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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. Martian Alteration in Unique Meteorite NWA 8159?

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Simpson, S.; Mark, D.; Lee, M. R.

    2016-08-01

    This study aims to determine if the olivine alteration in martian meteorite NWA 8159 has a martian origin. If so, the unique nature of this meteorite presents evidence for aqueous processes at a new time and location on the martian surface.

  3. 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.

  4. High-Resolution Multiple Sulfur Isotope Studies of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, S. J.

    2000-01-01

    Sensitive, high resolution measurements of S-32, S-31, and S-34 in individual pyrite grains in martian meteorite ALH84001 by an in situ ion microprobe multi-collection technique reveal mass-independent anomalies in Delta.S-33 (Delta.S-33 = delta.S-33 - 0.516delta.S-34) in addition to the lowest 634S found in an extraterrestrial material. Low delta.S-34 values in two pyrite grains intimately associated with carbonate in ALH84001 can be explained by the sensitivity of sulfur to fractionations in the geologic environment. Anomalies in Delta.S-33 recorded in ALH84001 pyrites probably formed by gas-phase reactions in the early martian atmosphere (>4 Ga). The discovery of clearly resolvable Delta-S33 anomalies in 2 of 12 ALH84001 pyrites analyzed in their petrographic context in thin section, is considered strong evidence for crust-atmosphere exchange and the global cycling of volatile sulfur species on early Mars. These results corroborate previous measurements by Farquhar and co-workers who used a different technique that measures that bulk Delta.S-33 values of martian meteorites. These independent techniques, and their results, suggest that sulfur affected by mass-independent fractionation is common on Mars.

  5. Martian Meteorites Record Surface Temperatures on Mars

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2005-07-01

    Using published data for argon (Ar) released when Martian meteorites are heated, David Shuster (California Institute of Technology, now at Berkeley Geochronology Center, Berkeley, CA) and Benjamin Weiss (Massachusetts Institute of Technology) show that the nakhlite group of Martian meteorites and unique Martian meteorite ALH 84001 were probably not heated above about 0 degree C for most of their histories. This indicates that the surface of Mars has been cold for almost four billion years. If a warm, wet environment existed on Mars (inferred from previous studies of surface features and geochemical parameters), it occurred before four billion years ago.

  6. An Adulterated Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    1999-07-01

    Martian meteorite, Elephant Moraine EETA79001, is composed of two distinct rock types. Scientists have thought that both formed from magmas, hence are igneous rocks and contain important information about the interior of Mars, the nature of lava flows on its surface, and the timing of igneous events on Mars. All that is now open to question, as a group of investigators at Lockheed Martin Space Operations and the Johnson Space Center led by David Mittlefehldt (Lockheed) has shown that one of the rock types making up EETA79001, designated lithology A, is almost certainly a melted mixture of other rocks. Mittlefehldt and coworkers suggest that formation by impact melting is the most likely explanation for the chemical and mineralogical features seen in the rock. If confirmed by other investigations, this may change the way we view the igneous evolution of Mars.

  7. 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.

  8. 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.

  9. Martian soil component in impact glasses in a Martian meteorite.

    PubMed

    Rao, M N; Borg, L E; McKay, D S; Wentworth, S J

    1999-11-01

    Chemical compositions of impact melt glass veins, called Lithology C (Lith C) in Martian meteorite EET79001 were determined by electron microprobe analysis. A large enrichment of S, and significant enrichments of Al, Ca, and Na were observed in Lith C glass compared to Lithology A (Lith A). The S enrichment is due to mixing of plagioclase- enriched Lith A material with Martian soil, either prior to or during impact on Mars. A mixture of 87% Lith A, 7% plagioclase, and 6% Martian soil reproduces the average elemental abundances observed in Lith C. Shock melting of such a mixture of plagioclase-enriched, fine-grained Lith A host rock and Martian soil could yield large excesses of S (observed in this study) and Martian atmospheric noble gases (found by Bogard et al., 1983) in Lith C. These mixing proportions can be used to constrain the elemental abundance of phosphorus in Martian soil.

  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. Martian Meteorite Ages and Implications for Martian Cratering History

    NASA Technical Reports Server (NTRS)

    Nyquist, Laurence E.

    2006-01-01

    New radiometrically determined ages of Martian meteorites add to the growing number with crystallization ages < 1.4 Ga. The observation of mainly geologically young ages for the Martian meteorites, the only exception being the 4.5 Ga ALH84001 [1], is paradoxical when viewed in context of a Martian surface thought to be mostly much older as inferred from the surface density of meteorite craters [2]. There appears to be at least a twofold difference between the observed ages of Martian meteorites and their expected ages as inferred from the ages of Martian surfaces obtained from crater densities.

  12. 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.

  13. 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

  14. Lunar and martian meteorite delivery services

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    1994-01-01

    Launch mechanisms for lunar and martian meteorites have been investigated, by integrating physical modeling constraints, geochemical cosmic-ray exposure (CRE) constraints, and petrologic constraints. The potential source region for lunar meteorites is remarkably small compared to the final crater volume. CRE constraints indicate that most launches start at depths of less than or equal to 3.2 m, and cratering theory implies derivation of suitably accelerated objects from a subvolume with diameter only about 0.3 x the final crater diameter. The shallow depth provenance is probably related to shock-wave interference, enhanced by the lunar regolith's extremely low compressional wave velocity. CRE constraints alone imply that four to five separate launch events are represented among the eight well-studied lunar meteorites. Most of the lunar meteorites are regolith breccias, which tend to show only limited compositional diversity within any kilometer-scale region of the Moon. Several others are polymict breccias, which also show relatively subdued compositional diversity, compared to igneous rocks. The observed diversity among these samples in terms of abundances of mare basalt and KREEP, and in Mg/(Mg + Fe) ratio, implies that among eight well-studied lunar meteorites only two potential source craters pairings are plausible: between Asuka-881757 + Y-793169 (most probable) and between Y-793274 + EET875721. Altogether, these eight lunar meteorites apparently represent at least six separate source craters, including three in the past 10(exp 5) years and five in the past 10(exp 6) years. CRE constraints imply that SNC meteorites are launched from systematically greater than lunar meteorites. SNCs are also systematically bigger, and all nine well-studied SNCs are uncommonly young (by martian standards) mafic igneous rocks. Comparison between Viking and Apollo results reveals that rocks the size of common meteorites are remarkably scarce in the martian regolith, probably due

  15. 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.

  16. Timescales of shock processes in chondritic and martian meteorites.

    PubMed

    Beck, P; Gillet, Ph; El Goresy, A; Mostefaoui, S

    2005-06-23

    The accretion of the terrestrial planets from asteroid collisions and the delivery to the Earth of martian and lunar meteorites has been modelled extensively. Meteorites that have experienced shock waves from such collisions can potentially be used to reveal the accretion process at different stages of evolution within the Solar System. Here we have determined the peak pressure experienced and the duration of impact in a chondrite and a martian meteorite, and have combined the data with impact scaling laws to infer the sizes of the impactors and the associated craters on the meteorite parent bodies. The duration of shock events is inferred from trace element distributions between coexisting high-pressure minerals in the shear melt veins of the meteorites. The shock duration and the associated sizes of the impactor are found to be much greater in the chondrite (approximately 1 s and 5 km, respectively) than in the martian meteorite (approximately 10 ms and 100 m). The latter result compares well with numerical modelling studies of cratering on Mars, and we suggest that martian meteorites with similar, recent ejection ages (10(5) to 10(7) years ago) may have originated from the same few square kilometres on Mars.

  17. Carbonates in Martian Meteorites - A Reappraisal

    NASA Astrophysics Data System (ADS)

    Grady, M. M.; Wright, I. P.; Douglas, C.; Pillinger, C. T.

    1995-09-01

    the mineralogy of the carbonates to be constrained. since the peak decomposition temperature of carbonates varies with mineralogical composition. Preliminary results indicate that the carbonates in martian meteorites might indeed be more 13C-enriched than previously inferred [6]. Stepped combustion of Nakhla reveals a maximum in yield at 475 degrees C, corresponding to the release of an iron-rich carbonate, with delta^(13)C +21 per mil. Since there is an overlap of the carbonate with low temperature carbonaceous material, this value is a lower limit. Indeed, delta^(13)C from acid leaching experiments reaches a value around +50 per mil, similar to the ALH 84001 studies [1, 5]. Models of surface processes on Mars [e.g. 4, 6] have assumed that C07 from the martian atmosphere is in equilibrium with CO2 dissolved in circulating crustal fluids, resulting in the precipitation of isotopically heavy carbonates. However, if the delta^(13)C of martian carbonates is ~ +50 per mil, then the models must be re-adjusted. It is unlikely that delta^(13)C of the carbonate has increased with time, e.g. by decarbonation reactions, since there is no parallel effect in delta^(18)O, and no petrographic evidence for the reaction. The delta^(13)C of the martian atmosphere is poorly-constrained; it is possible that its isotopic composition is heavier than believed, and that delta^(13)C has decreased with time, perhaps by the addition of isotopically light magmatic carbon degassed from the planet [8]. Additional measurements of carbonates in martian meteorites will allow better comprehension of fluid-atmosphere interactions on Mars. References: [1] Carr R. H. et al. (1985) Nature, 314, 248-250. [2] Gooding J. L. et al. (1991) Meteoritics, 26, 135-143. [3] Grady M. M. et al. (1994) Meteoritics, 29, 469. [4] Romanek C. S. et al. (1994) Nature, 372, 655-657. [5] Jull A. J. T. et al. (1995) Meteoritics, 30, 311-318. [6] Wright I. P. et al. (1992) GCA, 56, 817-826. [7] Rosenbaum J. and Sheppard S. F

  18. 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

  19. Phosphates and Carbon in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Mojzsis, Stephen J.

    2000-01-01

    This paper proposes tests for exobiological examination of samples prior to obtaining martian rocks of known provenance via future sample-return missions. If we assume that all of the secondary minerals in martian meteorite ET79001 were indeed cogenetic and originate from Mars, we list conclusions that can be drawn that are of exobiological interest. This work serves as a preamble for the subsequent work listed below.

  20. 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.

  1. 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.; Anand, M.; Moser, D. E.; Delhaye, T.; Shearer, C. K.; Agee, C. B.

    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.

  2. 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.

  3. Lunar and Planetary Science XXXV: Martian Meteorites: Chemical Weathering

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Chemical Weathering" included the following reports:Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001; Synchrotron X-Ray Diffraction Analysis of Meteorites in Thin Section: Preliminary Results; A Survey of Olivine Alteration Products Using Raman Spectroscopy; and Rb-Sr and Sm-Nd Isotope Systematics of Shergottite NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC Meteorites.

  4. A Pb isotopic resolution to the Martian meteorite age paradox

    NASA Astrophysics Data System (ADS)

    Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Kielman, R. B.; Bland, P. A.; Benedix, G. K.

    2016-01-01

    Determining the chronology and quantifying various geochemical reservoirs on planetary bodies is fundamental to understanding planetary accretion, differentiation, and global mass transfer. The Pb isotope compositions of individual minerals in the Martian meteorite Chassigny have been measured by Secondary Ion Mass Spectrometry (SIMS). These measurements indicate that Chassigny has mixed with a Martian reservoir that evolved with a long-term 238U/204Pb (μ) value ∼ two times higher than those inferred from studies of all other Martian meteorites except 4.428 Ga clasts in NWA7533. Any significant mixing between this and an unradiogenic reservoir produces ambiguous trends in Pb isotope variation diagrams. The trend defined by our new Chassigny data can be used to calculate a crystallization age for Chassigny of 4.526 ± 0.027 Ga (2σ) that is clearly in error as it conflicts with all other isotope systems, which yield a widely accepted age of 1.39 Ga. Similar, trends have also been observed in the Shergottites and have been used to calculate a >4 Ga age or, alternatively, attributed to terrestrial contamination. Our new Chassigny data, however, argue that the radiogenic component is Martian, mixing occurred on the surface of Mars, and is therefore likely present in virtually every Martian meteorite. The presence of this radiogenic reservoir on Mars resolves the paradox between Pb isotope data and all other radiogenic isotope 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 is also consistent with an absence of tectonic recycling throughout Martian history.

  5. 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.

  6. 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.

  7. Amino Acids in the Martian Meteorite Nakhla

    NASA Astrophysics Data System (ADS)

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

    1999-08-01

    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.

  8. Observations from a 4-year contamination study of a sample depth profile through Martian meteorite Nakhla.

    PubMed

    Toporski, Jan; Steele, Andrew

    2007-04-01

    Morphological, compositional, and biological evidence indicates the presence of numerous well-developed microbial hyphae structures distributed within four different sample splits of the Nakhla meteorite 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 martian materials as a first-order assessment. Time-resolved in situ observations further allow observation of possible (bio)dynamics within the system.

  9. 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.

  10. 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

  11. Evidence for methane in Martian meteorites

    NASA Astrophysics Data System (ADS)

    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.

    2015-06-01

    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.

  12. 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.

  13. 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.

  14. Study of a possible magnetite biosignature in Martian meteorite ALH84001: Implications for the biological toxicology of Mars

    NASA Astrophysics Data System (ADS)

    Thomas-Keprta, Kathie Louise

    "Why do we have such a longstanding fascination with Mars? Very simply put, it's about life. The search for life elsewhere in our Solar System has been a major driver for exploring Mars, pretty much since we began seriously looking at that planet."1 The major objective of this work is to describe signs of possible life, that is biosignatures, in rocks from Mars if indeed they are present. Biosignatures are specific identifiable properties that result from living things; they may be implanted in the environment and may persist even if the living thing is no longer present. Over 100 mineral biosignatures have been discussed in the literature; however, only one, magnetite, is addressed by this study. Magnetite is found in many rock types on earth and in meteorites. Previous studies of terrestrial magnetite have used few properties, such as size and chemical composition, to determine one of the modes of origins for magnetite (e.g., biogenic, inorganic). This study has established a rigorous set of six criteria for the identification of intracellularly precipitated biogenic magnetite. These criteria have been applied to a subpopulation of magnetites embedded within carbonates in Martian meteorite ALH84001. These magnetites are found to be chemically and physically indistinguishable from those produced by magnetotactic bacteria strain MV-1, hence, they were likely formed by biogenic processes on ancient Mars. These criteria may be also used to distinguish origins for magnetites from terrestrial samples with complex or unknown histories. The presence of purported past life on early Mars suggests that, if life once began it may still exist today, possibly in oases in the Martian subsurface. Future manned missions should consider potential hazards of an extant biological environment(s) on Mars. 1 Quote attributed to Jack Farmer of Arizona State University in discussing NASA's program of Mars Exploration (see "Deciphering Mars: Follow the Water," Astrobiology Magazine Sept

  15. Cosmic-ray exposure histories of Martian meteorites studied from neutron capture reactions of Sm and Gd isotopes

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Yoneda, Shigekazu; Nishiizumi, Kunihiko

    2009-11-01

    The isotopic compositions of Sm and Gd in twelve Martian meteorites, ALH 77005, ALH 84001, DaG 735, Dhofar 019, EET 79001, Lafayette, Los Angeles, Nakhla, SaU 005, Y 000593, Y 000749 and Zagami, were determined to quantify the neutron capture records of individual meteorite specimens. Seven of these twelve samples, ALH 84001, Y 000749, DaG 735, Dhofar 019, EET 79001, SaU 005 and Zagami, showed significant isotopic shifts of 150Sm/ 149Sm and/or 158Gd/ 157Gd corresponding to neutron fluences of (0.7-3.4) × 10 15 n cm - 2 . Among these seven meteorites, the neutron fluences of ALH 84001, Y 000749, and Dhofar 019 apparently correlated with their cosmic-ray exposure ages, indicating that most of the irradiation took place while the meteoroids were small bodies in space after the ejection from Mars. However, our results suggest an accumulation of their inherited irradiation occurred on Mars. On the other hand, the exposure histories of the other four meteorites (basaltic shergottites), DaG 735, EET 79001, SaU 005, and Zagami, cannot be explained as single- or multistage irradiations in space, or as a single irradiation on the Martian surface. The mixing between basaltic lava with a significantly irradiated Martian regolith is a reasonable interpretation of the excess neutron capture records observed in these four basaltic shergottites.

  16. Hydrogen isotopic composition of the Martian mantle inferred from the newest Martian meteorite fall, Tissint

    NASA Astrophysics Data System (ADS)

    Mane, P.; Hervig, R.; Wadhwa, M.; Garvie, L. A. J.; Balta, J. B.; McSween, H. Y.

    2016-11-01

    The hydrogen isotopic composition of planetary reservoirs can provide key constraints on the origin and history of water on planets. The sources of water and the hydrological evolution of Mars may be inferred from the hydrogen isotopic compositions of mineral phases in Martian meteorites, which are currently the only samples of Mars available for Earth-based laboratory investigations. Previous studies have shown that δD values in minerals in the Martian meteorites span a large range of -250 to +6000‰. The highest hydrogen isotope ratios likely represent a Martian atmospheric component: either interaction with a reservoir in equilibrium with the Martian atmosphere (such as crustal water), or direct incorporation of the Martian atmosphere due to shock processes. The lowest δD values may represent those of the Martian mantle, but it has also been suggested that these values may represent terrestrial contamination in Martian meteorites. Here we report the hydrogen isotopic compositions and water contents of a variety of phases (merrillites, maskelynites, olivines, and an olivine-hosted melt inclusion) in Tissint, the latest Martian meteorite fall that was minimally exposed to the terrestrial environment. We compared traditional sample preparation techniques with anhydrous sample preparation methods, to evaluate their effects on hydrogen isotopes, and find that for severely shocked meteorites like Tissint, the traditional sample preparation techniques increase water content and alter the D/H ratios toward more terrestrial-like values. In the anhydrously prepared Tissint sample, we see a large range of δD values, most likely resulting from a combination of processes including magmatic degassing, secondary alteration by crustal fluids, shock-related fractionation, and implantation of Martian atmosphere. Based on these data, our best estimate of the δD value for the Martian depleted mantle is -116 ± 94‰, which is the lowest value measured in a phase in the

  17. Exposure and Terrestrial Histories of New Lunar and Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Hillegonds, D. J.; McHargue, L. R.; Jull, A. J. T.

    2004-01-01

    Cosmogenic nuclide studies of lunar and Martian meteorites have contributed significantly to our understanding of these objects. By measuring a combination of cosmogenic stable- and radionuclides, we can determine a number of important properties of those meteorites. Most lunar meteorites have complex cosmic ray exposure histories, having been exposed both at some depth on the lunar surface (2 irradiation) before their ejection and as small bodies in space (4 irradiation) during transport from the Moon to the Earth. On the other hand, we have not observed evidence of complex exposure history for any Martian meteorites, so far. These exposures were then followed by residence on Earth s surface, a time commonly referred to as the terrestrial age. In addition to their complement of galactic cosmic ray (GCR) produced nuclides some lunar and Martian meteorites contain nuclides produced by solar cosmic rays (SCR). Unraveling the complex history of these objects requires the measurement of at least four cosmogenic nuclides. The specific goals of these measurements are to constrain or set limits on the following shielding or exposure parameters: (1) the depth of the sample at the time of ejection from the Moon or Mars; (2) the transit time (4 exposure age) from ejection off the lunar or Martian surface to the time of capture by the Earth and (3) the terrestrial residence time. The sum of the transit time and residence time yield an ejection age. The ejection age, in conjunction with the sample depth on the Moon or Mars, can then be used to model impact and ejection mechanisms.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. Practicability of In Situ K-Ar Age Dating by Martian Landers; A Study of Mars Analogs and Meteorites

    NASA Astrophysics Data System (ADS)

    Park, Jisun; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.

    2009-12-01

    Purpose of this noble gas investigation was to evaluate the feasibility of in situ K-Ar radiometric age dating of Martian surface rocks by future robotic missions, such as the Mars Science Laboratory(MSL), under constraints inherent to the Martian surface and lander design. The MSL Sample Analysis at Mars(SAM) instrument has the capability to measure noble gas compositions of Martain rocks and atmosphere. We evaluate requirements for SAM to obtain adequate noble gas abundances and compositions within the current instrumental operating conditions. In particular, maximum furnace temperature is limited to 1100ºC or lower due to power supply constraints. As a simulation experiment, we analyzed three Martian shergottites and terrestrial MORB, under the same conditions afforded SAM on the Martian surface. Our results suggest that SAM noble gas recoveries might be sufficient for K-Ar age determinations. Comparing these results with previous experiments performed on Martian meteorites at NASA-JSC, we can asses the capability of Mars lander designs with a variety of Martian rock types. The noble gas composition of Martian meteorites can be difficult to interpret due to the combined signals of in situ 40K decay, shock implanted 40Ar from Martian atmosphere[2,3], and 40Ar inherited from parent magma[4,5]. These components should also be considered in interpreting lander data. A possible advantage for landers is that K concentrations reported from the Martian surface are variable and possibly quite high, a desirable trait for K-Ar age dating. Spirit APXS reports 3000-7000ppm K for most locations but in some areas, concentrations as high as 25000ppm have been observed[6,7]. [1] Bogard (2009) MaPS44, 3-14; [2] Bogard and Johnson (1983) Science221,651-654 [3] Marti et al. (1995) Science267, 1981-1984; [4] Bogard and Park (2008) MAPS43, 1113-1126. [5] Bogard et al. (2009) MAPS44, 905-923. [6] Ming et al. (2006) JGR111, E02S12. [7] Ming D.W. et al. (2008) JGR113, E12S39.

  3. 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

  4. 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.

  5. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.

    1986-01-01

    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  6. Identification of Iron-Bearing Phases on the Martian Surface and in Martian Meteorites and Analogue Samples by Moessbauer Spectroscopy

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Agresti, D. G.; Schroeder, C.; Rodionov, D.; Yen, A.; Ming, Doug; Morris, Richard V.

    2007-01-01

    The Moessbauer spectrometers on the Mars Exploration Rovers (MER) Spirit (Gusev Crater) and Opportunity (Meridiani Planum) have each analyzed more than 100 targets during their ongoing missions (>1050 sols). Here we summarize the Fe-bearing phases identified to date and compare the results to Moessbauer analyses of martian meteorites and lunar samples. We use lunar samples as martian analogues because some, particularly the low-Ti Apollo 15 mare basalts, have bulk chemical compositions that are comparable to basaltic martian meteorites [1,2]. The lunar samples also provide a way to study pigeonite-rich samples. Pigeonite is a pyroxene that is not common in terrestrial basalts, but does often occur on the Moon and is present in basaltic martian meteorites

  7. 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.

  8. 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

  9. Searching for the Meteoritic Contribution to Martian Soils and Sediments

    NASA Astrophysics Data System (ADS)

    Clark, B. C.

    2015-07-01

    Martian soils and surface sediments will contain contributions from meteoritic (and IDP) input, with multiple important consequences. Determination of this input must interpret in situ measurements which focus on trace elements and evolved gases.

  10. Pyroxenes in Martian meteorites as petrogenetic indicators

    NASA Technical Reports Server (NTRS)

    McKay, Gordon; Le, L.; Mikouchi, T.; Makishima, J.; Schwandt, C.

    2006-01-01

    Pyroxenes in Martian meteorites are important recorders of petrogenetic processes. Understanding the details of pyroxene major and minor element compositional variations can provide important insights into those processes. A combination of careful petrographic analysis of natural samples and experimental crystallization studies can lead to better understanding of the processes that gave rise to these samples on Mars. In addition, experimentally determined major, minor and trace element partition coefficients are important for using natural pyroxenes to estimate the compositions of the melts from which they crystallized and the oxidation conditions that prevailed during crystallization. We will report on minor element (Al, Ti, Cr) zoning in nakhlite pyroxenes and in synthetic pyroxenes that we have grown for the purposes of determining pyroxene/melt partition coefficients for Sr and REE. The natural pyroxenes have patchy Al zoning that, by analogy with our experimental pyroxenes, we interpret as sector zoning. The irregular patchy nature of the zoning is probably the result of the vagaries of growth kinetics and local environment during crystal growth. More slowly cooled nakhlites have the most distinct bimodal zoning, with one mode having Al2O3 around 0.5-0.6 wt%, and the other around 0.9 %. Average Al content increases with increasing cooling rate. This feature is puzzling, since the cumulus pyroxenes were almost certainly present at the time of eruption. Al and Ti are strongly correlated, but Cr is completely decoupled from those elements. The synthetic pyroxenes are distinctly sector zoned in Al and Ti, and the sector-to-sector variation in Al within a single crystal has important effects on trace element partition coefficients. Trivalent REE are strongly correlated with Al, while divalent elements (Sr, Eu+2) show a significantly weaker correlation. For example, as the Al2O3 content varies from 0.3 to 0.6 wt % from one sector to another, D(Gd) increases by

  11. 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.

  12. Northwest Africa 8159: New Type of Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Agee, C. B.; Muttik, N.; Ziegler, K. G.; Walton, E. L.; Herd, C. D. K.; McCubbin, F. M.; Santos, A. R.; Simon, J. I.

    2014-12-01

    Up until recently the orthopyroxenite ALH 84001 and basaltic breccia NWA 7034 were the only martian meteorites that did not fit within the common SNC types. However with the discovery of Northwest Africa (NWA) 8159, the diversity is expanded further with a third unique non-SNC meteorite type. The existence of meteorite types beyond the narrow range seen in SNCs is what might be expected from a random cratering sampling of a volcanically long-lived and geologically complex planet such as Mars. NWA 8159, a fine-grained, augite basalt, is a new type of martian meteorite, with SNC-like oxygen isotopes and Fe/Mn values, but having several characteristics that make it distinct from other known martian meteorite types. NWA 8159 is the only martian basalt type known to have augite as the sole pyroxene phase in its mineralogy. NWA 8159 is unique among martian meteorites in that it possesses both crystalline plagioclase and shock amorphized plagioclase, often observed within a single grain, the bracketing of plagioclase amorphization places the estimated peak shock pressures at >15 GPa and <23 GPa. Magnetite in NWA 8159 is exceptionally pure, whereas most martian meteorites contain solid-solution titano-magnetites, and this pure magnetite is a manifestation of the highest oxygen fugacity (fO2) yet observed in a martian meteorite. Although NWA 8159 has the highest fO2 of martian meteorites, it has a pronounced light rare earth (LREE) depletion pattern similar to that of very low fO2 basaltic shergottites such as QUE 94201. Thus NWA 8159 displays a striking exception to well documented correlation between fO2 and LREE patterns in SNC meteorites. Finally, NWA 8159 stands apart from other martian meteorites in that it has an an early Amazonian age that is not represented in the SNCs, ALH 84001, or the NWA 7034 pairing group. NWA 8159 appears to be from an eruptive flow or shallow intrusion that is petrologically distinct from shergottite basalts, and its crystallization age

  13. Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.

    2003-01-01

    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 study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

  14. 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.

  15. Martian meteorite launch: high-speed ejecta from small craters.

    PubMed

    Head, James N; Melosh, H Jay; Ivanov, Boris A

    2002-11-29

    We performed high-resolution computer simulations of impacts into homogeneous and layered martian terrain analogs to try to account for the ages and characteristics of the martian meteorite collection found on Earth. We found that craters as small as approximately 3 kilometers can eject approximately 10(7) decimeter-sized fragments from Mars, which is enough to expect those fragments to appear in the terrestrial collection. This minimum crater diameter is at least four times smaller than previous estimates and depends on the physical composition of the target material. Terrain covered by a weak layer such as an impact-generated regolith requires larger, therefore rarer, impacts to eject meteorites. Because older terrain is more likely to be mantled with such material, we estimate that the martian meteorites will be biased toward younger ages, which is consistent with the meteorite collection.

  16. Lunar and Planetary Science XXXV: Martian Meteorites: Petrology

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Petrology: included the following reports:Volatile Behavior in Lunar and Terrestrial Basalts During Shock: Implications for Martian Magmas; Problems with a Low-Pressure Tholeiitic Magmatic History for the Chassigny Dunite; Fast Cooling History of the Chassigny Martian Meteorite; Rehomogenized Interstitial and Inclusion Melts in Lherzolitic Shergottite ALH 77005: Petrologic Significance; Compositional Controls on the Formation of Kaersutite Amphibole in Shergottite Meteorites; Chemical Characteristics of an Olivine-Phyric Shergottite, Yamato 980459; Pb-Hf-Sr-Nd Isotopic Systematics and Age of Nakhlite NWA 998; Noble Gases in Two Samples of EETA 79001 (Lith. A); Experimental Constraints on the Iron Content of the Martian Mantle; and Mars as the Parent Body for the CI Carbonaceous Chondrites: New Data.

  17. Geochemistry and setting of Martian weathering: The Lafayette meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Barrett, R. A.; Gooding, J. L.

    1992-01-01

    Lafayette, one of the SNC (martian) meteorites, contains preterrestrial alteration materials rich in smectite and ferric oxides. The compositions and textures of the veinlets suggest that they were formed in episodic alteration events by waters that contained a relatively small load of dissolved salts. The Lafayette achondrite, one of the nakhlites of probable martian origin, is an igneous rock consisting mostly of augite and olivine, with interstitial feldspar, sulfides (pyrite), high-Si glass, and other phases. Like Nakhla itself, Lafayette contains veinlets of hydrous alteration materials. We studied thin sections of sample ME2116 (Field Museum, Chicago), using scanning and transmission electron microscopy (SEM and TEM) with energy dispersive X-ray spectrometry (EDS).

  18. Alteration Products and Secondary Minerals in Martian Meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Wentworth, S. J.; Thomas-Keprta, K. L.; McKay, D. S.

    1998-01-01

    The martian meteorites contain alteration products and secondary minerals that are a critical part of understanding their near-surface histories on both Mars and Earth. In some martian meteorites, suspected martian preterrestrial alteration products can be distinguished from terrestrial weathering effects Using scanning electron microscopy (SEM), field emission SEM (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analysis (EDS), we are studying natural fracture surfaces of ALH 84001 chips, including samples from both the interior and the exterior of the meteorite. Exterior samples include fusion crust surfaces, which are important in determining the extent of terrestrial weathering of meteorites. The focus of this study is weathering features and secondary minerals other than the distinctive carbonate globules that continue to be studied by many researchers.

  19. 'Bounce' and Martian Meteorite of the Same Mold

    NASA Technical Reports Server (NTRS)

    2004-01-01

    These two sets of bar graphs compare the elemental compositions of six martian rocks: 'Bounce,' located at Meridiani Planum; EETA79001-B, a martian meteorite found in Antarctica in 1979; a rock found at the Mars Pathfinder landing site; Shergotty, a martian meteorite that landed in India in 1865; 'Adirondack,' located at Gusev Crater; and 'Humphrey,' also located at Gusev Crater. The graph on the left compares magnesium/iron ratios in the rocks, and the graph on the right compares aluminum/calcium ratios. The results illustrate the diversity of rocks on Mars and indicate that Bounce probably shares origins with the martian meterorite EETA79001-B. The Bounce data was taken on sol 68 by the alpha particle X-ray spectrometer on Mars Exploration Rover Opportunity.

  20. 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).

  1. If a Meteorite of Martian Sandstone Hit You on the Head Would You Recognize It?

    NASA Astrophysics Data System (ADS)

    Ashley, G. M.; Delaney, J. S.

    1999-03-01

    Martian meteorites are igneous but Mars is Earthlike with sediments, igneous and maybe sedimentary rocks. Sedimentary meteorites should occur in proportion to the igneous/sedimentary ratio. Sedimentary meteorites would impact climatology and the search for life on Mars.

  2. 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.

  3. Volatile/mobile trace elements in meteoritic, non-lunar basalts: Guides to Martian sample contents

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.; Paul, R. L.

    1988-01-01

    A variety of genetic processes on or in extraterrestrial objects can be examined by study of volatile/mobile trace elements. Doubtless, considerable efforts will be expended on determining these elements in returned Martian samples. The purpose is to estimate levels of such elements expected to be present in returned Martian samples. Some ideas about Martian genesis were already advanced from the volatile/mobile element contents in SNC meteorites, assuming that Mars was their parent body. Even is Mars and the SNC meteorite parent body are identical, compositional ranges for returned Martian samples should exceed those of SNC meteorites. It is expected, therefore, that Martian samples returned from locations other than Polar regions will have indigenous volatile/mobile element contents within howardite-diogenite ranges. Elements with strong lithophile tendences may be more abundant, as they are in many lunar samples. Most of these elements should be at ppb levels except for Co, Ga, Zn, and Rb, which should lie at ppm levels. If Martian volcanism was accompanied by fumarolic emanations, it should be reflected in occasional huge enrichments of mobile trance elements, as in lunar meteorite Y 791197. During collection and transport Earthward, samples must be contained under conditions appropriate to ppb concentrations. Materials must be used that will not cause contamination which occurred during the Apollo program, where indium from seals contaminated many samples.

  4. 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.

  5. 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

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

    PubMed

    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.

  7. 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.

  8. 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.

  9. Magnetic tests for magnetosome chains in Martian meteorite ALH84001.

    PubMed

    Weiss, Benjamin P; Kim, Soon Sam; Kirschvink, Joseph L; Kopp, Robert E; Sankaran, Mohan; Kobayashi, Atsuko; Komeili, Arash

    2004-06-01

    Transmission electron microscopy studies have been used to argue that magnetite crystals in carbonate from Martian meteorite ALH84001 have a composition and morphology indistinguishable from that of magnetotactic bacteria. It has even been claimed from scanning electron microscopy imaging that some ALH84001 magnetite crystals are aligned in chains. Alignment of magnetosomes in chains is perhaps the most distinctive of the six crystallographic properties thought to be collectively unique to magnetofossils. Here we use three rock magnetic techniques, low-temperature cycling, the Moskowitz test, and ferromagnetic resonance, to sense the bulk composition and crystallography of millions of ALH84001 magnetite crystals. The magnetic data demonstrate that although the magnetite is unusually pure and fine-grained in a manner similar to terrestrial magnetofossils, most or all of the crystals are not arranged in chains.

  10. Evolution of water reservoirs on Mars: Constraints from hydrogen isotopes in martian meteorites

    NASA Astrophysics Data System (ADS)

    Kurokawa, H.; Sato, M.; Ushioda, M.; Matsuyama, T.; Moriwaki, R.; Dohm, J. M.; Usui, T.

    2014-05-01

    Martian surface morphology implies that Mars was once warm enough to maintain persistent liquid water on its surface. While the high D/H ratios (˜6 times the Earth's ocean water) of the current martian atmosphere suggest that significant water has been lost from the surface during martian history, the timing, processes, and the amount of the water loss have been poorly constrained. Recent technical developments of ion-microprobe analysis of martian meteorites have provided accurate estimation of hydrogen isotope compositions (D/H) of martian water reservoirs at the time when the meteorites formed. Based on the D/H data from the meteorites, this study demonstrates that the water loss during the pre-Noachian (>41-99 m global equivalent layers, GEL) was more significant than in the rest of martian history (>10-53 m GEL). Combining our results with geological and geomorphological evidence for ancient oceans, we propose that undetected subsurface water/ice (≃100-1000 m GEL) should exist, and it exceeds the observable present water inventory (≃20-30 m GEL) on Mars.

  11. The source crater of martian shergottite meteorites.

    PubMed

    Werner, Stephanie C; Ody, Anouck; Poulet, François

    2014-03-21

    Absolute ages for planetary surfaces are often inferred by crater densities and only indirectly constrained by the ages of meteorites. We show that the <5 million-year-old and 55-km-wide Mojave Crater on Mars is the ejection source for the meteorites classified as shergottites. Shergottites and this crater are linked by their coinciding meteorite ejection ages and the crater formation age and by mineralogical constraints. Because Mojave formed on 4.3 billion-year-old terrain, the original crystallization ages of shergottites are old, as inferred by Pb-Pb isotope ratios, and the much-quoted shergottite ages of <600 million years are due to resetting. Thus, the cratering-based age determination method for Mars is now calibrated in situ, and it shifts the absolute age of the oldest terrains on Mars backward by 200 million years.

