mountains and adjacent plains on the surface of Mars were examined. These features, located in the southern polar region were photographed by Mariner 9. Comparisons are made with characteristics of a lunar basin and mare; Mare imbrium in particular. The <span class="hlt">martian</span> feature is interpreted to have originated in the same way as its lunar analog- by volcanic flooding of a large impact basin. Key data and methodology leading to this conclusion are cited.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910010684','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910010684"><span>Ancient oceans and <span class="hlt">Martian</span> paleohydrology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baker, Victor R.; Strom, Robert G.; Gulick, Virginia C.; Kargel, Jeffrey S.; Komatsu, Goro; Kale, Vishwas S.</p> <p>1991-01-01</p> <p>The global model of ocean formation on Mars is discussed. The <span class="hlt">studies</span> of impact crater densities on certain <span class="hlt">Martian</span> landforms show that late in <span class="hlt">Martian</span> history there could have been coincident formation of: (1) glacial features in the Southern Hemisphere; (2) ponded water and related ice features in the northern plains; (3) fluvial runoff on <span class="hlt">Martian</span> uplands; and (4) active ice-related mass-movement. This model of transient ocean formation ties these diverse observations together in a long-term cyclic scheme of global planetary operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940019026','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940019026"><span>Correlated petrographic, electron microprobe, and ion microprobe <span class="hlt">studies</span> of selected primitive and processed phase assemblages in <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Albee, Arden L.</p> <p>1993-01-01</p> <p>During the past three years we have received support to continue our research in elucidating the formation and alteration histories of selected <span class="hlt">meteoritic</span> materials by a combination of petrographic, trace element, and isotopic analyses employing optical and scanning electron microscopes and electron and ion microprobes. The awarded research funds enabled the P.I. to attend the annual LPSC, the co-I to devote approximately 15 percent of his time to the research proposed in the grant, and partial support for a visiting summer post-doctoral fellow to conduct electron microprobe analyses of <span class="hlt">meteoritic</span> samples in our laboratory. The research funds, along with support from the NASA Education Initiative awarded to P.I. G. Wasserburg, enabled the co-I to continue a mentoring program with inner-city minority youth. The support enabled us to achieve significant results in the five projects that we proposed (in addition to the Education Initiative), namely: <span class="hlt">studies</span> of the accretional and post-accretional alteration and thermal histories in CV <span class="hlt">meteorites</span>, characterization of periclase-bearing Fremdlinge in CV <span class="hlt">meteorites</span>, characterization of Ni-Pt-Ge-Te-rich Fremdlinge in CV <span class="hlt">meteorites</span> in an attempt to determine the constraints they place on the petrogenetic and thermal histories of their host CAI's, correlated electron and ion microprobe <span class="hlt">studies</span> of silicate and phosphate inclusions in the Colomera <span class="hlt">meteorite</span> in an attempt to determine the petrogenesis of the IE iron <span class="hlt">meteorites</span>, and development of improved instrumental and correction procedures for improved accuracy of analysis of <span class="hlt">meteoritic</span> materials with the electron microprobe. This grant supported, in part or whole, 18 publications so far by our research team, with at least three more papers anticipated. The list of these publications is included. The details of the research results are briefly summarized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/289430-bacterial-mineralization-patterns-basaltic-aquifers-implications-possible-life-martian-meteorite-alh84001','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/289430-bacterial-mineralization-patterns-basaltic-aquifers-implications-possible-life-martian-meteorite-alh84001"><span>Bacterial mineralization patterns in basaltic aquifers: Implications for possible life in <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Thomas-Keprta, K.L.; Wentworth, S.J.; Allen, C.C.</p> <p></p> <p>To explore the formation and preservation of biogenic features in igneous rocks, the authors have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralizedmore » filaments are recognized in martial <span class="hlt">meteorite</span> ALH84001.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616430G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616430G"><span>Variability of the <span class="hlt">Martian</span> thermospheric temperatures during the last 7 <span class="hlt">Martian</span> Years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez-Galindo, Francisco; Lopez-Valverde, Miguel Angel; Millour, Ehouarn; Forget, François</p> <p>2014-05-01</p> <p>The temperatures and densities in the <span class="hlt">Martian</span> upper atmosphere have a significant influence over the different processes producing atmospheric escape. A good knowledge of the thermosphere and its variability is thus necessary in order to better understand and quantify the atmospheric loss to space and the evolution of the planet. Different global models have been used to <span class="hlt">study</span> the seasonal and interannual variability of the <span class="hlt">Martian</span> thermosphere, usually considering three solar scenarios (solar minimum, solar medium and solar maximum conditions) to take into account the solar cycle variability. However, the variability of the solar activity within the simulated period of time is not usually considered in these models. We have improved the description of the UV solar flux included on the General Circulation Model for Mars developed at the Laboratoire de Météorologie Dynamique (LMD-MGCM) in order to include its observed day-to-day variability. We have used the model to simulate the thermospheric variability during <span class="hlt">Martian</span> Years 24 to 30, using realistic UV solar fluxes and dust opacities. The model predicts and interannual variability of the temperatures in the upper thermosphere that ranges from about 50 K during the aphelion to up to 150 K during perihelion. The seasonal variability of temperatures due to the eccentricity of the <span class="hlt">Martian</span> orbit is modified by the variability of the solar flux within a given <span class="hlt">Martian</span> year. The solar rotation cycle produces temperature oscillations of up to 30 K. We have also <span class="hlt">studied</span> the response of the modeled thermosphere to the global dust storms in <span class="hlt">Martian</span> Year 25 and <span class="hlt">Martian</span> Year 28. The atmospheric dynamics are significantly modified by the global dust storms, which induces significant changes in the thermospheric temperatures. The response of the model to the presence of both global dust storms is in good agreement with previous modeling results (Medvedev et al., Journal of Geophysical Research, 2013). As expected, the simulated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.140..334W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.140..334W"><span>Heterogeneous mineral assemblages in <span class="hlt">martian</span> <span class="hlt">meteorite</span> Tissint as a result of a recent small impact event on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walton, E. L.; Sharp, T. G.; Hu, J.; Filiberto, J.</p> <p>2014-09-01</p> <p>The microtexture and mineralogy of shock melts in the Tissint <span class="hlt">martian</span> <span class="hlt">meteorite</span> were investigated using scanning electron microscopy, Raman spectroscopy, transmission electron microscopy and synchrotron micro X-ray diffraction to understand shock conditions and duration. Distinct mineral assemblages occur within and adjacent to the shock melts as a function of the thickness and hence cooling history. The matrix of thin veins and pockets of shock melt consists of clinopyroxene + ringwoodite ± stishovite embedded in glass with minor Fe-sulfide. The margins of host rock olivine in contact with the melt, as well as entrained olivine fragments, are now amorphosed silicate perovskite + magnesiowüstite or clinopyroxene + magnesiowüstite. The pressure stabilities of these mineral assemblages are ∼15 GPa and >19 GPa, respectively. The ∼200-μm-wide margin of a thicker, mm-size (up to 1.4 mm) shock melt vein contains clinopyroxene + olivine, with central regions comprising glass + vesicles + Fe-sulfide spheres. Fragments of host rock within the melt are polycrystalline olivine (after olivine) and tissintite + glass (after plagioclase). From these mineral assemblages the crystallization pressure at the vein edge was as high as 14 GPa. The interior crystallized at ambient pressure. The shock melts in Tissint quench-crystallized during and after release from the peak shock pressure; crystallization pressures and those determined from olivine dissociation therefore represent the minimum shock loading. Shock deformation in host rock minerals and complete transformation of plagioclase to maskelynite suggest the peak shock pressure experienced by Tissint ⩾ 29-30 GPa. These pressure estimates support our assessment that the peak shock pressure in Tissint was significantly higher than the minimum 19 GPa required to transform olivine to silicate perovskite plus magnesiowüstite. Small volumes of shock melt (<100 μm) quench rapidly (0.01 s), whereas thermal equilibration will</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170000498','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170000498"><span>Asteroid 2008 TC3 Breakup and <span class="hlt">Meteorite</span> Fractions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goodrich, C.; Jenniskens, P.; Shaddad, M. H.; Zolensky, M. E.; Fioretti, A. M.</p> <p>2017-01-01</p> <p>The recovery of <span class="hlt">meteorites</span> from the impact of asteroid 2008 TC3 in the Nubian Desert of Sudan on October 7, 2008, marked the first time <span class="hlt">meteorites</span> were collected from an asteroid observed in space by astronomical techniques before impacting. Search teams from the University of Khartoum traced the location of the strewn field and collected about 660 <span class="hlt">meteorites</span> in four expeditions to the fall region, all of which have known fall coordinates. Upon further <span class="hlt">study</span>, the Almahata Sitta <span class="hlt">meteorites</span> proved to be a mixed bag of mostly ureilites (course grained, fine grained, and sulfide-metal assemblages), enstatite chondrites (EL3-6, EH3, EH5, breccias) and ordinary chondrites (H5-6, L4-5). One bencubbinite-like carbonaceous chondrite was identified, as well as one unique Rumuruti-like chondrite and an Enstatite achondrite. New analysis: The analysed <span class="hlt">meteorites</span> so far suggest a high 30-40 percent fraction of non-ureilites among the recovered samples, but that high fraction does not appear to be in agreement with the <span class="hlt">meteorites</span> in the University of Khartoum (UoK) collection. Ureilites dominate the <span class="hlt">meteorites</span> that were recovered by the Sudanese teams. To better understand the fraction of recovered materials that fell to Earth, a program has been initiated to type the <span class="hlt">meteorites</span> in the UoK collection in defined search areas. At this meeting, we will present some preliminary results from that investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910010694','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910010694"><span>Relative chronology of <span class="hlt">Martian</span> volcanoes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Landheim, R.; Barlow, N. G.