  12. Hosts of hydrogen in ALH 84001: Evidence for hydrous martian salts in the oldest martian meteorite?

    NASA Astrophysics Data System (ADS)

    Eiler, John M.; Kitchen, Nami; Leshin, Lauri; Strausberg, Melissa

    2002-03-01

    The Martian meteorite, ALH84001, contains D-rich hydrogen of plausible Martian origin (Leshin et al. 1996). The phase identity of the host(s) of this hydrogen are not well known and could include organic matter (McKay et al., 1996), phlogopite (Brearley 2000), glass (Mittlefehldt 1994) and/or other, unidentified components of this rock. Previous ion microprobe studies indicate that much of the hydrogen in ALH84001 as texturally associated with concretions of nominally anhydrous carbonates, glass and oxides (Boctor et al., 1998; Sugiura and Hoshino, 2000). We examined the physical and chemical properties of the host(s) of this hydrogen by stepped pyrolysis of variously pre-treated sub-samples. A continuous-flow method of water reduction and mass spectrometry (Eiler and Kitchen 2001) was used to permit detailed study of the small amounts of this hydrogen-poor sample available for study. We find that the host(s) of D-rich hydrogen released from ALH84001 at relatively low temperatures (~500 deg C) is soluble in orthophosphoric and dilute hydrochloric acids and undergoes near-complete isotopic exchange with water within hours at temperatures of 200 to 300 deg C. These characteristics are most consistent with the carrier phase(s) being a hydrous salt (e.g., carbonate, sulfate or halide); the thermal stability of this material is inconsistent with many examples of such minerals (e.g., gypsum) and instead suggests one or more relatively refractory hydrous carbonates (e.g., hydromagnesite). Hydrous salts (particularly hydrous carbonates) are common on the earth only in evaporite, sabkha, and hydrocryogenic-weathering environments; we suggest that much (if not all) of the 'Martian' hydrogen in ALH84001 was introduced in analogous environments on or near the martian surface rather than through biological activity or hydrothermal alteration of silicates in the crust.

  13. The age of the carbonates in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Borg, L. E.; Connelly, J. N.; Nyquist, L. E.; Shih, C. Y.; Wiesmann, H.; Reese, Y.

    1999-01-01

    The age of secondary carbonate mineralization in the martian meteorite ALH84001 was determined to be 3.90 +/- 0.04 billion years by rubidium-strontium (Rb-Sr) dating and 4.04 +/- 0.10 billion years by lead-lead (Pb-Pb) dating. The Rb-Sr and Pb-Pb isochrons are defined by leachates of a mixture of high-graded carbonate (visually estimated as approximately 5 percent), whitlockite (trace), and orthopyroxene (approximately 95 percent). The carbonate formation age is contemporaneous with a period in martian history when the surface is thought to have had flowing water, but also was undergoing heavy bombardment by meteorites. Therefore, this age does not distinguish between aqueous and impact origins for the carbonates.

  14. Formation and Evolution of Mars Inferred from Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Borg, L. E.; Symes, S.

    2011-12-01

    The return of samples from Mars has been a long standing NASA objective that, if achieved, would dramatically change our view of the formation and evolution of the terrestrial planets, as well as the physical and chemical conditions in the solar system at the time when life formed on Earth. Significant insight into Mars has been gleaned from the >50 martian meteorites that have landed on Earth. These meteorites fall into 3 categories: First, 165 to 570 Ma basalts and basaltic cumulates, second 1.3 Ga clinopyroxenites and dunites, and third a >4 Ga orthopyroxenite. The basaltic meteorites form a continuum between those with geochemical and isotopic characteristics indicating derivation from depleted and enriched sources. This is most easily explained as mixing between a depleted mantle reservoir and a poorly constrained enriched reservoir in the mantle or crust. Like some basalts. the clinopyroxenites/dunites are slightly enriched in incompatible elements relative to chondrites, but cannot be related to the basaltic meteorites by any simple process. This is most clearly supported by their vastly different short-lived isotopic compositions (e.g. 182W and 142Nd) compared to the basalts. Although all samples have undergone some low temperature alteration on Mars, the orthopyroxenite has undergone significantly more. These observations led to several fundamental conclusions: (1) the young ages indicate the planet is geologically active at present, (2) non-chondritic 182W and 142Nd suggest core formation and silicate differentiation occurred <5 Ma and <25Ma after CAIs, respectively, (3) preservation of isotopic anomalies in short-lived isotopic systems requires geochemical reservoirs on Mars to remain isolated for much of Mars history, (4) basalt geochemical relationships indicate these reservoirs mixed recently during basalt genesis and that these samples are closely related, and (5) water based alteration present in the meteorites occurred throughout martian history

  15. 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.

  16. Martian Pyroxenes in the Shergottite Meteorites; Zagami, SAU005, DAG476 and EETA79001

    NASA Astrophysics Data System (ADS)

    Stephen, N.; Benedix, G. K.; Bland, P.; Hamilton, V. E.

    2010-12-01

    The geology and surface mineralogy of Mars is characterised using remote sensing techniques such as thermal emission spectroscopy (TES) from instruments on a number of spacecraft currently orbiting Mars or gathered from roving missions on the Martian surface. However, the study of Martian meteorites is also important in efforts to further understand the geological history of Mars or to interpret mission data as they are believed to be the only available samples that give us direct clues as to Martian igneous processes [1]. We have recently demonstrated that the spectra of Martian-specific minerals can be determined using micro-spectroscopy [2] and that these spectra can be reliably obtained from thin sections of Martian meteorites [3]. Accurate modal mineralogy of these meteorites is also important [4]. In this study we are using a variety of techniques to build upon previous studies of these particular samples in order to fully characterise the nature of the 2 common pyroxenes found in Martian Shergottites; pigeonite and augite [5], [6]. Previous studies have shown that the Shergottite meteorites are dominated by pyroxene (pigeonite and augite in varying quantities) [4], [5], commonly but not always olivine, plagioclase or maskelynite/glass and also hydrous minerals, which separate the Martian meteorites from other achondrites [7]. Our microprobe study of meteorites Zagami, EETA79001, SAU005 and DAG476 in thin-section at the Natural History Museum, London shows a chemical variability within both the pigeonite and augite composition across individual grains in all thin sections; variation within either Mg or Ca concentration varies from core to rim within the grains. This variation can also be seen in modal mineralogy maps using SEM-derived element maps and the Photoshop® technique previously described [4], and in new micro-spectroscopy data, particularly within the Zagami meteorite. New mineral spectra have been gathered from the Shergottite thin-sections by

  17. 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.

  18. 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.

  19. Water in SNC meteorites: evidence for a martian hydrosphere.

    PubMed

    Karlsson, H R; Clayton, R N; Gibson, E K; Mayeda, T K

    1992-03-13

    The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.

  20. Water in SNC meteorites - Evidence for a Martian hydrosphere

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.; Gibson, Everett K., Jr.; Mayeda, Toshiko K.

    1992-01-01

    The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of Martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.

  1. 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.

  2. Rare-Earth minerals in Martian Meteorite NWA 7034/7533: Evidence for Fluid-Rock Interaction in Martian Crust

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Ma, C.; Chen, Y.; Beckett, J.; Guan, Y.

    2015-07-01

    Previously, we reported finding of monazite, chevikinite-perrierite and xenotime in the ‘Black Beauty’ meteorite (NWA 7034/7533). Here, we show textural and compositional evidence of these minerals that suggest hydrothermal fluids in martian crust.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Ferric saponite and serpentine in the nakhlite martian meteorites

    NASA Astrophysics Data System (ADS)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2014-07-01

    Transmission electron microscopy and Fe-K X-ray absorption spectroscopy have been used to determine structure and ferric content of the secondary phase mineral assemblages in the nakhlite martian meteorites, NWA 998, Lafayette, Nakhla, GV, Y 000593, Y 000749, MIL 03346, NWA 817, and NWA 5790. The secondary phases are a rapidly cooled, metastable assemblage that has preserved Mg# and Ca fractionation related to distance from the fluid source, for most of the nakhlites, though one, NWA 5790, appears not to have experienced a fluid pathway. All nine nakhlite samples have also been analysed with scanning electron microscopy, electron probe micro analysis, Bright Field high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction. By measuring the energy position of the Fe-K XANES 1s → 3d pre-edge transition centroid we calculate the ferric content of the minerals within the nakhlite meteorites. The crystalline phyllosilicates and amorphous silicate of the hydrothermal deposits filling the olivine fractures are found to have variable Fe3+/ΣFe values ranging from 0.4 to 0.9. In Lafayette, the central silicate gel parts of the veins are more ferric than the phyllosilicates around it, showing that the fluid became increasingly oxidised. The mesostasis of Lafayette and NWA 817 also have phyllosilicate, which have a higher ferric content than the olivine fracture deposits, with Fe3+/ΣFe values of up to 1.0. Further study, via TEM analyses, reveal the Lafayette and NWA 817 olivine phyllosilicates to have 2:1 T-O-T lattice structure with a the d001-spacing of 0.96 nm, whereas the Lafayette mesostasis phyllosilicates have 1:1 T-O structure with d001-spacings of 0.7 nm. Based on our analyses, the phyllosilicate found within the Lafayette olivine fractures is trioctahedral ferric saponite (Ca0.2K0.1)∑0.3(Mg2.6Fe2+1.3Fe3+1.7Mn0.1)∑5.7[(Si6.7AlIV0.9Fe3+0.4)∑8.0O20](OH)4·nH2O, and that found in the mesostasis fractures is an Fe

  8. 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

  9. Amphibole in Martian Meteorites: Composition and Implication for Volatile Content of Parental Magma

    NASA Astrophysics Data System (ADS)

    Williams, K. B.; Sonzogni, Y.; Treiman, A. H.

    2013-12-01

    Titanium-rich amphibole is present in melt inclusions in many martian (SNC) meteorites, suggesting that martian magmas contained water. Amphibole has been reported in melt inclusions within olivine grains in chassignites [1-3], and occurs in melt inclusions within pigeonite grains in most shergottites [4-10]. This study focuses on a comparison of amphibole compositions in two olivine-phyric shergottites: Tissint and Elephant Moraine (EETA) 79001, Lithology A. While amphibole (commonly of kaersutitic composition) is rare in martian meteorites, the mineral is widespread and may be useful in constraining volatile abundances in the martian mantle. Amphibole incorporates hydroxyl into its mineral structure on its O(3) site, which can also contain F-, Cl-, and O2-. Previous chemical analyses of amphiboles in martian meteorites show low halogen abundances, implying high proportions of OH- and/or O2- in the O(3) site [6, 11]. Presence of O2- on O(3) is not considered in this study, even though oxy-kaersutite can be stable at 1 bar pressure [11, 12]. Our chemical data on amphibole in martian meteorites will expand the current compositional database and provide amphibole water content estimates that can then be used to constrain the water content of the parental magma. Amphiboles were identified in polished thin sections of Tissint and EETA79001A by their yellow-orange to light brown pleochroism. Consistent with previous observations of amphibole in shergottites [4-10], the amphiboles are present only in melt inclusions in the cores of pigeonite grains, and never in augite, olivine, or mesostasis. The amphibole grains are subhedral, and range up to 15 μm in diameter. Amphibole formulae were calculated from chemical analyses by normalizing to 23 O, assuming that all iron is ferrous, and assuming that halogens and hydroxyl fully occupy the O(3) site (i.e., F-+Cl-+OH-= 2). Variability in iron oxidation and the possibility of internal amphibole dehydrogenation provide

  10. A Younger Age for the Oldest Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2010-05-01

    The Allan Hills (ALH) 84001 Martian meteorite is famous for containing fiercely-disputed evidence for fossil life. Equally important to many cosmochemists, the meteorite also contains important information about the construction of the Martian crust by magmas derived from the interior, and the subsequent modification of those igneous rocks by large impacts and circulating water. A surprising feature of ALH 84001 has been its extremely ancient age, 4.50 billion years, as determined by samarium-neodymium (Sm-Nd) and rubidium-strontium (Rb-Sr) isotopic dating. If correct, the ancient age implies that the magma in which ALH 84001 formed intruded the primordial crust, perhaps forming in a deep ocean of magma that surrounded Mars during its initial differentiation into metallic core, rocky mantle, and primary crust. New age determinations by Thomas Lapen (University of Houston) and colleagues there and at the Johnson Space Center, the Lunar and Planetary Institute, the University of Wisconsin, and the University of Brussels, Belgium, indicate that the rock crystallized in a magma 4.091 billion years ago. They used lutetium-hafnium (Lu-Hf) isotopes in determining the new age. This isotopic system has the advantage of not being affected as readily by impact heating and water alteration as are Sm-Nd and Rb-Sr. The new age is consistent with igneous activity throughout Martian history and with a period of heavy bombardment between 4.2 and 4.1 billion years as inferred from the ages of large impact basins on Mars.

  11. 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].

  12. Evaporite mineral assemblages in the nakhlite (martian) meteorites

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Grady, M. M.

    2000-03-01

    A mineralogical study of the three nakhlite (martian) meteorites has revealed that they contain evaporite mineral assemblages. Lafayette has Ca-siderite and clay minerals (smectite/illite) along fractures within olivine; Governador Valadares contains clay mineral veins in olivine, with siderite, gypsum and anhydrite in interstitial areas; Nakhla has clay and gypsum veins in olivine, with Mg-, Mn-rich siderite, anhydrite and halite in interstitial sites. Minor goethite is also present in the three meteorites. Lafayette siderite has the range of compositions (mol%) CaCO 3 21.6-36.8, MnCO 3 4.2-35.3, MgCO 3 0.1-1.6, FeCO 3 27.4-67.0; Governador Valadares has CaCO 3 3.6-11.1, MnCO 3 1.1-2.1, MgCO 3 9.0-29.2, FeCO 3 64.3-77.8; Nakhla has CaCO 3 0.1-5.7, MnCO 3 1.0-39.9, MgCO 3 2.0-40.9, FeCO 3 23.2-87.0. Trace element abundances for clay, siderite and gypsum are all similar with LREE, Y>HREE, Zr, Nb and La 0.9-95×CI; Y 0.2-2.4×CI. This pattern of abundances reflects the trace element contents of the parent fluid, which in turn were derived through dissolution of LREE-enriched feldspathic mesostasis. The close similarities in silicate petrography and radiometric ages determined by other workers for these olivine clinopyroxenites suggests that the parent rocks were close to one another on Mars and therefore the same fluid may have been responsible for the precipitation of the evaporite mineral assemblages. Lafayette contains the mineral assemblage and siderite composition which are least soluble in water and Nakhla contains the most soluble minerals and carbonate composition. On the basis of our new data we consider a new model of progressive evaporation from a Na-Mg-Fe-Ca-SO 4-Cl-H 2O-HCO 3- acidic brine in an area of enclosed drainage (e.g. crater or low-lying flood plain) on Mars. Partial dissolution of near-surface rocks by the acidic brine released Fe, Mg and trace elements from mesostasis and olivine into the fluid. The Lafayette assemblage was formed where >25

  13. 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).

  14. 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.

  15. 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.

  16. A combined electron microprobe (EMP) and Raman spectroscopic study of the alteration products in Martian meteorite MIL 03346

    NASA Astrophysics Data System (ADS)

    Kuebler, K. E.

    2013-03-01

    We examine the secondary alteration products in MIL 03346 using Raman spectroscopic and electron microprobe traverses. Discussion focuses on the single olivine in ,177 supplemented with observations from ,168 and ,169. Traverses start at the rim and progress into the interior. Dark brown, nearly opaque, laihunite [Fe2+Fe3+2(SiO4)2] is present as overgrowths, and 20-50 µm veins of reddish-brown stilpnomelane [(K,Na,Ca)4(Ti0.1,Al2.3,Fe3+35.5,Mn0.8,Mg9.3) (Si63Al9)(O,OH)206∗n(H2O)] occur inside the olivine. Stilpnomelane crosscuts and postdates the laihunite; veins are in sharp contact with the host olivine but lined by ~5 µm films of jarosite [KFe3+3(SO4)2(OH)6] from a later generation of alteration. An interstitial laihunite also hosts stilpnomelane. The most recent secondary phases are gypsum and bassanite in our X-ray maps of ,168 and ,169. Ca-sulfates were not observed in X-ray maps of ,177 but were detected in our Raman point count. All sulfates are believed to be Martian. The groundmass of MIL indicates rapid cooling from elevated temperatures with fO2 near QFM. Reports of laihunite synthesis by olivine oxidation at elevated temperatures (100-800°C) suggest the overgrowths formed during consolidation. In terrestrial rocks, stilpnomelane is a product of late diagenesis to garnet-grade metamorphism. In MIL, stilpnomelane appears to be a secondary phase formed at the lower end of this stability range, at conditions akin to diagenesis. Raman spectra indicate that the stilpnomelane, jarosite, and Ca-sulfates are hydrated. The stilpnomelane contains Cl- and was followed by jarosite, a product of acid alteration, and the deposition of Ca-sulfates and halide salts from more neutral chloride solutions.

  17. 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.

  18. Los Angeles: The Most Differentiated Basaltic Martian Meteorite

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Warren, Paul H.; Greenwood, James P.; Verish, Robert S.; Leshin, Laurie A.; Hervig, Richard L.; Clayton, Robert N.; Mayeda, Toshiko K.

    2000-01-01

    Los Angeles is a new martian meteorite that expands the compositional range of basaltic shergottites. Compared to Shergotty, Zagami, QUE94201, and EET79001-B, Los Angeles is more differentiated, with higher concentrations of incompatible elements (e.g., La) and a higher abundance of late-stage phases such as phosphates and K-rich feldspathic glass. The pyroxene crystallization trend starts at compositions more ferroan than in other martian basaits. Trace elements indicate a greater similarity to Shergotty and Zagami than to QUE94201 or EET79001-B, but the Mg/Fe ratio is low even compared to postulated parent melts of Shergotty and Zagami. Pyroxene in Los Angeles has 0.7-4-microns-thick exsolution lamellae, approx. 10 times thicker than those in Shergotty and Zaganii. Opaque oxide compositions suggest a low equilibration temperature at an oxygen fugacity near the fayafite-magnetitequartz buffer. Los Angeles cooled more slowly than Shergotty and Zagami. Slow cooling, coupled with the ferroan bulk composition, produced abundant fine-grained intergrowths of fayalite, hedenbergite, and silica, by the breakdown of pyroxferroite. Shock effects in Los Angeles include maskelynitized plagioclase, pyroxene with mosaic extinction, and rare fault zones. One such fault ruptured a previously decomposed zone of pyroxferroite. Although highly differentiated, the bulk composition of Los Angeles is not close to the low-Ca/Si composition or the globally wind-stirred soil of Mars.

  19. New Bulk Sulfur Measurements of Martian Meteorites - Implications for Sulfur Cycle on Mars

    NASA Astrophysics Data System (ADS)

    Ding, S.; Dasgupta, R.; Lee, C.; Wadhwa, M.

    2013-12-01

    Magmatic degassing was likely critical in giving rise to a thick atmosphere of ancient Mars and SO2 and H2S could have been key greenhouse gases. How much S was released depends on (1) the S content of the mantle-derived magma and (2) the magmatic sulfur budget of the basaltic crust. While the former is estimated by S content of basaltic melts at sulfide saturation (SCSS) [1,2], assuming mantle-derived magma is sulfide saturated, it is unclear how much S gets trapped during crystallization of basalts in the crust versus how much is released to the atmosphere. S content of the martian crust can be estimated from martian meteorites, yet bulk S concentration data of martian meteorites is limited [3]. Further, most martian meteorites contain cumulus minerals and some have experienced secondary alteration (weathering/ impact effects), which could either deplete or enrich S in these samples. To better constrain the degassing of S from the martian interior, we measured bulk S contents of 7 martian meteorites via high mass-resolution solution ICP-MS [4]. Basaltic shergottites Los Angeles, Zagami and NWA 856 have S contents of 2865×224, 1954×91 and 1584×10 ppm, respectively while clinopyroxenites Nakhla and NWA 998 give values of 690×60 and 253×42 ppm S. Olivine-phyric shergottites NWA 1068 and Tissint have intermediate S contents of 1280×48 and 2120×68 ppm. The meteorites have lower S contents than the predicted SCSS of ~3500-4500 ppm [2] along liquid line of descent for a liquid similar to Yamato 980459 at 1 GPa, estimated using alphaMELTS. Taking into account the possible proportion of inter-cumulus liquid (f= 6-70 wt.%) in the analyzed meteorites estimated by previous studies, the degassed S could be as low as ~300-1900 ppm (estimated by the difference between the SCSS×f and the S in the meteorites). However, nakhlite Nakhla and basaltic shergottites NWA 856 and Zagami show higher S than the calculated SCSS×f. In these two meteorites, sulfides occur as

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  1. 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

  2. Attempts to comprehend Martian surface processes through interpretation of the oxygen isotopic compositions of carbonates in SNC meteorites

    NASA Technical Reports Server (NTRS)

    Wright, I. P.; Pillinger, C. T.; Grady, Monica M.

    1992-01-01

    The SNC meteorites are known to contain trace quantities of a variety of secondary minerals such as carbonates, sulfates, and aluminosilicates. Since these constituents are thought to be mostly preterrestrial in origin, their study has the potential to provide rigorous constraints on the nature of martian weathering processes. However, this line of investigation is potentially complicated by the presence within the meteorite samples of any additional weathering products produced by terrestrial processes. Examination of such terrestrial components is important since weathering processes that affect meteorite samples following their fall to Earth might have some bearing on the nature of analogous processes at the surface of Mars. It is obviously necessary to try and distinguish which secondary components in SNC meteorites are terrestrial in origin from those that are preterrestrial. Herein consideration is made of the stable isotopic compositions of weathering products in two SNC meteorites: EET A79001 (a sample collected from Antarctica) and Nakhla (a fall from Egypt, 1911).

  3. Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A. H.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.

    2004-01-01

    Magnetite crystals produced by terrestrial magnetotactic bacterium MV-1 are elongated on a [111] crystallographic axis, in a so-called truncated hexa-Octahedral shape. This morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes). A subpopulation of magnetite crystals associated with carbonate globules in Martian meteorite ALH84001 is reported to have this morphology, and the observation has been taken as evidence for biological activity on Mars. In this study, we present evidence for the exclusively inorganic origin of [111]-elongated magnetite crystals in ALH84001. We report three-dimensional(3-D) morphologies for approx.1000 magnetite crystals extracted from: (1) thermal decomposition products of Fe-rich carbonate produced by inorganic hydrothermal precipitation in laboratory experiments; (2) carbonate globules in Martian meteoriteeALH84001; and (3) cells of magnetotactic bacterial strain MV-1. The 3-D morphologies were derived by fitting 3-D shape models to two-dimensional bright-field transmission-electron microscope (TEAM) images obtained at a series of viewing angles. The view down the {110} axes closest to the [111] elongation axis of magnetite crystals ([111]x{110) not equal to 0) provides a 2-D projection that uniquely discriminates among the three [111]-elongated magnetite morphologies found in these samples: [111]-elongated truncated hexaoctahedron ([111]-THO), [111]-elongated cubo-octahedron ([111]-ECO), and [111]-elongated simple octahedron ([111]-ESO). All [111] -elongated morphologies are present in the three types of sample, but in different proportions. In the ALH84001 Martian meteorite and in our inorganic laboratory products, the most common [111]-elongated magnetite crystal morphology is [111]-ECO. In contrast, the most common morphology for magnetotactic bacterial strain MV-1 is [111]-THO. These results show that: (1) the morphology of [111]-elongated magnetite crystals associated with the carbonate

  4. The temperature of formation of carbonate in Martian meteorite ALH84001: constraints from cation diffusion

    SciTech Connect

    Hutcheon, I D; Kent, A; Phinney, D L; Ryerson, F J

    1999-08-13

    An important test of the hypothesis that Martian meteorite ALH84001 contains fossil remnants of an ancient Martian biota is the thermal history of the carbonate rosettes associated with the proposed biomarkers. If carbonates formed at temperatures over {approximately} 110 C (the limit for terrestrial life), it is unlikely that these minerals are associated with a terrestrial-like biota.

  5. Martian Meteorite Chronology and Effects of Impact Metamorphism (Invited)

    NASA Astrophysics Data System (ADS)

    Bouvier, A.; Blichert-Toft, J.; Albarede, F.

    2009-12-01

    Martian (SNC) meteorites provide important clues to processes of alteration or shock at the surface of the planet as many of them contain secondary phases and/or high-pressure assemblages, which are the products of aqueous alteration and impact events, respectively. They include gabbros (shergottites), pyroxenites (nakhlites), and dunites (chassignites), and a single orthopyroxenite, ALH 84001. Pb-Pb isotope systematics of Martian meteorites favor three groups of formation ages: 4.3 Ga for depleted shergottites, 4.1 Ga for ALH 84001 and intermediate and enriched shergottites, and 1.3 Ga for nakhlites and Chassigny [1]. This contrasts with the young mineral isochron ages obtained by Ar-Ar dating or phosphate-based chronometers (e.g., U-Pb, Sm-Nd). In addition to Pb-Pb isotope systematics [1], we have obtained preliminary Sm-Nd and Lu-Hf mineral isochron data for the shergottite NWA 480 and find an age of ~345 Ma in contrast to its ~4.1 Ga Pb-Pb age. For the nakhlites MIL 03346 and Yamato-000593, we find Sm-Nd and Lu-Hf ages at ~1335 Ma, consistent with their ~1.3 Ga Pb-Pb age. Hence, all shergottites unambiguously show evidence of resetting events, which is not the case for nakhlites. We interpret the young ages indicated by shergottite Rb-Sr, Sm-Nd, Lu-Hf, and U-Pb internal isochrons as recent resetting by fluids, impacts, or both. Internal isochrons date the last closure, whether initial cooling or late resetting, of the chronometric system in coexisting minerals. Problems arise in part because the carriers of the parent and daughter nuclides have been wrongly assigned to major rather than accessory minerals, and in part because, with the exception of the Pb-Pb chronometer, the rock samples have been strongly leached and, hence, the parent and daughter nuclides became fractionated in the process. The Rb-Sr, U-Pb, Sm-Nd, and Lu-Hf mineral isochrons of shergottites show young age clusters around 180, 350, 475, and 575 Ma. Each cluster of young mineral isochron ages

  6. 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

  7. Electron Microscopy Studies, Surface Analysis and Microbial Culturing Experiments on a Depth Profile Through Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, J. K. W.; Steele, A.; Westall, F.; Griffin, C.; Whitby, C.; Avci, R.; McKay, D. S.

    2000-01-01

    Combined electron microscopy studies and culturing experiments have shown that Nakhla became contaminated with recent terrestrial microorganisms. Additional surface analysis detected an as yet unknown organic species which may represent a biomarker.

  8. Nanophase Magnetite and Pyrrhotite in ALH84001 Martian Meteorite: Evidence for an Abiotic Origin

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Lauer, H. V., Jr. III; Ming, D. W.; Morris, R. V.

    2006-01-01

    The nanophase magnetite crystals in the black rims of pancake-shaped carbonate globules of the Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al.that they are biogenic in origin. A subpopulation of these magnetite crystals are reported to conform to a unique elongated shape called "truncated hexa-octahedral" or "THO" by Thomas-Keprta et al. They claim these THO magnetite crystals can only be produced by living bacteria thus forming a biomarker in the meteorite. In contrast, thermal decomposition of Fe-rich carbonate has been suggested as an alternate hypothesis for the elongated magnetite formation in ALH84001 carbonates. The experimental and observational evidence for the inorganic formation of nanophase magnetite and pyrrhotite in ALH84001 by decomposition of Fe-rich carbonate in the presence of pyrite are provided.

  9. 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).

  10. 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.

  11. Remote Laser Induced Breakdown Spectroscopy (LIBS) of Martian Meteorites and Other Basaltic Samples

    NASA Astrophysics Data System (ADS)

    Clegg, S. M.; Thompson, J. R.; Wiens, R. C.; Barefield, J. E.; Vaniman, D. T.; Newsom, H. E.

    2005-12-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a rapid and quantitative analytical tool for elemental analysis in terrestrial1 and Martian environments. LIBS is one of two instruments comprising the "ChemCam" package recently selected for the Mars Science Laboratory (MSL) Rover Mission scheduled to launch in 2009. LIBS will be the first active remote sensing instrument to fly on a NASA rover, designed to interrogate samples to a distance of 9 m. In preparation for the MSL mission, we are working to improve our ability to extract quantitative results under the Martian environment. We recently completed a study in which we extracted quantitative elemental concentrations and calculated the oxide concentrations from two Martian basaltic shergottite meteorites, Dar al Gani (DaG) 476 and Zagami. The current LIBS laboratory setup involves ablating some material from the sample surface with a focused Nd:YAG (1064nm) laser. The ablated material produces a supersonically expanding plasma of electronically excited atoms. A dispersive spectrometer and an ICCD camera are used to record the spectral signatures emitted from the electronically excited atoms. In our experimental set-up, samples were placed at a distance of 5.4 m from the instrument in a vacuum chamber filled with 7 Torr CO2 to simulate the Martian atmosphere. Terrestrial basalt standards were used to generate calibration curves for all of the major elements and some of the minor and trace species including Si, Fe, Mg, Ca, Ti, Al, and Na. First, two blind basalt standards were analyzed and their compositions were found to match the actual compositions within the uncertainty of the measurement, being correctly distinguished from other available basalt standards. Next, LIBS was used to distinguish between two different basaltic Martian meteorites. Using 14 analysis spots of ~400 μm diameter on DaG 476 and 9 analysis spots on Zagami, LIBS distinguished the olivine-phyric (DaG 476) from the basaltic (Zagami

  12. Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Impact-melt glasses, rich in Martian atmospheric gases, contain Martian 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 Martian 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 Martian 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 study, 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 Martian atmospheric noble gases are found.

  13. Light lithophile elements in pyroxenes of Northwest Africa (NWA) 817 and other Martian meteorites: Implications for water in Martian magmas

    NASA Astrophysics Data System (ADS)

    Treiman, Allan H.; Musselwhite, Donald S.; Herd, Christopher D. K.; Shearer, Charles K.

    2006-06-01

    Zoning patterns of light lithophile elements (the LLE: Li, Be, and B) in pyroxenes of some Martian basaltic meteorites have been used to suggest that the parent basalts were saturated in water and exsolved an aqueous fluid phase. Here, we examine LLE zoning in the augites of a quickly cooled Martian basalt that was not water-saturated—the Northwest Africa (NWA) 817 nakhlite. Analyses for LLE were by secondary ion mass spectrometry (SIMS), supported by EMP analyses of major and minor elements. In NWA 817, zoning of Be and B is consistent with igneous fractionations while Li abundances are effectively constant across wide ranges in abundance of other incompatible elements (Be, B, Ti, and Fe*). The lack of strong zoning in Li can be ascribed to intracrystalline diffusion, despite the rapid cooling of NWA 817. Most other nakhlites, notably Nakhla and Lafayette, cooled more slowly than did NWA 817 [Treiman, A.H., 2005. The nakhlite Martian meteorites: augite-rich igneous rock from Mars. Chem. Erde65, 203-270]. In them Li abundances are constant across augite, as are abundances of other elements. In Nakhla pyroxenes, all the LLE have effectively constant abundances across significant ranges in Fe* and Ti abundance. Lafayette is more equilibrated still, and shows constant abundances of LLE and nearly constant Fe*. A pyroxene in the NWA480 shergottite has constant Li abundances, and was interpreted to represent mineral fractionation coupled with exsolution of aqueous fluid. A simple quantitative model of this process requires that the partitioning of Li between basalt and aqueous fluid, LiDaq/bas, be 15 times larger than its experimentally determined value. Thus, its seems unlikely that the Li zoning pattern in NWA480 augite represents exsolution of aqueous fluid. Late igneous or sub-solidus diffusion seems more likely as is suggested by Li isotopic studies [Beck, P., Chaussidon, M., Barrat, J.-A., Gillet, Ph., Bohn, M., 2005. An ion-microprobe study of lithium isotopes

  14. Exsolution and shock microstructures of igneous pyroxene clasts in the Northwest Africa 7533 Martian meteorite

    NASA Astrophysics Data System (ADS)

    Leroux, Hugues; Jacob, Damien; Marinova, Maya; Hewins, Roger H.; Zanda, Brigitte; Pont, Sylvain; Lorand, Jean-Pierre; Humayun, Munir

    2016-05-01

    Northwest Africa (NWA) 7533 is a Martian regolith breccia. This meteorite (and its pairings) offers a good opportunity to study (near-) surface processes that occurred on early Mars. Here, we have conducted a transmission electron microscope study of medium- and coarse-grained (a few tens to hundreds of micrometers) Ca-rich pyroxene clasts in order to define their thermal and shock histories. The pyroxene grains have a high-temperature (magmatic) origin as revealed by the well-developed pigeonite-augite exsolution microstructure. Exsolution lamella characteristics (composition, thickness, and spacing) indicate a moderately slow cooling. Some of the pyroxene clasts display evidence for local decomposition into magnetite and silica at the submicron scale. This phase decomposition may have occurred at high temperature and occurred at high oxygen fugacity at least 2-3 log units above the QFM buffer, after the formation of the exsolution lamellae. This corresponds to oxidizing conditions well above typical Martian magmatic conditions. These oxidizing conditions seem to have prevailed early and throughout most of the history of NWA 7533. The shock microstructure consists of (100) mechanical twins which have accommodated plastic deformation. Other pyroxene shock indicators are absent. Compared with SNC meteorites that all suffered significant shock metamorphism, NWA 7533 appears only mildly shocked. The twin microstructure is similar from one clast to another, suggesting that the impact which generated the (100) twins involved the compacted breccia and that the pyroxene clasts were unshocked when they were incorporated into the NWA 7533 breccia.

  15. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Astrophysics Data System (ADS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-09-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  16. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-01-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

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

    PubMed

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

    2000-03-01

    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.

  18. 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

  19. 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.

  20. The chlorine isotopic composition of Martian meteorites 1: Chlorine isotope composition of Martian mantle and crustal reservoirs and their interactions

    NASA Astrophysics Data System (ADS)

    Williams, J. T.; Shearer, C. K.; Sharp, Z. D.; Burger, P. V.; McCubbin, F. M.; Santos, A. R.; Agee, C. B.; McKeegan, K. D.

    2016-11-01

    The Martian meteorites record a wide diversity of environments, processes, and ages. Much work has been done to decipher potential mantle sources for Martian magmas and their interactions with crustal and surface environments. Chlorine isotopes provide a unique opportunity to assess interactions between Martian mantle-derived magmas and the crust. We have measured the Cl-isotopic composition of 17 samples that span the range of known ages, Martian environments, and mantle reservoirs. The 37Cl of the Martian mantle, as represented by the olivine-phyric shergottites, NWA 2737 (chassignite), and Shergotty (basaltic shergottite), has a low value of approximately -3.8‰. This value is lower than that of all other planetary bodies measured thus far. The Martian crust, as represented by regolith breccia NWA 7034, is variably enriched in the heavy isotope of Cl. This enrichment is reflective of preferential loss of 35Cl to space. Most basaltic shergottites (less Shergotty), nakhlites, Chassigny, and Allan Hills 84001 lie on a continuum between the Martian mantle and crust. This intermediate range is explained by mechanical mixing through impact, fluid interaction, and assimilation-fractional crystallization.

  1. Fractionated (Martian) Noble Gases — EFA, Experiments and Meteorites

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Barnes, G.; Bridges, J. C.; Bullock, M. A.; Chavez, C. L.; Filiberto, J.; Herrmann, S.; Hicks, L. J.; Kelley, S. P.; Miller, M. A.; Moore, J. M.; Ott, U.; Smith, H. D.; Steer, E. D.; Swindle, T. D.; Treiman, A. H.

    2016-08-01

    Noble gases are tracers for physical processes, including adsorption, dissolution and secondary mineral formation. We examine the Martian fractionated atmosphere through literature, terrestrial analogs and experiments.