</p> <p>1991-01-01</p> <p>Impact cratering is one of the major geological processes that has affected the <span class="hlt">Martian</span> surface throughout the planet's history. The frequency of craters within particular size ranges provides information about the formation ages and obliterative episodes of <span class="hlt">Martian</span> geologic units. The Barlow chronology was extended by measuring small craters on the volcanoes and a number of standard terrain units. Inclusions of smaller craters in units previously analyzed by Barlow allowed for a more direct comparison between the size-frequency distribution data for volcanoes and established chronology. During this <span class="hlt">study</span>, 11,486 craters were mapped and identified in the 1.5 to 8 km diameter range in selected regions of Mars. The results are summarized in this three page report and give a more precise estimate of the relative chronology of the <span class="hlt">Martian</span> volcanoes. Also, the results of this <span class="hlt">study</span> lend further support to the increasing evidence that volcanism has been a dominant geologic force throughout <span class="hlt">Martian</span> history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930022755&hterms=clay&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclay','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022755&hterms=clay&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclay"><span>Aqueous geochemistry on Mars: Possible clues from salts and clays in SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.</p> <p>1992-01-01</p> <p>All subgroups of the shergottite, nakhlite, and chassignite (SNC) <span class="hlt">meteorites</span> contain traces of water precipitated minerals that include various combinations of carbonates, sulfates, halides, ferric oxides, and aluminosilicate clays of preterrestrial origin. Oxygen three-isotope analysis of thermally extracted bulk water has confirmed that at least some of the water in SNC's is, indeed, extraterrestrial. A mixture of aqueous precipitates found in the SNC's, comprising smectite, illite, and gypsum (with minor halite +/- calcite and hematite), provides a self-consistent, though not unique, model for the bulk elemental composition of surface sediments at the Viking Lander sites. Therefore, if the salts and clays in SNC's are truly linked to aqueous alteration and soil formation on Mars, then the suite of SNC secondary minerals might provide the best currently available insight into near-surface <span class="hlt">martian</span> chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100009797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100009797"><span>Is EETA79001 Lithology B A True Melt Composition?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arauza, S. J.; Jones, John H.; Mittlefehldt, D. W.; Le, L.</p> <p>2010-01-01</p> <p>EETA79001 is a member of the SNC (shergottite, nakhlite, chassignite) group of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Most SNC <span class="hlt">meteorites</span> are cumulates or partial cumulates [1] inhibiting calculation of parent magma compositions; only two (QUE94201 and Y- 980459) have been previously identified as true melt compositions. The goal of this <span class="hlt">study</span> is to test whether EETA79001-B may also represent an equilibrium melt composition, which could potentially expand the current understanding of <span class="hlt">martian</span> petrology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002918','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002918"><span>The Mineralogical Record of Oxygen Fugacity Variation and Alteration in Northwest Africa 8159: Evidence for Interaction Between a Mantle Derived <span class="hlt">Martian</span> Basalt and a Crustal Component(s)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, Charles K.; Burger, Paul V.; Bell, Aaron S.; McCubbin, Francis M.; Agee, Carl; Simon, Justin I.; Papike, James J.</p> <p>2015-01-01</p> <p>A prominent geochemical feature of basaltic magmatism on Mars is the large range in initial Sr isotopic ratios (approx. 0.702 - 0.724) and initial epsilon-Nd values (approx. -10 to greater than +50). Within this range, the shergottites fall into three discreet subgroups. These subgroups have distinct bulk rock REE patterns, mineral chemistries (i.e. phosphate REE patterns, Ni, Co, V in olivine), oxygen fugacity of crystallization, and stable isotopes, such as O. In contrast, nakhlites and chassignites have depleted epsilon-Nd values (greater than or equal to +15), have REE patterns that are light REE enriched, and appear to have crystallized near the FMQ buffer. The characteristics of these various <span class="hlt">martian</span> basalts have been linked to different reservoirs in the <span class="hlt">martian</span> crust and mantle, and their interactions during the petrogenesis of these magmas. These observations pose interesting interpretive challenges to our understanding of the conditions of the <span class="hlt">martian</span> mantle (e.g. oxygen fugacity) and the interaction of mantle derived magmas with the <span class="hlt">martian</span> crust and surface. <span class="hlt">Martian</span> <span class="hlt">meteorite</span> NWA 8159 is a unique fine-grained augite basalt derived from a highly depleted mantle source as reflected in its initial epsilon-Nd value, contains a pronounced light REE depleted pattern, and crystallized presumably under very oxidizing conditions. Although considerably older than both shergottites and nahklites, it has been petrogenetically linked to both styles of <span class="hlt">martian</span> magmatism. These unique characteristics of NWA 8159 may provide an additional perspective for deciphering the petrogenesis of <span class="hlt">martian</span> basalts and the nature of the crust of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PS...47..929P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PS...47..929P"><span>The Old Woman, California, IIAB iron <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Plotkin, Howard; Clarke, Roy S.; McCoy, Timothy J.; Corrigan, Catherine M.</p> <p>2012-05-01</p> <p>The Old Woman <span class="hlt">meteorite</span>, discovered in March 1976 by two prospectors searching for a fabled lost Spanish gold mine in mountains ˜270 km east of Los Angeles, has achieved the status of a legend among <span class="hlt">meteorite</span> hunters and collectors. The question of the ownership of the 2753 kg group IIAB <span class="hlt">meteorite</span>, the second largest ever found in the United States (34°28'N, 115°14'W), gave rise to disputes involving the finders, the Bureau of Land Management, the Secretary of the Department of the Interior, the State of California, the California members of the U.S. Congress, various museums in California, the Smithsonian Institution, and the Department of Justice. Ultimately, ownership of the <span class="hlt">meteorite</span> was transferred to the Smithsonian under the powers of the 1906 Antiquities Act, a ruling upheld in a U.S. District Court and a U.S. Court of Appeals. After additional debate, the Smithsonian removed a large cut for <span class="hlt">study</span> and curation, and for disbursement of specimens to qualified researchers. The main mass was then returned to California on long-term loan to the Bureau of Land Management's Desert Discovery Center in Barstow. The Old Woman <span class="hlt">meteorite</span> litigation served as an important test case for the ownership and control of <span class="hlt">meteorites</span> found on federal lands. The Old Woman <span class="hlt">meteorite</span> appears to be structurally unique in containing both hexahedral and coarsest octahedral structures in the same mass, unique oriented schreibersites within hexahedral areas, and polycrystalline parent austenite crystals. These structures suggest that different portions of the <span class="hlt">meteorite</span> may have transformed via different mechanisms upon subsolidus cooling, making the large slices of Old Woman promising targets for future research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019356','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019356"><span>Thermoluminescence and Antarctic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sears, D. W. G.; Hasan, F. A.</p> <p>1986-01-01</p> <p>The level of natural thermoluminescence (TL) in <span class="hlt">meteorites</span> is the result of competition between build-up, due to exposure to cosmic radiation, and thermal decay. Antarctic <span class="hlt">meteorites</span> tend to have lower natural TL than non-Antarctic <span class="hlt">meteorites</span> because of their generally larger terrestrial ages. However, since a few observed falls have low TL due to a recent heating event, such as passage within approximately 0.7 astronomical units of the Sun, this could also be the case for some Antarctic <span class="hlt">meteorites</span>. Dose rate variations due to shielding, heating during atmospheric passage, and anomalous fading also cause natural TL variations, but the effects are either relatively small, occur infrequently, or can be experimentally circumvented. The TL sensitivity of <span class="hlt">meteorites</span> reflects the abundance and nature of the feldspar. Thus intense shock, which destroys feldspar, causes the TL sensitivity to decrease by 1 to 2 orders of magnitude, while metamorphism, which generates feldspar through the devitrification of glass, causes TL sensitivity to increase by a factor of approximately 10000. The TL-metamorphism relationship is particularly strong for the lowest levels of metamorphism. The order-disorder transformation in feldspar also affect the TL emission characteristics and thus TL provides a means of paleothermometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930050902&hterms=water+meter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dwater%2Bmeter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930050902&hterms=water+meter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dwater%2Bmeter"><span>Outgassed water on Mars - Constraints from melt inclusions in SNC <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, Harry Y., Jr.; Harvey, Ralph P.</p> <p>1993-01-01</p> <p>The SNC (shergottite-nakhlite-chassignite) <span class="hlt">meteorites</span>, thought to be igneous rocks from Mars, contain melt inclusions trapped at depth in early-formed crystals. Determination of the pre-eruptive water contents of SNC parental magmas from calculations of the solidification histories of these amphibole-bearing inclusions indicates that <span class="hlt">Martian</span> magmas commonly contained 1.4 percent water by weight. When combined with an estimate of the volume of igneous materials on Mars, this information suggests that the total amount of water outgassed since 3.9 billion years ago corresponds to global depths on the order of 200 meters. This value is significantly higher than previous geochemical estimates but lower than estimates based on erosion by floods. These results imply a wetter Mars interior than has been previously thought and support suggestions of significant outgassing before formation of a stable crust or heterogeneous accretion of a veneer of cometary matter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007epsc.conf...30G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007epsc.conf...30G"><span><span class="hlt">Martian</span> interior structure models with different crustal density</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gudkova, T. V.; Zharkov, V. N.</p> <p>2007-08-01</p> <p>The information necessary to construct a model of Mars (observation data, a choice of a chemical model, a cosmogonic aspect of the problem) is discussed. We consider an interior structure model which comprises four submodels - a model of the outer porous layer, a model of the crust, a model of the mantle and a model of the core. The first 10-11 km layer is considered as an averaged transition from regolith to consolidated rock. The mineral composition of the crustal basaltic rock varies with depth because of the gabbro-eclogite phase transition. Mineralogical and seismic models of the <span class="hlt">Martian</span> crust were constructed by numerical thermodynamic simulation by Babeiko and Zharkov (2000). For the obtained from this simulation densities at the crust-mantle boundary (about 3.3-3.4 g/cm3) a density contrast between the crust and the mantle is low enough. However, the joint interpretation of gravity and topography data assumes that there is a noticeable density jump at the crust-mantle boundary. As discussed by many authors a plausible range of bulk crustal densities is from 2.7 to 3.1 g/ cm3. It can be interpreted as either the composition of rocks at the surface of Mars is somewhat different than those of the <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span> or a certain amount of crustal porosity might be expected if water (or some other substances) is present in the subsurface. Assuming a range of crustal densities (2.7-3.2 g/cm3) and the average thickness of the <span class="hlt">martian</span> crust of 50 and 100 km we have recalculated a set of interior structure models of Mars to determine this effect on the other model parameters. The models are stronly constrained by new values of Love number k2 and the mean moment of inertia have been derived by Konopliv et al. (2006). The inferred radius of <span class="hlt">Martian</span> core (from the Love number k2) is between 1700 and 1800 km. Keeping in mind that the estimated value of the correction introduced to the Love number k2 due to the inelasticity of the interior can be both somewhat</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050174593','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050174593"><span>Synchrotron-based Infrared Microspectroscopy as a Useful Tool to <span class="hlt">Study</span> Hydration States of <span class="hlt">Meteorite</span> Constituents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moroz, L. V.; Schmidt, M.; Schade, U.; Hiroi, T.; Ivanova, M. A.</p> <p>2005-01-01</p> <p>The <span class="hlt">meteorites</span> Dho 225 and Dho 735 were recently found in Oman. <span class="hlt">Studies</span> of their mineralogical and chemical composition suggest that these unusual <span class="hlt">meteorites</span> are thermally metamorphosed CM2 chondrites [1,2,3]. Similar to Antarctic metamorphosed carbonaceous chondrites, the Dho 225 and Dho 735 are enriched in heavy oxygen compared to normal CMs [1,2]. However, IR <span class="hlt">studies</span> indicating dehydration of matrix phyllosilicates are needed to confirm that the two new <span class="hlt">meteorites</span> from Oman are thermally metamorphosed [4]. Synchrotron-based IR microspectroscopy is a new promising technique which allows the acquisition of IR spectra from extremely small samples. Here we demonstrate that this non-destructive technique is a useful tool to <span class="hlt">study</span> hydration states of carbonaceous chondrites in situ. In addition, we acquired reflectance spectra of bulk powders of the Dho 225 and Dho 735 in the range of 0.3-50 microns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880021189','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880021189"><span>Antarctic <span class="hlt">Meteorite</span> Newsletter, Volume 11, Number 2, August 1988</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1988-01-01</p> <p>Presented are classifications and descriptions of a large number of <span class="hlt">meteorites</span> which include the last samples from the 1984 collection and the first samples from the 1987 collection. There is a particularly good selection of <span class="hlt">meteorites</span> of special petrologic type in the 1987 collection. The achondrites include aubrites, ureilites, howardites, eucrites, and a diogenite. The howardites are particularly notable because of their size and previous scarcity in the Antarctic collection. Noteworthy among the 7 irons and 3 mesosiderities are 2 anamolous irons and 2 large mesosiderites. The carbonaceous chondrites include good suites of C2 and C4 <span class="hlt">meteorites</span>, and 2 highly equilibrated carbonaceous chondrites tentatively identified as C5 and C6 <span class="hlt">meteorites</span>. Also included are surveys of numerous <span class="hlt">meteorites</span> for Al-26 and thermoluminescence. These <span class="hlt">studies</span> provide information on the thermal and radiation histories of the <span class="hlt">meteorites</span> and can be used as measures of their terrestrial ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011974"><span>Enantiomer Ratios of <span class="hlt">Meteoritic</span> Sugar Derivatives</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooper, George</p> <p>2012-01-01</p> <p>Carbonaceous <span class="hlt">meteorites</span> contain a diverse suite of soluble organic compounds. <span class="hlt">Studies</span> of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in <span class="hlt">meteorites</span> are keto acids (pyruvic acid, etc.), hydroxy tricarboxylic acids (1), amino acids, amides, purines and pyrimidines. The Murchison and Murray <span class="hlt">meteorites</span> are the most <span class="hlt">studied</span> for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) <span class="hlt">meteoritic</span> compounds are racemic, (i.e., their D/L enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino acids contain slightly more of one enantiomer (usually the L) than the other. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) <span class="hlt">meteoritic</span> sugar acids. The molecular and enantiomer analysis of corresponding sugar alcohols will also be discussed. Detailed analytical procedures for sugar-acid enantiomers have been described. Results of several <span class="hlt">meteorite</span> analyses show that glyceric acid is consistently racemic (or nearly so) as expected of non-biological mechanisms of synthesis. Also racemic are 4-C deoxy sugar acids: 2-methyl glyceric acid; 2,4-dihydroxybutyric acid; 2,3-dihydroxybutyric acid (two diastereomers); and 3,4-dihydroxybutyric acid. However, a 4C acid, threonic acid, has never been observed as racemic, i.e., it possesses a large D excess. In several samples of Murchison and one of GRA 95229 (possibly the most pristine carbonaceous <span class="hlt">meteorite</span> yet analyzed) threonic acid has nearly the same D enrichment. In Murchison, preliminary isotopic measurements of individual threonic acid enantiomers point towards extraterrestrial sources of the D enrichment. Enantiomer analyses of the 5C mono-sugar acids, ribonic, arabinonic, xylonic, and lyxonic also show large D excesses. It is worth noting that all four of these acids (all of the possible straight-chained 5C sugar acids) are present in <span class="hlt">meteorites</span>, including the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009928','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009928"><span>Shock Experiments on Basalt - Ferric Sulfate Mixes at 21 GPa & 49 GPa and their Relevance to <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Impact Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Ross, D. K.; See, T. H.; Nyquist, L. E.; Sutton, S.; Asimow, P.</p> <p>2013-01-01</p> <p>Large abundance of <span class="hlt">Martian</span> atmospheric gases and neutron-induced isotopic excesses as well as Rb-Sr isotopic variations determined in some impact glasses in basaltic shergottites (e.g., Shergotty #DBS, Zagami #H1 and EET79001 #27, #8 and #104) provide definitive evidence for the occurrence of a <span class="hlt">Martian</span> regolith component in their constituent mineral assemblages. Some of these glass-es, known as gas-rich impact-melts (GRIM), contain numerous micron-sized iron sulfide blebs along with minor amounts of iron sulfate particulates. As these GRIM glasses contain a <span class="hlt">Martian</span> regolith component and as iron sulfates (but not sulfides) are found to occur abundantly on the Mars surface, we suggested that the sulfide blebs in GRIMs were likely generated by shock-reduction of the parental iron sulfate bearing regolith material that had been incorporated into the cavities/crevices of basaltic host rock prior to the impact event on Mars. To test whether the sulfates could be reduced to sulfides by impact shock, we carried out laboratory shock experiments on a basalt plus ferric sulfate mixture at 49 GPa at the Caltech Shock Wave Laboratory and at 21 GPa at Johnson Space Center (JSC) Experimental Impact Laboratory. The experimental details and the preliminary results for the Caltech 49 GPa experiment were presented at LPSC last year. Here, we report the results for the 21 GPa experiment at JSC and compare these results to obtain further insight into the mechanism of the bleb formation in the GRIM glasses.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130011620','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130011620"><span>Mid-Infrared <span class="hlt">Study</span> of Samples from Several Stones from the Sutter's Mill <span class="hlt">Meteorite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sandford, Scott; Nuevo, Michel; Flynn, George J.; Wirick, Sue</p> <p>2013-01-01</p> <p>On April 22, 2012, a fireball was observed over California and Nevada, and the falling fragments of the <span class="hlt">meteorite</span> were detected by weather radar near small townships in the El Dorado County, California. Some of these stones were collected at Sutter s Mill, in the historic site where the California gold rush was initiated, giving the name to this <span class="hlt">meteorite</span>. Thus far, 77 pieces of the <span class="hlt">meteorite</span> have been collected, for a total mass of 943 g, with the biggest stone weighing 205 g [1].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020043257','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020043257"><span>Sugar-Related Organic Compounds in Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooper, G.; Kimmich, N.; Belisle, W.; Sarinana, J.; Brabham, K.; Garrel, L.; DeVincenzi, Donald L. (Technical Monitor)</p> <p>2001-01-01</p> <p>Sugars and related polyols are critical components of all organisms and may have been necessary for the origin of life. To date, this class of organic compounds had not been definitively identified in <span class="hlt">meteorites</span>. This <span class="hlt">study</span> was undertaken to determine if polyols were present in the early Solar System as constituents of carbonaceous <span class="hlt">meteorites</span>. Results of analyses of the Murchison and Murray <span class="hlt">meteorites</span> indicate that formaldehyde and sugar chemistry may be responsible for the presence of a variety of polyols. We conclude that polyols were present on the early Earth through delivery by asteroids and possibly comets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.P51E..08L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.P51E..08L"><span>Prospecting for Diverse Igneous Rock Types on Mars: Pixl on "black Beauty" Nwa 7533</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Y.; Flannery, D.; Allwood, A.; Thompson, D. R.; Hodyss, R. P.; Clark, B. C.; Elam, W. T.; Hurowitz, J.</p> <p>2015-12-01</p> <p>In order to understand the evolution of the <span class="hlt">Martian</span> crust and mantle, we need to acquire and analyze samples of igneous rocks other than the basaltic and ultramafic lithologies represented by the majority of <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Recent results from the Curiosity Rover demonstrate that diverse rock types exist in some <span class="hlt">Martian</span> sedimentary environments in the form of conglomerate components or float, some of which shed light on the nature of early <span class="hlt">Martian</span> crust (e.g., Sautter et al., 2015). We are developing investigation strategies for the in-situ instruments that will be flown on the Mars 2020 rover. These instruments will be used to inform the sampling campaigns required for future sample return missions. To achieve this, we applied PIXL (Planetary Instrument for X-ray Lithochemistry), an instrument for the Mars 2020 rover mission, to the <span class="hlt">meteorite</span> NWA 7533. This <span class="hlt">meteorite</span> is a pairing of NWA 7034, known informally as "Black Beauty", a new type of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> that is broadly similar to the average composition of the <span class="hlt">Martian</span> crust. This type of <span class="hlt">meteorite</span> is essentially a 'conglomerate', with many diverse rock types, including mafic, feldspathic, and exotic rock fragments such as feldspar-ilmenite-phosphate clasts, as observed using higher-spatial resolution and higher sensitivity laboratory instruments (e.g., Agee et al., 2013; Humayun et al., 2014; Santos et al., 2015). Using PIXL, we analyzed a mm-scale cut and polished surface and applied algorithms developed by the PIXL team to semi-autonomously define and group regions containing similar lithological components (Thompson et al., 2015). PIXL data rapidly reveal distinctive zircon-bearing lithologies and feldspar-ilmenite-phosphate clasts similar to the detailed petrographic and mineralogical observations. Results suggest that PIXL readily identifies lithologies with minerals and elements (e.g., Rb and Sr) that are important for geochronology <span class="hlt">studies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980107900','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980107900"><span>The Weathering of Antarctic <span class="hlt">Meteorites</span>: Climatic Controls on Weathering Rates and Implications for <span class="hlt">Meteorite</span> Accumulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benoit, P. H.; Akridge, J. M. C.; Sears, D. W. G.; Bland, P. A.