  2. (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

  3. A search for amino acids and nucleobases in the Martian meteorite Roberts Massif 04262 using liquid chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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 β-alanine and γ-amino-n-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 n-ω-amino acids in RBT 04262 resembled those previously measured in thermally altered carbonaceous meteorites (Burton et al. 2012; Chan et al. 2012). A carbon isotope ratio of -24‰ ± 6‰ for β-alanine in RBT 04262 is in the range of reduced organic carbon previously measured in Martian meteorites (Steele et al. 2012). The presence of n-ω-amino acids may be due to a high temperature Fischer-Tropsch-type synthesis during igneous processing on Mars or impact ejection of the meteorites from Mars, but more experimental data are needed to support these hypotheses.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Evidence for a Second Generation of Magnesite in Martian Meteorite Allan Hills 84001

    NASA Technical Reports Server (NTRS)

    Corrigan, C. M.; Harvey, R. P.

    2003-01-01

    Single-stage formation mechanisms for carbonate and other secondary minerals in ALH84001 are rapidly being revised to include multiple stages of carbonate growth and later thermal and mechanical events including alteration. In an effort to confirm some of these more complex histories we have been studying carbonate-bearing regions within this meteorite. Magnesitic carbonates found in contact with unique 'slab' carbonates in two thin sections of ALH84001 show indications of being of a later generation. The results of our observations help clarify the origins of the carbonate and related minerals in ALH84001, and how these minerals can be used to understand the history of interactions between the martian crust and its volatile inventory.

  9. 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.

  10. 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.

  11. 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.

  12. An assessment of the meteoritic contribution to the Martian soil

    SciTech Connect

    Flynn, G.J. ); McKay, D.S. )

    1990-08-30

    The addition of meteoritic material to the Mars soils should perturb their chemical compositions, as has been detected for soils on the Moon and sediments on Earth. Using the measured mass influx at Earth and estimates of the Mars/Earth flux ratio, the authors estimate the continuous, planet-wide meteoritic mass influx on Mars to be between 2,700 and 59,000 t/yr. If distributed uniformly into a soil with a mean planetary production rate of 1 m/b.y., consistent with radar estimates of the soil depth overlaying a bouldered terrain in the Tharsis region, their estimated mass influx would produce a meteoritic concentration in the Mars soil ranging from 2 to 29% by mass. Analysis of the Viking X ray fluorescence data indicates that the Mars soil composition is inconsistent with typical basaltic rock fragments but can be fit by a mixture of 60% basaltic rock fragments and 40% meteoritic material. The meteoritic influx they calculate is sufficient to provide most or all of the material required by the Clark and Baird model. Particles in the mass range from 10{sup {minus}7} to 10{sup {minus}3} g, about 60-1,200 {mu}m in diameter, contribute 80% of the total mass flux of meteoritic material in the 10{sup {minus}13} to 10{sup 6} g mass range at Earth. On Earth atmospheric entry all but the smallest particles (generally {le} 50 {mu}m in diameter) in the 10{sup {minus}7} to 10{sup {minus}3} g mass range are heated sufficiently to melt or vaporize. Mars, because of its lower escape velocity and larger atmospheric scale height, is a much more favorable site for unmelted survival of micrometeorites on atmospheric deceleration. They calculate that a significant fraction of particles throughout the 60-1,200 {mu}m diameter range will survive Mars atmospheric entry unmelted.

  13. In Situ Mars Compositions Determined by Alpha Particle X-Ray Spectrometry (APXS): Overview and Comparison with Martian Meteorite Dataset

    NASA Astrophysics Data System (ADS)

    Thompson, L. M.; Gellert, R.; Spray, J. G.; Schmidt, M. E.; Izawa, M.; MSL APXS Team

    2016-08-01

    APXS instruments have flown on every rover mission to Mars. This work provides an overview of the diverse in situ chemistry encountered, with emphasis on MSL Curiosity mission results, and compares this with the martian meteorite data set.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    1994-09-01

    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 Fo64 to Fo70, (avg. Fo67), more ferroan and with more variation than in ALHA77005 (Fo69 to Fo73). Pyroxene compositions fall between En77Wo4 and En65Wo15 and in clusters near En63Wo9 and En53Wo33, 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), noble gas isotope abundances in LEW88516 are consistent with exposure to

  16. Micro-Spectroscopy as a Tool for Detecting Micron-Scale Mineral Variations Across a Rock Surface: An Example Using a Thin Section of Martian Meteorite ALH 84001

    NASA Technical Reports Server (NTRS)

    Dalton, J. Brad; Bishop, Janice L.

    2003-01-01

    Imaging spectroscopy is a powerful tool for mineral detection across broad spatial regions. A prototype micro-imaging spectrometer at NASA Ames is tested in this study on a scale of tens to hundreds of microns across rock surfaces. Initial measurements were performed in the visible spectral region on a thin section of martian meteorite ALH 84001.

  17. 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.

  18. Putative indigenous carbon-bearing alteration features in martian meteorite Yamato 000593.

    PubMed

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

    2014-02-01

    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.

  19. 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.

  20. Origin and age of the earliest Martian crust from meteorite NWA 7533.

    PubMed

    Humayun, M; Nemchin, A; Zanda, B; Hewins, R H; Grange, M; Kennedy, A; Lorand, J-P; Göpel, C; Fieni, C; Pont, S; Deldicque, D

    2013-11-28

    The ancient cratered terrain of the southern highlands of Mars is thought to hold clues to the planet's early differentiation, but until now no meteoritic regolith breccias have been recovered from Mars. Here we show that the meteorite Northwest Africa (NWA) 7533 (paired with meteorite NWA 7034) is a polymict breccia consisting of a fine-grained interclast matrix containing clasts of igneous-textured rocks and fine-grained clast-laden impact melt rocks. High abundances of meteoritic siderophiles (for example nickel and iridium) found throughout the rock reach a level in the fine-grained portions equivalent to 5 per cent CI chondritic input, which is comparable to the highest levels found in lunar breccias. Furthermore, analyses of three leucocratic monzonite clasts show a correlation between nickel, iridium and magnesium consistent with differentiation from impact melts. Compositionally, all the fine-grained material is alkalic basalt, chemically identical (except for sulphur, chlorine and zinc) to soils from Gusev crater. Thus, we propose that NWA 7533 is a Martian regolith breccia. It contains zircons for which we measured an age of 4,428 ± 25 million years, which were later disturbed 1,712 ± 85 million years ago. This evidence for early crustal differentiation implies that the Martian crust, and its volatile inventory, formed in about the first 100 million years of Martian history, coeval with earliest crust formation on the Moon and the Earth. In addition, incompatible element abundances in clast-laden impact melt rocks and interclast matrix provide a geochemical estimate of the average thickness of the Martian crust (50 kilometres) comparable to that estimated geophysically.

  1. 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.

  2. Distinctive Carbonates in Five Martian Meteorites: Search for Water on Mars

    NASA Technical Reports Server (NTRS)

    Wentworth, Susan J.; Bailey, Jake; McKay, David S.; Thomas-Keprta, Kathie L.; Velbel, Michael

    2003-01-01

    Recently published results from Mars orbital data strongly support both the idea that large bodies of water were present at the surface in the past and the possibility that significant amounts of water ice are currently present in the regolith just below the planet's surface. These new findings increase the significance of the evidence in martian meteorites that some low-temperature aqueous alteration and secondary mineral deposition occurred on Mars.

  3. Polycyclic Aromatic Hydrocarbons in the Martian (SNC) Meteorite ALH 84001: Hydrocarbons from Mars, Terrestrial Contaminants, or Both?

    NASA Astrophysics Data System (ADS)

    Thomas, K. L.; Clemett, S. J.; Romanek, C. S.; Macheling, C. R.; Gibson, E. K.; McKay, D. S.; Score, R.; Zare, R. N.

    1995-09-01

    Previous work has shown that pre-terrestrial polycyclic aromatic hydrocarbons (PAHs) exist in interplanetary dust particles (IDPs) and certain meteorites [1-3]. We previously reported the first observation of PAHs in the newest member of the SNC group, Allan Hills 84001 [4] and determined that particular types of organic compounds are indigenous to ALH 84001 because they are associated with certain mineralogical features [4]. We also analyzed two diogenites from Antarctica: one showed no evidence for aromatic hydrocarbons while the other contained PAHs with the same major peaks as those in ALH 84001[4]. PAHs in the diogenite meteorite are not associated with mineral features on the analyzed surface and the most abundant PAHs in the diogenite are lower by a factor of 3 than those in ALH 84001. Furthermore, ALH 84001 contains a number of minor PAHs not found in the diogenite or typical terrestrial soils [4]. In this study we are analyzing a more complete group of Antarctic and non-Antarctic meteorites, including SNCs, to determine: (1) PAHs abundance and diversity in Antarctic meteorites and (2) the contribution of PAHs in SNCs from martian and, possibly, terrestrial sources. ALH 84001 is an unusual orthopyroxenite which contains abundant carbonate spheroids which are ~100-200 micrometers in diameter and range in composition from magnesite to ferroan magnesite [5-7]. These spheroids are not the result of terrestrial contamination: oxygen isotopic compositions indicate that the carbonates probably precipitated from a low-temperature fluid within the martian crust [5] and carbon isotopic abundances are consistent with martian atmospheric CO2 as the carbon source [5]. PAHs may coexist with other low-temperature carbon-bearing phases in a subsurface martian environment. Samples: We are analyzing freshly-fractured meteorite samples, or chips, which have been extracted from the internal regions of the following meteorites: ALH 84001 (crush and uncrush zones), EETA79001

  4. A 4-Gyr shock age for a martian meteorite and implications for the cratering history of Mars

    NASA Astrophysics Data System (ADS)

    Ash, R. D.; Knott, S. F.; Turner, G.

    1996-03-01

    ANALYSES of meteorites that originated on Mars provide important insights into the geological and atmospheric evolution of the planet. Such analyses have hitherto been restricted to relatively young martian rocks1 (the oldest martian meteorites have an age of approximately 1.3 billion years). But the recently recognized2 martian meteorite, Allan Hills 84001, which is distinct from the other martian meteorites2-4, shows evidence for a much older age5,6. Here we report an analysis of the shock-alteration history of this meteorite based on argon isotope dating, from which we derive a shock age of 4.0 +/- 0.1 billion years. The age and geological history of this meteorite suggest that it came from the heavily cratered Noachian-age terrains of Mars's southern hemisphere, and it may thus provide an absolute chronology for this region of the planet, independent of that inferred from the cratering record. The shock age of the meteorite also coincides with that of the so-called Lunar Cataclysm (a relatively short period during which many of the craters on the Moon are believed to have formed), supporting the idea7 that intense bombardment was widespread throughout the inner Solar System between 3.9 and 4.1 billion years ago.

  5. Trace Element Geochemistry of Martian Iddingsite in the Lafayette Meteorite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Lindstrom, David J.

    1997-01-01

    The Lafayette meteorite contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite 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+).

  6. Origin of carbonate-magnetite-sulfide assemblages in Martian meteorite ALH84001

    NASA Astrophysics Data System (ADS)

    Scott, Edward R. D.

    1999-02-01

    A review of the mineralogical, isotopic, and chemical properties of the carbonates and associated submicrometer iron oxides and sulfides in Martian meteorite ALH84001 provides minimal evidence for microbial activity. Some magnetites resemble those formed by magnetotactic microorganisms but cubic crystals <50 nm in size and elongated grains <25 nm long are too small to be single-domain magnets and are probably abiogenic. Magnetites with shapes that are clearly unique to magnetotactic bacteria appear to be absent in ALH84001. Magnetosomes have not been reported in plutonic rocks and are unlikely to have been transported in fluids through fractures and uniformly deposited where abiogenic magnetite was forming epitaxially on carbonate. Submicrometer sulfides and magnetites probably formed during shock heating. Carbonates have correlated variations in Ca, Mg, and 18O/16O, magnetite-rich rims, and they appear to be embedded in pyroxene and plagioclase glass. Carbonates with these features have not been identified in carbonaceous chondrites and terrestrial rocks, suggesting that the ALH84001 carbonates have a unique origin. Carbonates and hydrated minerals in ALH84001, like secondary phases in other Martian meteorites, have O and H isotopic ratios favoring formation from fluids that exchanged with the Martian atmosphere. I propose that carbonates originally formed in ALH84001 from aqueous fluids and were subsequently shock heated and vaporized. The original carbonates were probably dolomite-magnesite-siderite assemblages that formed in pores at interstitial sites with minor sulfate, chloride, and phyllosilicates. These phases, like many other volatile-rich phases in Martian meteorites, may have formed as evaporite deposits from intermittent floods.

  7. Carbonates in fractures of Martian meteorite Allan Hills 84001: petrologic evidence for impact origin

    NASA Technical Reports Server (NTRS)

    Scott, E. R.; Krot, A. N.; Yamaguchi, A.

    1998-01-01

    Carbonates in Martian meteorite Allan Hills 84001 occur as grains on pyroxene grain boundaries, in crushed zones, and as disks, veins, and irregularly shaped grains in healed pyroxene fractures. Some carbonate disks have tapered Mg-rich edges and are accompanied by smaller, thinner and relatively homogeneous, magnesite microdisks. Except for the microdisks, all types of carbonate grains show the same unique chemical zoning pattern on MgCO3-FeCO3-CaCO3 plots. This chemical characteristic and the close spatial association of diverse carbonate types show that all carbonates formed by a similar process. The heterogeneous distribution of carbonates in fractures, tapered shapes of some disks, and the localized occurrence of Mg-rich microdisks appear to be incompatible with growth from an externally derived CO2-rich fluid that changed in composition over time. These features suggest instead that the fractures were closed as carbonates grew from an internally derived fluid and that the microdisks formed from a residual Mg-rich fluid that was squeezed along fractures. Carbonate in pyroxene fractures is most abundant near grains of plagioclase glass that are located on pyroxene grain boundaries and commonly contain major or minor amounts of carbonate. We infer that carbonates in fractures formed from grain boundary carbonates associated with plagiociase that were melted by impact and dispersed into the surrounding fractured pyroxene. Carbonates in fractures, which include those studied by McKay et al. (1996), could not have formed at low temperatures and preserved mineralogical evidence for Martian organisms.

  8. 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.

  9. 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.

  10. Isotope Geochemistry of Possible Terrestrial Analogue for Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Mojzsis, Stephen J.

    2000-01-01

    We have studied 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 martian meteorite 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.

  11. Origin of Magnetite Crystals in Martian Meteorite ALH84001 Carbonate Disks

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Martian meteorite 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 studies of sideritic carbonates under a range of plausible geological heating scenarios.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  13. 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.

  14. A search for endogenous amino acids in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Bada, J. L.; Glavin, D. P.; McDonald, G. D.; Becker, L.

    1998-01-01

    Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the L enantiomer, low concentrations (<0.1 parts per million) of endogenous D-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as D-alanine are preserved in the meteorite.

  15. 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.

  16. Modern atmospheric signatures in 4.4 Ga Martian meteorite NWA 7034

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ott, U.; Herrmann, S.; Agee, C. B.

    2014-08-01

    The NWA 7034 Martian basaltic breccia, dated at ˜4.4 Ga, represents an entirely new type of Martian meteorite. However, due to the unique make-up of NWA 7034 compared to other Martian meteorite types (including its anomalous oxygen isotope ratios), noble gas analyses - a key tool for Martian meteorite identification - are important to confirm its Martian origin. Here, we report the first noble gas results for NWA 7034, which show the presence of a trapped component that resembles the current Martian atmosphere. This trapped component is also similar in composition to trapped gases found in the much younger shergottites (˜150-600 Ma). Our formation ages for the sample suggest events at ˜1.6 Ga (K-Ar), and ˜170 Ma (U-Th/He), which are considerably younger than those observed by Rb-Sr (2.1 Ga), and Sm-Nd (4.4 Ga; zircons ˜4.4 Ga). However, our K-Ar age is similar to a disturbance in the U-Pb zircon data at ˜1.7 Ga, which could hint that both chronometers have been subjected to disturbance by a common process or event. The U-Th/He age of ˜170 Ma could relate to complete loss of radiogenic 4He at this time, and is a similar age to the crystallisation age of most shergottites. While this may be coincidental, it could indicate that a single event is responsible for both shergottite formation and NWA 7034 thermal metamorphism. As for cosmic ray exposure ages, our favoured age is ˜5 Ma, which is outside the ranges for other Martian meteorite groups, and may suggest a distinct ejection event. NWA 7034 shows evidence for neutron capture on Br, which has caused elevations in Kr isotopes 80Kr and 82Kr. These elevated abundances indicate significant shielding, and could relate to either a large meteoroid size, and/or shielding in relation to a regolithic origin. We have also applied similar neutron capture corrections to Ar and Xe data, which further refine the likelihood of a modern atmospheric component, though such corrections remain speculative. Cosmogenic production

  17. Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    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.

    1998-01-01

    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 martian meteorite ALH84001.

  18. 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

  19. Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice

    SciTech Connect

    Becker, L. |; Glavin, D.P.; Bada, J.L.

    1997-01-01

    Recent analyses of the carbonate globules present in the Martian meteorite 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 meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars. 33 refs., 3 figs., 1 tab.

  20. 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

  1. Martian polar geological studies

    NASA Technical Reports Server (NTRS)

    Cutts, J. A. J.

    1977-01-01

    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 martian 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.

  2. Morphological Evidence for an Exclusively Inorganic Origin for Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.; McKay, G. A.

    2003-01-01

    The origin of magnetite crystals in Martian Meteorite ALH84001 is the focus of a debate about the possibility of past (and present) life on Mars. McKay et al. originally suggested that some of the magnetite crystals associated with carbonate globules in Martian Meteorite ALH84001 are biogenic in ori-gin, because they are single magnetic domain, free of crystalline defects, chemically pure, and coexist with other metastable phases in apparent disequilibrium. Thomas-Keprta et al. reported that a subpopulation of magnetite crystals (approx. 25%) associated with carbonate globules in ALH84001 and magnetite crystals produced by magnetotactic bacterial strain MV-1 have similar morphologies with crystal elongation along the [111] crystallographic axis that they describe as "truncated hexa-octahedral" ([111-THO]) magnetite. Along with several other properties, the [111]-THO morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes), so that the presence of [111]-THO magnetite in ALH84001 may be evidence for past life on Mars.

  3. Organic Carbon Exists in Mars Meteorites: where is it on the Martian Surface?

    NASA Astrophysics Data System (ADS)

    McKay, David; Clemett, Simon; Gibson, Everett; Thomas-Keprta, Kathie; Wentworth, Susan

    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 meteorites were from Mars [2], [3-5] reported C isotopic compositional information which suggested a reduced C component present in the Martian meteorites. [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 martian or ancient meteoritic 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 studies 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

  4. ALH84001, a cumulate orthopyroxenite member of the Martian meteorite clan

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    1994-01-01

    ALH84001, originally classified as a diogenite, is a coarse-grained, cataclastic, orthopyroxenite meteorite related to the martian (SNC) meteorites. The orthopyroxene is relatively uniform in composition, with a mean composition of Wo3.3En69.4Fs27.3. Minor phases are euhedral to subhedral chromite and interstitial maskelynite, An31.1Ab63.2Or5.7, with accessory augite, Wo42.2En45.1Fs12.7, apatite, pyrite and carbonates, Cc11.5Mg58.0Sd29.4Rd1.1. The pyroxenes and chromites in ALH84001 are similar in composition to these phases in EETA79001 lithology a megacrysts but are more homogeneous. Maskelynite is similar in composition to feldspars in the nakhlites and Chassigny. Two generations of carbonates are present, early (pre-shock) strongly zoned carbonates and late (post-shock) carbonates. The high Ca content of both types of carbonates indicates that they were formed at moderately high temperature, possibly approximately 700 C. ALH84001 has a slightly LREE-depleted pattern with La 0.67x and Lu 1.85x CI abundances and with a negative Eu anomaly (Eu/Sm 0.56x CI). The uniform pyroxene composition is unusual for martian meteorites, and suggests that ALH84001 cooled more slowly than did the shergottites, nakhlites of Chassigny. The nearly monomineralic composition, coarse-grain size, homogeneous orthopyroxene and chromite compositions, the interstitial maskelynite and apatite, and the REE pattern suggest that ALH84001 is a cumulate orthopyroxenite containing minor trapped, intercumulus material.

  5. 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.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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. These data are 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 meteorites and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of 146Sm-142Nd whole rock isochrons are not dependent on the assumed 142Nd/144Nd 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 143Nd-142Nd 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 143Nd-142Nd 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 147Sm/144Nd 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 which large scale

  9. First evidence for infiltration metasomatism in a martian meteorite, ALH 84001

    NASA Astrophysics Data System (ADS)

    Wadhwa, M.; Crozaz, G.

    1994-07-01

    ALH 84001, originally classified as a diogenite, was recently recognized by Mittlefehldt as a new member of the clan of martian meteorites. It is a coarse-grained orthopyroxenite with same O isotopic composition as the nakhlites. Most of this meteorite consists of orthopyroxene grains; it also contains maskelynite, chromite, and accessory minerals including apatite, augite, pyrite, and Mg-Ca-Mn-Fe carbonates. With the ion microprobe, we measured the concentrations of Rare Earth Elements (REEs) and other selected minor and trace elements in individual grains of orthopyroxene, maskelynite, and apatite. Although in all SNCs phosphate is the mineral with the highest REE concentrations, it is not the major REE carrier in ALH 84001. Using the most appropriate partition coefficients for these minerals in SNCs, we estimated the compositions of the metals that may have been in equilibrium with the 'average' orthopyroxene, the apatite, and the maskelynite. The orthopyroxene equilibrium melt is slightly LREE depleted, whereas the apatite and maskelynite equilibrium melts have higher REE concentrations and are strikingly LREE enriched. We tried unsuccessfully to derive the apatite and maskelynite melts from the orthopyroxene melt by fractional crystallization. We therefore suggest that an infiltrating fluid enriched in LREE is responsible for the formation of the apatite and maskelynite that occur as interstitial grains in ALH 84001. The similarity of REE patterns for the parent melts of ALH 84001, Shergotty, and Zagami seems to indicate that the new SNC meteorite is more closely related to these two shergottites than to any of the other meteorites thought to have come from Mars.

  10. Cosmochemical Studies: Meteorites and their Parent Asteroids

    NASA Technical Reports Server (NTRS)

    Wasson, John T.

    2003-01-01

    This a final technical report that focuses on cosmochemical studies of meteorites and their parent asteroids. The topics include: 1) Formation of iron meteorites and other metal rich meteorites; 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.

  11. A Petrographic History of Martian Meteorite ALH84001: Two Shocks and an Ancient Age

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1995-01-01

    ALH84001 is an igneous meteorite, an orthopyroxenite of martian 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 martian 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 martian 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

  12. Martian surface weathering studies

    NASA Technical Reports Server (NTRS)

    Calvin, M.

    1973-01-01

    The nature of the Martian surface was characterized by means of its reflectance properties. The Mariner 9 photography was used to establish terrain units which were crossed by the Mariner 6 and 7 paths. The IR reflectance measured by the IR spectrometers on these spacecraft was to be used to indicate the nature of the surface within these units. There is an indication of physical size and/or compositional variation between units but too many natural parameters can vary (size, shape, composition, adsorbed phases, reradiation, atmospheric absorbtion, temperature gradients, etc.) to be certain what effect is causing those variations observed. It is suggested that the characterization could be fruitfully pursued by a group which was dedicated to peeling back the layers of minutia affecting IR reflectance.

  13. Hydrothermal Origin for Carbonate Globules in Martian Meteorite ALH84001: A Terrestrial Analogue from Spitsbergen (Norway)

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; Bunch, Ted

    2002-01-01

    Carbonate minerals in the ancient Martian meteorite 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.

  14. Experimental Shock Decomposition of Siderite and the Origin of Magnetite in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Bell, Mary Sue

    2007-01-01

    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 Martian meteorite 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 Martian meteorite ALH84001 could be a product of shock devolatilization of

  15. 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

  16. The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

    SciTech Connect

    Symes, S; Borg, L; Shearer, C; Irving, A

    2007-04-05

    Samarium-neodymium isotopic analyses of unleached and acid-leached mineral fractions from the recently identified olivine-bearing shergottite Northwest Africa 1195 yield a crystallization age of 348 {+-} 19 Ma and an {var_epsilon}{sub Nd}{sup 143} value of +40.1 {+-} 1.3. Maskelynite fractions do not lie on the Sm-Nd isochron and appear to contain a martian surface component with low {sup 147}Sm/{sup 144}Nd and {sup 143}Nd/{sup 144}Nd ratios that was added during shock. The Rb-Sr system is disturbed and does not yield an isochron. Terrestrial Sr appears to have affected all of the mineral fractions, although a maximum initial {sup 87}Sr/{sup 86}Sr ratio of 0.701614 {+-} 16 is estimated by passing a 348 Ma reference isochron through the maskelynite fraction that is least affected by contamination. The high initial {var_epsilon}{sub Nd}{sup 143} value and the low initial {sup 87}Sr/{sup 86}Sr ratio, combined with the geologically young crystallization age, indicate that Northwest Africa 1195 is derived from a source region characterized by a long-term incompatible element depletion. The age and initial Sr and Nd isotopic compositions of Northwest Africa 1195 are very similar to those of Queen Alexandra Range 94201, indicating these samples were derived from source regions with nearly identical Sr-Nd isotopic systematics. These similarities suggest that these two meteorites share a close petrogenetic relationship and might have been erupted from a common volcano. The meteorites Yamato 980459, Dar al Gani 476, Sayh al Uhaymir 005/008, and Dhofar 019 also have relatively old ages between 474-575 Ma and trace element and/or isotopic systematics that are indicative of derivation from incompatible-element-depleted sources. This suggests that the oldest group of meteorites is more closely related to one another than they are to the younger meteorites that are derived from less incompatible-element-depleted sources. Closed-system fractional crystallization of this suite of

  17. 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.

  18. 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.

  19. Sayh al Uhaymir 094 a new martian meteorite from the Oman desert

    NASA Astrophysics Data System (ADS)

    Gnos, E.; Hofmann, B.; Franchi, I. A.; Al-Kathiri, A.; Hauser, M.; Moser, L.

    2003-04-01

    The new martian meteorite Sayh al Uhaymir 094 was found in february 2001 during a joint meteorite search campaign of the University of Berne, the Natural History Museum Bern, and the Ministry of Commerce and Industry, Sultanate of Oman. The martian meteorite is a 223.3 g partially crusted, strongly to very strongly shocked melanocratic olivine-porphyric rock of the shergottite group showing a microgabbroic texture. The rock consists of 52.0 58.2 vol% prismatic pigeonite (En60-68Fs20-27Wo7-9) and augite (En46-49Fs15-16Wo28-31), oxydized olivine (Fo65-69;22.1 31%), completely isotropic interstitial plagioclase glass (maskelynite; 8.6 13.0%), chromite and titanian magnesian chromite (0.9 1.0%), traces of ilmenite (ilm80-86), pyrrhotite (Fe92-100; 0.1 0.2%), merrillite, Ca9Na(Mg,Fe)(PO4)7, (<< 0.1%). Shock melt pockets (4.8 6.7%) consist of green basaltic to basaltic andesite glass that is devitrified into a brown to black product along the boundaries to the primary minerals. The average maximum dimensions of minerals are: olivine (1.5 mm), pyroxene (0.3 mm) and maskelynite (0.3 mm). Melt inclusions in olivine are common and account for 0.1 0.6% of the rock. X-ray tomography revealed that the specimen contains approximately 0.4 vol% of shock-melt associated vesicles, up to 3 mm in size, which show a preferred orientation. Fluidization of the maskelynite, melting and recrystallization of pyroxene, olivine and pyrrhotite indicate shock stage S6. Terrestrial weathering resulted in calcite-veining and minor oxidation of sulfides. The modal composition is similar to some basaltic shergottites, with the exception that neither mesostasis nor titanomagnetite nor apatite are present and that all phases show little zonation. The restricted mineral composition, predominance of chromite among the oxides, and abundance of olivine indicate affinities to the ultramafic shergottites.

  20. Ni/S/Cl systematics and the origin of impact-melt glasses in Martian meteorite Elephant Moraine 79001

    NASA Astrophysics Data System (ADS)

    Schrader, Christian M.; Cohen, Barbara A.; Donovan, John J.; Vicenzi, Edward P.

    2016-04-01

    Martian meteorite 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 Martian 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 study 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 Martian 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.

  1. Meteorites

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter

    2015-08-01

    Meteorites 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 studies of meteorites 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 studies of freshly fallen meteorites. 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 meteorite consortium, which grew to over 50 researchers in the case of Chelyabinsk. New technologies were used to probe the organic content of the meteorites 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 meteorites 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 meteorite types will help tie meteorite types to their asteroid family source regions. Work so far suggests that future laboratory studies 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

  2. Bulk and Stable Isotopic Compositions of Carbonate Minerals in Martian Meteorite Allan Hills 84001: No Proof of High Formation Temperature

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Romanek, Christopher S.

    1998-01-01

    Understanding the origin of carbonate minerals in the Martian meteorite Allan Hills (ALH) 84001 is crucial to evaluating the hypothesis that they contain traces of ancient Martian life. Using arguments based on chemical equilibria among carbonates and fluids, an origin at greater than 650 C (inimical to life) has been proposed. However, the bulk and stable isotopic compositions of the carbonate minerals are open to multiple interpretations and so lend no particular support to a high-temperature origin. Other methods (possibly less direct) will have to be used to determine the formation temperature of the carbonates in ALH 84001.

  3. The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

    NASA Astrophysics Data System (ADS)

    Symes, Steven J. K.; Borg, Lars E.; Shearer, Charles K.; Irving, Anthony J.

    2008-03-01

    Samarium-neodymium isotopic analyses of unleached and acid-leached mineral fractions from the recently identified olivine-bearing shergottite Northwest Africa 1195 yield a crystallization age of 347 ± 13 Ma and an ɛNd143 value of +40.1 ± 0.9. Maskelynite fractions do not lie on the Sm-Nd isochron and appear to contain a martian surface component with low 147Sm/ 144Nd and 143Nd/ 144Nd ratios that was added during shock. The Rb-Sr system is disturbed and does not yield an isochron. Terrestrial Sr appears to have affected all of the mineral fractions, although a maximum initial 87Sr/ 86Sr ratio of 0.7016 is estimated by passing a 347 Ma reference line through the maskelynite fraction that is least affected by contamination. The high initial ɛNd143 value and the low initial 87Sr/ 86Sr ratio, combined with the geologically young crystallization age, indicate that Northwest Africa 1195 is derived from a source region characterized by a long-term incompatible-element depletion. The age and initial Sr and Nd isotopic compositions of Northwest Africa 1195 are very similar to those of Queen Alexandra Range 94201, indicating these samples were derived from source regions with similar Sr-Nd isotopic systematics. These similarities suggest that these two meteorites share a close petrogenetic relationship and might have been erupted from a common volcano. The meteorites Yamato 980459, Dar al Gani 476, Sayh al Uhaymir 005/008, and Dhofar 019 also have relatively old ages between 474 and 575 Ma and trace element and/or isotopic systematics that are indicative of derivation from incompatible-element-depleted sources. This suggests that the oldest group of meteorites is more closely related to one another than they are to the younger meteorites that are derived from less incompatible-element-depleted sources. Closed-system fractional crystallization of this suite of meteorites is modeled with the MELTS algorithm using the bulk composition of Yamato 980459 as a parent. These

  4. The Microbiological Contamination of Meteorites: A Null Hypothesis

    NASA Technical Reports Server (NTRS)

    Steele, A.; Toporski, J. K. W.; Westall, F. W.; Thomas-Keprta, K.; Gibson, E. K.; Avci, R.; Whitby, C.; McKay, D. S.; Griffin, C.

    2000-01-01

    Using 4 different techniques we have studied 9 meteorites including the Martian meteorites ALH84001 and Nakhla for terrestrial contamination in all 9 we have found evidence of terrestrial microorganisms.

  5. Chalcophile elements in Martian meteorites indicate low sulfur content in the Martian interior and a volatile element-depleted late veneer

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2017-04-01

    It is generally believed that the Martian mantle and core are rich in sulfur and that shergottites originated from sulfide-saturated magma. However, recent work suggests that the high FeO contents would require very high S concentrations in shergottite parent magmas at sulfide saturation. Here we combine new and published data on chalcophile elements in shergottites, nakhlites and ALH84001 to constrain the sulfide saturation state of the parent magmas and the chalcophile element concentrations in their mantle sources. Regardless of the MgO content and the long-term depletion history of incompatible lithophile elements as indicated by initial ε143Nd, different groups of shergottites display limited variations in ratios of Pt, Pd, Re, Cu, S, Se and Te. The emplacement of most shergottites within the crust and limited variations of ratios of chalcophile elements with substantial differences in volatility during eruption (e.g., Cu/S, Cu/Se and Pt/Re) indicate little degassing losses of S, Se, Te and Re from shergottites. Limited variations in ratios of elements with very different sulfide-silicate melt partition coefficients and negative correlations of chalcophile elements with MgO require a sulfide-undersaturated evolution of the parent magmas from mantle source to emplacement in the crust, consistent with the FeO-based argument. Sulfide petrography and the komatiite-like fractionation of platinum group elements (PGE) in shergottites also support this conclusion. The absence of accumulated sulfides in the ancient Martian cumulate ALH84001 results in very low contents of PGE, Re, Cu, Se and Te in this meteorite, hinting that sulfide-undersaturated magmas may have occurred throughout the Martian geological history. The negative correlation of Cu and MgO contents in shergottites suggests approximately 2 ± 0.4 (1s) μg/g Cu in the Martian mantle. The ratios of Cu, S, Se and Te indicate 360 ± 120 μg/g (1s) S, 100 ± 27 ng/g (1s) Se and 0.50 ± 0.25 ng/g (1s) Te in the

  6. Oxygen Isotopic Constraints on the Genesis of Carbonates from Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Leshin, Laurie A.; McKeegan, Kevin D.; Carpenter, Paul K.; Harvey, Ralph P.

    1998-01-01

    Ion microprobe oxygen isotopic measurements of a chemically diverse suite of carbonates from Martian meteorite ALH84001 are reported. The delta(sup 18)O values are highly variable, ranging from +5.4 to + 25.3%, and are correlated with major element compositions of the carbonate. The earliest forming (Ca-rich) carbonates have the lowest delta(sup 18)O values and the late-forming (Mg-rich) carbonates have the highest delta(sup 18)O values. Two models are presented which can explain the isotopic variations. The carbonates could have formed in a water rich environment at relatively low, but highly variable temperatures. In this open-system case the lower limit to the temperature variation is approx. 125 C, with fluctuations of over 250 C possible within the constraints of the model. Alternatively, the data can be explained by a closed-system model in which the carbonates precipitated from a limited amount of CO2-rich fluid. This scenario can reproduce the isotopic variations observed at a range of temperatures, including relatively high temperatures (less than 500 C). Thus the oxygen isotopic compositions do not provide unequivocal evidence for formation of the carbonates at low temperature. Although more information is needed in order to distinguish between the models, neither of the implied environments is consistent with biological activity. Thus, we suggest that features associated with the carbonates which have been interpreted to be the result of biological activity were most probably formed by inorganic processes.

  7. P Isotope Data of SNC Meteorites and Implications on the Age of the Martian Surface

    NASA Astrophysics Data System (ADS)

    Jagoutz, E.; Jotter, R.; Kubny, A.; Zartman, R.