</p> <p>1995-01-01</p> <p>Weathering of <span class="hlt">meteorites</span> includes a variety of chemical and mineralogical changes, including conversion of metal to iron oxides, or rust. Other changes include the devitrification of glass, especially in fusion crust. On a longer time scale, major minerals such as olivine, pyroxene, and feldspar are partially or wholly converted to various phyllosilicates. The degree of weathering of <span class="hlt">meteorite</span> finds is often noted using a qualitative system based on visual inspection of hand specimens. Several quantitative weathering classification systems have been proposed or are currently under development. Wlotzka has proposed a classification system based on mineralogical changes observed in polished sections and Mossbauer properties of <span class="hlt">meteorite</span> powders have also been used. In the current paper, we discuss induced thermoluminescence (TL) as an indicator of degree of weathering of individual <span class="hlt">meteorites</span>. The quantitative measures of weathering, including induced TL, suffer from one major flaw, namely that their results only apply to small portions of the <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT.......157T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.......157T"><span>The formation and stability of saline minerals at the <span class="hlt">Martian</span> surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tosca, Nicholas James, III</p> <p></p> <p>Evaporite minerals have been identified throughout the <span class="hlt">martian</span> sedimentary record. Because evaporites can record detailed paleo-environmental information and often host fossil biosignatures on Earth, they are priority targets for future exploration. However, understanding processes that control the formation of these minerals on Mars requires an understanding of the behavior of Fe in highly concentrated evaporating fluids. In this <span class="hlt">study</span>, a model is developed using the Pitzer ion interaction approach that accurately describes thermodynamic properties of the Fe2(SO4)3-H2SO4-H 2O system. Incorporating this model into a multicomponent thermodynamic database enables detailed <span class="hlt">study</span> of evaporite mineral formation and stability on Mars. From geochemical modeling, the variation in evaporite mineralogy on Mars may be traced to volatile-anion input -- a variable intimately tied to pH. Using the "chemical divide" concept, evaporites at the <span class="hlt">martian</span> surface can be used as sensitive probes of pH, atmospheric composition, and cation proportion in solution. Applying this approach to saline assemblages in Nakhlite <span class="hlt">meteorites</span> and in Meridiani Planum sediments reveals two geochemical systems; each characterized by different pH and anion proportion. A complicating factor however is the concomitant oxidation of soluble Fe-bearing minerals. Such a process may have contributed to complex Fe mineralogy observed at Meridiani Planum through diagenesis. Fe-oxidation experiments at high ionic strength show a progression of mineral phases that begins with the formation of schwertmannite and subsequent ageing to jarosite and nano-crystalline goethite; a process strongly controlled by pH. Low water activity and small particle size drive the ageing of goethite to hematite which provides the final step of a mechanism that is consistent with the distribution of Fe-minerals at Meridiani Planum. These results show that the instability of Fe2+-sulfate minerals at the <span class="hlt">martian</span> surface may lead to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1781b0015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1781b0015C"><span>Iron <span class="hlt">meteorite</span> fragment <span class="hlt">studied</span> by atomic and nuclear analytical methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cesnek, Martin; Štefánik, Milan; Kmječ, Tomáš; Miglierini, Marcel</p> <p>2016-10-01</p> <p>Chemical and structural compositions of a fragment of Sikhote-Alin iron <span class="hlt">meteorite</span> were investigated by X-ray fluorescence analysis (XRF), neutron activation analysis (NAA) and Mössbauer spectroscopy (MS). XRF and NAA revealed the presence of chemical elements which are characteristic for iron <span class="hlt">meteorites</span>. XRF also showed a significant amount of Si and Al on the surface of the fragment. MS spectra revealed possible presence of α-Fe(Ni, Co) phase with different local Ni concentration. Furthermore, paramagnetic singlet was detected in Mössbauer spectra recorded at room temperature and at 4.2 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100003131','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003131"><span>Mineralogy of SNC <span class="hlt">Meteorite</span> EET79001 by Simultaneous Fitting of Moessbauer Backscatter Spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morris, Richard V.; Agresti, D. G.</p> <p>2010-01-01</p> <p>We have acquired M ssbauer spectra for SNC <span class="hlt">meteorite</span> EET79001 with a MIMOS II backscatter M ssbauer spectrometer [1] similar to those now operating on Mars as part of the Mars Exploration Rover (MER) missions. We are working to compare the Fe mineralogical composition of <span class="hlt">martian</span> <span class="hlt">meteorites</span> with in-situ measurements on Mars. Our samples were hand picked from the >1 mm size fraction of saw fines on the basis of lithology, color, and grain size (Table 1). The chips were individually analyzed at approx.300K by placing them on a piece of plastic that was in turn supported by the contact ring of the instrument (oriented vertically). Tungsten foil was used to mask certain areas from analysis. As shown in Figure 1, a variety of spectra was obtained, each resulting from different relative contributions of the Fe-bearing minerals present in the sample. Because the nine samples are reasonably mixtures of the same Fe-bearing phases in variable proportions, the nine spectra were fit simultaneously (simfit) with a common model, adjusting parameters to a single minimum chi-squared convergence criterion [2]. The starting point for the fitting model and values of hyperfine parameters was the work of Solberg and Burns [3], who identified olivine, pyroxene, and ferrous glass as major, and ilmenite and a ferric phase as minor (<5%), Fe-bearing phases in EET79001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000002826','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000002826"><span>Investigations in <span class="hlt">Martian</span> Sedimentology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moore, Jeffrey M.</p> <p>1998-01-01</p> <p>The purpose of this report is to investigate and discuss the <span class="hlt">Martian</span> surface. This report was done in specific tasks. The tasks were: characterization of <span class="hlt">Martian</span> fluids and chemical sediments; mass wasting and ground collapse in terrains of volatile-rich deposits; Mars Rover terrestrial field investigations; Mars Pathfinder operations support; and <span class="hlt">Martian</span> subsurface water instrument.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070038326','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070038326"><span>Microfossils of Cyanobacteria in Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.</p> <p>2007-01-01</p> <p>During the past decade, Environmental and Field Emission Scanning Electron Microscopes have been used at the NASA/Marshall Space Flight Center to investigate freshly fractured interior surfaces of a large number of different types of <span class="hlt">meteorites</span>. Large, complex, microfossils with clearly recognizable biological affinities have been found embedded in several carbonaceous <span class="hlt">meteorites</span>. Similar forms were notably absent in all stony and nickel-iron <span class="hlt">meteorites</span> investigated. The forms encountered are consistent in size and morphology with morphotypes of known genera of Cyanobacteria and microorganisms that are typically encountered in associated benthic prokaryotic mats. Even though many coccoidal and isodiametric filamentous cyanobacteria have a strong morphological convergence with some other spherical and filamentous bacteria and algae, many genera of heteropolar cyanobacteria have distinctive apical and basal regions and cellular differentiation that makes it possible to unambiguously recognize the forms based entirely upon cellular dimensions, filament size and distinctive morphological characteristics. For almost two centuries, these morphological characteristics have historically provided the basis for the systematics and taxonomy of cyanobacteria. This paper presents ESEM and FESEM images of embedded filaments and thick mats found in-situ in the Murchison CM2 and Orgueil cn carbonaceous <span class="hlt">meteorites</span>. Comparative images are also provided for known genera and species of cyanobacteria and other microbial extremophiles. Energy Dispersive X-ray Spectroscopy (EDS) <span class="hlt">studies</span> indicate that the <span class="hlt">meteorite</span> filaments typically exhibit dramatic chemical differentiation with distinctive difference between the possible microfossil and the <span class="hlt">meteorite</span> matrix in the immediate proximity. Chemical differentiation is also observed within these microstructures with many of the permineralized filaments enveloped within electron transparent carbonaceous sheaths. Elemental distributions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080012485','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080012485"><span>Amino Acid Degradation after <span class="hlt">Meteoritic</span> Impact Simulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bertrand, M.; Westall, F.; vanderGaast, S.; Vilas, F.; Hoerz, F.; Barnes, G.; Chabin, A.; Brack, A.</p> <p>2008-01-01</p> <p>Amino acids are among the most important prebiotic molecules as it is from these precursors that the building blocks of life were formed [1]. Although organic molecules were among the components of the planetesimals making up the terrestrial planets, large amounts of primitive organic precursor molecules are believed to be exogenous in origin and to have been imported to the Earth via micrometeorites, carbonaceous <span class="hlt">meteorites</span> and comets, especially during the early stages of the formation of the Solar System [1,2]. Our <span class="hlt">study</span> concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by <span class="hlt">meteorites</span> or micrometeorites. We are particularly concerned with the formation and fate of amino acids. We have already shown that amino acid synthesis is possible inside cometary grains under interstellar environment conditions [3]. We are now interested in the effects of space conditions and <span class="hlt">meteoritic</span> impact on these amino acids [4-6]. Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite <span class="hlt">meteorites</span> [7]. One of the components of these <span class="hlt">meteorites</span> is a clay with a composition close to that of saponite, used in our experiments. Two American teams have <span class="hlt">studied</span> the effects of impact on various amino acids [8,9]. [8] investigated amino acids in saturated solution in water with pressure ranges between 5.1 and 21 GPa and temperature ranges between 412 and 870 K. [9] <span class="hlt">studied</span> amino acids in solid form associated with and without minerals (Murchison and Allende <span class="hlt">meteorite</span> extracts) and pressure ranges between 3 and 30 GPa. In these two experiments, the amino acids survived up to 15 GPa. At higher pressure, the quantity of preserved amino acids decreases quickly. Some secondary products such as dipeptides and diketopiperazins were identified in the [8] experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001959','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001959"><span><span class="hlt">Martian</span> Chlorobenzene Identified by Curiosity in Yellowknife Bay: Evidence for the Preservation of Organics in a Mudstone on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glavin, D.; Freissinet, C.; Mahaffy, P.; Miller, K.; Eigenbrode, J.; Summons, R.; Martin, M.; Franz, H.; Steele, A.; Archer, D.