    SNC meteorites might originate from the Martian surface. However, these meteorites have experienced a relative young metamorphosis which obscures their origin. Pb isotopes seem to be the best way to look through these young disturbances. A major fraction of the U and Th in the SNCs is not a primary constituent but was introduced at the time of disturbance and resides in the phosphates. By contrast, the Pb in the silicate minerals seems to have remained essentially in isotopic equilibration with the U and Th in the mineral since the time of original crystallization. The main cause of any scatter in the determined initial composition is probably due to the addition of terrestrial Pb, although some minor in situ isotopic disturbance cannot be ruled out. Our best values for the initial isotopic ratios of Shergotty, Zagami, and Los Angeles will be shown. The parent body formed and differentiated at 4.55 Ga, and the various meteorite source lithologies evolved isotopically undisturbed until 0.45 Ga (Los Angeles with a µ =238 U/204 Pb of ˜4, Zagami with a µ of ˜4.5, and Shergotty with a µ of ˜5). At ˜0.45 Ga the "young event" affected each of these meteorites and the initial Pb ratios, after being corrected for subsequent in situ growth of radiogenic Pb, are scattering on a fossilized 0.45 Ga geochron. Additional insight is gained from isotopic data for the Nakhlites, including several that have been newly found and analyzed. All Nakhlites appear to have been derived from an isotopic uniform reservoir, and share a well-defined "young event" age of 1.25 Ga. Of particular note is the fact that their initial Pb isotopic composition does not plot on the modern geochron, but instead to the right of it. If experiencing only a single stage evolution prior to 1.25 Ga, its initial Pb should actually plot on a fossilized 1.25 Ga geochron considerably to the left of the modern geochron. Only a relatively recent increase of the U/Pb ratio in the Nakhlite reservoir could

  8. Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits

    NASA Technical Reports Server (NTRS)

    Brandenburg, J. E.

    1993-01-01

    Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian 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 Martian 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

  9. Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. E.

    Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian 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 Martian 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

  10. A new Martian meteorite from Morocco: the nakhlite North West Africa 817

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Barrat, J. A.; Jambon, A.; Lorand, J. P.; Gillet, Ph.; Javoy, M.; Joron, J. L.; Lesourd, M.

    2002-02-01

    North West Africa (NWA 817) is a single stone of 104 g found in the Sahara (Morocco) by meteorite hunters in November 2000. The meteorite is an unbrecciated, medium-grained olivine-bearing clinopyroxenite with a cumulate texture. It consists of zoned euhedral subcalcic augite (Wo 42En 38-22Fs 20-36), olivine spanning a wide range of compositions (from Fa 56 in the core to Fa 86) with rare magmatic inclusions and an intercumulus mesostasis made of Fe-bearing albitic plagioclase, Si-rich glass, Ti-magnetite with unusual skeletal growth morphologies containing ilmenite exsolutions, acicular pyroxene, olivine and cristobalite. Trace minerals are sulfide droplets and Cl-apatite. Mineral modes (in vol%) are augite 69%, olivine 10%, mesostasis 20% and Fe-Ti oxides 1%. Pervasive alteration produced a reddish clay mineral (hydrous ferrous silicate) in both olivine crystals and the mesostasis. The major element composition of NWA 817 is very similar to that of the other nakhlites: high FeO, MgO and CaO concentrations reflect the abundance of cumulus augite and olivine. Key element ratios such as FeO/MnO (=37), Na/Al (=0.40), K/La (=449), Ga/Al (=3.9×10 -4) and oxygen isotopic composition (Δ 17O=+0.37‰) are clear evidence for a Martian origin. The incompatible trace element pattern as in Nakhla displays a strong light rare earth element enrichment relative to chondrite (La n/Yb n=4.89). However, when compared to the other nakhlites, NWA 817 has specific features: (1) a higher modal proportion of mesostasis; (2) quench textures of Ti-magnetite and Fe-rich clinopyroxene; (3) more Mg-rich olivine core compositions whereas the augite core composition is identical for all nakhlites; (4) a stronger Fe enrichment toward crystal rims of these cumulus minerals. The intercumulus minerals (Ti-magnetite with skeletal growth morphology, acicular chains of clinopyroxene and Fe 3+-rich feldspar) indicate rapid crystallization in response to a high degree of undercooling at the end of

  11. 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

  12. Significance of the cosmogenic argon correction in deciphering the 40Ar/39Ar ages of the Nakhlite (Martian) meteorites

    NASA Astrophysics Data System (ADS)

    Cohen, B. E.; Cassata, W.; Mark, D. F.; Tomkinson, T.; Lee, M. R.; Smith, C. L.

    2015-12-01

    All meteorites 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 meteorite fragment. However, if Cl is present in the meteorite, 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 Martian meteorites, which can contain over 1000 ppm Cl [1]. An alternative method for the cosmogenic Ar correction uses the meteorite'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 meteorites. [1] Cartwright J. A. et al. (2013) GCA, 105, 255-293. [2] Cassata W. S., and Borg L. E. (2015) 46th LPSC, Abstract #2742.

  13. 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.

  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. Cosmogenic Nuclides Study of Large Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Hutzler, A.; Smith, T.; Rochette, P.; Bourles, D. L.; Leya, I.; Gattacceca, J.

    2014-09-01

    Six large iron meteorites were selected (Saint-Aubin, Mont-Dieu, Caille, Morasko, Agoudal, and Gebel Kamil). We measured stable and radiogenic cosmogenic nuclides, to study pre-atmospheric size, cosmic-ray exposure ages and terrestrial ages.

  16. The variability of ruthenium in chromite from chassignite and olivine-phyric shergottite meteorites: New insights into the behavior of PGE and sulfur in Martian magmatic systems

    NASA Astrophysics Data System (ADS)

    Baumgartner, Raphael J.; Fiorentini, Marco L.; Baratoux, David; Ferrière, Ludovic; Locmelis, Marek; Tomkins, Andrew; Sener, Kerim A.

    2017-02-01

    The Martian meteorites comprise mantle-derived mafic to ultramafic rocks that formed in shallow intrusions and/or lava flows. This study reports the first in situ platinum-group element data on chromite and ulvöspinel from a series of dunitic chassignites and olivine-phyric shergottites, determined using laser-ablation ICP-MS. As recent studies have shown that Ru has strongly contrasting affinities for coexisting sulfide and spinel phases, the precise in situ analysis of this element in spinel can provide important insights into the sulfide saturation history of Martian mantle-derived melts. The new data reveal distinctive differences between the two meteorite groups. Chromite from the chassignites Northwest Africa 2737 (NWA 2737) and Chassigny contained detectable concentrations of Ru (up to 160 ppb Ru) in solid solution, whereas chromite and ulvöspinel from the olivine-phyric shergottites Yamato-980459 (Y-980459), Tissint, and Dhofar 019 displayed Ru concentrations consistently below detection limit (<42 ppb). The relatively elevated Ru signatures of chromite from the chassignites suggest a Ru-rich ( 1-4 ppb) parental melt for this meteorite group, which presumably did not experience segregation of immiscible sulfide liquids over the interval of mantle melting, melt ascent, and chromite crystallization. The relatively Ru-depleted signature of chromite and ulvöspinel from the olivine-phyric shergottites may be the consequence of relatively lower Ru contents (<1 ppb) in the parental melts, and/or the presence of sulfides during the crystallization of the spinel phases. The results of this study illustrate the significance of platinum-group element in situ analysis on spinel phases to decipher the sulfide saturation history of magmatic systems.

  17. Degradation studies of Martian impact craters

    NASA Technical Reports Server (NTRS)

    Barlow, N. G.

    1991-01-01

    The amount of obliteration suffered by Martian 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 studies performed on fresh Martian impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by Martian impact craters.

  18. Martian Volatiles and Isotopic Signatures

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    1997-01-01

    Data on martian volatiles gathered from Viking atmosphere measurements, modest groundbased spectra, shock-implanted atmospheric gases in martian (SNC) meteorites, trapped mantle gases in martian meteorites, and volatile-rich solid phases in martian meteorites, are presented. Atmospheric volatiles, surface volatiles, and isotopic chronologies are discussed, along with energetic particle interactions.

  19. 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].

  20. Hydrogeological Interpretation of Candidate Origin Sites for Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Gulick, Virginia C.; McKay, Chris; Cuzzi, Jeffrey N. (Technical Monitor)

    1996-01-01

    Barlow (this meeting) has identified two potential source craters for the martian meteorite 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

  1. A Parent Magma for the Nakhla Martian Meteorite: Reconciliation of Estimates from 1-Bar Experiments, Magmatic Inclusions in Olivine, and Magmatic Inclusions in Augite

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Goodrich, Cyrena Anne

    2001-01-01

    The composition of the parent magma for the Nakhla (martian) meteorite 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.

  2. Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: Implications for oxidants and organics

    NASA Astrophysics Data System (ADS)

    Kounaves, Samuel P.; Carrier, Brandi L.; O'Neil, Glen D.; Stroble, Shannon T.; Claire, Mark W.

    2014-02-01

    The results from the Viking mission in the mid 1970s provided evidence that the martian surface contained oxidants responsible for destroying organic compounds. In 2008 the Phoenix Wet Chemistry Lab (WCL) found perchlorate (ClO4-) in three soil samples at concentrations from 0.5 to 0.7 wt%. The detection of chloromethane (CH3Cl) and dichloromethane (CH2Cl2) by the Viking pyrolysis gas chromatograph-mass spectrometer (GC-MS) may have been a result of ClO4- at that site oxidizing either terrestrial organic contaminates or, if present, indigenous organics. Recently, the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) Curiosity directly measured the presence of CH3Cl, CH2Cl2 and, along with measurements of HCl and oxygen, indirectly indicate the presence of ClO4-. However, except for Phoenix, no other direct measurement of the ClO4- anion in martian soil or rock has been made. We report here ion chromatographic (IC) and isotopic analyses of a unique sawdust portion of the martian meteorite EETA79001 that show the presence by mass of 0.6 ± 0.1 ppm ClO4-, 1.4 ± 0.1 ppm ClO3-, and 16 ± 0.2 ppm NO3- at a quantity and location within the meteorite that is difficult to reconcile with terrestrial contamination. The sawdust sample consists of basaltic material with a minor salt-rich inclusion in a mass ratio of ∼300:1, thus the salts may be 300 times more concentrated within the inclusion than the whole sample. The molar ratios of NO3-:ClO4- and Cl:ClO4-, are very different for EETA79001 at ∼40:1 and 15:1, respectively, than the Antarctic soils and ice near where the meteorite was recovered at ∼10,000:1 and 5000:1, respectively. In addition, the isotope ratios for EETA79001 with δ15N = -10.48 ± 0.32‰ and δ18O = +51.61 ± 0.74‰ are significantly different from that of the nearby Miller Range blue ice with δ15N = +102.80 ± 0.14‰ and δ18O = +43.11 ± 0.64‰. This difference is notable, because if the meteorite had been

  3. Thirteen Iron Meteorites Found at Gale Crater, Meridiani Planum, and Gusev Crater — Exogenic Witnesses to Weathering Processes Near the Martian Equator

    NASA Astrophysics Data System (ADS)

    Ashley, J.

    2014-12-01

    At least 20 meteorites and meteorite candidates have now been found by science teams at three Mars rover landing sites, all within 15 degrees of the martian equator. Thirteen of these are iron meteorites, comprising 65% of the population — an order of magnitude greater abundance than found among witnessed iron falls in Earth-based collections (~6%). Chondritic meteorites, 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 martian 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 study 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

  4. The chlorine isotope composition of Martian meteorites 2. Implications for the early solar system and the formation of Mars

    NASA Astrophysics Data System (ADS)

    Sharp, Zachary; Williams, Jeffrey; Shearer, Charles; Agee, Carl; McKeegan, Kevin

    2016-11-01

    We determined the chlorine isotope composition of 16 Martian meteorites using gas source mass spectrometry on bulk samples and in situ secondary ion microprobe analysis on apatite grains. Measured δ37Cl values range from -3.8 to +8.6‰. The olivine-phyric shergottites are the isotopically lightest samples, with δ37Cl mostly ranging from -4 to -2‰. Samples with evidence for a crustal component have positive δ37Cl values, with an extreme value of 8.6‰. Most of the basaltic shergottites have intermediate δ37Cl values of -1 to 0‰, except for Shergotty, which is similar to the olivine-phyric shergottites. We interpret these data as due to mixing of a two-component system. The first component is the mantle value of -4 to -3‰. This most likely represents the original bulk Martian Cl isotope value. The other endmember is a 37Cl-enriched crustal component. We speculate that preferential loss of 35Cl to space has resulted in a high δ37Cl value for the Martian surface, similar to what is seen in other volatile systems. The basaltic shergottites are a mixture of the other two endmembers. The low δ37Cl value of primitive Mars is different from Earth and most chondrites, both of which are close to 0‰. We are not aware of any parent-body process that could lower the δ37Cl value of the Martian mantle to -4 to -3‰. Instead, we propose that this low δ37Cl value represents the primordial bulk composition of Mars inherited during accretion. The higher δ37Cl values seen in many chondrites are explained by later incorporation of 37Cl-enriched HCl-hydrate.

  5. Reassessing the cooling rate and geologic setting of Martian meteorites MIL 03346 and NWA 817

    NASA Astrophysics Data System (ADS)

    Richter, Frank; Chaussidon, Marc; Mendybaev, Ruslan; Kite, Edwin

    2016-06-01

    Lithium concentration and isotopic fractionation profiles across augite grains from two Martian meteorites - MIL 03346 and NWA 817 - were used to determine their thermal history and implications for their geologic setting. The iron-magnesium zoning and associated magnesium isotopic fractionation of olivine grains from NWA 817 were also measured and provide a separate estimate of the cooling rate. The observed correlation of concentration with isotopic fractionation provides the essential evidence that the zoning of these grains was in fact due to diffusion and thus can be used as a measure of their cooling rate. The diffusion rate of lithium in augite depends on the oxygen fugacity, which has to be taken into account when determining a cooling rate based on the lithium zoning. The Fe-Mg exchange in olivine is much less sensitive to oxygen fugacity, but it is significantly anisotropic and for this reason we determined the direction relative to crystallographic axes of the line along which the Fe-Mg zoning was measured. We found that the cooling rate of NWA 817 determined from the lithium zoning in augite grains and that based on the Fe-Mg zoning of olivines are in good agreement at an oxygen fugacity close to that of quartz-fayalite-magnetite oxygen buffer. The cooling rate of MIL 03346 was found to be resolvably faster than that of NWA 817 - of the order of 1 °C/h for the former and of the order of 0.2 °C/h for the latter. An important observation regarding the history of MIL 03346 and NWA 817 is that the lithium and Fe-Mg zoning are only observed where the augite or olivine is in contact with the mesostasis, which implies that they were already about 80% crystallized at the time diffusion began. The augite and olivine core compositions while very homogeneous are not in equilibrium with each other, which we interpret to imply that prior to the rapid cooling there must have been a protracted period of the order of years above the solidus, during which the much