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150001959'); toggleEditAbsImage('author_20150001959_show'); toggleEditAbsImage('author_20150001959_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150001959_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150001959_hide"></p> <p>2015-01-01</p> <p>The Sample Analysis at Mars (SAM) instrument on the Curiosity rover is designed to determine the inventory of organic and inorganic volatiles thermally evolved from solid samples using a combination of evolved gas analysis (EGA), gas chromatography mass spectrometry (GCMS), and tunable laser spectroscopy. The first sample analyzed by SAM at the Rocknest (RN) aeolian deposit revealed chlorohydrocarbons derived primarily from reactions between a <span class="hlt">martian</span> oxychlorine phase (e.g. perchlorate) and terrestrial carbon from N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) vapor present in the SAM instrument background. No conclusive evidence for <span class="hlt">martian</span> chlorohydrocarbons in the RN sand was found. After RN, Curiosity traveled to Yellowknife Bay and drilled two holes separated by 2.75 m designated John Klein (JK) and Cumberland (CB). Analyses of JK and CB by both SAM and the CheMin x-ray diffraction instrument revealed a mudstone (called Sheepbed) consisting of approx.20 wt% smectite clays, which on Earth are known to aid the concentration and preservation of organic matter. Last year at LPSC we reported elevated abundances of chlorobenzene (CBZ) and a more diverse suite of chlorinated hydrocarbons including dichloroalkanes in CB compared to RN, suggesting that <span class="hlt">martian</span> or <span class="hlt">meteoritic</span> organic compounds may be preserved in the mudstone. Here we present SAM data from additional analyses of the CB sample and of Confidence Hills (CH), another drill sample collected at the base of Mt. Sharp. This new SAM data along with supporting laboratory analog experiments indicate that most of the chlorobenzene detected in CB is derived from <span class="hlt">martian</span> organic matter preserved in the mudstone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040066033&hterms=NAA&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DNAA','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040066033&hterms=NAA&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DNAA"><span>Lunar and Planetary Science XXXV: <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The session "<span class="hlt">Meteorites</span>" included the following reports:Description of a New Stony <span class="hlt">Meteorite</span> Find from Bulloch County, Georgia; <span class="hlt">Meteorite</span> Ablation Derived from Cosmic Ray Track Data Dhofar 732: A Mg-rich Orthopyroxenitic Achondrite Halogens, Carbon and Sulfur in the Tagish Lake <span class="hlt">Meteorite</span>: Implications for Classification and Terrestrial Alteration; Electromagnetic Scrape of <span class="hlt">Meteorites</span> and Probably Columbia Tiles; Pre-Atmospheric Sizes and Orbits of Several Chondrites; Research of Shock-Thermal History of the Enstatite Chondrites by Track, Thermoluminescence and Neutron-Activation (NAA) Methods; Radiation and Shock-thermal History of the Kaidun CR2 Chondrite Glass Inclusions; On the Problem of Search for Super-Heavy Element Traces in the <span class="hlt">Meteorites</span>: Probability of Their Discovery by Three-Prong Tracks due to Nuclear Spontaneous Fission Trace Element Abundances in Separated Phases of Pesyanoe, Enstatite Achondrite; Evaluation of Cooling Rate Calculated by Diffusional Modification of Chemical Zoning: Different Initial Profiles for Diffusion Calculation; Mineralogical Features and REE Distribution in Ortho- and Clinopyroxenes of the HaH 317 Enstatite Chondrite Dhofar 311, 730 and 731: New Lunar <span class="hlt">Meteorites</span> from Oman; The Deuterium Content of Individual Murchison Amino Acids; Clues to the Formation of PV1, an Enigmatic Carbon-rich Chondritic Clast from the Plainview H-Chondrite Regolith Breccia ;Numerical Simulations of the Production of Extinct Radionuclides and ProtoCAIs by Magnetic Flaring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070020023&hterms=kuhn&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkuhn','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070020023&hterms=kuhn&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkuhn"><span><span class="hlt">Meteoritic</span> Microfossils in Eltanin Impact Deposits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kyte, Frank T.; Gersonde, Rainer; Kuhn, Gerhard</p> <p>2006-01-01</p> <p>We report the unique occurrence of microfossils composed largely of <span class="hlt">meteoritic</span> ejecta particles from the late Pliocene (2.5 Ma) Eltanin impact event. These deposits are unique, recording the only known km-sized asteroid impact into a deep-ocean (5 km) basin. First discovered as in Ir anomaly in sediment cores that were collected in 1965, the deposits contain nun-sized shock-melted asteroidal material, unmelted <span class="hlt">meteorite</span> fragments (named the Eltanin <span class="hlt">meteorite</span>), and trace impact spherules. Two oceanographic expeditions by the FS Polarstern in 1995 and 2001 explored approximately 80,000 sq-km. of the impact region, mapping the distribution of <span class="hlt">meteoritic</span> ejecta, disturbance of seafloor sediments by the impact, and collected 20 new cores with impact deposits in the vicinity of the Freeden Seamounts (57.3S, 90.5W). Analyses of sediment cores show that the impact disrupted sediments on the ocean floor, redepositing them as a chaotic jumble of sediment fragments overlain by a sequence of laminated sands, silts and clays deposited from the water column. Overprinted on this is a pulse of <span class="hlt">meteoritic</span> ejecta, likely transported ballistically, then settled through the water column. At some localities, <span class="hlt">meteoritic</span> ejecta was as much as 0.4 to 2.8 g/cm2. This is the most <span class="hlt">meteorite</span>-rich locality known on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987Icar...69..550H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987Icar...69..550H"><span>Detection of a <span class="hlt">meteorite</span> 'stream' - Observations of a second <span class="hlt">meteorite</span> fall from the orbit of the Innisfree chondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Halliday, I.</p> <p>1987-03-01</p> <p>The first observational evidence of multiple <span class="hlt">meteorite</span> falls from the same orbit is adduced from the February 6, 1980 fall of a <span class="hlt">meteorite</span> precisely 3 yr after the fall of the Innisfree <span class="hlt">meteorite</span>. Due consideration of the detection probability for two related objects with the <span class="hlt">meteorite</span> camera network in western Canada suggests that the Innisfree brecciated LL chondrite was a near-surface fragment from a parent object whose radius was of the order of several tens of meters. A <span class="hlt">meteorite</span> mass of 1.8 kg is predicted for the new object, whose recovery in the vicinity of Ridgedale, Saskatchewan, is now sought for the sake of comparison with the Innisfree chondrite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780038313&hterms=chihuahuas&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dchihuahuas','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780038313&hterms=chihuahuas&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dchihuahuas"><span>Four new iron <span class="hlt">meteorite</span> finds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scott, E. R. D.; Wasson, J. T.; Bild, R. W.</p> <p>1977-01-01</p> <p>Four new iron <span class="hlt">meteorites</span> are described: Buenaventura (IIIB) from Chihuahua, Mexico: mass 114 kg; Denver City (anomalous) from Texas, USA: mass 26.1 kg; Kinsella (IIIB) from Alberta, Canada: mass 3.7 kg; and Tacoma (IA) from Washington, USA: mass 17 g. Denver City is unique - i.e., not related to any other known iron. Tacoma is the smallest iron <span class="hlt">meteorite</span> recorded. The <span class="hlt">meteorites</span> were initially discovered in 1969, 1975, 1946, and between 1925 and 1932, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010097879','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010097879"><span>Organic Compounds in Carbonaceous <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooper, Grorge</p> <p>2001-01-01</p> <p>Carbonaceous <span class="hlt">meteorites</span> are relatively enriched in soluble organic compounds. To date, these compounds provide the only record available to <span class="hlt">study</span> a range of organic chemical processes in the early Solar System chemistry. The Murchison <span class="hlt">meteorite</span> is the best-characterized carbonaceous <span class="hlt">meteorite</span> with respect to organic chemistry. The <span class="hlt">study</span> of its organic compounds has related principally to aqueous <span class="hlt">meteorite</span> parent body chemistry and compounds of potential importance for the origin of life. Among the classes of organic compounds found in Murchison are amino acids, amides, carboxylic acids, hydroxy acids, sulfonic acids, phosphonic acids, purines and pyrimidines (Table 1). Compounds such as these were quite likely delivered to the early Earth in asteroids and comets. Until now, polyhydroxylated compounds (polyols), including sugars (polyhydroxy aldehydes or ketones), sugar alcohols, sugar acids, etc., had not been identified in Murchison. Ribose and deoxyribose, five-carbon sugars, are central to the role of contemporary nucleic acids, DNA and RNA. Glycerol, a three-carbon sugar alcohol, is a constituent of all known biological membranes. Due to the relative lability of sugars, some researchers have questioned the lifetime of sugars under the presumed conditions on the early Earth and postulated other (more stable) compounds as constituents of the first replicating molecules. The identification of potential sources and/or formation mechanisms of pre-biotic polyols would add to the understanding of what organic compounds were available, and for what length of time, on the ancient Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040191823','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040191823"><span>New Perspectives on Ancient Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Solomon, Sean C.; Aharonson, O.; Aurnou, J. M.; Banerdt, W. B.; Carr, M. H.; Dombard, A. J.; Frey, H. V.; Golombek, M. P.; Hauck, S. A., II; Head, J. W., III</p> <p>2004-01-01</p> <p>Global data sets returned by the Mars Global Surveyor (MGS), Mars Odyssey, and Mars Express spacecraft and recent analyses of <span class="hlt">Martian</span> <span class="hlt">meteorites</span> suggest that most of the major geological events of <span class="hlt">Martian</span> history occurred within the first billion years of solar system formation. This period was a time of heavy impact bombardment of the inner solar system, a process that strongly overprinted much of the <span class="hlt">Martian</span> geological record from that time. Geophysical signatures nonetheless remain from that period in the <span class="hlt">Martian</span> crust, and several geochemical tracers of early events are found in <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Collectively, these observations provide insight into the earliest era in <span class="hlt">Martian</span> history when the conditions favoring life were best satisfied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70029665','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70029665"><span>An integrated view of the chemistry and mineralogy of <span class="hlt">martian</span> soils</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Yen, A. S.; Gellert, Ralf; Schroder, C.; Morris, R.V.; Bell, J.F.; Knudson, A.T.; Clark, B. C.; Ming, D. W.; Crisp, J.A.; Arvidson, R. E.; Blaney, D.; Brückner, J.; Christensen, P.R.; DesMarais, D.J.; De Souza, P.A.; Economou, T.E.; Ghosh, A.; Hahn, B.C.; Herkenhoff, K. E.; Haskin, L.A.; Hurowitz, J.A.; Joliff, B.L.; Johnson, J. R.; Klingelhofer, G.; Madsen, M.B.; McLennan, S.M.; McSween, H.Y.; Richter, L.; Rieder, R.; Rodionov, D.; Soderblom, L.; Squyres, S. W.; Tosca, N.J.; Wang, A.; Wyatt, M.; Zipfel, J.</p> <p>2005-01-01</p> <p>The mineralogical and elemental compositions of the <span class="hlt">martian</span> soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent <span class="hlt">meteoritic</span> material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760016032','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760016032"><span>Investigations of <span class="hlt">Martian</span> history</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hartmann, W. K.</p> <p>1976-01-01</p> <p>Geologic and stratigraphic analyses of <span class="hlt">Martian</span> channels were accomplished using Mariner frames of high resolution. Crater counts were made to determine which forms had the least relative age. Results indicate that major channel and chaotic systems were relatively young, and that Mars experienced periods of enhanced erosive activity during a period of early dense atmospheric activity with rain. The problem of absolute age determination is discussed and geomorphological <span class="hlt">studies</span> of selected Local <span class="hlt">Martian</span> Regions are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170006049&hterms=history&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhistory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170006049&hterms=history&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dhistory"><span><span class="hlt">Meteoritic</span> Amino Acids: Diversity in Compositions Reflects Parent Body Histories</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elsila, Jamie E.; Aponte, Jose C.; Blackmond, Donna G.; Burton, Aaron S.; Dworkin, Jason P.; Glavin, Daniel P.</p> <p>2016-01-01</p> <p>The analysis of amino acids in <span class="hlt">meteorites</span> dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of <span class="hlt">meteorite</span> groups (exemplied by the Murchison <span class="hlt">meteorite</span>) into <span class="hlt">meteorites</span> of other types and classes. These new <span class="hlt">studies</span> have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in <span class="hlt">meteorites</span>, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain <span class="hlt">meteorites</span> and across carbonaceous <span class="hlt">meteorite</span> groups. Large -enantiomeric excesses of some extraterrestrial protein amino acids (up to 60) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent <span class="hlt">meteoritic</span> analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4919777','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4919777"><span><span class="hlt">Meteoritic</span> Amino Acids: Diversity in Compositions Reflects Parent Body Histories</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2016-01-01</p> <p>The analysis of amino acids in <span class="hlt">meteorites</span> dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of <span class="hlt">meteorite</span> groups (exemplified by the Murchison <span class="hlt">meteorite</span>) into <span class="hlt">meteorites</span> of other types and classes. These new <span class="hlt">studies</span> have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in <span class="hlt">meteorites</span>, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain <span class="hlt">meteorites</span> and across carbonaceous <span class="hlt">meteorite</span> groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent <span class="hlt">meteoritic</span> analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018DokES.479..390B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018DokES.479..390B"><span>Mineral Composition and Structure of the Sverdlovsk <span class="hlt">Meteorite</span> (H4-5)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berzin, S. V.; Koroteev, V. A.; Ivanov, K. S.; Kleimenov, D. A.; Kiseleva, D. V.; Cherednichenko, N. V.</p> <p>2018-03-01</p> <p>A fragment of the Sverdlovsk <span class="hlt">Meteorite</span>, which was found in 1985 in the Central Urals, is <span class="hlt">studied</span> by modern analytical methods. It belongs to H chondrites of petrologic type 4-5; shock stage of <span class="hlt">meteorite</span> is S1-2, terrestrial weathering is W1. The composition of minerals of the <span class="hlt">meteorite</span> is <span class="hlt">studied</span>. It is found for the first time that the metal and sulfides are concentrated in fine veinlets of the recrystallized matrix of the chondrite and are accompanied by segregations of metal and troilite inside these veinlets. The distribution of trace elements of the metal phase of the <span class="hlt">meteorite</span> is <span class="hlt">studied</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.V12B..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.V12B..04M"><span>A 4.43 Ga Transition from Mega-impact to Habitability Deduced from Microstructural Geochronology of <span class="hlt">Martian</span> Zircon and Baddeleyite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moser, D.; Reinhard, D. A.; Larson, D. J.; McCubbin, F. M.; Darling, J.; White, L. F.; Arcuri, G.; Irving, A. J.; Tait, K.; Barker, I.</p> <p>2017-12-01</p> <p>The rates at which early planetary surfaces like those of Mars and Earth transitioned to stability within the heavy bombardment epoch are poorly constrained. Here we show through analysis of the shock history of the earliest mineral remnants of Mars crust, specifically the accessory and highly refractory phases zircon and baddeleyite in <span class="hlt">martian</span> <span class="hlt">meteorites</span>, that the transition for Mars was relatively rapid and early. The Moon-sized impactor widely believed to have generated the <span class="hlt">martian</span> hemispheric dichotomy, would have caused catastrophic heating, impact metamorphism and global re-surfacing by magma.This process would either destroy any primordial accessory phases through melting and vaporization, or impart micro- or nano-structural signatures of ultra-high temperature and/or pressure metamorphism on survivor crystals. We have conducted atom probe and/or correlative electron microscopy on intensely shocked and heated zircon and baddeleyite reference samples from Earth and the Moon, as well as from 4.43 Ga grains occurring as crystals and in lithic clasts in six polished surfaces of the Rabt Sbayta suite of <span class="hlt">martian</span> polymict regolith breccias (NWA 7475, NWA 7034, NWA 7906, Rabt Sbayta 003). The <span class="hlt">martian</span> population (n=68) shows no micro- or nano-signatures of ultra high temperature or pressure metamorphism. Instead, it exhibits mostly low-grade shock and thermal features consistent with regolith formation at 1.5 Ga and recent low pressure ( 5GPa) launch to Earth. Taken together with the time for decay of the mega-impact heat effects, as well as the 4.50 Ga age estimate for <span class="hlt">martian</span> mantle solidification (modelled by other workers) our results indicate an early, 70 million year long transition from initiation of the hemispheric dichotomy to establishment of at least one domain of persistently stable and potentially habitable crust. The accelerated deep mantle convection prompted by mega-impact may have also increased the transport rate of volatiles to the <span class="hlt">Martian</span> exterior</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008epsc.conf..650C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008epsc.conf..650C"><span>Field <span class="hlt">Studies</span> of Gullies and Pingos on Svalbard - a <span class="hlt">Martian</span> Analog.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carlsson, E.; Johannsson, H. A. B.; Johnsson, A.; Heldmann, J. L.; McKay, C. P.; Olvmo, M.; Johansson, L.; Fredriksson, S.; Schmidt, H. T.; McDaniel, S.; Reiss, D.; Hiesinger, H.; Hauber, E.; Zanetti, M.</p> <p>2008-09-01</p> <p>Introduction: The gully systems on Mars [1] have been found to superpose young geological surfaces such as dunes and thermal contraction polygons [2]. This in combination with the general absence of superimposed impact craters suggest that the gullies are relatively recent geological formations [3]. The observed gullies display a wide set of morphologies ranging from features seemingly formed by fluvial erosion to others pointing to dry landslide processes. A recent discovery [4] suggests that this is an ongoing process, which appears to occur even today. Several formation mechanisms have been proposed for the <span class="hlt">Martian</span> gullies, such as liquid carbon dioxide reservoirs [5], shallow liquid water aquifer [6], melting ground ice [7], dry landslide [8], snow melt [9] and deep liquid water aquifer [10]. However, none of these models can alone explain all the gullies discovered on Mars. So far <span class="hlt">Martian</span> gullies have been <span class="hlt">studied</span> only from orbit via remote sensing data. Hydrostatic pingos are perennial ice-cored mounds that may reach an elongated or circular radius of approximately 150 m. They are found in periglacial environments where they are formed by freezing processes in the continuous permafrost. The pingos go through different evolutionary stages as they mature, where the final stage leaves an annular rim left by the collapse of the summit. Images from the High Resolution Imaging Science Experiment (HiRISE) show small fractured mounds in the <span class="hlt">Martian</span> mid-latitudes [11]. Even though some differences are observed, the best terrestrial analogues for the observed mound morphology are pingos [11]. Gullies and pingos found in Arctic climates on Earth could be an analog for the <span class="hlt">Martian</span> ones. A comparative analysis might help to understand the formation mechanisms of the <span class="hlt">Martian</span> pingos and gullies and their possible eroding agent. Svalbard as a <span class="hlt">Martian</span> Analog: Svalbard is situated at 74°-81°N and 10°-35°E, in the discontinuous zone of permafrost, and is a fairly good</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019352','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019352"><span>Terrestrial and exposure histories of Antarctic <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishiizumi, K.</p> <p>1986-01-01</p> <p>Records of cosmogenic effects were <span class="hlt">studied</span> in a large suite of Antarctic <span class="hlt">meteorites</span>. The cosmogenic nuclide measurements together with cosmic ray track measurements on Antartic <span class="hlt">meteorites</span> provide information such as exposure age, terrestrial age, size and depth in meteoroid or parent body, influx rate in the past, and pairing. The terrestrail age is the time period between the fall of the <span class="hlt">meteorite</span> on the Earth and the present. To define terrestrial age, two or more nuclides with different half-lives and possibly noble gases are required. The cosmogenic radionuclides used are C-14, Kr-81, Cl-36, Al-26, Be-10, Mn-53, and K-40.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980213322','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980213322"><span>Trace element and isotope <span class="hlt">studies</span> in oxide/phosphate/silicate inclusions of iron <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Olsen, Edward J.</p> <p>1996-01-01</p> <p>Under the above grant research was funded in the following areas: 1. Pallasites: Rare earth element measurements in phosphates to determine if all pallasites fit into only two trace element groups. This work has been completed. 2. HIAB irons: To complete work on the only known silicate inclusion in a IIIAB iron <span class="hlt">meteorite</span>. This work has been completed. 3. IIIAB irons: To continue the search for Cr-53 excesses in IIIAB iron <span class="hlt">meteorite</span> phosphates. A part of this work has been completed 4. IIIAB irons: To complete the identification of the phosphate minerals in IIIAB iron <span class="hlt">meteorites</span> and try to determine the phase relations and chemical history of trace element distributions during the core formation process. Work on this has been largely completed and preliminary results have been reported. The final work is being assessed prior to preparation of a manuscript for publication. 