  6. 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://adsabs.harvard.edu/abs/2011psrd.reptE.160T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011psrd.reptE.160T"><span>Formation of Carbonate Minerals in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH 84001 from Cool Water Near the Surface 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>Taylor, G. J.</p> <p>2011-12-01</p> <p>Carbonate minerals in the Allan Hills 84001 <span class="hlt">meteorite</span> are important because they ought to contain information about the chemistry and temperature of the water they formed in. They are also an important part of testing the idea that the <span class="hlt">meteorite</span> contains evidence of past life on Mars. Hypotheses for the origin of the carbonates are impressively varied. A key test of the ideas is to determine the temperature at which the carbonates formed. Estimates up to now range from a bit below freezing to 700 oC, too big a range to test anything! To address the problem Itay Halevy, Woodward Fischer, and John Eiler (Caltech) used an approach that involves "clumped" isotope thermometry, which makes comparisons among different isotopic compositions of extracted CO2. This allowed the investigators to use the isotopic abundances of both carbon and oxygen. The results indicate that the carbonates formed at 18 ± 4 oC from a shallow subsurface (upper few meters to tens of meters) pool of water that was gradually evaporating. The wet episode did not last long, leading Halevy and his colleagues to conclude that the environment may have been too transient for life to have emerged here from scratch. On the other hand, if life already existed on the <span class="hlt">Martian</span> surface this wet near-surface environment would have provided a happy home. An impact blasted the <span class="hlt">Martian</span> home of ALH 84001, causing a transient heating event, perhaps disturbing the isotopic record...or perhaps not because the event was so short. In any case, the clumped isotope thermometry approach seems to have given a good measurement of the temperature at which the carbonate minerals formed.</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://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/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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060013610&hterms=burial&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dburial','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060013610&hterms=burial&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dburial"><span>Mineralogy of nakhlite <span class="hlt">Martian</span> <span class="hlt">meteorites</span>: Implications for their relative burial depths</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mikouchi, T.; McKay, Gordon; Miyamoto, M.</p> <p>2006-01-01</p> <p>Nakhlites are <span class="hlt">Martian</span> cumulate rocks mainly composed of augite with variable amounts of olivine and groundmass (mesostasis). Currently seven samples are known: Nakhla (Nak), Governador Valadares (GV), Lafayette (Laf), NWA817, Y000593 (Y), NWA998 and MIL03346 (MIL). All the nakhlites show a similar unbrecciated cumulate texture, and their identical crystallization and exposure ages suggest that they originated from the same igneous body on Mars and were ejected by the same impact event. It is important to <span class="hlt">study</span> difference of their mineralogy to reconstruct the igneous body from which nakhlites originated. Augite grains in all nakhlites have a nearly identical core composition (En39Fs22Wo39) and have thin Fe-rich rims. These Fe-rich rims are zoned to Ca-poor pyroxene compositions and the degree of chemical zoning varies from one sample to another. NWA998 has the most Mg-rich edge composition. The edge composition becomes more Fe-rich in the order of Laf, Nak/GV, Y and NWA817. Unlike other samples, the Fe-rich edge of MIL augite is zoned to the hedenbergite composition. Olivine grains in all samples except Laf and NWA998 show extensive chemical zoning whose degree is clearly related to the chemical zoning of pyroxenes. MIL and NWA817 have the widest compositional ranges (Fa54-93). Y has a slightly narrower compositional range of Fa58-85. Nak and GV have even narrower ranges (Fa58-72). In contrast to these samples, olivines in Laf and NWA998 are homogeneous (Fa66-67 and Fa61-62, respectively). Such chemical zoning (Fa and Ca) can be used to quantitatively estimate their cooling rates (burial depths) because it was clearly formed by interaction with the intercumulus melt. The obtained burial depths are 1-2 m for NWA817, 4 m for MIL, 7 m for Y, approx.10 m for Nak and GV, and >30 m for Laf and NWA998. This order is clearly related to the degree of pyroxene chemical zoning. The abundance and mineralogy of nakhlite groundmass are also consistent with this order. In Nak, GV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/289430','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/289430"><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/scitech">SciTech Connect</a></p> <p>Thomas-Keprta, K.L.; Wentworth, S.J.; Allen, C.C.; McKay, D.S.; Gibson, E.K. Jr.; Stevens, T.O.; Taunton, A.E.; Coleman, A.; Romanek, C.S.</p> <p>1998-11-01</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, mineralized filaments are recognized in martial <span class="hlt">meteorite</span> ALH84001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30R.567R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30R.567R"><span>Carbon- and Sulfur-bearing Minerals in the <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> ALH 84001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romanek, C. S.; Thomas, K. L.; Gibson, E. K., Jr.; McKay, D. S.; Socki, R. A.</p> <p>1995-09-01</p> <p>Unusual carbonate minerals in ALH 84001 [1] provide insights into surficial processes that may have occurred on Mars, but despite detailed geochemical <span class="hlt">studies</span> [2-4] carbonate petrogenesis has yet to be fully-characterized. High-resolution TEM and SEM analyses were performed on C- and S-bearing mineral grains to better constrain the nature and timing of carbonate mineralization events. Morphological elements: C- and S-bearing minerals in ALH 84001 commonly occur as spheroidal aggregates or fine-grained vug-filling structures. Spheroids are either orange or black, ~150 micrometers (+/- 50 micrometers) in diameter and highly-flattened (10-30 micrometers thick). Orange spheroids have limpid amber-colored cores and white to translucent mantles which are sometimes bound by thin black rims (< 10 micrometers). When viewed under cathodoluminescence, cores are non-luminescent while mantles luminesce a uniform bright-orange color. Black spheroids are less frequently observed; while they are similar in dimension to the orange spheroids they are chemically more heterogeneous. Black irregular aggregates fill residual pore-space between mineral grains. These structures are comprised of extremely fine-grained (< 2 micrometers) material that occasionally forms lenticular stringers up to 50 micrometers in length. Chemistry and Mineralogy: Small grains (30 micrometers dia.) were removed from C- and S-bearing aggregates, microtomed (~100 nm thick) and examined by TEM for imaging, electron diffraction, and elemental analysis. The orange spheroids have cores composed of Fe-Mg-Ca carbonate, with the centers having the highest concentration of Fe (45 mol%) and Ca (15 mol%). The concentration of Mg increases outward to almost pure MgCO3. TEM results support previous analyses of carbonate chemistry [1-4] and clearly indicate that a wide range of Mg-Fe-Ca solid solution exists in carbonate at a scale of ~10 nm. White mantles of the orange spheroids are composed of nearly pure MgCO3 (<5 mol</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010045010&hterms=Evaporites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEvaporites','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010045010&hterms=Evaporites&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEvaporites"><span>Weathering of <span class="hlt">Martian</span> Evaporites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wentworth, S. J.; Velbel, M. A.; Thomas-Keprta, K. L.; Longazo, T. G.; McKay, D. S.</p> <p>2001-01-01</p> <p>Evaporites in <span class="hlt">martian</span> <span class="hlt">meteorites</span> contain weathering or alteration features that may provide clues about the <span class="hlt">martian</span> near-surface environment over time. Additional information is contained in the original extended abstract.</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/2060/20080026155','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/2060/20140011731','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011731"><span>Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Tissint and Petrogenesis of Depleted Shergottites</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.; Park, J.; Agee, Carl B.</p> <p>2014-01-01</p> <p>Tissint is a very fresh <span class="hlt">Martian</span> <span class="hlt">meteorite</span> 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 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> 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 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. 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 <span class="hlt">meteorite</span> 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.</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://hdl.handle.net/2060/20110007846','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007846"><span>Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; <span class="hlt">Martian</span> <span class="hlt">Meteorites</span>, Carbonaceous Chondrites and Standard Rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.</p> <p>2011-01-01</p> <p>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 <span class="hlt">Martian</span> 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 <span class="hlt">meteoritic</span> and planetary materials. We present here results for several standard rocks and <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.154...49L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.154...49L"><span>Formation of iddingsite veins in the <span class="hlt">martian</span> crust by centripetal replacement of olivine: Evidence from the nakhlite <span class="hlt">meteorite</span> Lafayette</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, M. R.; Tomkinson, T.; Hallis, L. J.; Mark, D. F.</p> <p>2015-04-01</p> <p>The Lafayette <span class="hlt">meteorite</span> is an olivine clinopyroxenite that crystallized on Mars ∼1300 million years ago within a lava flow or shallow sill. Liquid water entered this igneous rock ∼700 million years later to produce a suite of secondary minerals, collectively called 'iddingsite', that occur as veins within grains of augite and olivine. The deuterium/hydrogen ratio of water within these secondary minerals shows that the aqueous solutions were sourced from one or more near-surface reservoirs. Several petrographically distinct types of veins can be recognised by differences in their width, shape, and crystallographic orientation. Augite and olivine both contain veins of a very fine grained hydrous Fe- and Mg-rich silicate that are ∼1-2 μm in width and lack any preferred crystallographic orientation. These narrow veins formed by cementation of pore spaces that had been opened by fracturing and probably in response to shock. The subset of olivine-hosted veins whose axes lie parallel to (0 0 1) have serrated walls, and formed by widening of the narrow veins by interface coupled dissolution-precipitation. Widening started by replacement of the walls of the narrow precursor veins by Fe-Mg silicate, and a crystallographic control on the trajectory of the dissolution-precipitation front created micrometre-scale {1 1 1} serrations. The walls of many of the finely serrated veins were subsequently replaced by siderite, and the solutions responsible for carbonation of olivine also partially recrystallized the Fe-Mg silicate. Smectite was the last mineral to form and grew by replacement of siderite. This mineralization sequence shows that Lafayette was exposed to two discrete pulses of aqueous solutions, the first of which formed the Fe-Mg silicate, and the second mediated replacement of vein walls by siderite and smectite. The similarity in size, shape and crystallographic orientation of iddingsite veins in the Lafayette <span class="hlt">meteorite</span> and in terrestrial basalts demonstrates a</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/2015M%26PS...50..326W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50..326W"><span>Petrography and composition of <span class="hlt">Martian</span> regolith breccia <span class="hlt">meteorite</span> Northwest Africa 7475</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmann, Axel; Korotev, Randy L.; Jolliff, Bradley L.; Irving, Anthony J.; Moser, Desmond E.; Barker, Ivan; Rumble, Douglas</p> <p>2015-02-01</p> <p>The Northwest Africa (NWA) 7475 <span class="hlt">meteorite</span> is one of the several stones of paired regolith breccias from Mars based on petrography, oxygen isotope, mineral compositions, and bulk rock compositions. Its inventory of lithic clasts is dominated by vitrophyre impact melts that were emplaced while they were still molten. Other clast types include crystallized impact melt rocks, evolved plutonic rocks, possible basalts, contact metamorphosed rocks, and siltstones. Impact spherules and vitrophyre shards record airborne transport, and accreted dust rims were sintered on most clasts, presumably during residence in an ejecta plume. The clast assemblage records at least three impact events, one that formed an impact melt sheet on Mars ≤4.4 Ga ago, a second that assembled NWA 7475 from impactites associated with the impact melt sheet at 1.7-1.4 Ga, and a third that launched NWA 7475 from Mars ~5 Ma ago. Mildly shocked pyroxene and plagioclase constrain shock metamorphic conditions during launch to >5 and <15 GPa. The mild postshock-heating that resulted from these shock pressures would have been insufficient to sterilize this water-bearing lithology during launch. Magnetite, maghemite, and pyrite are likely products of secondary alteration on Mars. Textural relationships suggest that calcium-carbonate and goethite are probably of terrestrial origin, yet trace element chemistry indicates relatively low terrestrial alteration. Comparison of Mars Odyssey gamma-ray spectrometer data with the Fe and Th abundances of NWA 7475 points to a provenance in the ancient southern highlands of Mars. Gratteri crater, with an age of ~5 Ma and an apparent diameter of 6.9 km, marks one possible launch site of NWA 7475.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=Allan&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAllan','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010035473&hterms=Allan&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAllan"><span>Olivine in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Allan Hills 84001: Evidence for a High-Temperature Origin and Implications for Signs of Life</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.; Leshin, L. A.; Adcock, C. T.</p> <p>1999-01-01</p> <p>Olivine from <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001 occurs as clusters within orthopyroxene adjacent to fractures containing disrupted carbonate globules and feldspathic shock glass. The inclusions are irregular in shape and range in size from approx. 40 microns to submicrometer. Some of the inclusions are elongate and boudinage-like. The olivine grains are in sharp contact with the enclosing orthopyroxene and often contain small inclusions of chromite The olivine exhibits a very limited range of composition from Fo(sub 65) to Fo(sub 66) (n = 25). The delta(sup 18)O values of the olivine and orthopyroxene analyzed by ion microprobe range from +4.3 to +5.3% and are indistinguishable from each other within analytical uncertainty. The mineral chemistries, O-isotopic data, and textural relationships indicate that the olivine inclusions were produced at a temperature greater than 800 C. It is unlikely that the olivines formed during the same event that gave rise to the carbonates in ALH 84001, which have more elevated and variable delta(sup 18)O values, and were probably formed from fluids that were not in isotopic equilibrium with the orthopyroxene or olivine The reactions most likely instrumental in the formation of olivine could be either the dehydration of hydrous silicates that formed during carbonate precipitation or the reduction of orthopyroxene and spinel If the olivine was formed by either reaction during a postcarbonate beating event, the implications are profound with regards to the interpretations of McKay et al. Due to the low diffusion rates in carbonates, this rapid, high-temperature event would have resulted in the preservation of the fine-scale carbonate zoning' while partially devolatilizing select carbonate compositions on a submicrometer scale. This may have resulted in the formation of the minute magnetite grains that McKay et al attributed to biogenic activity.</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=19910041576&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthermoluminescence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910041576&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthermoluminescence"><span>Metamorphism of eucrite <span class="hlt">meteorites</span> <span class="hlt">studied</span> quantitatively using induced thermoluminescence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Batchelor, J. David; Sears, Derek W. G.</p> <p>1991-01-01</p> <p>Induced thermoluminescence <span class="hlt">studies</span> provide a new and quantitative means of determining relative metamorphic intensities for eucrite <span class="hlt">meteorites</span>, the simplest and most ancient products of basaltic volcanism. Using this technique, it is shown that the eucrites constitute a continuous metamorphic series and not, as commonly assumed, two groups of metamorphosed and nonmetamorphosed <span class="hlt">meteorites</span>. It is suggested that the method may have applications to other basalts.</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://adsabs.harvard.edu/abs/2002M%26PS...37..835G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002M%26PS...37..835G"><span>Sayh al Uhaymir 094: A new <span class="hlt">martian</span> <span class="hlt">meteorite</span> from the Oman desert</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gnos, E.; Hofmann, B.; Franchi, I. A.; Al-Kathiri, A.; Hauser, M.; Moser, L.</p> <p>2002-06-01</p> <p>Sayh al Uhaymir (SaU) 094 is a 223.3 g, partially crusted, strongly to very strongly shocked melanocratic olivine-porphyric rock of the shergottite group showing a microgabbroic texture. The rock consists of pyroxene (52.0-58.2 vol%)-dominantly prismatic pigeonite (En60-68Fs20-27Wo7-9) associated with minor augite (En46-49Fs15-16Wo28-31)-brown (shock-oxidized) olivine (Fo65-69; 22.1-31%), completely isotropic interstitial plagioclase glass (maskelynite; An50-64Or0.3-0.9; 8.6-13.0%), chromite and titanian magnesian chromite (0.9-1.0%), traces of ilmenite (Ilm80-86), pyrrhotite (Fe92-100; 0.1-0.2%), merrillite (<<0.1%), and pockets (4.8-6.7%) consisting of green basaltic to basaltic andesitic shock glass that is partially devitrified into a brown to black product along boundaries with the primary minerals. The average maximum dimensions of minerals are: olivine (1.5 mm), pyroxene (0.3 mm) and maskelynite (0.3 mm). Primary melt inclusions in olivine and chromite are common and account for 0.1-0.6% of the rock. X-ray tomography revealed that the specimen contains ~0.4 vol% of shock-melt associated vesicles, up to 3 mm in size, which show a preferred orientation. Fluidization of the maskelynite, melting and recrystallization of pyroxene, olivine and pyrrhotite indicate shock stage S6. Minor terrestrial weathering resulted in calcite-veining and minor oxidation of sulfides. The <span class="hlt">meteorite</span> is interpreted as paired with SaU 005/008/051. The modal composition is similar to Dar al Gani 476/489/670/735/876, with the exception that neither mesostasis nor titanomagnetite nor apatite are present and that all phases show little zonation. The restricted mineral composition, predominance of chromite among the oxides, and abundance of olivine indicate affinities to the lherzolitic shergottites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..493L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..493L"><span>The Ksar Ghilane 002 shergottite—The 100th registered <span class="hlt">Martian</span> <span class="hlt">meteorite</span> fragment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Llorca, Jordi; Roszjar, Julia; Cartwright, Julia A.; Bischoff, Addi; Ott, Ulrich; Pack, Andreas; Merchel, Silke; Rugel, Georg; Fimiani, Leticia; Ludwig, Peter; Casado, José V.; Allepuz, David</p> <p>2013-03-01</p> <p>We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse-grained basaltic shergottite, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe-rich olivine (approximately 4.5 vol%), large Ca-phosphates, including both merrillites and Cl-apatites (approximately 3.4 vol%), minor amounts of silica or SiO2-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26-96En5-50Wo2-41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41-49An39-58Or1-7 in composition, but some can be as anorthitic as An93. Olivine (Fa91-96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for <span class="hlt">Martian</span> interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35-65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography, and mineral chemistry, suggesting a possible launch-pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000004369&hterms=dinosaur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddinosaur','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000004369&hterms=dinosaur&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddinosaur"><span><span class="hlt">Meteorites</span> and the Evolution of Our Solar System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nava, David F.</p> <p>1999-01-01</p> <p>The <span class="hlt">study</span> of <span class="hlt">meteorites</span> has long been of intense interest ever since these objects were discovered to be of extraterrestrial origin. <span class="hlt">Meteorite</span> research contributes to unraveling the mysteries in understanding the formation and evolution processes of our solar system. <span class="hlt">Meteorites</span>, 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 <span class="hlt">studied</span> 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 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, lunar <span class="hlt">meteorites</span>, a <span class="hlt">meteorite</span> containing indigenous water, and the recovery from the Cretaceous layer of a small <span class="hlt">meteorite</span> fragment thought to be from the dinosaur-killing asteroid have fueled additional excitement for <span class="hlt">studying</span> <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=mars+AND+investigation&pg=2&id=ED248165','ERIC'); return false;" href="http://eric.ed.gov/?q=mars+AND+investigation&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://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.; Nyquist, L.; Park, J.; Peng, Z. X.; Shih, C.-Y.; Simon, J. I.; Zeigler, R. A.</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=20030110601&hterms=clean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclean','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030110601&hterms=clean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclean"><span>Comparison of Synchrotron MicroXANES Determination of Fe(3+)/Sigma Fe with Moessbauer Values for Clean Mineral Separates of Pyroxene from <span class="hlt">Martian</span> <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>Delaney, J. S.; Dyar, M. D.</p> <p>2003-01-01</p> <p>The oxidation state of Fe in <span class="hlt">Martian</span> <span class="hlt">meteorites</span> is a parameter of great interest and the ability to determine this value in micrometer scale samples is important. Intense, tunable x-ray sources at large synchrotron storage rings are being exploited to examine the Fe K-absorption edge with energy resolution of approx. 1-1.5eV in spots of 10x15 microns on thin sections of a wide variety of materials including several <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. Synchrotron microXANES (SmX) spectroscopy is the technique that provides the most flexible capability for investigating Fe(3+)/Sigma Fe. Variation of Fe(3+)/Sigma Fe is manifested as a function of the energy of the pre-edge to the Fe absorption edge produced by the sample. SmX is at present the only technique that can be used with conventional polished thin sections. Data for a broad spectrum of minerals have been produced and indicate that SmX can be used with a large variety of samples types.</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('https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=fusion+crust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfusion%2Bcrust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850007298&hterms=fusion+crust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfusion%2Bcrust"><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('https://www.osti.gov/scitech/biblio/7242171','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7242171"><span><span class="hlt">Meteoritic</span> basalts. Final report, 1986-1989</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Treiman, A.H.</p> <p>1989-10-01</p> <p>The objectives were to: explain the abundances of siderophile elements in the SNC <span class="hlt">meteorite</span> suite, of putative <span class="hlt">Martian</span> origin; discover the magmatic origins and possibly magma compositions behind the Nakhla <span class="hlt">meteorite</span>, one of the SNC <span class="hlt">meteorites</span>; and a re-evaluation of the petrology of Angra dos Reis, a unique <span class="hlt">meteorite</span> 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 <span class="hlt">meteorite</span>'s textures (Treiman). More likely is that the <span class="hlt">meteorite</span> represents a prophyritic igneous rock, originally with magma dominant. <span class="hlt">Studies</span> of the Nakhla <span class="hlt">meteorite</span>, of possible <span class="hlt">Martian</span> origin, although difficult, were successful. It became necessary to reject the basic categorization of Nakhla: that is was a cumulate igneous rock. Detailed <span class="hlt">studies</span> of the chemical zoning of Nakhlas' minerals, coupled with the failure of experimental <span class="hlt">studies</span> 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. <span class="hlt">Study</span> of the siderophile element abundances in the SNC <span class="hlt">meteorite</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780060590&hterms=martensitic+transformation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmartensitic%2Btransformation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780060590&hterms=martensitic+transformation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmartensitic%2Btransformation"><span>A microstructural <span class="hlt">study</span> of the Tishomingo <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>Ives, L. K.; Kasen, M. B.; Schramm, R. E.; Ruff, A. W.; Reed, R. P.</p> <p>1978-01-01</p> <p>Metallography, electron microscopy, and X-ray diffraction techniques were employed to <span class="hlt">study</span> a fragment of the Tishomingo iron <span class="hlt">meteorite</span>. The results suggest the following thermal-mechanical history: The fragment was originally a large crystal of taenite (gamma). Cooling through the alpha + gamma phase boundary did not result in accompanying precipitation of kamacite (alpha). Transformation to a martensitic structure initiated between -25 and -65 C. Transformation continued as the temperature fell to -75 to -115 C, resulting in approx 80% martensite (alpha-prime). Subsequent shock deformation and thermal aging processes substantially modified the taenite and martensite microstructures. Twins in the retained taenite phase are attributed to shock deformation at a pressure estimated for a single event at about 170 kbar. The existing complex altered martensite structure containing both taenite and kamacite (3-15% Ni) particles was apparently the product of both shock deformation and thermal aging processes. The maximum temperature reached during thermal aging is estimated to be less than 400 C and perhaps below 310 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990027237','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990027237"><span><span class="hlt">Studies</span> of the <span class="hlt">Martian</span> Magnetic Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.</p> <p>1998-01-01</p> <p>This report covers two awards: the first NAGW-2573 was awarded to enable participation in the Mars 94 mission that slipped to become the Mars 96 mission. Upon the unfortunate failure of Mars 96 to achieve its intended trajectory, the second grant was awarded to closeout the Mars 96 activities. Our initial efforts concentrated on assisting our colleagues: W. Riedler, K. Schwingenschuh, K. Gringanz, M. Verigin and Ye. Yeroshenko with advice on the development of the magnetic field portion of the investigation and to help them with test activities. We also worked with them to properly analyze the Phobos magnetic field and plasma data in order to optimize the return from the Mars 94/96 mission. This activity resulted in 18 papers on Mars scientific topics, and two on the instrumentation. One of these latter two papers was the last of the papers written, and speaks to the value of the closeout award. These 20 papers are listed in the attached bibliography. Because we had previously <span class="hlt">studied</span> Venus and Titan and since it was becoming evident that the magnetic field was very weak, we compared the various properties of the <span class="hlt">Martian</span> interaction with those of the analogous interactions at Venus and Titan while other papers simply analyzed the properties of the interaction as Phobos 2 observed them. One very interesting observation was the identification of ions picked up in the solar wind, originating in Mars neutral atmosphere. These had been predicted by our earlier observation of cyclotron waves at the proton gyrofrequency in the region upstream from Mars in the solar wind. Of course, the key question we addressed was that of the intrinsic or induced nature of the <span class="hlt">Martian</span> magnetic field. We found little evidence for the former and much for the latter point of view. We also discussed the instrumentation planned for the Mars balloon and the instrumentation on the orbiter. In all these <span class="hlt">studies</span> were very rewarding despite the short span of the Phobos data. Although they did not</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/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('http://adsabs.harvard.edu/abs/2014AGUFM.P54B..06G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P54B..06G"><span>Comparison of Laser Induced Breakdown Spectroscopy (LIBS) on <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> NWA 7034 to ChemCam Observations at Gale Crater, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gordon, S.; Newsom, H. E.; Agee, C. B.; Santos, A. R.; Clegg, S. M.; Wiens, R. C.; Lasue, J.; Sautter, V.</p> <p>2014-12-01</p> <p>The ChemCam instrument on board the Mars Science Laboratory (MSL) Curiosity rover uses laser-induced breakdown spectroscopy (LIBS) to analyze rock and soil targets on Mars from up to 7 m away. The Nd:KGW laser can shoot up to 1000 shots at one location and profile up to 1 mm depth into a rock. Identical LIBS instrumentation is located at Los Alamos National Laboratory and was used to analyze <span class="hlt">martian</span> <span class="hlt">meteorite</span> NWA 7034, a non-SNC basaltic breccia whose bulk composition matches the <span class="hlt">martian</span> surface. Initial LIBS analysis of NWA 7034 included observations on two basaltic clasts in the <span class="hlt">meteorite</span>. Electron microprobe analysis (EPMA) was performed on the two clasts for comparison with elemental compositions measured using LIBS. The two instruments give similar compositions of major oxides within the error of both techniques. EPMA analysis was also completed on three light-toned clasts and a dark-toned clast in the <span class="hlt">meteorite</span>. The light-toned clasts have Al/Si vs. (Fe+Mg)/Si compositions ranging from felsic to mafic, and the dark-toned clast shows a mafic composition. A Sammon's map was created to compare LIBS data for NWA 7034 and ChemCam targets Stark, Crestaurum, Link, Portage, Jake_M, Mara, Thor_Lake, Coronation, Pearson, and Prebble. This nonlinear statistical mapping technique is used for clustering assessment of LIBS data in two dimensions. The map shows NWA 7034 clustering in its own location, and the closest similar ChemCam rock targets are La_Reine and Ashuamipi, which are both coarse grained targets that have a mafic component consistent with augite. The most similar ChemCam soil targets are the Crestaurum and Portage. Creation of maps with a greater number of targets will show more of the similarities between NWA 7034 and ChemCam target rocks and soils. Further analysis will compare NWA 7034 LIBS data, data from the paired <span class="hlt">meteorite</span> NWA 7533, and a variety of ChemCam targets that are similar in morphology and texture.</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> </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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343502','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343502"><span>Shock-transformation of whitlockite to merrillite and the implications for <span class="hlt">meteoritic</span> phosphate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>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.</p> <p>2017-01-01</p> <p><span class="hlt">Meteorites</span> represent the only samples available for <span class="hlt">study</span> on Earth of a number of planetary bodies. The minerals within <span class="hlt">meteorites</span> 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 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been interpreted as evidence of water-limited late-stage <span class="hlt">Martian</span> melts. However, recent research on apatite in the same <span class="hlt">meteorites</span> suggests higher water content in melts. One complication of using <span class="hlt">meteorites</span> rather than direct samples is the shock compression all <span class="hlt">meteorites</span> have experienced, which can alter <span class="hlt">meteorite</span> mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The results open the possibility that at least part of <span class="hlt">meteoritic</span> merrillite may have originally been H+-bearing whitlockite with implications for interpreting <span class="hlt">meteorites</span> and the need for future sample return. PMID:28262701</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814667A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814667A"><span>Shock-transformation of whitlockite to merrillite and the implications for <span class="hlt">meteoritic</span> phosphate</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.; Tschauner, O.; Hausrath, E. M.; Udry, A.; Luo, S. N.; Cai, Y.; Ren, M.; Lanzirotti, A.; Newville, M.; Kunz, M.; Lin, C.</p> <p>2017-03-01</p> <p><span class="hlt">Meteorites</span> represent the only samples available for <span class="hlt">study</span> on Earth of a number of planetary bodies. The minerals within <span class="hlt">meteorites</span> 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 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> has been interpreted as evidence of water-limited late-stage <span class="hlt">Martian</span> melts. However, recent research on apatite in the same <span class="hlt">meteorites</span> suggests higher water content in melts. One complication of using <span class="hlt">meteorites</span> rather than direct samples is the shock compression all <span class="hlt">meteorites</span> have experienced, which can alter <span class="hlt">meteorite</span> mineralogy. Here we show whitlockite transformation into merrillite by shock-compression levels relevant to <span class="hlt">meteorites</span>, including <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. The results open the possibility that at least part of <span class="hlt">meteoritic</span> merrillite may have originally been H+-bearing whitlockite with implications for interpreting <span class="hlt">meteorites</span> and the need for future sample return.</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('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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228422','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228422"><span>Combining <span class="hlt">meteorites</span> and missions to explore Mars</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McCoy, Timothy J.; Corrigan, Catherine M.; Herd, Christopher D. K.</p> <p>2011-01-01</p> <p>Laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> 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 <span class="hlt">martian</span> origin came with the discovery of trapped atmospheric gases in one <span class="hlt">meteorite</span>. Since then, the <span class="hlt">study</span> of <span class="hlt">martian</span> <span class="hlt">meteorites</span> and findings from missions have been linked. Although the <span class="hlt">meteorite</span> 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 <span class="hlt">martian</span> <span class="hlt">meteorites</span> 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 <span class="hlt">martian</span> <span class="hlt">meteorites</span> conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the <span class="hlt">meteorites</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21969535','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21969535"><span>Combining <span class="hlt">meteorites</span> and missions to explore Mars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCoy, Timothy J; Corrigan, Catherine M; Herd, Christopher D K</p> <p>2011-11-29</p> <p>Laboratory <span class="hlt">studies</span> of <span class="hlt">meteorites</span> 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 <span class="hlt">martian</span> origin came with the discovery of trapped atmospheric gases in one <span class="hlt">meteorite</span>. Since then, the <span class="hlt">study</span> of <span class="hlt">martian</span> <span class="hlt">meteorites</span> and findings from missions have been linked. Although the <span class="hlt">meteorite</span> 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 <span class="hlt">martian</span> <span class="hlt">meteorites</span> 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 <span class="hlt">martian</span> <span class="hlt">meteorites</span> conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the <span class="hlt">meteorites</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940020876','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940020876"><span>A geochemical <span class="hlt">study</span> of acapulcoite and lodranite <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>Field, Stephen W.</p> <p>1993-01-01</p> <p>Lodranites and acapulcoites (primitive achondrites) are two classes of <span class="hlt">meteorites</span> with geochemical signatures similar to chondrite <span class="hlt">meteorites</span>. Lodranites and acapulcoites, however, have few or none of the chondrules characteristic of the chondrites. Texturally the primitive achondrites appear to have been recystallized though planetary igneous or metamorphic processes. A <span class="hlt">study</span> of five primitive achondrites, two lodranites, two acapulcoites, and one supposedly intermediate acapulcoite/lodranite, were analyzed petrographically and geochemically to determine the igneous and metamorphic processes which have affected them. Acapulcoites show little evidence of melt extraction. The geochemistry of lodranite samples indicates silicate and metal/sulfide melts were removed from the rocks. The mineralogy and geochemistry of the intermediate <span class="hlt">meteorite</span> suggest the rock is a metal rich acapulcoite and not a lodranite.</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/2016LPICo1921.6557O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6557O"><span><span class="hlt">Study</span> of the Circumstance of <span class="hlt">Meteorites</span> "Northwest Africa" Finds Contribution to an Appropriate Renomenclature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouknine, L.; Kliri, F.; Ibhi, A.</p> <p>2016-08-01</p> <p>This work tries to respond to solicitations from researchers of the region to highlight the <span class="hlt">meteorites</span> recovered in Morocco and neighboring countries. The objectives assigned to this <span class="hlt">study</span> are the contextualization of the finds of <span class="hlt">meteorites</span> NWA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.1010P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.1010P"><span>Experimental <span class="hlt">Martian</span> Eclogite with a QUE 94201 Composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Papike, J. J.; Burger, P. V.; Shearer, C. K.; McCubbin, F. M.; Elardo, S. M.</p> <p>2012-03-01</p> <p>High-pressure techniques were used to synthesize a <span class="hlt">martian</span> eclogite based on the composition of <span class="hlt">martian</span> <span class="hlt">meteorite</span> QUE 94201. The resultant eclogite may be representative of <span class="hlt">martian</span> melts whose ascent has been arrested in the upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, D. S.; Jnes, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. These efforts have been motivated by reports of redox variations among the shergottites . We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt rare earth element partitioning as a function of fO2.</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> <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://adsabs.harvard.edu/abs/2000psrd.reptE..39T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000psrd.reptE..39T"><span>Liquid Water on Mars: The Story from <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>Taylor, G. J.</p> <p>2000-05-01</p> <p>Two <span class="hlt">studies</span> shed light on the nature and timing of alteration by water of rocks from Mars. One is an experimental <span class="hlt">study</span> of the alteration of a rock similar to <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, conducted by Leslie Baker, Deborah Agenbroad, and Scott Wood (University of Idaho). They exposed crushed pieces of terrestrial lava flows to water at 23 C and 75 C and normal atmospheric pressure, and to hot water at 200 C to 400 C and a pressure 1000 times normal atmospheric to see what minerals would form. On the basis of a detailed comparison between the experimental products and the <span class="hlt">Martian</span> <span class="hlt">meteorites</span> Baker and colleagues conclude that the rocks from which <span class="hlt">Martian</span> <span class="hlt">meteorites</span> derived were intermittently exposed to water or water vapor; they were not exposed for a long time to large volumes of water. In an independent <span class="hlt">study</span>, a team led by Tim Swindle (University of Arizona) tried to determine the time of formation of a reddish-brown alteration product in the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Lafayette. This <span class="hlt">meteorite</span> appears to have formed from magma 1.3 billion years ago, but the rusty-looking weathering product, a mixture of clay minerals, iron oxide, and iron hydride, formed long after the original rock had crystallized. Although the precise time is not pinned down, their measurements indicate formation during the past 650 million years. Taken together, these <span class="hlt">studies</span> suggest that water flowed intermittently on the surface of Mars during the past 650 million years.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842"><span>Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowüstite in a shocked <span class="hlt">Martian</span> <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo</p> <p>2011-01-01</p> <p>We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa34-41) adjacent to or entrained in the shock melt vein and melt pockets of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO3 perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO3 Pv and Mw have 50–100 nm in diameter, and lamellar (Mg,Fe)SiO3 Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, KPv/Mw = [FeO/MgO]/[FeO/MgO]Mw, between (Mg,Fe)SiO3 Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700 °C at least. PMID:21444781</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://adsabs.harvard.edu/abs/2016M%26PS...51..407W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..407W"><span>Noble gases in 18 <span class="hlt">Martian</span> <span class="hlt">meteorites</span> and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in shergottites and other achondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wieler, R.; Huber, L.; Busemann, H.; Seiler, S.; Leya, I.; Maden, C.; Masarik, J.; Meier, M. M. M.; Nagao, K.; Trappitsch, R.; Irving, A. J.</p> <p>2016-02-01</p> <p>We present noble gas data for 16 shergottites, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the shergottites fall in the 1-6 Ma range found in previous <span class="hlt">studies</span>. Three depleted olivine-phyric shergottites (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9-13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event. A Tissint glass sample contains Xe from the <span class="hlt">Martian</span> atmosphere. Several samples show a remarkably low (21Ne/22Ne)cos ratio < 0.80, as previously observed in a many shergottites and in various other rare achondrites. This was explained by solar cosmic ray-produced Ne (SCR Ne) in addition to the commonly found galactic cosmic ray-produced Ne, implying very low preatmospheric shielding and ablation loss. We revisit this by comparing measured (21Ne/22Ne)cos ratios with predictions by cosmogenic nuclide production models. Indeed, several shergottites, acalpulcoites/lodranites, angrites (including NWA 7812), and the Brachina-like <span class="hlt">meteorite</span> LEW 88763 likely contain SCR Ne, as previously postulated for many of them. The SCR contribution may influence the calculation of exposure ages. One likely reason that SCR nuclides are predominantly detected in <span class="hlt">meteorites</span> from rare classes is because they usually are analyzed for cosmogenic nuclides even if they had a very small (preatmospheric) mass and hence low ablation loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011psrd.reptE.155M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011psrd.reptE.155M"><span>Timeline of <span class="hlt">Martian</span> Volcanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martel, L. M. V.</p> <p>2011-05-01</p> <p>A recent <span class="hlt">study</span> of <span class="hlt">Martian</span> volcanism presents a timeline of the last major eruptions from 20 large volcanoes, based on the relative ages of caldera surfaces determined by crater counting. Stuart Robbins, Gaetano Di Achille, and Brian Hynek (University of Colorado) counted craters on high-resolution images from the the Context Camera (CTX) on Mars Reconnaissance Orbiter to date individual calderas, or terraces within calderas, on the 20 major <span class="hlt">Martian</span> volcanoes. Based on their timeline and mapping, rates and durations of eruptions and transitions from explosive to effusive activity varied from volcano to volcano. The work confirms previous findings by others that volcanism was continuous throughout <span class="hlt">Martian</span> geologic history until about one to two hundred million years ago, the final volcanic events were not synchronous across the planet, and the latest large-scale caldera activity ended about 150 million years ago in the Tharsis province. This timing correlates well with the crystallization ages (~165-170 million years) determined for the youngest basaltic <span class="hlt">Martian</span> <span class="hlt">meteorites</span>.</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> </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://adsabs.harvard.edu/abs/1996LPI....27..705K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..705K"><span>QUE94201, a New <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> that May Represent a Bulk Melt Rather than a Cumulate Fraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kring, D. A.; Gleason, J. D.; Hill, D. H.; Jull, A. J. T.; Boynton, W. V.</p> <p>1996-03-01</p> <p>QUE94201 is a new mafic achondrite dominated by pyroxene and plagioclase. Petrologic and geochemical analyses of a bulk chip (,16) and thin-section (,7) indicate the sample is a basaltic gabbro that is related to previously described basaltic and lherzolitic shergottites of suspected <span class="hlt">martian</span> origin. However, unlike the cumulate fractions represented by other shergottites, QUE94201 is a plutonic rock that fractionally crystallized in what appears (petrographically) to be a closed system. QUE94201 contains more Fe-rich pyroxene and more bulk Al, Ti, and P than other shergottites, including lithology B of EETA79001, and thus appears to be more evolved. However, QUE94201 is also more LREE-depleted than other shergottites which suggests it has not assimilated as much of the LREE-enriched mantle component thought to have affected the compositions of other shergottites.</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/2060/19800023802','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800023802"><span>Mineralogic and petrologic <span class="hlt">studies</span> of lunar samples 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>Wood, J. A.</p> <p>1980-01-01</p> <p>Experimental and thermodynamic research on the pressure temperature limits of the stability of the mineral assemblages found in pristine, spinel bearing lunar highland lithologies demonstrated the likelihood that the minerals originated in the lower stratigraphic levels of the primordial crust. The phase equilibrium in silicate solid/liquid systems of planetary importance were thermochemically interpreted in order to model the early formation of the crusts and maneles of Earth and Moon sized planets. The petrography and chemical composition of coarse grained gabbro, the chemical analysis and age dating of clasts from Apollo 16 breccia, the analysis of glass particles from Apollo 16 soil samples, the <span class="hlt">study</span> of Allende and Mokoia <span class="hlt">meteorites</span> as a source of information about events in the solar nebula, and the hydrothermal alteration of amorphous materials were also investigated. The capabilities of a model for addressing the problem of the origin of the Earth's moon by the disruptive capture mechanism are examined as well as models of the thermal evolution of hypothetical <span class="hlt">meteorite</span> bodies. Progress in determining the composition of stony <span class="hlt">meteorite</span> specimens collected at the Allan Hills site during the Antarctic field exploration is reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=visible+spectroscopy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvisible%2Bspectroscopy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111247&hterms=visible+spectroscopy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvisible%2Bspectroscopy"><span>Lunar Mare Basalts as Analogues for <span class="hlt">Martian</span> Volcanic Compositions: Evidence from Visible, Near-IR, and Thermal Emission Spectroscopy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Graff, T. G.; Morris, R. V.; Christensen, P. R.</p> <p>2003-01-01</p> <p>The lunar mare basalts potentially provide a unique sample suite for understanding the nature of basalts on the <span class="hlt">martian</span> surface. Our current knowledge of the mineralogical and chemical composition of the basaltic material on Mars comes from <span class="hlt">studies</span> of the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> and from orbital and surface remote sensing observations. Petrographic observations of basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> (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 <span class="hlt">meteorites</span> [4,5]. Furthermore, lunar basalts may be mineralogically better suited as analogues of the <span class="hlt">martian</span> surface basalts than the basaltic <span class="hlt">martian</span> <span class="hlt">meteorites</span> because the plagioclase feldspar in the basaltic <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 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 <span class="hlt">martian</span> thermal emission spectra, because the spectral library apparently contains a single pigeonite spectrum derived from a synthetic sample [6].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012M%26PSA..75.5133O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012M%26PSA..75.5133O"><span>UV-Radiation Induced Methane Emission from Murchison - Possible Implications for Methane in the <span class="hlt">Martian</span> Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ott, U.; Keppler, F.; Vigano, I.; McLeod, A.; Früchtl, M.; Röckmann, T.</p> <p>2012-09-01</p> <p>Exposure of the Murchison <span class="hlt">meteorite</span> to UV radiation releases large quantities of methane. Acting on <span class="hlt">meteoritic</span> debris on the <span class="hlt">Martian</span> surface, the process may be of importance for the <span class="hlt">Martian</span> atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002653','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002653"><span>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>Clemett, S. J.; Thomas-Keprta, K. L.; Rahman, Z.; Le, L.; Wentworth, S. J.; Gibson, E. K.; McKay, D. S.</p> <p>2016-01-01</p> <p>Detailed microanalysis of the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> 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 <span class="hlt">Martian</span> surface is estimated to have acquired at least 10(exp15) kg of C as a consequence of <span class="hlt">meteoritic</span> accretion over the last several Ga. The dearth of organics at the <span class="hlt">Martian</span> surface has been attributed to various oxidative processes including UV photolysis and peroxide activity. Consequently, investigations of <span class="hlt">Martian</span> organics need to be focused on the sub-surface regolith where such surface processes are either severely attenuated or absent. Fortuitously since <span class="hlt">Martian</span> <span class="hlt">meteorites</span> are derived from buried regolith materials they provide a unique opportunity to <span class="hlt">study</span> <span class="hlt">Martian</span> organic geochemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=exercise+depression&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexercise%2Bdepression','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10640&hterms=exercise+depression&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dexercise%2Bdepression"><span>Durham, North Carolina, Students <span class="hlt">Study</span> <span class="hlt">Martian</span> Volcanism</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2008-01-01</p> <p><p/> This image of the wall of a graben a depressed block of land between two parellel faults in Tyrrhena Terra, in Mars' ancient southern highlands, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0914 UTC (4:14 a.m. EST) on February 6, 2008, near 17.3 degrees south latitude, 95.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 35 meters (115 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point. <p/> This image was part of an investigation planned by students in four high schools in Durham, North Carolina. The students are working with the CRISM science team in a project called the Mars Exploration Student Data Teams (MESDT), which is part of NASA's Mars Public Engagement Program and Arizona State University's Mars Education Program. Starting with a medium-resolution map of the area, taken as part of CRISM's 'multispectral survey' campaign to map Mars in 72 colors at 200 meters (660 feet) per pixel, the students identified a key rock outcrop to test their hypothesis that the irregular depression was formed by <span class="hlt">Martian</span> volcanism. They provided the coordinates of the target to CRISM's operations team, who took a high-resolution image of the site. The Context Imager (CTX) accompanied CRISM with a 6 meter (20 feet) per pixel, high-resolution image to sharpen the relationship of spectral variations to the underlying surface structures. The Durham students worked with a mentor on the CRISM team to analyze the data, and presented their results at the 39th Lunar and Planetary Science Conference, held in League City, Texas, on March 10-14, 2008. <p/> The upper panel of the image shows the location of the CRISM data and the surrounding, larger CTX image, overlain on an image mosaic taken by the Thermal Emission Imaging System (THEMIS) on Mars Odyssey. The mosaic has been color-coded for elevation using data from the Mars</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/11543519','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11543519"><span>An abiotic origin for hydrocarbons in the Allan Hills 84001 <span class="hlt">martian</span> <span class="hlt">meteorite</span> through cooling of magmatic and impact-generated gases.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zolotov MYu; Shock, E L</p> <p>2000-05-01</p> <p>Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO2, and H2 below approximately 250-300 degrees C during rapid cooling of trapped magmatic or impact-generated gases. Depending on temperature, bulk composition, and oxidation-reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO2 ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01-0.001 together with high CO/CO2 ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO2 ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine-grain magnetite, formation of a CO-rich local gas phase, reduction of water vapor to H2, reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high-temperature quenching of CO-, H2-rich impact gases could have led to magnetite-catalyzed hydrocarbon synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=prevent+volcanic+eruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprevent%2Bvolcanic%2Beruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088818&hterms=prevent+volcanic+eruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dprevent%2Bvolcanic%2Beruption"><span>An abiotic origin for hydrocarbons in the Allan Hills 84001 <span class="hlt">martian</span> <span class="hlt">meteorite</span> through cooling of magmatic and impact-generated gases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shock, E. L.</p> <p>2000-01-01</p> <p>Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">martian</span> <span class="hlt">meteorite</span> Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO2, and H2 below approximately 250-300 degrees C during rapid cooling of trapped magmatic or impact-generated gases. Depending on temperature, bulk composition, and oxidation-reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO2 ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01-0.001 together with high CO/CO2 ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO2 ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine-grain magnetite, formation of a CO-rich local gas phase, reduction of water vapor to H2, reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high-temperature quenching of CO-, H2-rich impact gases could have led to magnetite-catalyzed hydrocarbon synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.187..279C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.187..279C"><span>A new approach to cosmogenic corrections in 40Ar/39Ar chronometry: Implications for the ages of <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>Cassata, W. S.; Borg, L. E.</p> <p>2016-08-01</p> <p>Anomalously old 40Ar/39Ar ages are commonly obtained from Shergottites and are generally attributed to uncertainties regarding the isotopic composition of the trapped component and/or the presence of excess 40Ar. Old ages can also be obtained if inaccurate corrections for cosmogenic 36Ar are applied. Current methods for making the cosmogenic correction require simplifying assumptions regarding the spatial homogeneity of target elements for cosmogenic production and the distribution of cosmogenic nuclides relative to trapped and reactor-derived Ar isotopes. To mitigate uncertainties arising from these assumptions, a new cosmogenic correction approach utilizing the exposure age determined on an un-irradiated aliquot and step-wise production rate estimates that account for spatial variations in Ca and K is described. Data obtained from NWA 4468 and an unofficial pairing of NWA 2975, which yield anomalously old ages when corrected for cosmogenic 36Ar using conventional techniques, are used to illustrate the efficacy of this new approach. For these samples, anomalous age determinations are rectified solely by the improved cosmogenic correction technique described herein. Ages of 188 ± 17 and 184 ± 17 Ma are obtained for NWA 4468 and NWA 2975, respectively, both of which are indistinguishable from ages obtained by other radioisotopic systems. For other Shergottites that have multiple trapped components, have experienced diffusive loss of Ar, or contain excess Ar, more accurate cosmogenic corrections may aid in the interpretation of anomalous ages. The trapped 40Ar/36Ar ratios inferred from inverse isochron diagrams obtained from NWA 4468 and NWA 2975 are significantly lower than the <span class="hlt">Martian</span> atmospheric value, and may represent upper mantle or crustal components.</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('https://ntrs.nasa.gov/search.jsp?R=19790055301&hterms=Wedekind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWedekind','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055301&hterms=Wedekind&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DWedekind"><span>Experimental <span class="hlt">studies</span> of oblique impact. [of <span class="hlt">meteorites</span> on planetary surfaces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gault, D. E.; Wedekind, J. A.</p> <p>1978-01-01</p> <p><span class="hlt">Meteoritic</span> materials most probably impact planetary bodies along oblique trajectories inclined less than 45 deg above their surfaces. Laboratory <span class="hlt">studies</span> of hypervelocity impacts against rock and particulate media are presented that indicate important effects of obliquity on crater size, shape, and ejecta distribution. The effects are particularly important to crater size-frequency analyses and geologic interpretations of crater formations. Impacts at shallow incidence, which are not uncommon, lead to ricochet of the impacting object accompanied with some entrained excavated materials at velocities only slightly reduced from the pre-impact value.</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('https://www.osti.gov/scitech/biblio/947812','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/947812"><span>New electron microscopy techniques of the <span class="hlt">study</span> of <span class="hlt">meteoritic</span> metal.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Michael, Joseph Richard; Goldstein, Joseph I.; Kotula, Paul Gabriel; Jones, R. H.</p> <p>2005-02-01</p> <p>Metallic Phases in extraterrestrial materials are composed of Fe-Ni with minor amounts of Co, P, Si, Cr, etc. Electron microscopy techniques (SEM, TEM, EPMA, AEM) have been used for almost 50 years to <span class="hlt">study</span> micron and submicron microscopic features in the metal phases (Fig. 1) such as clear taenite, cloudy zone, plessite, etc [1,2]. However lack of instrumentation to prepare TEM thin foils in specific sample locations and to obtain micro-scale crystallographic data have limited these investigations. New techniques such as the focused ion beam (FIB) and the electron backscatter electron diffraction (EBSD) techniques have overcome these limitations. The application of the FIB instrument has allowed us to prepare {approx}10 um long by {approx} 5um deep TEM thin sections of metal phases from specific regions of metal particles, in chondrites, irons and stony iron <span class="hlt">meteorites</span>, identified by optical and SEM observation. Using a FEI dual beam FIB we were able to <span class="hlt">study</span> very small metal particles in samples of CH chondrites [3] and zoneless plessite (ZP) in ordinary chondrites. Fig. 2 shows a SEM photomicrograph of a {approx}40 um ZP particle in Kernouve, a H6 chondrite. Fig. 3a,b shows a TEM photograph of a section of the FIB prepared TEM foil of the ZP particle and a Ni trace through a tetrataenite/kamacite region of the particle. It has been proposed that the Widmanstatten pattern in low P iron <span class="hlt">meteorites</span> forms by martensite decomposition, via the reaction {gamma} {yields} {alpha}{sub 2} + {gamma} {yields} {alpha} + {gamma} in which {alpha}{sub 2}, martensite, decomposes to the equilibrium {alpha} and {gamma} phases during the cooling process [4]. In order to show if this mechanism for Widmanstatten pattern formation is correct, crystallographic information is needed from the {gamma} or taenite phases throughout a given <span class="hlt">meteorite</span>. The EBSD technique was employed in this <span class="hlt">study</span> to obtain the orientation of the taenite surrounding the initial martensite phase and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhDT........24M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhDT........24M"><span>Laboratory <span class="hlt">studies</span> in planetary science and quantitative analysis of evaporation rates under current <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>Moore, Shauntae</p> <p>2005-12-01</p> <p>Laboratory measurements have been performed that are intended to shed light on several problems in planetary science. Thermoluminescence measurements of ordinary chondrites have been performed as part of an effort to identify the most primitive materials in the solar system. Experiments to <span class="hlt">study</span> the fractionation of metal and silicate grains on asteroid surfaces have been performed on NASA's microgravity facility because of its relevance to <span class="hlt">meteorite</span> origins and the exploration of asteroids by robotic spacecraft. The results of these <span class="hlt">studies</span> are presented in this thesis as a conference presentation whose summary appeared in the journal <span class="hlt">Meteoritics</span> and Planetary Science and a paper that appeared in the journal Geophysical Research Letters. The rest of the thesis describes measurements on the stability of water on the surface of Mars and is submitted in normal thesis format, although at the time of submission some of this work has appeared in Geophysical Research Letters and some has been submitted to the journal Astrobiology. The thermoluminescence <span class="hlt">studies</span> were used to derive petrologic classifications for several type 3 ordinary chondrites from North Africa, some of which are very low and have the potential to provide new insights to the early solar system and its formation. The metal-silicate fractionation work suggests that the differences in composition observed among the major chondrite groups, the H, L and LL chondrites, could be the result of processes occurring on the surface of the <span class="hlt">meteorite</span> parent body, probably an asteroid. They also suggest that minor disturbances of the surface will cause separation of components in the asteroid regolith and this should be borne in mind in robotics exploration of asteroids. The stability of water on Mars was investigated by measuring the evaporation rate of liquid water in a Mars-like environment produced in a large chamber on Earth. The evaporation rates measured are in good agreement with model-dependent theoretical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017hsa9.conf..543C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017hsa9.conf..543C"><span><span class="hlt">Study</span> of clouds and dust aerosols in the <span class="hlt">Martian</span> atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen-Chen, H.; Pérez-Hoyos, S.; Sánchez-Lavega, A.</p> <p>2017-03-01</p> <p>Observation of Mars’ atmosphere has evolved to a state of permanent monitoring of its main components. In this work, we focus on the <span class="hlt">study</span> of clouds and dust aerosols in the <span class="hlt">Martian</span> atmosphere by means of spacecraft observations, particularly VMC on-board Mars Express, and surface vehicles, mainly cameras on the MSL rover. Orbiting instrument observations provide a general view of the planet, which allows covering a huge area in a short time. This is very interesting, for example, to <span class="hlt">study</span> global dust events in Mars. On the other hand, ground-based instruments are better suited to analyse local properties of dust particles from in-situ acquired first hand data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1661R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1661R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 101</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; Herd, Christopher D. K.; Agee, Carl B.</p> <p>2015-09-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 101 contains 2639 <span class="hlt">meteorites</span> accepted by the Nomenclature Committee in 2012, including 1 fall (Battle Mountain), with 2308 ordinary chondrites, 156 carbonaceous chondrites, 63 HED achondrites, 17 relict <span class="hlt">meteorites</span>, 16 Rumuruti chondrites, 15 enstatite chondrites, 15 ureilites, 10 iron <span class="hlt">meteorites</span>, 9 lunar <span class="hlt">meteorites</span>, 9 primitive achondrites, 8 ungrouped achondrites, 7 mesosiderites, 4 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, and 2 Pallasites, and with 1812 from Antarctica, 437 from Asia, 301 from Africa, 43 from South America, 21 from Europe (including Russia), 21 from North America, 3 from Oceania, and 1 from unknown. 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('http://hdl.handle.net/2060/19950008255','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950008255"><span>Engine system assessment <span class="hlt">study</span> using <span class="hlt">Martian</span> propellants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pelaccio, Dennis; Jacobs, Mark; Scheil, Christine; Collins, John</p> <p>1992-01-01</p> <p>A top-level feasibility <span class="hlt">study</span> was conducted that identified and characterized promising chemical propulsion system designs which use two or more of the following propellant combinations: LOX/H2, LOX/CH4, and LOX/CO. The engine systems examined emphasized the usage of common subsystem/component hardware where possible. In support of this <span class="hlt">study</span>, numerous mission scenarios were characterized that used various combinations of Earth, lunar, and Mars propellants to establish engine system requirements to assess the promising engine system design concept examined, and to determine overall exploration leverage of such systems compared to state-of-the-art cryogenic (LOX/H2) propulsion systems. Initially in the <span class="hlt">study</span>, critical propulsion system technologies were assessed. Candidate expander and gas generator cycle LOX/H2/CO, LOX/H2/CH4, and LOX/CO/CH4 engine system designs were parametrically evaluated. From this evaluation baseline, tripropellant Mars Transfer Vehicle (MTV) LOX cooled and bipropellant Lunar Excursion Vehicle (LEV) and Mars Excursion Vehicle (MEV) engine systems were identified. Representative tankage designs for a MTV were also investigated. Re-evaluation of the missions using the baseline engine design showed that in general the slightly lower performance, smaller, lower weight gas generator cycle-based engines required less overall mission Mars and in situ propellant production (ISPP) infrastructure support compared to the larger, heavier, higher performing expander cycle engine systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.107..299W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.107..299W"><span>Shock metamorphism of Elephant Moraine A79001: Implications for olivine-ringwoodite transformation and the complex thermal history of heavily shocked <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>Walton, Erin L.</p> <p>2013-04-01</p> <p>Lithology A of <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Elephant Moraine (EET) A79001 contains fragments entrained within a 100 μm-thick shear-induced shock vein. These fragments, the shock vein matrix and walls of olivine along the vein, as well as shock deformation and transformation in rock-forming minerals in the bulk rock, were investigated using scanning electron microscopy, the electron microprobe and Raman spectroscopy. The presence of ringwoodite, the spinel-structured high-pressure (Mg,Fe)2SiO4 polymorph, has been confirmed in EETA79001 for the first time. Ringwoodite occurs within and around the shock vein, exhibiting granular and lamellar textures. In both textures ringwoodite consists of ˜500 nm size distinct grains. Ringwoodite lamellae are 115 nm to 1.3 μm wide. Planar fractures in olivine provided sites for heterogeneous nucleation of ringwoodite. Analyses performed on the largest grains (⩾1 μm) show that ringwoodite is consistently higher in iron (Fa27.4-32.4) relative to surrounding olivine (Fa25.1-267.7), implying that there was Fe-Mg exchange during their transformation, and therefore their growth was diffusion-controlled. In the shock environment, diffusion takes place dynamically, i.e., with concurrent deformation and grain size reduction. This results in enhanced diffusion rates (⩾10-8 m2/s) over nm - μm distances. Shock deformation in host rock minerals including strong mosaicism, pervasive fracturing, polysynthetic twinning (pyroxene only), extensive shock melting, local transformation of olivine to ringwoodite, and complete transformation of plagioclase to maskelynite in the bulk rock, indicate that EETA79001 was strongly shocked. The short shock duration (0.01 s) combined with a complex thermal history, resulted in crystallization of the 100 μm thick shock vein in EETA79001 during the pressure release, and partial back-transformation of ringwoodite to olivine. Based on the pressure stabilities of clinopyroxene + ringwoodite, crystallization at 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_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('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://adsabs.harvard.edu/abs/2013M%26PS...48..270B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..270B"><span><span class="hlt">Meteorites</span> from meteor showers: A case <span class="hlt">study</span> of the Taurids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, Peter; Marchenko, Valerie; Moser, Danielle E.; Weryk, Robert; Cooke, William</p> <p>2013-02-01</p> <p>We propose that the Taurid meteor shower may contain bodies able to survive and be recovered as <span class="hlt">meteorites</span>. We review the expected properties of <span class="hlt">meteorite</span>-producing fireballs, and suggest that end heights below 35 km and terminal speeds below 10 km s-1 are necessary conditions for fireballs expected to produce <span class="hlt">meteorites</span>. Applying the meteoroid strength index (PE criteria) of Ceplecha and McCrosky (1976) to a suite of 33 photographically recorded Taurid fireballs, we find a large spread in the apparent meteoroid strengths within the stream, including some very strong meteoroids. We also examine in detail the flight behavior of a Taurid fireball (SOMN 101031) and show that it has the potential to be a (small) <span class="hlt">meteorite</span>-producing event. Similarly, photographic observations of a bright, potential Taurid fireball recorded in November of 1995 in Spain show that it also had <span class="hlt">meteorite</span>-producing characteristics, despite a very high entry velocity (33 km s-1). Finally, we note that the recent Maribo <span class="hlt">meteorite</span> fall may have had a very high entry velocity (28 km s-1), further suggesting that survival of <span class="hlt">meteorites</span> at Taurid-like velocities is possible. Application of a numerical entry model also shows plausible survival of <span class="hlt">meteorites</span> at Taurid-like velocities, provided the initial meteoroids are fairly strong and large, both of which are characteristics found in the Taurid stream.</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://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=origin+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Blife','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010044901&hterms=origin+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Blife"><span>A Hypothesis for the Abiotic and Non-<span class="hlt">Martian</span> Origins of Putative Signs of Ancient <span class="hlt">Martian</span> Life in ALH84001</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>2001-01-01</p> <p>Putative evidence of <span class="hlt">martian</span> life in ALH84001 can be explained by abiotic and non-<span class="hlt">martian</span> processes consistent with the <span class="hlt">meteorite</span>'s geological history. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JMatS..20..590H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JMatS..20..590H"><span>A transmission electron microscopic <span class="hlt">study</span> of the Bethany 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>Hasan, F.; Axon, H. J.</p> <p>1985-02-01</p> <p>The Bethany iron <span class="hlt">meteorite</span>, which is a part of the Gibeon shower, is a fine octahedrite with zoned plessite fields of various sizes. The optically irresolvable microstructural details inside the plessitic fields have been <span class="hlt">studied</span> by transmission electron microscopy, and the crystallographic relationships between the primary kamacite (alpha) and the parent taenite (gamma), and between the alpha and gamma particles in the coarse plessite, have been examined using electron diffraction. In the case of primary kamacite, the orientation-relationship with gamma was close to the Nishiyama-Wasserman relationship, whereas, for the plessitic alpha, the orientation-relationship with gamma was close to Kurdjumov-Sachs. It was also found that the (111)-gamma and (110)-alpha planes were not strictly parallel. Additionally, measurements of the composition profile through the zoned plessite have been made using STEM microanalysis technique, and related to microstructure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1662R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1662R"><span>The <span class="hlt">Meteoritical</span> Bulletin, No. 102</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; Herd, Christopher D. K.; Agee, Carl B.</p> <p>2015-09-01</p> <p><span class="hlt">Meteoritical</span> Bulletin 102 contains 3141 <span class="hlt">meteorites</span> including 12 falls (Boumdeid (2003), Boumdeid (2011), Braunschweig, Chelyabinsk, Dongyang, Draveil, Heyetang, Indian Butte, Katol, Ladkee, Ouadangou, Xining), with 2611 ordinary chondrites, 264 HED achondrites, 124 carbonaceous chondrites, 30 ureilites, 20 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, 16 primitive achondrites, 16 Rumuruti chondrites, 15 mesosiderites, 12 iron <span class="hlt">meteorites</span>, 10 lunar <span class="hlt">meteorites</span>, 9 enstatite chondrites, 4 enstatite achondrites, 4 Pallasites, 4 ungrouped achondrites, and 2 angrites, and with 1708 from Antarctica, 956 from Africa, 294 from South America, 126 from Asia, 47 from North America, 6 from Europe (including Russia), and 4 from Oceania. 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('http://hdl.handle.net/2060/19970040877','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970040877"><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, Moti; Arritt, Raymond W.</p> <p>1997-01-01</p> <p>The <span class="hlt">study</span> objectives were to evaluate by numerical modeling various possible mesoscale circulation on Mars and related atmospheric boundary layer processes. The <span class="hlt">study</span> was in collaboration with J. Tillman of the University of Washington (who supported the <span class="hlt">study</span> observationally). Interaction has been made with J. Prusa of Iowa State University in numerical modeling investigation of dynamical effects of topographically-influenced flow. Modeling simulations included evaluations of surface physical characteristics on: (i) the <span class="hlt">Martian</span> atmospheric boundary layer and (ii) their impact on thermally and dynamically forced mesoscale flows. Special model evaluations were made in support of selection of the Pathfinder landing sites. J. Tillman's finding of VL-2 inter-annual temperature difference was followed by model simulations attempting to point out the forcing for this feature. Publication of the results in the reviewed literature in pending upon completion of the manuscripts in preparation as indicated later.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990064166&hterms=Reference+point&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReference%2Bpoint','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990064166&hterms=Reference+point&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReference%2Bpoint"><span><span class="hlt">Martian</span> Aerocapture Terminal Point Guidance: A Reference Path Optimization <span class="hlt">Study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ro, Theodore U.; Queen, Eric M.; Striepe, Scott A.</p> <p>1999-01-01</p> <p>An effective method of terminal point guidance is to employ influence coefficients, which are solved from a set of differential equations adjoint to the linearized perturbations of the equations of motion about a reference trajectory. Hence, to optimize this type of guidance, one must first optimize the reference trajectory that the guidance is based upon. This <span class="hlt">study</span> concentrates on various methods to optimize a reference trajectory for a <span class="hlt">Martian</span> aerocapture maneuver, including a parametric analysis and first order gradient method. Resulting reference trajectories were tested in separate 2000 6-DOF Monte Carlo runs, using the Atmospheric Guidance Algorithm Testbed for the Mars Surveyor Program 2001 (MSP '01) Orbiter. These results were compared to an August 1998 <span class="hlt">study</span> using the same terminal point control guidance algorithm and simulation testbed. Satisfactory improvements over the 1998 <span class="hlt">study</span> are amply demonstrated.</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://adsabs.harvard.edu/abs/2014me13.conf...57J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014me13.conf...57J"><span>Recent documented <span class="hlt">meteorite</span> falls, a review of <span class="hlt">meteorite</span> - asteroid links</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jenniskens, P.</p> <p>2014-07-01</p> <p>Since the previous Meteoroids 2010 meeting, 25 confirmed <span class="hlt">meteorite</span> falls have been reported, and one additional <span class="hlt">meteorite</span> was linked tentatively to an observed fireball. All but two of those are classified as ordinary chondrites. Sutter's Mill is a rare carbonaceous chondrite, while <span class="hlt">Martian</span> <span class="hlt">meteorite</span> Tissint is a Shergotite. For 18 of these falls the associated fireball was observed, but only four provided a pre-atmospheric orbit derived from video and photographic records. Results were published for Sutter's Mill, Novato, and Chelyabinsk, providing insight into the asteroid belt source regions for CM2, L and LL type chondrites, respectively. Proposed <span class="hlt">meteorite</span>-asteroid links are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22407548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22407548"><span>Pyrolysis and mass spectrometry <span class="hlt">studies</span> of <span class="hlt">meteoritic</span> organic matter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sephton, M A</p> <p>2012-01-01</p> <p><span class="hlt">Meteorites</span> are fragments of extraterrestrial materials that fall to the Earth's surface. The carbon-rich <span class="hlt">meteorites</span> are derived from ancient asteroids that have remained relatively unprocessed since the formation of the Solar System 4.56 billion years ago. They contain a variety of extraterrestrial organic molecules that are a record of chemical evolution in the early Solar System and subsequent aqueous and thermal processes on their parent bodies. The major organic component (>70%) is a macromolecular material that resists straightforward solvent extraction. In response to its intractable nature, the most common means of investigating this exotic material involves a combination of thermal decomposition (pyrolysis) and mass spectrometry. Recently the approach has also been used to explore controversial claims of organic matter in <span class="hlt">meteorites</span> from Mars. This review summarizes the pyrolysis data obtained from <span class="hlt">meteorites</span> and outlines key interpretations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.2805A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.2805A"><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.; Galindo, C.; Luckey, M.; Reustle, J.; Todd, N.; Allen, C.</p> <p>2012-03-01</p> <p>Lunar and <span class="hlt">meteorite</span> thin sections sets are available from JSC Curation for loans to domestic university petrology classes. See the new website for information http://curator.jsc.nasa.gov/Education/index.cfm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009093','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009093"><span>Anhydrous Liquid Line of Descent of Yamato 980459 and Evolution of <span class="hlt">Martian</span> Parental Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rapp, J. F.; Draper, David S.; Mercer, C. M.</p> <p>2013-01-01</p> <p><span class="hlt">Martian</span> basalts represented by the shergottite <span class="hlt">meteorites</span> reflect derivation from highly depleted mantle sources (high Nd, strong LREE depletions, low fO2)[1-3], with evidence of mixing with a much more enriched and oxidized reservoir, most likely a late-stage product of crystallization of an initial <span class="hlt">martian</span> magma ocean [3-6]. The <span class="hlt">martian</span> basaltic <span class="hlt">meteorites</span> Yamato 980459 (Y98) and QUE 94201 (QUE) have bulk compositions that appear to represent bonafide liquids, rather than products of protracted crystallization. These two <span class="hlt">meteorites</span> also represent the most primitive and evolved examples of the depleted basaltic shergottite suite. Magmatic liquids serve as effective probes of their source regions, and thus <span class="hlt">studying</span> the potential relationship between magmas represented by Y98 and QUE can yield important information on the formation and evolution of <span class="hlt">martian</span> basalts. Although the ages of these <span class="hlt">meteorites</span> preclude that they are petrogenetically related to each other, they represent the best existing candidates for genuine liquids (other <span class="hlt">meteorites</span> are suggested to represent liquid compositions, including LAR 06319 [7] and NWA 5789 [8], but only Y98 and QUE have been verified experimentally). They span much of the bulk-compositional range of <span class="hlt">martian</span> basaltic <span class="hlt">meteorites</span>, and represent end-member liquid compositions likely to arise from partial melting of the <span class="hlt">martian</span> mantle. Recent efforts to model Y98-like parent liquid evolution by fractional crystallization using MELTS [6] produced a derivative liquid composition that closely matches QUE bulk composition, although it required a some-what unusual crystallization sequence. Experimental endeavours to verify this result at 1 bar have, however, been inconclusive [9].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dthermoluminescence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850037919&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dthermoluminescence"><span>Thermoluminescence and the shock and reheating history of <span class="hlt">meteorites</span>. II - Annealing <span class="hlt">studies</span> of the Kernouve <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>Sears, D. W. G.; Bakhtiar, N.; Keck, B. D.; Weeks, K. S.</p> <p>1984-01-01</p> <p>Samples of the unshocked, equilibrated chondrite, Kernouve (H6), have been annealed for 1-100 hours at 500-1200 C, their thermoluminescence sensitivity measured and Na, K, Mn, Ca, and Sc determined by instrumental neutron activation analysis. The TL sensitivity decreased with temperature until by 1000 C it had fallen by 40 percent. The process responsible has an activation energy of 8 kcal/mole and probably involves diffusion. Samples annealed 1000-1200 C had TL sensitivities 0.01 times the unannealed values, most of the decrease occurring at 1100 C. This process has an activation energy of 100 kcal/mole and is probably related to the melting of the TL phosphor, feldspar, with some decomposition and loss of Cs, Na and K. <span class="hlt">Meteorites</span> whose petrography indicates heating above 1100 C by natural shock heating events (shock facies d-f), have TL sensitivities similar to samples annealed above 1100 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........58C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........58C"><span><span class="hlt">Martian</span> Chlorine Chemistry: A <span class="hlt">Study</span> of Perchlorate on the <span class="hlt">Martian</span> Surface, Evidence of an Ongoing Formation Mechanism and Implications of a Complex Chlorine Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrier, Brandi L.</p> <p>2015-10-01</p> <p>The research presented herein addresses the detection of perchlorate on Mars, evidence of perchlorate in Mars <span class="hlt">meteorite</span> EETA 79001, determination of the perchlorate parent salts at the Phoenix landing site, and the ongoing formation of perchlorate from chloride minerals as well as from other oxychlorine species. The detection of perchlorate in three samples by the Phoenix Wet Chemistry Laboratory and the implication of these results are discussed. The further detection of perchlorate in Mars <span class="hlt">meteorite</span> EETA 79001 by ion chromatography and the determination of the parent salts of the perchlorate detected at the Phoenix landing site by electrochemical analyses and ion chromatography are detailed and the implications of the identity of the parent salts are discussed. The possible formation pathways for <span class="hlt">martian</span> perchlorate are then explored and a possible mechanism for ongoing perchlorate formation on the <span class="hlt">martian</span> surface is detailed. Perchlorate is shown to be formed upon exposure of chloride minerals, as well as of chlorite and chlorate salts, to current Mars relevant conditions including temperature, pressure, ultraviolet radiation and atmospheric composition. The implications of this ongoing perchlorate formation for the survival and detection of organics, the oxidizing nature of the soil, formation of liquid brines and recurring slope lineae are discussed. Further preliminary experiments have been conducted to investigate the effects of perchlorate formation on the survival and degradation of organic compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPICo1679.4355E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPICo1679.4355E"><span>Explore and <span class="hlt">Study</span> a <span class="hlt">Martian</span> Lava Tube or Cave</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edberg, S. J.</p> <p>2012-06-01</p> <p>A rover exploring <span class="hlt">Martian</span> lava tubes would provide crucial data for geology, exobiology, and human exploration disciplines. It would engage the public and provide valuable data on the history of Mars and on potential sites for human habitats.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980211455','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980211455"><span>Mineralogic and Petrologic <span class="hlt">Studies</span> of <span class="hlt">Meteorites</span> and Lunar Samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, John A.</p> <p>1998-01-01</p> <p>In the period named, P.I. Wood and his Research Associate M.I. Petaev published or submitted for publication the following papers and abstracts, which address the subjects: Simulation of melting-crystallization relationships in chondritic and achondritic igneous systems. METEOMOD: A numerical model for the calculation of melting-crystalyization relationships in <span class="hlt">meteoritic</span> igneous systems. Secondary Ca-Fe-rich minerals in the Bali-like and Allende-like oxidized CV3 chondrites and Allende dark inclusions. Silica minerals in the Gibeon IVA iron <span class="hlt">meteorite</span>. Drusy vugs in the Albion iron <span class="hlt">meteorite</span>: Mineralogy and textures. Search for exsolved ferromagnesian olivines: A <span class="hlt">meteoritic</span> survey. Cr-bearing minerals in the Gibeon IVA iron: Indicators of sulfur and oxygen fugacities in the parent body. Lunar Planet. Computer modelling of ordinary chondrite melting. Drusy vugs in the Albion iron <span class="hlt">meteorite</span>: Early speculation on the origin. Also Processing of chondritic and planetary material in spiral density waves in the nebula. Chondrite formation by turbulence and shock in the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.104..358P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.104..358P"><span>Experimental and crystal chemical <span class="hlt">study</span> of the basalt-eclogite transition in Mars and implications for <span class="hlt">martian</span> magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Papike, J. J.; Burger, P. V.; Shearer, C. K.; McCubbin, F. M.</p> <p>2013-03-01</p> <p>This paper represents the start of a campaign to identify possible source regions for pyroxene-phyric "enriched" and "depleted" <span class="hlt">martian</span> basalts using high pressure <span class="hlt">studies</span> on <span class="hlt">martian</span> <span class="hlt">meteorite</span> compositions that represent liquids or near liquids. Our first experiments focus upon mineralogical and crystal chemical aspects of the basalt-eclogite transformation on Mars. It is anticipated that like Earth, eclogites are not the dominant upper mantle assemblage. However, like Earth they may be important hosts for P, Cl, F, OH, Ti, REE, Sr, Y, high-field-strength elements, Hf, and Zr in the upper mantle. This initial experimental <span class="hlt">study</span> evaluates the major and trace element crystal chemistry of potential <span class="hlt">martian</span> eclogite assemblages using a <span class="hlt">martian</span> melt composition (QUE 94201). This composition is appropriate for this <span class="hlt">study</span> because it is evolved, so it is pyroxene-phyric, contains abundant phosphate, which is important for storage of REE, and is very well <span class="hlt">studied</span>. In the high pressure experiments, garnet and omphacitic pyroxene are the dominant phases. The garnet has a compositional range from Al56.9Gr + An24.6Py18.5 to Al41.5Gr + An28.1Py30.4 to Al40.3Gr + An22.6Py37.1 (where Al = almandine, Gr+An = grossular + andradite, and Py = Pyrope) and the pyroxene has jadeite and acmite components of up to 26.0 and 9.9%, respectively. The garnet is enriched in REE over omphacite; this is especially true for the HREE which likely remain sequestered in residual garnet during melting. This observation suggests that garnet may play a key role in producing the relatively flat REE patterns of enriched <span class="hlt">martian</span> basalts. The prime substitution couple that incorporates REE into garnet is: REE3+X Site + Mg2+Y Site ↔ R2+X Site + Al3+Y Site, where R2+ = Ca, Mn2+, Fe2+, and Mg. This is a very effective couple that accounts for both charge balance and ionic size restrictions in individual sites. The prime substitution couple that incorporates REE into omphacite is: REE3+M2 Site + Na1+M2 Site</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRE..113.6002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRE..113.6002R"><span>The nature of <span class="hlt">Martian</span> fluids based on mobile element <span class="hlt">studies</span> in salt-assemblages from <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>Rao, M. N.; Nyquist, L. E.; Wentworth, S. J.; Sutton, S. R.; Garrison, D. H.</p> <p>2008-06-01</p> <p>The S, Cl, and Br abundances determined in salt assemblages in Nakhla and Lafayette olivine fracturefillings and in gas-rich impact-melt (GRIM) glasses from Shergotty and EET79001 Lithologies A & B using EMPA/EDS/APS X-ray Microprobe techniques are compared with the S and Cl abundances determined by Gooding and coworkers in similar samples using quadrupole mass-spectrometric techniques. All the analytical methods yield relatively high Cl and low SO3 abundances in Nakhla indicating a SO3/Cl ratio of ~0.2. The same ratio in Lafayette secondary salts seems to be ~2. In the case of GRIM glasses from Shergotty and EET79001 Lith A & Lith B, the SO3 abundance is found to be high whereas the Cl abundance is low yielding a SO3/Cl ratio of ~5-300 (large errors are associated with these ratios because of low Cl signals). The salts found in Nakhla fracturefillings are inferred to have formed from Cl-rich fluids (high pH) near nakhlite source region on Mars, whereas the secondary minerals found in shergottite GRIM glasses seem to be associated with SO3-rich fluids (low pH) near shergottite source region on Mars. The Cl-rich fluids seem to have infiltrated into the nakhlite source region ~600 Ma ago, whereas the SO3-rich fluids likely percolated into the shergottite source region at ~180 Ma (or less) suggesting the possible existence of two types of fluid sources on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1006637','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1006637"><span>The nature of <span class="hlt">Martian</span> fluids based on mobile element <span class="hlt">studies</span> in salt-assemblages from <span class="hlt">Martian</span> <span class="hlt">meteorites</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rao, M.N.; Nyquist, L.E.; Wentworth, S.J.; Sutton, S.R.; Garrison, D.H.</p> <p>2008-08-04</p> <p>The S, Cl, and Br abundances determined in salt assemblages in Nakhla and Lafayette olivine fracture fillings and in gas-rich impact-melt (GRIM) glasses from Shergotty and EET79001 Lithologies A & B using EMPA/EDS/APS X-ray Microprobe techniques are compared with the S and Cl abundances determined by Gooding and coworkers in similar samples using quadrupole mass-spectrometric techniques. All the analytical methods yield relatively high Cl and low SO{sub 3} abundances in Nakhla indicating a SO{sub 3}/Cl ratio of {approx}0.2. The same ratio in Lafayette secondary salts seems to be {approx}2. In the case of GRIM glasses from Shergotty and EET79001 Lith A & Lith B, the SO{sub 3} abundance is found to be high whereas the Cl abundance is low yielding a SO{sub 3}/Cl ratio of {approx}5--300 (large errors are associated with these ratios because of low Cl signals). The salts found in Nakhla fracturefillings are inferred to have formed from Cl-rich fluids (high pH) near nakhlite source region on Mars, whereas the secondary minerals found in shergottite GRIM glasses seem to be associated with SO{sub 3}-rich fluids (low pH) near shergottite source region on Mars. The Cl-rich fluids seem to have infiltrated into the nakhlite source region {approx}600 Ma ago, whereas the SO{sub 3}-rich fluids likely percolated into the shergottite source region at {approx}180 Ma (or less) suggesting the possible existence of two types of fluid sources on Mars.</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/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/2060/20120013688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013688"><span><span class="hlt">Martian</span> Igneous Geochemistry: The Nature 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>Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.</p> <p>2012-01-01</p> <p>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 <span class="hlt">martian</span> <span class="hlt">meteorites</span> to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most <span class="hlt">martian</span> <span class="hlt">meteorites</span> contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. <span class="hlt">Martian</span> <span class="hlt">meteorites</span> 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).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=Palagonitic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPalagonitic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030062176&hterms=Palagonitic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPalagonitic"><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('https://ntrs.nasa.gov/search.jsp?R=PIA07269&hterms=Basketball&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DBasketball','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07269&hterms=Basketball&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DBasketball"><span>Iron <span class="hlt">Meteorite</span> on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> NASA's Mars Exploration Rover Opportunity has found an iron <span class="hlt">meteorite</span> on Mars, the first <span class="hlt">meteorite</span> of any type ever identified on another planet. The pitted, basketball-size object is mostly made of iron and nickel. Readings from spectrometers on the rover determined that composition. Opportunity used its panoramic camera to take the images used in this approximately true-color composite on the rover's 339th <span class="hlt">martian</span> day, or sol (Jan. 6, 2005). This composite combines images taken through the panoramic camera's 600-nanometer (red), 530-nanometer (green), and 480-nanometer (blue) filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920019834&hterms=Percent+Composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPercent%2BComposition','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920019834&hterms=Percent+Composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPercent%2BComposition"><span>On the isotopic composition of magmatic carbon 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>Wright, I. P.; Grady, M. M.; Pillinger, C. T.