5. IIE irons: To complete work on the unique silicate assemblage in the IIE iron <span class="hlt">meteorite</span>. Work on this was completed and a paper published. 6. Ungrouped irons: A partially devitrified silicate glass inclusion has been found in the ungrouped iron <span class="hlt">meteorite</span>. Preliminary work on this has been reported. All the work on this has been now completed and a manuscript has been prepared and submitted for publication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996M%26PS...31..589P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996M%26PS...31..589P"><span>The Wold Cottage <span class="hlt">meteorite</span>: Not just any ordinary chondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pillinger, C. T.; Pillinger, J. M.</p> <p>1996-09-01</p> <p>The Wold Cottage <span class="hlt">meteorite</span> (fell, 1795), as is well known, played an important part in <span class="hlt">meteorites</span> being accepted as stones from the sky. In most cases, the very select group of people who have been privileged to witness any <span class="hlt">meteorite</span> fall, let alone one as important as Wold Cottage, enjoy a moment's fame but then disappear into obscurity. In this respect, Wold Cottage is very different; Edward Topham, the man who reported the fall and who became the <span class="hlt">meteorite</span>'s publicist, was already very well known for many other reasons. This fact contributed substantially to the evidence provided by his workmen being accepted, following two public exhibitions of the <span class="hlt">meteorite</span>, the second after sworn testimonies were obtained. Here we explore Topham's background in order to reveal his character, particularly the value he placed on truth. When he passed the <span class="hlt">meteorite</span> over to a public museum, he did so in the belief that he was acting for the benefit of posterity. At a time when the idea of <span class="hlt">meteorites</span> being extraterrestrial was still controversial, the Wold Cottage stone vitally prompted the observation that specimens from different parts of the globe closely resembled each other, thus stimulating the crucial chemical analyses which verified that they were indeed related. During its first twenty years on Earth, the Wold Cottage <span class="hlt">meteorite</span> was a prized specimen, a public attraction and sought after for scientific teaching purposes. In researching Wold Cottage, we have been able to discover information about many of the personalities who were involved in providing and <span class="hlt">studying</span> the first few <span class="hlt">meteorites</span> to become available for scientific research. The Wold Cottage story gives an interesting perspective on the cultural scene at the end of the eighteenth and beginning of the nineteenth centuries when there was no clear distinction between the arts and sciences, and <span class="hlt">meteoritics</span> was the prerogative of often rather flamboyant gentlemen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990098008&hterms=shale+Oil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dshale%2BOil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990098008&hterms=shale+Oil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dshale%2BOil"><span>Evidence for Microfossils in Ancient Rocks and <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.; Rozanov, A. Y.; Zhmur, S. I.; Gorlenko, V. M.</p> <p>1998-01-01</p> <p>The McKay et all. detection of chemical biomarkers and possible microfossils in an ancient <span class="hlt">meteorite</span> from Mars (ALH84001) stimulated research in several areas of importance to the newly emerging field of Astrobiology. Their report resulted in a search for additional evidence of microfossils in ancient terrestrial rocks and <span class="hlt">meteorites</span>. These <span class="hlt">studies</span> of ancient rocks and <span class="hlt">meteorites</span> were conducted independently (and later collaboratively) in the United States and Russia using the SEM, Environmental Scanning Electron Microscope (ESEM), and Field Emission Scanning Electron Microscope (FESEM). We have encountered in-situ in freshly broken carbonaceous chondrites a large number of complex microstructures that appear to be lithified microbial forms. The <span class="hlt">meteoritic</span> microstructures have characteristics similar to the lithified remains of filamentous cyanobacteria and bacterial microfossils we have found in ancient phosphorites, ancient graphites and oil shales. Energy Dispersive Spectroscopy (EDS) and Link microprobe analysis shows the possible microfossils have a distribution of chemical elements characteristic of the <span class="hlt">meteorite</span> rock matrix, although many exhibit a superimposed carbon enhancement. We have concluded that the mineralized bodies encountered embedded in the rock matrix of freshly fractured <span class="hlt">meteoritic</span> surfaces can not be dismissed as recent surface contaminants. Many of the forms found in-situ in the Murchison, Efremovka, and Orgueil carbonaceous <span class="hlt">meteorites</span> are strikingly similar to microfossils of coccoid bacteria, cyanobacteria and fungi such as we have found in the Cambrian phosphorites of Khubsugul, Mongolia and high carbon Phanerozoic and Precambrian rocks of the Siberian and Russian Platforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008POBeo..85..199K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008POBeo..85..199K"><span>The Impact of International Scientific Teams on Investigations of Yugoslavian <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kolomejceva-Jovanovic, L.</p> <p>2008-10-01</p> <p>Investigations of scientific heritage is very important for every country. The evidence concerning the <span class="hlt">meteorites</span> which have fallen upon the territory of former Yugoslavia can be a nice example. The samples of Yugoslav <span class="hlt">meteorites</span> can be found in the biggest world museums of natural history (in Washington, Moscow, Vienna, Paris, Budapest, Berlin, Prague and London). In such a way scientists engaged in the area of <span class="hlt">meteorites</span>, cosmochemistry, cosmic mineralogy, astrochemistry, astrophysics and other multidisciplinary scientific branches have the possibility to <span class="hlt">study</span> these <span class="hlt">meteorites</span>. The huge impact on the <span class="hlt">study</span> of Yugoslav <span class="hlt">meteorites</span> is given by international teams from Institute of Physics (Belgrade), Joint Institute for Nuclear Investigations (Dubna, Russia), Naturhistorisches Museum (Vienna, Austria), Institute of Geochemistry and Analytical Chemistry (Moscow, Russia) and Museum of Natural History (Belgrade).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036449"><span>Chiral Biomarkers in <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoover, Richard B.</p> <p>2010-01-01</p> <p>The chirality of organic molecules with the asymmetric location of group radicals was discovered in 1848 by Louis Pasteur during his investigations of the rotation of the plane of polarization of light by crystals of sodium ammonium paratartrate. It is well established that the amino acids in proteins are exclusively Levorotary (L-aminos) and the sugars in DNA and RNA are Dextrorotary (D-sugars). This phenomenon of homochirality of biological polymers is a fundamental property of all life known on Earth. Furthermore, abiotic production mechanisms typically yield recemic mixtures (i.e. equal amounts of the two enantiomers). When amino acids were first detected in carbonaceous <span class="hlt">meteorites</span>, it was concluded that they were racemates. This conclusion was taken as evidence that they were extraterrestrial and produced by abiologically. Subsequent <span class="hlt">studies</span> by numerous researchers have revealed that many of the amino acids in carbonaceous <span class="hlt">meteorites</span> exhibit a significant L-excess. The observed chirality is much greater than that produced by any currently known abiotic processes (e.g. Linearly polarized light from neutron stars; Circularly polarized ultraviolet light from faint stars; optically active quartz powders; inclusion polymerization in clay minerals; Vester-Ulbricht hypothesis of parity violations, etc.). This paper compares the measured chirality detected in the amino acids of carbonaceous <span class="hlt">meteorites</span> with the effect of these diverse abiotic processes. IT is concluded that the levels observed are inconsistent with post-arrival biological contamination or with any of the currently known abiotic production mechanisms. However, they are consistent with ancient biological processes on the <span class="hlt">meteorite</span> parent body. This paper will consider these chiral biomarkers in view of the detection of possible microfossils found in the Orgueil and Murchison carbonaceous <span class="hlt">meteorites</span>. Energy dispersive x-ray spectroscopy (EDS) data obtained on these morphological biomarkers will be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EM%26P..110....1M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EM%26P..110....1M"><span>The New Peruvian <span class="hlt">Meteorite</span> Carancas: Mössbauer Spectroscopy and X-Ray Diffraction <span class="hlt">Studies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Munayco, P.; Munayco, J.; Varela, M. E.; Scorzelli, R. B.</p> <p>2013-02-01</p> <p>The Carancas <span class="hlt">meteorite</span> fell on 15 September 2007 approximately 10 km south of Desaguadero, near Lake Titicaca, Peru, producing bright lights, clouds of dust in the sky and intense detonations. The Carancas <span class="hlt">meteorite</span> is classified as a H4-5 ordinary chondrite with shock stage S3 and a degree of weathering W0. The Carancas <span class="hlt">meteorite</span> is characterized by well defined chondrules composed either of olivine or pyroxene. The Mössbauer spectra show an overlapping of paramagnetic and magnetic phases. The spectra show two quadrupole doublets associated to olivine and pyroxene; and two magnetic sextets, associated with the primary phases kamacite/taenite and Troilite (Fe2+). Metal particles were extracted from the bulk powdered samples exhibit only kamacite and small amounts of the intergrowth tetrataenite/antitaenite. X-Ray diffractogram shows the primary phases olivine, pyroxene, troilite, kamacite, diopside and albite. Iron oxides has not been detected by Mössbauer spectroscopy or XRD as can be expected for a <span class="hlt">meteorite</span> immediately recovered after its fall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....7743K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....7743K"><span>The Influence of Terrestrial Environment on <span class="hlt">Meteorite</span> Magnetic Records</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kohout, T.; Kletetschka, G.; Kobr, M.; Pruner, P.; Wasilewski, P. J.</p> <p>2003-04-01</p> <p>In early solar system history there are several electromagnetic processes expected that may be capable of magnetizing the primitive solid particles condensating from the Solar Nebula. The record of these magnetic events can be observed during laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> found on the Earth. Different terrestrial processes can affect the magneto mineralogy, can cause changes in magnetic parameters, and can overprint the primary magnetic record. The effect of surface heating (when falling through the atmosphere) was the subject of the <span class="hlt">study</span> with the Murchison <span class="hlt">meteorite</span>. Using the Allende <span class="hlt">meteorite</span> we <span class="hlt">studied</span> the effect of the shock pressure generated by the friction of the atmosphere during the <span class="hlt">meteorite</span> fall. Some of the <span class="hlt">meteorites</span> are found several days after the fall, some of them are deposited in the desert or on the Antarctic ice for thousands of years. Most of them contain visible traces of terrestrial oxidation and weathering. We used the sample of the LL chondrite found in the Libya desert (perhaps thousands years ago), sample of the iron <span class="hlt">meteorite</span> Campo del Cielo (found in Argentina 5000 years after the fall), and sample of the H 5 Zebrak <span class="hlt">meteorite</span> (found only several days after the fall) for weathering simulations. To document the results of our experiments we used low and high temperature measurements of magnetic susceptibility, measurements of magnetic remanence and its stability and hysteresis parameters. The results tell us, that the terrestrial processes are efficient factor in changing magnetic properties and can overprint the primary magnetic record. Therefore extreme care has to be taken when selecting samples for primary magnetic component <span class="hlt">study</span>. Acknowledgements: This work is supported by Charles University Grant Agency, Czech Republic and would not be possible without the help of following people: Jakub Haloda, Petr Jakes, Marcela Bukovanska, Jaroslav Kadlec, Libuse Kohoutova, Vladimir Kohout.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970041155','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970041155"><span>Antarctic <span class="hlt">Meteorite</span> Newsletter. Volume 20</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lindstrom, Marilyn M.; Satterwhite, Cecilia E.</p> <p>1997-01-01</p> <p>The availability of 116 new <span class="hlt">meteorites</span> from the 1994-1996 collections is announced. There are 4 special chondrites, 2 carbonaceous chondrites, and 1 achondrite among the new <span class="hlt">meteorites</span>. Also included is a redescription of Lodranite GRA95209.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050060790','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050060790"><span>Experimental <span class="hlt">Studies</span> of Phase Equilibria of <span class="hlt">Meteorites</span> and Planetary Bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stolper, Edward M.</p> <p>2005-01-01</p> <p>The primary theme of this project was the application of experimental petrology and geochemistry to a variety of problems in <span class="hlt">meteoritics</span> and planetary geology. The <span class="hlt">studies</span> were designed to help develop constraints on the histories of primitive <span class="hlt">meteorites</span> and their components, the environments in which they formed and evolved, and to understand quantitatively the processes involved in the evolution of igneous rocks on the earth and other planetary bodies. We undertook several projects relating to the origin of CAIs and chondrules. Systematics in the thermodynamic properties of CAI-like liquids were investigated and used to elucidate speciation of multi-valent cations and sulfide capacity of silicate melts and to constrain redox conditions and the vapor pressures of volatile species over molten chondrules. We experimentally determined vanadium speciation in <span class="hlt">meteoritic</span> pyroxenes and in pyroxenes crystallized from CAI-like melts under very reducing conditions. We also found that bulk oxygen isotope compositions of chondrules in the moderately unequilibrated LL chondrites are related to the relative timing of plagioclase crystallization. We completed an experimental <span class="hlt">study</span> on the vaporization of beta-SiC and SiO2 (glass or cristobalite) in reducing gases and established the conditions under which these presolar grains could have survived in the solar nebula. We expanded our technique for determining the thermodynamic properties of minerals and liquids to iron-bearing systems. We determined activity-composition relationships in Pt-Fe, Pt-Cr and Pt-Fe-Cr alloys. Results were used to determine the thermodynamic properties of chromite-picrochromite spinels including the free energy of formation of end-member FeCr2O4. We also established a new approach for evaluating Pt-Fe saturation experiments. We calculated the T-fO2 relationships in equilibrated ordinary chondrites and thereby constrained the conditions of metamorphism in their parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6159H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6159H"><span>New Insights in Preservation of <span class="hlt">Meteorites</span> in Hot Deserts: The Oldest Hot Desert <span class="hlt">Meteorite</span> Collection.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hutzler, A.; Rochette, P.; Bourlès, D.; Gattacceca, J.; Merchel, S.; Jull, A. J. T.; Valenzuela, M.</p> <p>2016-08-01</p> <p>Terrestrial ages of a subset of a chilean <span class="hlt">meteorite</span> collection have been determined with cosmogenic nuclides. We show here that provided the environnement is favorable enough, hot desert <span class="hlt">meteorites</span> can survive over a million year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011733','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011733"><span>Noble Gases in the Chelyabinsk <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haba, Makiko K.; Sumino, Hirochika; Nagao, Keisuke; Mikouchi, Takashi; Komatsu, Mutsumi; Zolensky, Michael E.</p> <p>2014-01-01</p> <p>The Chelyabinsk <span class="hlt">meteorite</span> fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this <span class="hlt">study</span>, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk <span class="hlt">meteorite</span> and the thermal history of its parent asteroid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12804373','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12804373"><span>Exchange of <span class="hlt">meteorites</span> (and life?) between stellar systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Melosh, H J</p> <p>2003-01-01</p> <p>It is now generally accepted that <span class="hlt">meteorite</span>-size fragments of rock can be ejected from planetary bodies. Numerical <span class="hlt">studies</span> of the orbital evolution of such planetary ejecta are consistent with the observed cosmic ray exposure times and infall rates of these <span class="hlt">meteorites</span>. All of these numerical <span class="hlt">studies</span> agree that a substantial fraction (up to one-third) of the ejecta from any planet in our Solar System is eventually thrown out of the Solar System during encounters with the giant planets Jupiter and Saturn. In this paper I examine the probability that such interstellar <span class="hlt">meteorites</span> might be captured into a distant solar system and fall onto a terrestrial planet in that system within a given interval of time. The overall conclusion is that it is very unlikely that even a single <span class="hlt">meteorite</span> originating on a terrestrial planet in our solar system has fallen onto a terrestrial planet in another stellar system, over the entire period of our Solar System's existence. Although viable microorganisms may be readily exchanged between planets in our solar system through the interplanetary transfer of <span class="hlt">meteoritic</span> material, it seems that the origin of life on Earth must be sought within the confines of the Solar System, not abroad in the galaxy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.254M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.254M"><span>Contemporary Inuit Traditional Beliefs Concerning <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mardon, A. A.; Mardon, E. G.; Williams, J. S.</p> <p>1992-07-01</p> <p>Inuit religious mythology and the importance of <span class="hlt">meteorites</span> as "messages" from the Creator of all things is only now being recognized. Field investigations near Resolute, Cornwallis Island in the high Canadian Arctic in 1988 are the bases for this paper. Through interpreters, several elders of the local Inuit described in detail the Inuit belief, recognition, and wonder at the falling meteors & <span class="hlt">meteorites</span> during the long Polar Night and Polar Day. Such events are passed on in the oral tradition from generation to generation by the elders and especially those elders who fulfill the shamanistic roles. The Inuit have come across rocks that they immediately recognize as not being "natural" and in the cases of a fall that was observed and the rock recovered the <span class="hlt">meteorite</span> is kept either on the person or in some hidden niche known only to that person. In one story recounted a <span class="hlt">meteorite</span> fell and was recovered at the birth of one very old elder and the belief was that if the rock was somehow damaged or taken from his possession he would die. Some indirect indication also was conveyed that the discovery and possession of <span class="hlt">meteorites</span> allow shaman to have "supernatural" power. This belief in the supernatural power of <span class="hlt">meteorites</span> can be seen historically in many societies, including Islam and the "black rock" (Kaaba) of Mecca. It should also be noted, however, that metallic <span class="hlt">meteorites</span> were clearly once the major source of iron for Eskimo society as is indicated from the recovery of <span class="hlt">meteoritical</span> iron arrow heads and harpoon heads from excavated pre-Viking contact sites. The one evident thing that became clear to the author is that the Inuit distinctly believe that these <span class="hlt">meteorites</span> are religious objects of the highest order and it brings into question the current academic practice of sending <span class="hlt">meteorites</span> south to research institutes. Any seeming conflict with the traditional use of meteoric iron is more apparent than real--the animals, the hunt, and the act of survival--all being</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015rasc.conf..148M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015rasc.conf..148M"><span>Dangerous Near-Earth Asteroids and <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mickaelian, A. M.; Grigoryan, A. E.</p> <p>2015-07-01</p> <p>The problem of Near-Earth Objects (NEOs; Astreoids and <span class="hlt">Meteorites</span>) is discussed. To have an understanding on the probablity of encounters with such objects, one may use two different approaches: 1) historical, based on the statistics of existing large <span class="hlt">meteorite</span> craters on the Earth, estimation of the source <span class="hlt">meteorites</span> size and the age of these craters to derive the frequency of encounters with a given size of <span class="hlt">meteorites</span> and 2) astronomical, based on the <span class="hlt">study</span> and cataloging of all medium-size and large bodies in the Earth's neighbourhood and their orbits to estimate the probability, angles and other parameters of encounters. Therefore, we discuss both aspects and give our present knowledge on both phenomena. Though dangerous NEOs are one of the main source for cosmic catastrophes, we also focus on other possible dangers, such as even slight changes of Solar irradiance or Earth's orbit, change of Moon's impact on Earth, Solar flares or other manifestations of Solar activity, transit of comets (with impact on Earth's atmosphere), global climate change, dilution of Earth's atmosphere, damage of ozone layer, explosion of nearby Supernovae, and even an attack by extraterrestrial intelligence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840036185&hterms=Organic+matter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DOrganic%2Bmatter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840036185&hterms=Organic+matter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DOrganic%2Bmatter"><span>Interstellar organic matter in <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yang, J.; Epstein, S.</p> <p>1983-01-01</p> <p>Deuterium-enriched hydrogen is present in organic matter in such <span class="hlt">meteorites</span> as noncarbonaceous chondrites. The majority of the unequilibrated primitive <span class="hlt">meteorites</span> contain hydrogen whose D/H ratios are greater than 0.0003, requiring enrichment (relative to cosmic hydrogen) by isotope exchange reactions taking place below 150 K. The D/H values presented are the lower limits for the organic compounds derived from interstellar molecules, since all processes subsequent to their formation, including terrestrial contamination, decrease their D/H ratios. In contrast, the D/H ratios of hydrogen associated with hydrated silicates are relatively uniform for the <span class="hlt">meteorites</span> analyzed. The C-13/C-12 ratios of organic matter, irrespective of D/H ratio, lie well within those observed for the earth. Present findings suggest that other interstellar material, in addition to organic matter, is preserved and is present in high D/H ratio <span class="hlt">meteorites</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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