</p> <p>1992-01-01</p> <p>SNC <span class="hlt">meteorites</span> are thought, from many lines of evidence, to come from Mars. A line of investigation which has been pursued in our laboratory over the years involves measurement of the stable isotopic composition of carbon, in its various forms, in SNC <span class="hlt">meteorites</span>. In order to establish a firm basis for <span class="hlt">studying</span> the isotopic systematics of carbon in the <span class="hlt">martian</span> surface environment, it is first necessary to try and constrain the delta C-13 of bulk Mars. Taking all of the available information, it would seem that the delta C-13 of the Earth's mantle lies somewhere in the range of -5 to -7 percent. Preliminary assessment of magnetic carbon in SNC <span class="hlt">meteorites</span>, would tend to suggest a delta C-13 of 20 to 30 percent, which is conspicuously different from that of the terrestrial mantle. It is not obvious why there should be such a difference between the two planets, although many explanations are possible. One of these possibilities, that previous delta C-13 measurements for magnetic carbon in SNC <span class="hlt">meteorites</span> are in error to some degree, is being actively investigated. The most recent results seem to constrain the theta C-13 of the magnetic carbon in SNC <span class="hlt">meteorites</span> to about -20 percent, which is not at odds with previous estimates. As such, it is considered that a detailed investigation of the carbon isotopic systematics of <span class="hlt">martian</span> surface materials does have the necessary information with which to proceed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PSA..76.5366I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PSA..76.5366I"><span>Fall, Searching and First <span class="hlt">Study</span> of the Chelyabinsk <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>Ivanova, M. A.; Badyukov, D. D.; Ryazantsev, K. M.; Lorenz, C. A.; Demidova, S. I.; Sadilenko, D. A.; Artemieva, N.; Korochantsev, A. V.; Skripnik, A. Ya.; Ivanov, A. V.; Nazarov, M. A.</p> <p>2013-09-01</p> <p>On the territory of Russian Federation the Chelyabinsk event was the biggest and the most dramatic observed LL5 chondrite <span class="hlt">meteorite</span> fall since the Tunguska event. For a moment 99% of the main mass was not found and probably presents atmospheric loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940007592&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940007592&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors"><span>Thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels and valleys using Termoskan data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Betts, B. H.; Murray, B. C.</p> <p>1993-01-01</p> <p>The Termoskan instrument on board the Phobos '88 spacecraft acquired the highest spatial resolution thermal data ever obtained for Mars. Included in the thermal images are 2 km per pixel observations of 4 major channel and valley systems: Shalbatana Vallis; Simud Vallis, Hydraotes Chaos, and the associated outflow channel connecting it with the eastern end of Vallis Marineris; Al-Qahira Vallis; and Ma'adim Vallis. Simultaneous broad band visible channel data were obtained for all but Ma'adim Vallis. We find that all 4 valley systems have higher inertias than their surroundings, consistent with previous thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels. We conclude that the higher inertia is likely due to some intrinsic difference associated with the channel floors, rather than due only to dark aeolian deposits as suggested by some previous <span class="hlt">studies</span>. Our conclusion is based largely upon the localized nature of the dark deposits in contrast with the thermal homogeneity of the channel floors. Thus, these channels and valleys show an uncommon (for Mars) connection between morphology and inertia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026875','USGSPUBS'); return false;" href="http://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://ntrs.nasa.gov/search.jsp?R=19890023540&hterms=John+holloway&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DJohn%2Bholloway','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890023540&hterms=John+holloway&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DJohn%2Bholloway"><span><span class="hlt">Martian</span> mantle primary melts - An experimental <span class="hlt">study</span> of iron-rich garnet lherzolite minimum melt composition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bertka, Constance M.; Holloway, John R.</p> <p>1988-01-01</p> <p>The minimum melt composition in equilibrium with an iron-rich garnet lherzolite assemblage is ascertained from a <span class="hlt">study</span> of the liquidus relations of iron-rich basaltic compositions at 23 kb. The experimentally determined primary melt composition and its calculated sodium content reveal that <span class="hlt">Martian</span> garnet lherzolite minimum melts are picritic alkali olivine basalts. <span class="hlt">Martian</span> primary melts are found to be more picritic than terrestrial garnet lherzolite primary melts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005LPI....36.1198C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005LPI....36.1198C"><span>Albedo <span class="hlt">Study</span> of the Depositional Fans Associated with <span class="hlt">Martian</span> Gullies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Craig, J.; Sears, D. W. G.</p> <p>2005-03-01</p> <p>This work is a two-part investigation of the albedo of the depositional aprons or fans associated with <span class="hlt">Martian</span> gully features. Using Adobe Systems Photoshop 5.0 software we analyzed numerous Mars Global Surveyor MOC and Mars Odyssey THEMIS images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023756','USGSPUBS'); return false;" href="http://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://adsabs.harvard.edu/abs/2015GeCoA.157...56S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.157...56S"><span>Petrology of igneous clasts in Northwest Africa 7034: Implications for the petrologic diversity of 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>Santos, Alison R.; Agee, Carl B.; McCubbin, Francis M.; Shearer, Charles K.; Burger, Paul V.; Tartèse, Romain; Anand, Mahesh</p> <p>2015-05-01</p> <p>The <span class="hlt">martian</span> <span class="hlt">meteorite</span> Northwest Africa (NWA) 7034 was examined both petrographically and geochemically using several micro-beam techniques including electron probe microanalysis and secondary ion mass spectrometry. We have identified various clast types of igneous, sedimentary, and impact origin that occur within the breccia, and we define a classification scheme for these materials based on our observations, although our primary focus here is on the petrology of the igneous clasts. A number of different igneous clasts are present in this <span class="hlt">meteorite</span>, and our <span class="hlt">study</span> revealed the presence of at least four different igneous lithologies (basalt, basaltic andesite, trachyandesite, and an Fe, Ti, and P (FTP) rich lithology). These lithologies do not appear to be related by simple igneous processes such as fractional crystallization, indicating NWA 7034 is a polymict breccia that contains samples from several different igneous sources. The basalt lithologies are a good match for measured rock compositions from the <span class="hlt">martian</span> surface, however more exotic lithologies (e.g., trachyandesite and FTP lithologies) show this <span class="hlt">meteorite</span> contains previously unsampled rock types from Mars. These new rock types provide evidence for a much greater variety of igneous rocks within the <span class="hlt">martian</span> crust than previously revealed by <span class="hlt">martian</span> <span class="hlt">meteorites</span>, and supports recent rover observations of lithologic diversity across the <span class="hlt">martian</span> surface. Furthermore, the ancient ages for the lithologic components in NWA 7034 indicate Mars developed this lithologic diversity in the early stages of crust formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Rutherford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRutherford','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Rutherford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRutherford"><span>An Experimental <span class="hlt">Study</span> of Eu/Gd Partitioning Between a Shergottite Melt and Pigeonite: Implications for the Oxygen Fugacity of 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>McCanta, M. C.; Rutherford, M. J.; Jones, J. H.</p> <p>2002-01-01</p> <p>We experimentally investigated the partitioning behavior of Eu/Gd between a synthetic shergottite melt and pigeonite as a function of oxygen fugacity. This has implications for the oxidation state of the source region of the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. Additional information is contained in the original extended abstract.</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/2060/19980021283','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('http://hdl.handle.net/2060/19840013410','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840013410"><span>Mineralogic and petrologic <span class="hlt">studies</span> of <span class="hlt">meteorites</span> and lunar samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, J. A.</p> <p>1984-01-01</p> <p>During a 13 year period beginning in 1971, the Extraterrestrial Petrology Group examined lunar soils from all 6 Apollo missions and those returned by the Soviet Luna 16, Luna 20, and Luna 24 missions. In addition, the properties and apparent origin of the carbonaceous chondrites were examined. Chondrules, calcium-aluminum-rich inclusions (CAI) and the fine grained matrix materials that accompany chondrules and CAI's in primitive <span class="hlt">meteorites</span> were investigated. The effects of planetary hydrothermal alteration of matrix materials in the C1 chondrite was also investigated. Full length papers and extended abstracts published during the grant are listed chronologically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Gadolinium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGadolinium"><span>Oxygen Fugacity of the <span class="hlt">Martian</span> Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, S.; Jones, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This <span class="hlt">study</span> is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the <span class="hlt">martian</span> <span class="hlt">meteorites</span>. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which <span class="hlt">meteorites</span> are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for <span class="hlt">martian</span> composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on <span class="hlt">martian</span> composition pigeonite/melt REE partitioning as a function of fO2.</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('https://ntrs.nasa.gov/search.jsp?R=19930068552&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DKoeberl','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930068552&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DKoeberl"><span>Lunar <span class="hlt">meteorite</span> Yamato-86032 - Mineralogical, petrological, and geochemical <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>Koeberl, Christian; Kurat, Gero; Brandstaetter, Franz</p> <p>1990-01-01</p> <p>Yamato-86032 is a shock-lithified anorthositic fragmental breccia. It consists mainly of highly feldspathic meta-breccias and meta-meltrocks and possibly contains a small contribution from mare lithologies, but there is no indication of a KREEP component. In many respects Y-86032 is similar to the previously described lunar <span class="hlt">meteorites</span> Y-82192/3, but there are some notable differences. We have analyzed about 40 major and trace elements in bulk matrix, impact melt, and clast samples from two chips of Y-86032. The abundances of most lithophile and incompatible elements are lower in Y-86032 than in Y-82192 (which contains very low abundances compared to normal lunar highland rocks). The REE abundances are comparable to those of Y-82192. The elements Sc, Cr, Mn, Fe and Co have significantly lower abundances than in Y-82192, and the siderophile element pattern is also different. Since cosmic ray exposure data indicate pairing of Y-86032 with Y-82192/3, the source region for these <span class="hlt">meteorites</span> on the moon must have been fairly heterogeneous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HyInt.237..107E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HyInt.237..107E"><span>57Fe Mössbauer <span class="hlt">study</span> of the chainpur <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>Elewa, Nancy N.; Cobas, R.; Cadogan, J. M.</p> <p>2016-12-01</p> <p>The Chainpur <span class="hlt">meteorite</span> is one of 23 ordinary chondrites classified as LL3-type (low-Fe & low-metal). It was observed as a shower of stones falling on May 9, 1907 in Uttar Pradesh, India. We report here the characterization of the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out at 298 K, 120 K, 50 K and 13 K. The paramagnetic doublets of olivine and pyroxene dominate the room temperature spectrum, accounting for around 70 % of the spectral area. Moreover, a doublet present with a spectral area of 5 % and assigned to a superparamagnetic Fe 3+ phase is a consequence of terrestrial weathering. On the basis of the measured 57Fe electric quadrupole splitting of the olivine component at room temperature we estimate the mean Fe:Mg ratio in this <span class="hlt">meteoritic</span> olivine to be around 35:65 % although there is clearly a wide range of composition. The effects of magnetic ordering of the major components olivine and pyroxene are observed at 13 K.</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/2017APS..APR.T1021D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..APR.T1021D"><span>Comparative <span class="hlt">study</span> of carbonaceous <span class="hlt">meteoritic</span> fragments by micro-Raman spectroscopy and SEM/EDS.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dall'Asén, AnalíA.; Mittelstaedt, Jacob; Kim, Jin-Sun; Baer, Brandon; Paul, Raka; Gerton, Jordan; Bromley, Benjamin; Kenyon, Scott</p> <p>2017-01-01</p> <p><span class="hlt">Meteorites</span> provide precious clues about the formation of planets in the solar system. In particular, carbonaceous chondritic <span class="hlt">meteorites</span>, considered the most primitive surviving materials from the early Solar System, can contribute to understand how planetisimals (the precursors to planets, of 1-100 km in radius) formed from dust (micron-size grains). These relics are mainly composed of chondrules (micro/millimeter-sized inclusions) surrounded by a matrix of microparticles. Here we present a comparative <span class="hlt">study</span> of the structure and composition of the chondrules and surrounding matrix of different carbonaceous chondritic <span class="hlt">meteorites</span> using low- and high-resolution micro-Raman spectroscopy and SEM/EDS (Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy). We examine how these properties vary in different regions of the chondrules and matrix, capturing details from micrometer to millimeter scales. We compare the structure and composition between different samples, looking for signatures of the physical processes that drove their formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=Neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNeon','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890057036&hterms=Neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNeon"><span>Neon isotope <span class="hlt">studies</span> of Fayetteville and Kapoeta <span class="hlt">meteorites</span> and clues to ancient solar activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Padia, J. T.; Rao, M. N.</p> <p>1989-01-01</p> <p>Under the assumption that the solar-flare bombardment of the irradiated grains of gas-rich <span class="hlt">meteorites</span> occurred about 4.5 b.y. ago on the parent body regoliths at 3 A.U., an estimate of the solar cosmic ray-produced Ne-21 is made by <span class="hlt">studying</span> etched pyroxene minera separates from both light and dark portions of the gas-rich <span class="hlt">meteorites</span> Fayetteville and Kapoeta. Excesses of solar cosmic ray Ne-21 were observed in dark portions of these <span class="hlt">meteorites</span>, after accounting for their galactic cosmic ray Ne-21 production and solar flare Ne-21. In order to produce the estimated solar cosmic ray Ne-21 in the present samples, highly enhanced solar cosmic ray proton fluxes from the ancient sun are required.</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('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://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://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('https://ntrs.nasa.gov/search.jsp?R=19990079409&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%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%3D40%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('http://adsabs.harvard.edu/abs/2017LPICo1963.2019K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017LPICo1963.2019K"><span>Preliminary Results on <span class="hlt">Studying</span> of <span class="hlt">Meteorites</span> from Geological Museum of Kazan University by X-Ray Fluorescence and Computed X-Ray Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzina, D. M.; Nurgaliev, D. K.; Gareev, B. I.; Batalin, G. A.; Silantev, V. V.; Statsenko, E. O.</p> <p>2017-02-01</p> <p>Micro X-ray fluorescence and X-ray computed tomography used for <span class="hlt">studying</span> <span class="hlt">meteorites</span> (particularly chondrules and iron-nickel alloys) from Geological Museum (Kazan), their elemental composition, and distribution of these objects in the body of <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011824','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011824"><span>Complex radiation-thermal history of Kaidun <span class="hlt">meteorite</span> on data of track <span class="hlt">study</span> of silicate minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kashkarov, L. L.; Korotkova, N. N.; Skripnik, A. YA.</p> <p>1993-01-01</p> <p>The results of track <span class="hlt">study</span> of approximately 80 individual silicate mineral crystals (ol, px, plag) picked out from Kaidun <span class="hlt">meteorite</span> are presented. A wide range of observed rho(sub VH) value distributions indicate the complex irradiation history of Kaidun minerals. In one anortite crystal having two track groups with different parameters the pre-accretion irradiation traces were observed in all probability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040056056&hterms=whole+grains&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhole%2Bgrains','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040056056&hterms=whole+grains&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwhole%2Bgrains"><span>Evidence for a Wet, Reduced <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>Dyar, M. D.; Mackwell, S. J.; Seaman, S. J.; Marchand, G. J.</p> <p>2004-01-01</p> <p>Knowledge of the oxygen fugacity and hydrogen content of the source regions of <span class="hlt">martian</span> <span class="hlt">meteorites</span> is of paramount importance in constraining phase equilibria, crystallization sequences, and geodynamic processes of the <span class="hlt">martian</span> interior, as well as models of the planet's evolution. To date, these interpretations have been hindered by the paucity in SNC <span class="hlt">meteorites</span> of Fe-Ti oxides used in conventional oxybarometry, and by the presence of secondary alteration products that make it impossible to quantify primary hydrogen abundances in SNC minerals and melts based on whole rock samples. We present here the first transmission FTIR spectra of individual mineral grains from SNC <span class="hlt">meteorites</span>, and interpret those results along with Mossbauer data on mineral separates from the same <span class="hlt">meteorites</span>. Our goal is to quantify the amount of water and the oxygen fugacity present in the source regions for the rocks comprising the <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3529V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3529V"><span>M-DLS - a multichannel diode laser spectrometer for <span class="hlt">Martian</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>Vinogradov, Imant; Rodin, Alexander V.; Klimchuk, Artem</p> <p></p> <p>A concept of <span class="hlt">Martian</span> atmosphere and soil volatiles <span class="hlt">study</span> was developed on the basis of diode laser spectroscopy by collaboration of IKI RAS, MIPT, GPI RAS, University of Reims (France), University of Cologne (Germany), and University of Edinburgh (Great Britain). An experiment, named as M-DLS, has been proposed for the stationery Landing Platform scientific payload of the ExoMars-2018 mission. The M-DLS instrument is targeted to long-term <span class="hlt">studies</span> of: chemical and isotopic composition of atmosphere near the <span class="hlt">Martian</span> surface, and its diurnal and seasonal variations; <span class="hlt">Martian</span> soil volatiles at the location of the Landing Platform; integral chemical and isotopic composition of <span class="hlt">Martian</span> atmosphere at low scales of altitude at the Landing Platform area, and its variations in respect to local time at the day-light; thermal and dynamic structure of the <span class="hlt">Martian</span> atmosphere. The M-DLS <span class="hlt">studies</span> are based on regular measurements of molecular absorption spectra in the IR range along several optical path trajectories, including: a suite of ICOS optical cells of up to 1 km effective optical path, which are directly linked to the ambient atmosphere; a capillary closed-volume optical cell, which is linked to pyrolytic output of a proposed MGAS instrument (<span class="hlt">Martian</span> Gas Analytic Suite); direct Solar observation open atmosphere path of heterodyne measurements, which is co-directional with the open path line of sight of a proposed FAST instrument (Fourier spectrometer for Atmospheric Components and Temperature). The M-DLS measurements will be carried out in series of narrow-band 2 cm (-1) wide intervals with spectral resolution of 3 MHz ( 0.0001 cm (-1) ), providing for fine recording of molecular absorption line contours. By measurement of H _{2}O and CO _{2} molecules diurnal and seasonal variations and their isotope ratios D/H, (18) O/ (17) O/ (16) O, (13) C/ (12) C, of soil volatiles H _{2}S, NH _{3}, C _{2}H _{2} and others, we expect to receive data for specifying of physical and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.2256M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.2256M"><span>Experimental <span class="hlt">study</span> of radon production and transport in an analogue for the <span class="hlt">Martian</span> regolith</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meslin, P. Y.; Sabroux, J. C.; Bassot, S.; Chassefière, E.</p> <p>2011-05-01</p> <p>The suggestion that radon could be used as a radioactive tracer of regolith-atmosphere exchanges and as a proxy for subsurface water on Mars, as well as its indirect detection in the <span class="hlt">Martian</span> atmosphere by the rover Opportunity, have raised the need for a better characterization of its production process and transport efficiency in the <span class="hlt">Martian</span> soil. More specifically, a proper estimation of radon exhalation rate on Mars requires its emanation factor and diffusion length to be determined. The dependence of the emanation factor as a function of pore water content (at 267 and 293 K) and the dependence of the adsorption coefficient on temperature, specific surface area and nature of the carrier gas (He, He + CO 2) have been measured on a <span class="hlt">Martian</span> soil analogue (Hawaiian palagonitized volcanic ash, JSC Mars-1), whose radiometric analysis has been performed. An estimation of radon diffusion lengths on Mars is provided and is used to derive a global average emanation factor (2-6.5%) that accounts for the exhalation rate inferred from the 210Po surface concentration detected on <span class="hlt">Martian</span> dust and from the 214Bi signal measured by the Mars Odyssey Gamma Ray Spectrometer. It is found to be much larger than emanation factors characterizing lunar samples, but lower than the emanation factor of the palagonite samples obtained under dry conditions. This result probably reflects different degrees of aqueous alteration and could indicate that the emanation factor is also affected by the current presence of pore water in the <span class="hlt">Martian</span> soil. The rationale of the "radon method" as a technique to probe subsurface water on Mars, and its sensitivity to soil parameters are discussed. These experimental data are useful to perform more detailed <span class="hlt">studies</span> of radon transport in the <span class="hlt">Martian</span> atmosphere using Global Climate Models and to interpret neutron and gamma data from Mars Odyssey Gamma Ray Spectrometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760004890','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760004890"><span>Comparative <span class="hlt">studies</span> of lunar, <span class="hlt">Martian</span>, and Mercurian craters and plains</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oberbeck, V. R.; Arvidson, R. E.; Aggarwal, H. R.</p> <p>1975-01-01</p> <p>The spatial distribution of lunar smooth plains is not consistent with experimental simulations of melt rock emplacement during cratering in layered materials. Nor is it consistent with the location of melt rocks (suevite) near the Ries basin. Lunar smooth plains surrounding Imbrium are most extensive in areas where pre-existing craters are most degraded. This observation suggests that plains form by impact of basin and local primary crater ejecta, together with deposition of debris excavated by the resultant secondary cratering events. Craters within the belt of smooth plains surrounding the Caloris basin on Mercury are most degraded nearest the basin; this suggests that Mercurian smooth plains must, at least in part, be emplaced in a manner similar to plains surrounding the Imbrium basin. Mercurian uplands have a primary crater population deficient in small crater diameters (less than approximately 30 km). Lunar uplands far from major basins also have a crater population deficient in small crater sizes. <span class="hlt">Martian</span> cratered terrain exhibits a similar crater deficiency, which was previously interpreted as due to obliteration of small craters (less than approximately 30 km) by some surface process. A crater size distribution deficient in small sizes (less than approximately 30 km) on the Mercurian, lunar, and <span class="hlt">Martian</span> uplands has implications for the origin of debris bombarding the inner solar system during the period recorded by these surfaces. It is proposed that during late heavy bombardment, the inner solar system was inundated with bodies that broke up under tidal fission as they approached the planets. Such a mechanism would lend to production of a crater population deficient in small crater sizes, and it would also explain the large degree of spatial clustering of primary craters on Mercury, the moon, and Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009M%26PS...44..891W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009M%26PS...44..891W"><span>Labile trace elements in basaltic achondrites: Can they distinguish between <span class="hlt">meteorites</span> from the Moon, Mars, and V-type asteroids?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolf, Stephen F.; Wang, Ming-Sheng; Lipschutz, Michael E.</p> <p>2009-06-01</p> <p>We report data for 14 mainly labile trace elements (Ag, Au, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn) in eight whole-rock lunar <span class="hlt">meteorites</span> (Asuka [A-] 881757, Dar al Gani [DaG] 262, Elephant Moraine [EET] 87521, Queen Alexandra Range [QUE] 93069, QUE 94269, QUE 94281, Yamato [Y-] 793169, and Y-981031), and <span class="hlt">Martian</span> <span class="hlt">meteorite</span> (DaG 476) and incorporate these into a comparative <span class="hlt">study</span> of basaltic <span class="hlt">meteorites</span> from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 <span class="hlt">Martian</span>, and 34 howardite, eucrite, and diogenite (HED) <span class="hlt">meteorites</span> demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar <span class="hlt">meteorites</span> are essentially lognormally distributed and generally more homogeneous than in <span class="hlt">Martian</span> and HED <span class="hlt">meteorites</span>. Mean siderophile and labile element concentrations in the 14 lunar <span class="hlt">meteorites</span> indicate the presence of a CI-equivalent micrometeorite admixture of 2.6% When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing micrometeorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the micrometeorite component. Apparently, the process(es) that contributed to establishing lunar <span class="hlt">meteorite</span> siderophile and labile trace element contents occurred in a system open to highly labile element transport.</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://adsabs.harvard.edu/abs/2009IJAsB...8...27B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009IJAsB...8...27B"><span>Electrochemical <span class="hlt">studies</span> of iron <span class="hlt">meteorites</span>: phosphorus redox chemistry on the early Earth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bryant, David E.; Greenfield, David; Walshaw, Richard D.; Evans, Suzanne M.; Nimmo, Alexander E.; Smith, Caroline L.; Wang, Liming; Pasek, Matthew A.; Kee, Terence P.</p> <p>2009-01-01</p> <p>The mineral schreibersite, (Fe,Ni)3P, a ubiquitous component of iron <span class="hlt">meteorites</span>, is known to undergo anoxic hydrolytic modification to afford a range of phosphorus oxyacids. H-phosphonic acid (H3PO3) is the principal hydrolytic product under hydrothermal conditions, as confirmed here by 31P-NMR spectroscopic <span class="hlt">studies</span> on shavings of the Seymchan pallasite (Magadan, Russia, 1967), but in the presence of photochemical irradiation a more reduced derivative, H-phosphinic (H3PO2) acid, dominates. The significance of such lower oxidation state oxyacids of phosphorus to prebiotic chemistry upon the early Earth lies with the facts that such forms of phosphorus are considerably more soluble and chemically reactive than orthophosphate, the commonly found form of phosphorus on Earth, thus allowing nature a mechanism to circumvent the so-called Phosphate Problem. This paper describes the Galvanic corrosion of Fe3P, a hydrolytic modification pathway for schreibersite, leading again to H-phosphinic acid as the key P-containing product. We envisage this pathway to be highly significant within a <span class="hlt">meteoritic</span> context as iron <span class="hlt">meteorites</span> are polymetallic composites in which dissimilar metals, with different electrochemical potentials, are connected by an electrically conducting matrix. In the presence of a suitable electrolyte medium, i.e., salt water, galvanic corrosion can take place. In addition to model electrochemical <span class="hlt">studies</span>, we also report the first application of the Kelvin technique to map surface potentials of a <span class="hlt">meteorite</span> sample that allows the electrochemical differentiation of schreibersite inclusions within an Fe:Ni matrix. Such experiments, coupled with thermodynamic calculations, may allow us to better understand the chemical redox behaviour of <span class="hlt">meteoritic</span> components with early Earth environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=Cais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCais','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950042229&hterms=Cais&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCais"><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('http://adsabs.harvard.edu/abs/2007LPI....38.1974S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007LPI....38.1974S"><span>The Ejecta of <span class="hlt">Martian</span> DLE Craters in Utopia Planitia: First Report on the <span class="hlt">Study</span> of Thermal Properties and New Methods for Measuring Volume Ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suzuki, A.; Baratoux, D.; Kurita, K.</p> <p>2007-03-01</p> <p>This is the first report on the <span class="hlt">study</span> for establishing new methods to measure the volume ratio of <span class="hlt">martian</span> DLE craters. This also include the preliminary result of the thermal properties of <span class="hlt">martian</span> DLE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026167','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026167"><span>Magnetite in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Mil 03346 and Gusev Adirondack Class Basalt: Moessbauer Evidence for Variability in the Oxidation State of Adirondack Lavas</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.; Ming, D. W.; Klingelhoefer, G.; Schroeder, C.; Rodionov, D.; Yen, A.</p> <p>2006-01-01</p> <p>The Moessbauer spectrometers on the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) have returned information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases [1,2,3]. To date, 100 and 85 surface targets have been analyzed by the Spirit and Opportunity spectrometers, respectively. Twelve component subspectra (8 doublets and 4 sextets) have been identified and most have been assigned to mineralogical compositions [4]. Two sextet subspectra result from the opaque and strongly magnetic mineral magnetite (Fe3O4 for the stoichiometric composition), one each for the crystallographic sites occupied by tetrahedrally-coordinated Fe3+ and by octahedrally-coordinated Fe3+ and Fe2+. At Gusev crater, the percentage of total Fe associated with magnetite for rocks ranges from 0 to 35% (Fig. 1) [3]. The range for soils (5 to 12% of total Fe from Mt, with one exception) is narrower. The ubiquitous presence of Mt in soil firmly establishes the phase as the strongly magnetic component in <span class="hlt">martian</span> soil</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026260','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026260"><span>Magnetite in <span class="hlt">Martian</span> <span class="hlt">Meteorite</span> Mil 03346 and Gusev Adirondack Class Basalt: Mossbauer Evidence for Variability in the Oxidation State of Adirondack Lavas</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.; Ming, D. W.; Klingelhoefer, G.; Schroeder, C.; Rodionov, D.; Yen, A.</p> <p>2006-01-01</p> <p>The Moessbauer spectrometers on the Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) have returned information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases [1,2,3]. To date, approx.100 and approx.85 surface targets have been analyzed by the Spirit and Opportunity spectrometers, respectively. Twelve component subspectra (8 doublets and 4 sextets) have been identified and most have been assigned to mineralogical compositions [4]. Two sextet subspectra result from the opaque and strongly magnetic mineral magnetite (Fe3O4 for the stoichiometric composition), one each for the crystallographic sites occupied by tetrahedrally-coordinated Fe3+ and by octahedrally-coordinated Fe3+ and Fe2+. At Gusev crater, the percentage of total Fe associated with magnetite for rocks ranges from 0 to approx. 35% (Fig. 1) [3]. The range for soils (approx.5 to approx.12% of total Fe from Mt, with one exception) is narrower. The ubiquitous presence of Mt in soil firmly establishes the phase as the strongly magnetic component in <span class="hlt">martian</span> soil [4,5].</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('https://www.osti.gov/pages/biblio/1332404-tissintite-ca-na-square-alsi2o6-highly-defective-shock-induced-high-pressure-clinopyroxene-tissint-martian-meteorite','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1332404-tissintite-ca-na-square-alsi2o6-highly-defective-shock-induced-high-pressure-clinopyroxene-tissint-martian-meteorite"><span>Tissintite, (Ca, Na,$${\\square}$$)AlSi2O6, a highly-defective, shock-induced, high-pressure clinopyroxene in the Tissint <span class="hlt">martian</span> <span class="hlt">meteorite</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ma, Chi; Tschauner, Oliver; Beckett, John R.; ...</p> <p>2015-04-24</p> <p>Here, tissintite is a new vacancy-rich, high-pressure clinopyroxene, with a composition essentially equivalent to plagioclase. It was discovered in maskelynite (shocked plagioclase) and is commonly observed included within, or in contact with, shock-melt pockets in the Tissint <span class="hlt">meteorite</span>, a depleted olivine-phyric shergottite fall from Mars. The simple composition of tissintite (An58-69) and its precursor plagioclase (An59-69) together with the limited occurrence, both spatially (only in maskelynite less than ~25 μm of a shock melt pocket) and in terms of bulk composition, make tissintite a "goldilocks" phase. It formed during a shock event severe enough to allow nucleation and growth of vacancy-rich clinopyroxene from a melt of not too calcic and not too sodic plagioclase composition that was neither too hot nor too cold. With experimental calibration, these limitations on occurrence can be used to place strong constraints on the thermal history of a shock event. The kinetics for nucleation and growth of tissintite are probably slower for more-sodic plagioclase precursors, so tissintite is most likely to occur in depleted olivinephyric shergottites like Tissint and other highly shocked <span class="hlt">meteorites</span> and lunar and terrestrial rocks that consistently contained calcic plagioclase precursors in the appropriate compositional range for a shock of given intensity. Tissintite, (Ca0.45Na0.31more » $${\\square}$$ 0.24)(Al0.97Fe0.03Mg0.01)(Si1.80Al0.20)O6, is a C2/c clinopyroxene, containing 42-60 mol% of the Ca-Eskola component, by far the highest known. The cell parameters are a = 9.21 (17) Å, b = 9.09 (4) Å, c = 5.20 (2) Å, β = 109.6 (9)°, V = 410 (8) Å3, Z = 4. The density is 3.32 g/cm(3) and we estimate a cell volume for the Ca-Eskola end-member pyroxene of 411 ±13 Å3, which is consistent with a previous estimate and, therefore, supports the importance of this component in clinopyroxenes from ultra-high pressure metamorphic rocks from the Earth's upper mantle</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.422..194M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.422..194M"><span>Tissintite, (Ca, Na, □)AlSi2O6, a highly-defective, shock-induced, high-pressure clinopyroxene in the Tissint <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>Ma, Chi; Tschauner, Oliver; Beckett, John R.; Liu, Yang; Rossman, George R.; Zhuravlev, Kirill; Prakapenka, Vitali; Dera, Przemyslaw; Taylor, Lawrence A.</p> <p>2015-07-01</p> <p>Tissintite is a new vacancy-rich, high-pressure clinopyroxene, with a composition essentially equivalent to plagioclase. It was discovered in maskelynite (shocked plagioclase) and is commonly observed included within, or in contact with, shock-melt pockets in the Tissint <span class="hlt">meteorite</span>, a depleted olivine-phyric shergottite fall from Mars. The simple composition of tissintite (An58-69) and its precursor plagioclase (An59-69) together with the limited occurrence, both spatially (only in maskelynite less than ˜25 μm of a shock melt pocket) and in terms of bulk composition, make tissintite a "goldilocks" phase. It formed during a shock event severe enough to allow nucleation and growth of vacancy-rich clinopyroxene from a melt of not too calcic and not too sodic plagioclase composition that was neither too hot nor too cold. With experimental calibration, these limitations on occurrence can be used to place strong constraints on the thermal history of a shock event. The kinetics for nucleation and growth of tissintite are probably slower for more-sodic plagioclase precursors, so tissintite is most likely to occur in depleted olivine-phyric shergottites like Tissint and other highly shocked <span class="hlt">meteorites</span> and lunar and terrestrial rocks that consistently contained calcic plagioclase precursors in the appropriate compositional range for a shock of given intensity. Tissintite, (Ca0.45Na0.31□0.24) (Al0.97Fe0.03Mg0.01) (Si1.80Al0.20)O6, is a C 2 / c clinopyroxene, containing 42-60 mol% of the Ca-Eskola component, by far the highest known. The cell parameters are a = 9.21 (17) Å, b = 9.09 (4) Å, c = 5.20 (2) Å, β = 109.6 (9)°, V = 410 (8) Å3, Z = 4. The density is 3.32 g/cm3 and we estimate a cell volume for the Ca-Eskola end-member pyroxene of 411 ± 13 Å3, which is consistent with a previous estimate and, therefore, supports the importance of this component in clinopyroxenes from ultra-high pressure metamorphic rocks from the Earth's upper mantle. At least in C 2 / c</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770048050&hterms=comparative+studies&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcomparative%2Bstudies','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770048050&hterms=comparative+studies&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcomparative%2Bstudies"><span>Comparative <span class="hlt">studies</span> of Lunar, <span class="hlt">Martian</span>, and Mercurian craters and plains</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oberbeck, V. R.; Quaide, W. L.; Arvidson, R. E.; Aggarwal, H. R.</p> <p>1977-01-01</p> <p>Lunar features provide a valuable interpretation data base for comparison with features on other planets which are believed to have been formed by the cratering process. The paper adopts the comparative approach by examining the smooth plains of the moon and Mercury, with special emphasis on crater degradation on the moon, Mercury, and Mars. A possible cause for the observed deficiency of craters with diameters no more than 50 km on certain areas of lunar uplands and on the entire uplands of Mercury and Mars is discussed. It is suggested that pertinent differences can be predicted on the basis of new concepts for production population and of effects of changes in planetary conditions on the secondary cratering process. It is concluded that the deficiency of craters with diameters no more than 50 km on parts of the lunar uplands and on the Mercurian and <span class="hlt">Martian</span> uplands may be evidence for a deficiency in production of primary craters in this size range. Origin of the late heavy bombardment in the inner solar system is examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=Magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920064072&hterms=Magnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetism"><span>The relict magnetism 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>Cisowski, S. M.; Hood, L. L.</p> <p>1991-01-01</p> <p><span class="hlt">Meteorite</span> paleomagnetic <span class="hlt">studies</span> are reviewed and evaluated. Possible mechanisms for producing early solar system magnetic fields that could have been responsible for the magnetization of some or all <span class="hlt">meteorite</span> classes are explored. A detailed review of paleointensity results derived from the various classes of <span class="hlt">meteorites</span> is given, and the likelihood that the results might related to solar or nebulawide magnetic fields is considered. The implications of <span class="hlt">meteorite</span> magnetism for early solar system evolution are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740018174','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740018174"><span>Magnetism 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>Herndon, J. M.; Rowe, M. W.</p> <p>1974-01-01</p> <p>An overview is presented of magnetism in <span class="hlt">meteorites</span>. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism <span class="hlt">studies</span> in <span class="hlt">meteorites</span> are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890008944','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890008944"><span><span class="hlt">Meteorites</span> on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Flynn, G. J.; Mckay, D. S.</p> <p>1988-01-01</p> <p>Four types of <span class="hlt">meteoritic</span> material should be found on Mars: (1) micrometeorites, many of which will survive atmospheric entry unmelted, which should fall relatively uniformly over the planet's surface, (2) ablation products from larger <span class="hlt">meteorites</span> which ablate, break up and burn up in the Mars atmosphere, (3) debris from large, crater forming objects, which, by analogy to terrestrial and lunar impact events, will be concentrated in the crater ejecta blankets (except for rare, large events, such as the proposed C-T event on earth, which can distribute debris on a planetary scale), and (4) debris from the early, intense bombardment, which, in many areas of the planet, may now be incorporated into rocks by geologic processes subsequent to the intense bombardment era. To estimate the extent of <span class="hlt">meteoritic</span> addition to indigenous <span class="hlt">Martian</span> material, the <span class="hlt">meteoritic</span> flux on Mars must be known. It is estimated that the overall flux is twice that for the Moon and 1.33 that for Earth. For small particles, whose orbital evolution is dominated by Poynting Robertson drag, the flux at Mars can be estimated from the Earth flux. The smaller <span class="hlt">Martian</span> gravitational enhancement as well as the decrease in the spatial density of interplanetary dust with increasing heliocentric distance should reduce the flux of small particles at Mars to about 0.33 times the flux at Earth. Because of the smaller planetary cross-section the total infalling mass at Mars is then estimated to be 0.09 time the infalling mass in the micrometeorite size range at Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48.1780R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48.1780R"><span>Anhydrous liquid line of descent of Yamato-980459 and evolution of <span class="hlt">Martian</span> parental magmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rapp, Jennifer F.; Draper, David S.; Mercer, Cameron M.</p> <p>2013-10-01</p> <p>We report the results of nominally anhydrous equilibrium and fractional crystallization experiments on a synthetic Yamato-980459 (Y98) bulk composition at 0.5 GPa. These experiments allow us to test a suggested fractional crystallization model, calculated using MELTS by Symes et al. (<link href="#maps12197-bib-0059"/>), in which a Y98-like initial liquid yielded a magma closely resembling the bulk composition of QUE 94201. Although the two <span class="hlt">meteorites</span> cannot be cogenetic owing to their age difference, they are thought to represent bona fide magmatic liquids rather than products of crystal accumulation, as are most <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span>. Hence, understanding possible petrogenetic links between these types of liquids could be revealing about processes of melting and crystallization that formed the range of <span class="hlt">Martian</span> basalts. We find that Y98 can, in fact, generate a residual liquid closely resembling QUE, but only after a very different crystallization process, and different degree of crystallization, than that modeled using MELTS. In addition, both the identity and sequence of crystallizing phases are very different between model and experiments. Our fractional crystallization experiments do not produce a QUE-like liquid, and the crystallizing phases are an even poorer match to the MELTS-calculated compositions than in the equilibrium runs. However, residual liquids from our experiments define a liquid line of descent that encompasses bulk compositions of parental melts calculated for several <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span>, suggesting that the known <span class="hlt">Martian</span> basaltic <span class="hlt">meteorites</span> had their ultimate origin from the same or very similar source lithologies. These are, in turn, similar to source rocks modeled by previous <span class="hlt">studies</span> as products of extensive crystallization of an initial <span class="hlt">Martian</span> magma ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51.2036M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51.2036M"><span>Heterogeneous distribution of H2O in the <span class="hlt">Martian</span> interior: Implications for the abundance of H2O in depleted and enriched mantle sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCubbin, Francis M.; Boyce, Jeremy W.; Srinivasan, Poorna; Santos, Alison R.; Elardo, Stephen M.; Filiberto, Justin; Steele, Andrew; Shearer, Charles K.</p> <p>2016-11-01</p> <p>We conducted a petrologic <span class="hlt">study</span> of apatite within 12 <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, including 11 shergottites and one basaltic regolith breccia. These data were combined with previously published data to gain a better understanding of the abundance and distribution of volatiles in the <span class="hlt">Martian</span> interior. Apatites in individual <span class="hlt">Martian</span> <span class="hlt">meteorites</span> span a wide range of compositions, indicating they did not form by equilibrium crystallization. In fact, the intrasample variation in apatite is best described by either fractional crystallization or crustal contamination with a Cl-rich crustal component. We determined that most <span class="hlt">Martian</span> <span class="hlt">meteorites</span> investigated here have been affected by crustal contamination and hence cannot be used to estimate volatile abundances of the <span class="hlt">Martian</span> mantle. Using the subset of samples that did not exhibit crustal contamination, we determined that the enriched shergottite source has 36-73 ppm H2O and the depleted 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, Cl, and F content of the <span class="hlt">Martian</span> crust using known crust-mantle distributions for incompatible lithophile elements. We determined that the bulk <span class="hlt">Martian</span> crust has 1410 ppm H2O, 450 ppm Cl, and 106 ppm F, and Cl and H2O are preferentially distributed toward the <span class="hlt">Martian</span> surface. The estimate of crustal H2O results in a global equivalent surface layer (GEL) of 229 m, which can account for at least some of the surface features on Mars attributed to flowing water and may be sufficient to support the past presence of a shallow sea on Mars' surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060041222&hterms=love&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlove','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060041222&hterms=love&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlove"><span>A Petrologic <span class="hlt">Study</span> of the IAB Iron <span class="hlt">Meteorites</span>: Constraints on the Formation of the IAB-Winonaite Parent Body</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benedix, G. K.; McCoy, T. J.; Keil, K.; Love, S. G.</p> <p>1998-01-01</p> <p>We have <span class="hlt">studied</span> IAB iron <span class="hlt">meteorites</span> and their silicate-bearing inclusions to elucidate the origin of their parent body. We have divided IAB irons into five categories which best describe the inclusions and other properties of the irons.</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://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('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('https://www.osti.gov/scitech/biblio/7024090','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7024090"><span>Annealing <span class="hlt">studies</span> of the thermoluminescence of <span class="hlt">meteorites</span> and implications for their metamorphic history</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guimon, R.K.</p> <p>1986-01-01</p> <p>The application of thermoluminescence to <span class="hlt">study</span> metamorphism in the type 3 ordinary chondrites and five CAI from the Allende <span class="hlt">meteorite</span> is explored. It has been found that the changes in the shape of the TL curve provide insight into the thermal history of the <span class="hlt">meteorites</span> and <span class="hlt">meteoritic</span> components. It is also shown that for ordinary chondrites, the TL sensitivity depends on the amount of feldspar present which, in turn, is governed by the intensity of metamorphism experienced. A type 3.4 ordinary chondrite shows changes in the peak temperature and width occurred upon annealing. These parameters showed a discontinuous increase after annealing at 800/sup 0/C; the peak temperature jumped from 130 to 200/sup 0/C and peak width increased from 90 to 150/sup 0/C. These changes in the TL emission characteristics suggest that type 3.3-3.5 ordinary chondrites have a low-feldspar as the dominant TL phosphor and > 3.5 have high feldspar as the phosphor. Thermoluminescence therefore provides a means of paleothermometry. In addition, experiments were performed aimed at causing the crystallization of feldspar in mesostasis glass in an attempt to reproduce the trends of increasing TL sensitivity with metamorphism. At high temperatures and longer annealing times, increases in TL sensitivity by factors of up to 40 were observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17777058','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17777058"><span><span class="hlt">Meteoritic</span> Zircon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marvin, U B; Klein, C</p> <p>1964-11-13</p> <p>Zircon (ZrSiO(5)) has been identified as an accessory mineral in the Vaca Muerta mesosiderite and in the troilite nodules of the Toluca iron <span class="hlt">meteorite</span>. The occurrence in Vaca Muerta is a new discovery confirmned by electron-probe nmicroanalysis of a grain in a polished section of the <span class="hlt">meteorite</span>. Our identification of zircon in Toluca substantiates an occurrence in this <span class="hlt">meteorite</span> reported in 1895 by Laspeyres and Kaiser.</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('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/2060/20050223596','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050223596"><span>Testing the Hypothesis of Young <span class="hlt">Martian</span> Volcanism: <span class="hlt">Studies</span> of the Tharsis Volcanoes and Adjacent Lava Plains</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grier, Jennifer A.</p> <p>2005-01-01</p> <p>We experienced much success in reaching our stated goals in our original MDAP proposal. Our work made substantial contributions towards an integrated understanding of the counting and calibration of crater data on Mars, and changing nature of the <span class="hlt">Martian</span> surface influenced by craters, water, and wind, and their general relationship to <span class="hlt">Martian</span> geothermal history. We accomplished this while being to responsive to the rapid changes in the field brought about by several key NASA missions that returned data during the life of the grant. Our integrated effort included three stages: The first major area of research (Crater Count Research) was conducted by Jennifer Grier (P.I.), Lazslo Keszthelyi (Collaborator), William Hartmann (Collaborator), with assistance from Dan Berman (Graduate student) and concerned the mapping and the collection of crater count data on various <span class="hlt">Martian</span> terrains. The second major area of <span class="hlt">study</span> (Absolute Age Calibration) was conducted by William Bottke (Co-I) at SWRI, and concerned constraining the nature of the Moon and Mars impactor populations to create better absolute age calibrations for counted areas. The third major area of <span class="hlt">study</span> was the integration and leverage of this effort with ongoing related Mars crater work at PSI (Integrated and Continuing <span class="hlt">Studies</span> - Older Volcanoes), headed by David Crown (PSI Scientist), assisted by Les Bleamaster (PSI Scientist) and Dan Berman (Graduate Student).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001600','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001600"><span>Spectroscopic analyses of Fe and water in clays: A <span class="hlt">Martian</span> surface weathering <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bishop, J. L.; Pieters, Carle M.; Edwards, J. O.; Coyne, L. M.; Chang, S.</p> <p>1991-01-01</p> <p><span class="hlt">Martian</span> surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the <span class="hlt">Martian</span> surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic <span class="hlt">studies</span> of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930022752&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIgneous%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022752&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIgneous%2Brocks"><span>On the weathering of <span class="hlt">Martian</span> igneous rocks</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.</p> <p>1992-01-01</p> <p>Besides the young crystallization age, one of the first arguments for the <span class="hlt">martian</span> origin of shergottite, nakhlite, and chassignite (SNC) <span class="hlt">meteorites</span> came from the chemical similarity of the <span class="hlt">meteorite</span> Shergotty and the <span class="hlt">martian</span> 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 <span class="hlt">martian</span> surface rocks. The <span class="hlt">martian</span> 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 <span class="hlt">martian</span> soils point to a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust. However, the chemical evolution of the <span class="hlt">martian</span> 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 <span class="hlt">meteorites</span> suggests that Mars is a very dry planet that should have lost almost all its initially large water inventory during its accretion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010M%26PS...45...21S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010M%26PS...45...21S"><span>High oxidation state during formation of <span class="hlt">Martian</span> nakhlites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szymanski, Anja; Brenker, Frank E.; Palme, Herbert; El Goresy, Ahmed</p> <p>2010-01-01</p> <p>The oxygen fugacities recorded in the nakhlites Nakhla, Yamato-000593 (Y-000593), Lafayette, and NWA998 were <span class="hlt">studied</span> by applying the Fe,Ti-oxide oxybarometer. Oxygen fugacities obtained cluster closely around the FMQ (Fayalite-Magnetite-Quartz) buffer (NWA998=FMQ-0.8 Y-000593=FMQ-0.7 Nakhla=FMQ Lafayette=FMQ+ 0.1). The corresponding equilibration temperatures are 810°C for Nakhla and Y-000593, 780°C for Lafayette and 710°C for NWA998. All nakhlites record oxygen fugacities significantly higher and with a tighter range than those determined for <span class="hlt">Martian</span> basalts, i.e., shergottites whose oxygen fugacities vary from FMQ-1 to FMQ-4. It has been known for some time that nakhlites are different from other <span class="hlt">Martian</span> <span class="hlt">meteorites</span> in chemistry, mineralogy, and crystallization age. The present <span class="hlt">study</span> adds oxygen fugacity to this list of differences. The comparatively large variation in fO2 recorded by shergottites was interpreted by Herd et al. (2002) as reflecting variable degrees of contamination with crustal fluids that would also carry a light rare earth element (REE)-enriched component. The high oxygen fugacities and the large light REE enrichment of nakhlites fit qualitatively in this model. In detail, however, it is found that the inferred contaminating phase in nakhlites must have been different from those in shergottites. This is supported by unique 182W/184W and 142Nd/144Nd ratios in nakhlites, which are distinct from other <span class="hlt">Martian</span> <span class="hlt">meteorites</span>. It is likely that the differences in fO2 between nakhlites and other <span class="hlt">Martian</span> <span class="hlt">meteorites</span> were established very early in the history of Mars. Parental trace element rich and trace element poor regions (reservoirs) of Mars mantle (Brandon et al. 2000) must have been kept isolated throughout <span class="hlt">Martian</span> history. Our results further show significant differences in closure temperature among the different nakhlites. The observed range in equilibration temperatures together with similar fO2 values is attributable to crystallization of</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/2014SPIE.9260E..35V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9260E..35V"><span>Comparison of analogous terrestrial and <span class="hlt">Martian</span> drainage systems: a remote sensing based <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vaishali, R.; Sujita, G.; Sanjeevi, S.</p> <p>2014-11-01</p> <p>With more and more missions being launched to explore the Mars, the fact that water must have once flown it is no more a mere speculation. Keeping this is mind, this paper attempts to interpret <span class="hlt">Martian</span> and terrestrial images and provides an insight into the conditions that must have prevailed on Mars when water flowed on it. This is achieved by comparing regions selected on Mars that have evidences of a fluvial past, with regions of the Earth having similar geologic, geomorphic and physiographic characteristics. The <span class="hlt">Martian</span> images and DEM were obtained from HiRISE onboard MRO of NASA. For the terrestrial regions, LandSat 8 (OLI) images and SRTM DEMs were used. This <span class="hlt">study</span> has brought out many similarities in the fluvial geomorphic regime of the two planets. The presence of lobate structures, mouth bars and bifurcated channels in the Eberswalde Delta system on Mars is an indication of the interaction of the fluvial system with a large standing body of water, similar to the Mississippi Delta system on Earth. Also, the presence of braided pattern, streamlined bars and palaeochannels observed in the channels to the south of Ascraeus Mons on Mars indicates a prominent flow of water through time, similar to the Yellowstone River system present on Earth. This <span class="hlt">study</span> thus aids in better understanding of the <span class="hlt">Martian</span> fluvial processes and landforms.</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://hdl.handle.net/2060/20020050541','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020050541"><span>A <span class="hlt">Study</span> of the Electrostatic Interaction Between Insulators and <span class="hlt">Martian</span>/Lunar Soil Simulants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mantovani, James G.</p> <p>2001-01-01</p> <p>Using our previous experience with the Mars Environmental Compatibility Assessment (MECA) electrometer, we have designed a new type of aerodynamic electrometer. The goal of the research was to measure the buildup of electrostatic surface charge on a stationary cylindrical insulator after windborne granular particles have collided with the insulator surface in a simulated dust storm. The experiments are performed inside a vacuum chamber. This allows the atmospheric composition and pressure to be controlled in order to simulate the atmospheric conditions near the equator on the <span class="hlt">Martian</span> surface. An impeller fan was used to propel the dust particles at a cylindrically shaped insulator under low vacuum conditions. We tested the new electrometer in a 10 mbar CO2 atmosphere by exposing two types of cylindrical insulators, Teflon (1.9 cm diameter) and Fiberglass (2.5 cm diameter), to a variety of windborne granular particulate materials. The granular materials tested were JSC Mars-1 simulant, which is a mixture of coarse and fine (<5microns diameter) particle sizes, and some of the major mineral constituents of the <span class="hlt">Martian</span> soil. The minerals included Ottawa sand (SiO2), iron oxide (Fe2O3), aluminum oxide (Al2O3) and magnesium oxide (MgO). We also constructed a MECA-like electrometer that contained an insulator capped planar electrode for measuring the amount of electrostatic charge produced by rubbing an insulator surface over <span class="hlt">Martian</span> and lunar soil simulants. The results of this <span class="hlt">study</span> indicate that it is possible to detect triboelectric charging of insulator surfaces by windborne <span class="hlt">Martian</span> soil simulant, and by individual mineral constituents of the soil simulant. We have also found that Teflon and Fiberglass insulator surfaces respond in different ways by developing opposite polarity surface charge, which decays at different rates after the particle impacts cease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20130010126&hterms=magnetite+alteration+basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmagnetite%2Balteration%2Bbasalt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20130010126&hterms=magnetite+alteration+basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmagnetite%2Balteration%2Bbasalt"><span>Mineralogy of <span class="hlt">Meteorite</span> Groups</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rubin, Alan E.</p> <p>1997-01-01</p> <p>Approximately 275 mineral species have been identified in <span class="hlt">meteorites</span>, reflecting diverse redox environments, and, in some cases, unusual nebular formation conditions. Anhydrous ordinary, carbonaceous and R chondrites contain major olivine, pyroxene and plagioclase; major opaque phases include metallic Fe-Ni, troilite and chromite. Primitive achondrites are mineralogically similar. The highly reduced enstatite chondrites and achondrites contain major enstatite, plagioclase, free silica and kamacite as well as nitrides, a silicide and Ca-, Mg-, Mn-, Na-, Cr-, K- and Ti-rich sulfides. Aqueously altered carbonaceous chondrites contain major amounts of hydrous phyllosilicates, complex organic compounds, magnetite, various sulfates and sulfides, and carbonates. In addition to kamacite and taenite, iron <span class="hlt">meteorites</span> contain carbides, elemental C, nitrides, phosphates, phosphides, chromite and sulfides. Silicate inclusions in IAB/IIICD and lIE iron <span class="hlt">meteorites</span> consist of mafic silicates, plagioclase and various sulfides, oxides and phosphates. Eucrites, howardites and diogenites have basaltic to orthopyroxenitic compositions and consist of major pyroxene and calcic plagioclase and several accessory oxides. Ureilttes .are made up mainly of calcic, chromian olivine and low-Ca clinopyroxene embedded in a carbonaceous matrix; accessory phases include the C polymorphs graphite, diamond, lonsdaleite and chaoite as well as metallic Fe-Ni, troilite and halides. Angrites are achondrites rich in fassaitic pyroxene (i.e. , AI-Ti diopside); minor olivine with included magnesian kirschsteinite is also present. <span class="hlt">Martian</span> <span class="hlt">meteorites</span> comprise basalts, Iherzolites, a dunite and an orthopyroxenite. Major phases include various pyroxenes and olivine; minor to accessory phases include various sulfides, magnetite, chromite and Ca-phosphates. Lunar <span class="hlt">meteorites</span> comprise mare basalts with major augite and calcic plagioclase and anorthositic breccias with major calcic plagioclase. Several <span class="hlt">meteoritic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040059926&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DBasalt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040059926&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DBasalt"><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/2016cosp...41E.374G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.374G"><span><span class="hlt">Study</span> of the dynamics of meteoroids through the Earth's atmosphere and retrieval 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>Guadalupe Cordero Tercero, Maria; Farah-Simon, Alejandro; Velázquez-Villegas, Fernando</p> <p>2016-07-01</p> <p>When a comet , asteroid or meteoroid impact with a planet several things can happen depending on the mass, velocity and composition of the impactor, if the planet or moon has an atmosphere or not, and the angle of impact. On bodies without an atmosphere like Mercury or the Moon, every object that strikes their surfaces produces impact craters with sizes ranging from centimeters to hundreds and even thousands of kilometers across. On bodies with an atmosphere, this encounter can produce impact craters, <span class="hlt">meteorites</span>, meteors and fragmentation. Each and every one of these phenomena is interesting because they provide information about the surfaces and the geological evolution of solar system bodies. Meteors (shooting stars) are luminous wakes on the sky due to the interaction between the meteoroid and the Earth's atmosphere. A meteoroid is asteroidal or cometary material ranging in size from 2 mm to a few tens of meters. The smallest tend to evaporate at heights between 80 and 120 km. Objects of less than 2 mm are called micrometeorites. If the meteor brightness exceeds the brightness of Venus, the phenomenon is called a bolide or fireball. If a meteoroid, or a fragment of it, survives atmospheric ablation and it can be recovered on the ground, that piece is called a <span class="hlt">meteorite</span>. Most meteoroids 2 meters long fragment suddenly into the atmosphere, it produces a shock wave that can affect humans and their environment like the Chelyabinsk event occurred on February 15, 2013 an two less energetic events in Mexico in 2010 and 2011. To understand the whole phenomenon, we proposed a video camera network for observing meteors. The objectives of this network are to: a) contribute to the <span class="hlt">study</span> of the fragmentation of meteoroids in the Earth's atmosphere, b) determine values of important physical parameters; c ) <span class="hlt">study</span> seismic waves produced by atmospheric shock waves, d) <span class="hlt">study</span> the dynamics of meteoroids and f ) recover and <span class="hlt">study</span> <span class="hlt">meteorites</span>. During this meeting, the academic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860063588&hterms=consortium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconsortium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860063588&hterms=consortium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconsortium"><span>The Shergotty consortium and SNC <span class="hlt">meteorites</span> - An overview</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Laul, J. C.</p> <p>1986-01-01</p> <p>The key up-to-date findings on the Shergotty and other SNC <span class="hlt">meteorites</span> are summarized. The <span class="hlt">Martian</span> origin of these <span class="hlt">meteorites</span> is strongly suggested by the evidence of trapped noble gases and nitrogen compositions in glasses of the EETA 79001 <span class="hlt">meteorite</span>, which compare well with the results of the <span class="hlt">Martian</span> atmosphere investigation by the Viking spacecraft. Age-dating and exposure scenarios suggest two possibilities for the ejection of SNC <span class="hlt">meteorites</span>: (1) ejection as a large (larger than 6 m) body by a single impact on Mars and then multiple breakup in the asteroidal belt, at about 11 Myr for Chassigny and nakhlites, at 2.5 Myr for Shergotty, Zagami and ALHA 77005, and at 0.6 Myr for EETA 79001; and (2) ejection of small (less than 0.5 m) objects by multiple impacts on the <span class="hlt">Martian</span> terrain at 11, 2.5, and 0.6 Myr, with no breakup in space.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000057331','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000057331"><span>Minerologic and Petrologic <span class="hlt">Studies</span> of <span class="hlt">Meteorites</span> and Lunar Samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, John</p> <p>2000-01-01</p> <p>In the past year this group continued essentially full time research on extraterrestrial materials, and the question of the origin of the solar system. The continuing scientific staff consists of the P.I. and Visiting Scientist Michael Petaev. Vitae for Wood and Petaev appear in Sec. 6. We benefit from the part time services of a Project Administrator (Judith Terry) and a Secretary (Muazzez Lohmiller). In January 1999 the P.I. assumed the Chairmanship of COMPLEX, the Committee on Planetary and Lunar Exploration of the Space <span class="hlt">Studies</span> Board, National Research Council. Wood and Petaev were authors or coauthors of 21 publications, new manuscripts, and abstracts in the last year. These are listed above, and referenced by number [n] in the discussion below. Other references to the literature made in this Section are listed in Sec. 3.</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/2060/20140012904','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('https://ntrs.nasa.gov/search.jsp?R=20000081423&hterms=master&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmaster','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000081423&hterms=master&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmaster"><span>Detectability of <span class="hlt">Martian</span> Evaporites: Terrestrial Analog <span class="hlt">Studies</span> with MASTER Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moersch, J. E.; Farmer, J.; Hook, S. J.</p> <p>2000-01-01</p> <p>No evaporite mineral deposits have yet been identified on Mars. We present initial results of a terrestrial analog <span class="hlt">study</span> in Death Valley using airborne hyperspectral data to determine thresholds of detectability for evaporites in current and upcoming Mars datasets.</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('https://ntrs.nasa.gov/search.jsp?R=19940016253&hterms=keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkeynes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940016253&hterms=keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkeynes"><span>A carbon and nitrogen isotope <span class="hlt">study</span> of carbonaceous vein material in ureilite <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>Russell, S. S.; Arden, J. W.; Franchi, I. A.; Pillinger, C. T.</p> <p>1993-01-01</p> <p>The ureilite <span class="hlt">meteorite</span> group is known to be rich in carbon in the form of graphite/diamond veins that are associated with planetary type noble gases. This paper reports preliminary data from a systematic <span class="hlt">study</span> of the carbon and nitrogen isotopic composition of this carbonaceous vein material. A previous <span class="hlt">study</span> focused on the whole rock signatures and reported that the carbon inventory appeared to be dominated by the graphitic/diamond intergrowths, whereas the nitrogen was clearly composed of several distinct components including one that was isotopically light, possibly associated with the carbonaceous material. Recent <span class="hlt">studies</span> have demonstrated that diamonds in the solar system formed in many different environments. C and N measurements from ureilitic diamond made in a similar way would be a useful addition to this overall <span class="hlt">study</span>. The methods used for isolating diamonds of possible presolar origin from primitive <span class="hlt">meteorites</span> are equally applicable to the processing of carbon bearing components in the ureilite group so that their stable isotopic composition can be determined. Herein we discuss conjoint C and N stepped combustion measurements made on crushed whole rock ureilite samples that have been treated with 1M HCl/9M HF to dissolve silicate and free metal. In addition, two samples have been further treated with oxidizing acids to leave a diamond rich residue.</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://adsabs.harvard.edu/abs/2017E%26PSL.458..192B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.458..192B"><span>Halogen and Cl isotopic systematics in <span class="hlt">Martian</span> phosphates: Implications for the Cl cycle and surface halogen reservoirs 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>Bellucci, J. J.; Whitehouse, M. J.; John, T.; Nemchin, A. A.; Snape, J. F.; Bland, P. A.; Benedix, G. K.</p> <p>2017-01-01</p> <p>The Cl isotopic compositions and halogen (Cl, F, Br, and I) abundances in phosphates from eight <span class="hlt">Martian</span> <span class="hlt">meteorites</span>, spanning most rock types and ages currently available, have been measured in situ by Secondary Ion Mass Spectrometry (SIMS). Likewise, the distribution of halogens has been documented by x-ray mapping. Halogen concentrations range over several orders of magnitude up to some of the largest concentrations yet measured in <span class="hlt">Martian</span> samples or on the <span class="hlt">Martian</span> surface, and the inter-element ratios are highly variable. Similarly, Cl isotope compositions exhibit a larger range than all pristine terrestrial igneous rocks. Phosphates in ancient (>4 Ga) <span class="hlt">meteorites</span> (orthopyroxenite ALH 84001 and breccia NWA 7533) have positive δ37Cl anomalies (+1.1 to + 2.5 ‰). These samples also exhibit explicit whole rock and grain scale evidence for hydrothermal or aqueous activity. In contrast, the phosphates in the younger basaltic Shergottite <span class="hlt">meteorites</span> (<600 Ma) have negative δ37Cl anomalies (-0.2 to - 5.6 ‰). Phosphates with the largest negative δ37Cl anomalies display zonation in which the rims of the grains are enriched in all halogens and have significantly more negative δ37Cl anomalies suggestive of interaction with the surface of Mars during the latest stages of basalt crystallization. The phosphates with no textural, major element, or halogen enrichment evidence for mixing with this surface reservoir have an average δ37Cl of - 0.6 ‰, supporting a similar initial Cl isotope composition for Mars, the Earth, and the Moon. Oxidation and reduction of chlorine are the only processes known to strongly fractionate Cl isotopes, both positively and negatively, and perchlorate has been detected in weight percent concentrations on the <span class="hlt">Martian</span> surface. The age range and obvious mixing history of the phosphates <span class="hlt">studied</span> here suggest perchlorate formation and halogen cycling via brines, which have been documented on the <span class="hlt">Martian</span> surface, has been active throughout <span class="hlt">Martian</span></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://ntrs.nasa.gov/search.jsp?R=19950031745&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950031745&hterms=Thermal+floors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DThermal%2Bfloors"><span>Thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels and valleys using Termoskan data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Betts, Bruce H.; Murray, Bruce C.</p> <p>1994-01-01</p> <p>The Termoskan instrument on board the Phobos '88 spacecraft acquired the highest spatial resolution thermal infrared emission data ever obtained for Mars. Included in the thermal images 2 km/pixel, midday observations of several major channel and valley systems including significant portions of Shalbatana, Ravi, Al-Qahira, and Ma'adim Valles, the channel connecting Valles Marineris with Hydraotes Chaos, and channel material in Eos Chasma. Termoskan also observed small portions of the southern beginnings of Simud, Tiu, and Ares Valles and some channel material in Gangis Chasma. Simultaneous broadband visible reflectance data were obtained for all but Ma'adim Vallis. We find that most of the channels and valleys have higher thermal inertias than their surroundings, consistent with previous thermal <span class="hlt">studies</span>. We show for the first time that the thermal inertia boundaries closely match flat channel floor boundaries. Also, buttes within channels have inertias similiar to the plains surrounding the channels, suggesting the buttes are remnants of a contiguous plains surface. Lower bounds on typical channel thermal inertias range from 8.4 to 12.5 (10(exp -3) cal cm(exp -2) s(exp -1/2)/K) (352 to 523 in SI units of J m(exp -2) s(exp -1/2)/K). Lower bounds on inertia differences with the surrounding heavily cratered plains range from 1.1 to 3.5 (46 to 147 SI). Atmospheric and geometric effects are not sufficient to cause the observed channel inertia enhancements. We favor nonaeolian explanations of the overall channel inertia enhancements based primarily upon the channel floors' thermal homogeneity and the strong correlation of thermal boundaries with floor boundaries. However, localized, dark regions within some channels are likely aeolian in nature as reported previously. Most channels with increased inertias have fretted morphologies such as flat floors with steep walls. Eastern Ravi and southern Ares Valles, the only major channel sections observed that have obvious</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.P13A0990L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.P13A0990L"><span>New Results from Topographic <span class="hlt">Studies</span> of <span class="hlt">Martian</span> Debris Aprons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, H.; Robinson, M. S.</p> <p>2004-12-01</p> <p>Lobate debris aprons in the mid- to high latitudes for Mars' northern and southern hemispheres have been interpreted as ice-related features [e.g. 1, 2, 3]. Using MOLA topographic profiles perpendicular to apron flow fronts, we surveyed 45 debris aprons in the 35-55° Nøª latitude range of both the northern and hemispheres, specifically Mareotis, Protonilus, and Deuteronilus Mensae and Acheron Fossae, Argyre and eastern Hellas Basin. The profiles of these aprons were compared with predictions from idealized simple plastic and viscous power law models for ice-rock mixtures. All aprons <span class="hlt">studied</span> exhibit convex profiles that closely match or follow the overall trend of a simple plastic model. This result is consistent with previous interpretations [1, 2, 3, 4] that debris aprons are ice-rich mixtures with rheologies similar to stagnant ice sheets and furthermore requires high ice concentration (>40 percent by volume) in apron deposits. About 60 percent of the surveyed debris apron population deviates from the idealized simple plastic model profile, which may be due to locally reduced ice content, with ice content likely being the primary control on apron topography. Although post-emplacement modification due to near-surface ice sublimation may play a secondary role in defining the overall shape of aprons, it causes conspicuous surface textures. Degradation by ice sublimation results in pitted and ridge-and-furrow surface textures revealed by high resolution MOC images. Such textures may indicate decreased near-surface ice stability since the formation of the aprons, consistent with a recently proposed interglacial period after their emplacement [5]. Despite their elevation difference, northern and southern hemisphere debris aprons have essentially identical profile shape and exhibit similar surface texture and surface age. These similarities suggest two groups of aprons share same origin and degradation processes and their most recent reactivation likely occurred</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000084334&hterms=edema&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dedema','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000084334&hterms=edema&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dedema"><span>Pulmonary Toxicity <span class="hlt">Study</span> of Lunar and <span class="hlt">Martian</span> Dust Simulants Intratracheally Instilled in Mice</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lam, Chiu-Wing; James, John T.; Latch, John A.; Holian, A.; McCluskey, R.</p> <p>2000-01-01</p> <p>NASA is contemplating sending humans to Mars and the Moon for further exploration. The properties of Hawaiian and Californian volcanic ashes allow them to be used to simulate <span class="hlt">Martian</span> and lunar dusts, respectively. NASA laboratories use these dust simulants to test performance of hardware destined for <span class="hlt">Martian</span> or lunar environments. Workers in these test facilities are exposed to low levels of these dusts. The present <span class="hlt">study</span> was conducted to investigate the toxicity of these dust simulants. Particles of respirable-size ranges of lunar simulant (LS), <span class="hlt">Martian</span> simulant (MS), TiO2 (negative control) and quartz (positive control) were each intratracheally instilled (saline as vehicle) to groups of 4 mice (C57BL, male, 2-3 month old) at a single treatment of 1 (Hi dose) or 0.1 (Lo dose) mg/mouse. The lungs were harvested at the end of 7 days or 90 days for histopathological examination. Lungs of the LS-Lo groups had no evidence of inflammation, edema or fibrosis. The LS-Hi-7d group had mild to moderate acute inflammation, and neutrophilic and lymphocytic infiltration; the LS-Hi-90d group showed signs of chronic inflammation and some fibrosis. Lungs of the MS-Lo-7d group revealed mild inflammation and neutrophilic and lymphocytic infiltration; the MS-Lo-90d group showed mild fibrosis and particle-laden macrophages (PLM). Lungs of the MS-Hi-7d group demonstrated mild to moderate inflammation and large foci of PLM; the MS-Hi-90d group showed chronic mild to moderate inflammation and fibrosis. To mimic the effects of the oxidative and reactive properties of <span class="hlt">Martian</span> soil surface, groups of mice were exposed to ozone (3 hour at 0.5 ppm) prior to MS dust instillation. Lung lesions in the MS group were more severe with the pretreatment. The results for the negative and positive controls were consistent with the known pulmonary toxicity of these compounds. The overall severity of toxic insults to the lungs were TiO2<LS<MS<Quartz. For the mice in the 90-d <span class="hlt">study</span>, blood samples were</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.; Sanborn, M. E.; Yin, Q.-Z.</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> </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://pubs.er.usgs.gov/publication/70025811','USGSPUBS'); return false;" href="http://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('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('https://ntrs.nasa.gov/search.jsp?R=19840035696&hterms=present+value+relevance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpresent%2Bvalue%2Brelevance','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840035696&hterms=present+value+relevance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpresent%2Bvalue%2Brelevance"><span>Experimental <span class="hlt">study</span> of segregation in plane front solidification and its relevance to iron <span class="hlt">meteorite</span> solidification</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sellamuthu, R.; Goldstein, J. I.</p> <p>1983-01-01</p> <p>A directional solidification technique was developed and applied to the problem of fractional crystallization of an iron <span class="hlt">meteorite</span> parent body. Samples of Fe-Ni alloys close to <span class="hlt">meteorite</span> compositions and containing S, P, and C were made. The solidified structures contain secondary phases such as sulphides within the proeutectic single crystal austenite (taenite). As a result of these experiments, we propose that the secondary phases observed in iron <span class="hlt">meteorites</span> were formed during primary solidification of austenite (taenite). The measured composition profiles of Ni, P and C in the alloys were used to explain the elemental distribution within a chemical group of iron <span class="hlt">meteorites</span>. An analytical procedure was applied to determine the equilibrium distribution coefficients as a function of fraction solidified for Ni and P from the composition profiles. The distribution coefficients of Ni and P agree with previous values. These distribution coefficients are of particular interest in the determination of the elemental distributions in iron <span class="hlt">meteorites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17443883','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17443883"><span>The chemistry that preceded life's origin: a <span class="hlt">study</span> guide from <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>Pizzarello, Sandra</p> <p>2007-04-01</p> <p>Carbonaceous <span class="hlt">meteorites</span> are rare fragments of asteroids that contain organic carbon of diverse composition, various complexity, and whose lineage can in several instances be traced back to pre-solar environments. Their analyses offer a unique glimpse into the chemistry of the solar system that preceded life and may have been available to its emergence on the early Earth. While the heterogeneity of the organic materials of <span class="hlt">meteorites</span> is indicative of random synthetic processes for their formation, some of their components have identical counterparts in the biosphere, and a group of <span class="hlt">meteoritic</span> amino acids were found to display chiral asymmetry, a property known since the time of Pasteur to be inextricably linked to life's processes. The ability of these amino acids to act as asymmetric catalysts, as well as indications that molecular asymmetry in <span class="hlt">meteorites</span> may not be limited to these compounds, encourage the suggestion of possible involvement of <span class="hlt">meteoritic</span> material in the induction of selective traits in molecular evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P11F..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P11F..04S"><span>Lafayette, a case <span class="hlt">study</span> for quantitative determination of P, T and X of a <span class="hlt">Martian</span> subsurface fluid - and application to orbiter and lander data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwenzer, S. P.; Bridges, J.</p> <p>2012-12-01</p> <p> the geologic context and assemblage information needed to determine formation conditions. <span class="hlt">Meteorite</span> work therefore provides the basis needed to more accurately use orbiter observations to assess <span class="hlt">Martian</span> subsurface conditions and habitability. The case <span class="hlt">study</span> of mineralogical observations combined with thermochemical modeling of Lafayette also demonstrates the insights to be gained from data returned from landed missions, which are capable of observing detailed geologic context in combination with mineral species and chemistry. In particular, the Mars Science Laboratory mission will obtain an accurate set of chemical and mineralogical data from ChemCam, CheMin, APXS, and SAM; the geologic context will be provided by a set of cameras, including close up views from MAHLI (Grotzinger et al. 2012, Space Sci. Rev., DOI 10.1007/s11214-012-9892-2). The likely data are comparable to that being gained from <span class="hlt">meteorites</span>. Thermochemical modeling routines as presented here are thus expected to give insights into P, T, and X of the observed sites, aiding the assessment of habitability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994Metic..29..696D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994Metic..29..696D"><span>The Chervettaz (L5) <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>Dominik, B.; Bussy, F.; Meisser, N.</p> <p>1994-09-01</p> <p>The Chervettaz <span class="hlt">meteorite</span> was an observed fall on 1901 November 30. Our <span class="hlt">study</span> confirms the previous classification as an L5 chondrite. Weak deformations indicate stage S3 of shock deformations. We present mineralogical and chemical <span class="hlt">studies</span> of this undescribed and poorly known Swiss <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002227','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002227"><span>Mid-infrared <span class="hlt">Study</span> of Stones from the Sutters 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>Nuevo, Michel; Sandford, Scott A.; Flynn, George; Wirick, Sue</p> <p>2013-01-01</p> <p>The Sutter's Mill <span class="hlt">meteorite</span> fell in northern California on April 22, 2012, and numerous pieces have been recovered and <span class="hlt">studied</span> with several analytical techniques [1]. We present a Fourier-transform infrared (FTIR) spectroscopy analysis of fragments from several stones of the <span class="hlt">meteorite</span>. Methods and analysis: Infrared spectra of samples SM2 and SM12 were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-650/cm; spectral resolution 4/cm), while samples SM20 and SM30 were analyzed with a synchrotron-based Nicolet Continuum IR microscope in the same range. Samples were deposited on a clean glass slide, crushed with either a stainless steel roller tool or between 2 slides, and placed directly on the focal plane of the microscopes. Results: IR spectra of non-fusion crust samples show several absorption features associated with minerals such as olivines, phyllosilicates, carbonates (calcite and dolomite), and pyroxenes, as well as organics [2]. The carbonates display a main, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm. Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands?a broad band centered at 3415/cm that is probably due to adsorbed H2O, and occasionally a much weaker, narrower feature centered near 3680/cm due to structural O-H. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. However, some of these bands show unusual relative intensities, mainly because of carbonate overtone bands that fall in the same spectral range, which can make the identification of C-H stretching bands problematic. The positions and relative strengths of the aliphatic -CH2- and -CH3 features, where they can be distinguished from overlapping carbonate bands, are consistent with those in interplanetary dust particles (IDPs) and Murchison. Finally, the absence of a strong C</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140004914','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140004914"><span>Mid-Infrared <span class="hlt">Study</span> of Samples from Multiple Stones from the Sutters 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, S. A.; Nuevo, M.; Flynn, G. J.; Wirick, S.</p> <p>2013-01-01</p> <p>The Sutter's Mill <span class="hlt">meteorite</span> fell in N. California on April 22, 2012 and numerous pieces have been recovered and <span class="hlt">studied</span>. We present Fourier transform infrared (FTIR) spectra of fragments from several stones of the <span class="hlt">meteorite</span>. Methods and analysis: Infrared spectra of the samples were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-675/cm; spectral resolution 4/cm). All samples were deposited on a clean glass slide, crushed with a stainless steel roller tool, and placed directly on the focal plane of the microscope. IR spectra were collected by averaging 128 scans. Results: Preliminary IR spectra of the non-fusion crust samples show mineral compositions that are dominated by phyllosilicates, carbonates, or mixtures of both [2]. The carbonates display a dominant, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm). Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands. The O-H shows up in two forms (1) a broadband centered at 3415/cm that is probably largely due to adsorbed H2O and (2) a much weaker, narrower feature centered near 3680/cm due to structural -OH. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. The relative intensities of the bands in this range are somewhat unusual. Typically, the asymmetric aliphatic CH stretching bands are stronger than the symmetric stretching bands, but in this case the reverse is true. This unusual pattern is well matched by the aliphatic features seen in the spectrum of a terrestrial calcite (CaCO3) standard. This observation, and the fact that the strength of the carbonate and aliphatic bands seem to correlate, suggest the organics are associated with the carbonates. Conclusions: IR spectra of samples from the Sutter's Mill <span class="hlt">meteorite</span> show absorption features associated with carbonates, phyllosilicates, and organics. Both</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.396..125B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.396..125B"><span>Nanopaleomagnetism of <span class="hlt">meteoritic</span> Fe-Ni <span class="hlt">studied</span> using X-ray photoemission electron microscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bryson, James F. J.; Herrero-Albillos, Julia; Kronast, Florian; Ghidini, Massimo; Redfern, Simon A. T.; van der Laan, Gerrit; Harrison, Richard J.</p> <p>2014-06-01</p> <p>X-ray photoemission electron microscopy (XPEEM) enables natural remanent magnetisation to be imaged with ˜30 nm resolution across a field of view of 5-20 μm. The method is applied to structural features typical of the Widmanstätten microstructure (kamacite - tetrataenite rim - cloudy zone - plessite) in the Tazewell IIICD iron <span class="hlt">meteorite</span>. Kamacite lamellae and the tetrataenite rim are multidomain, whereas plessite consists of laths of different phases displaying a range of stable magnetisation directions. The cloudy zone (CZ) displays a complex interlocking domain pattern resulting from nanoscale islands of tetrataenite with easy axes distributed along three possible crystallographic directions. Quantitative analysis of the coarse and intermediate CZ was achieved using a combination of image simulations and histogram profile matching. Remanence information was extracted from individual regions of interest ˜400 nm wide, demonstrating for the first time the capability of XPEEM to perform quantitative paleomagnetic analysis at sub-micron length scales. The three tetrataenite easy axis orientations occur with equal probability in the coarse and intermediate CZ, suggesting that spinodal decomposition in these regions was not strongly influenced by internal interaction fields, and that they are suitable candidates for future paleomagnetic <span class="hlt">studies</span>. The fine CZ shows a strong dominance of one easy axis. This effect is attributed to island-island exchange interactions that render the fine CZ unsuitable for paleomagnetic <span class="hlt">study</span>. Variations in the relative strength (proportion of dominant easy axis) and direction (direction of dominant easy axis) of a paleomagnetic field can be resolved from different regions of the CZ using XPEEM, raising the prospect of obtaining a time-resolved measurement of the active dynamo period in <span class="hlt">meteorites</span> originating from the upper unmelted regions of differentiated asteroids (e.g. chondrites, pallasites, mesosiderites).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890063360&hterms=Accelerator+mass+spectrometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DAccelerator%2Bmass%2Bspectrometry','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890063360&hterms=Accelerator+mass+spectrometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DAccelerator%2Bmass%2Bspectrometry"><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>Nishiizumi, K.; Elmore, D.; Kubik, P. W.</p> <p>1989-01-01</p> <p>Cosmic-ray produced Cl-36 (half-life = 3.01 x 10 to the 5th years) has been measured in 90 Antarctic <span class="hlt">meteorites</span> by accelerator mass spectrometry. The terrestrial ages of the <span class="hlt">meteorites</span> were calculated from the results. After excluding possible paired objects, 138 terrestrial ages from 18 different locations are available from C-14, Kr-81, and Cl-36 measurements for application to Antarctic <span class="hlt">meteorite</span> and glaciological <span class="hlt">studies</span>. The terrestrial ages of Allan Hills <span class="hlt">meteorites</span> vary from 2000 years to 1 million years and are clearly longer than those of Yamato <span class="hlt">meteorites</span> and other Antarctic <span class="hlt">meteorites</span>. The oldest Allan Hills <span class="hlt">meteorites</span> were found close to the eastern edge and in the southeast of the main icefield. Among all Antarctic <span class="hlt">meteorites</span> measured to date, only L and LL chondrites have terrestrial ages older than 370,000 years.</p> </li> <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/2060/19860013036','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860013036"><span><span class="hlt">Meteorite</span> craters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ivanov, B. A.; Bazilevskiy, A. T.</p> <p>1986-01-01</p> <p>The origin and formation of various types of craters, both on the Earth and on other planetary bodies, are discussed. Various models are utilized to depict various potential causes of the types and forms of <span class="hlt">meteorite</span> craters in our solar system, and the geological structures are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002Icar..158...72M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002Icar..158...72M"><span>Planetary Bioresources and Astroecology. 1. Planetary Microcosm Bioassays of <span class="hlt">Martian</span> and Carbonaceous Chondrite Materials: Nutrients, Electrolyte Solutions, and Algal and Plant Responses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mautner, Michael N.</p> <p>2002-07-01</p> <p>The biological fertilities of planetary materials can be assessed using microcosms based on <span class="hlt">meteorites</span>. This <span class="hlt">study</span> applies microcosm tests to <span class="hlt">martian</span> <span class="hlt">meteorites</span> and analogues and to carbonaceous chondrites. The biological fertilities of these materials are rated based on the soluble electrolyte nutrients, the growth of mesophile and cold-tolerant algae, and plant tissue cultures. The results show that the <span class="hlt">meteorites</span>, in particular the Murchison CM2 carbonaceous chondrite and DaG 476 <span class="hlt">martian</span> shergottite, contain high levels of water-extractable Ca, Mg, and SO 4-S. The <span class="hlt">martian</span> <span class="hlt">meteorites</span> DaG 476 and EETA 79001 also contain higher levels of extractable essential nutrients NO 3-N (0.013-0.017 g kg -1) and PO 4-P (0.019-0.046 g kg -1) than the terrestrial analogues. The yields of most of the water-extractable electrolytes vary only by factors of 2-3 under a wide range of planetary conditions. However, the long-term extractable phosphate increases significantly under a CO 2 atmosphere. The biological yields of algae and plant tissue cultures correlate with extractable NO 3-N and PO 4-P, identifying these as the limiting nutrients. Mesophilic algae and Asparagus officinalis cultures are identified as useful bioassay agents. A fertility rating system based on microcosm tests is proposed. The results rate the fertilities in the order <span class="hlt">martian</span> basalts > terrestrial basalt, agricultural soil > carbonaceous chondrites, lava ash > cumulate igneous rock. The results demonstrate the application of planetary microcosms in experimental astroecology to rate planetary materials as targets for astrobiology exploration and as potential space bioresources. For example, the extractable materials in Murchison suggest that concentrated internal solutions in carbonaceous asteroids (3.8 mol L -1 electrolytes and 10 g L -1 organics) can support and disperse microorganisms introduced by natural or directed panspermia in early solar systems. The results also suggest that carbonaceous asteroids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020002133&hterms=Radioactivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DRadioactivity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020002133&hterms=Radioactivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DRadioactivity"><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://adsabs.harvard.edu/abs/2016LPICo1921.6082L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6082L"><span>Chalcophile Siderophile Trace Element Systematics of Hydrothermal Pyrite from <span class="hlt">Martian</span> Regolith Breccia 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>Lorand, J.-P.; Hewins, R. H.; Humayun, M.; Remusat, L.; Zanda, B.; La, C.; Pont, S.</p> <p>2016-08-01</p> <p><span class="hlt">Martian</span> impact breccia NWA 7533 contains hydrothermal pyrite. Laser ablation ICPMS analyses show that its chalcophile siderophile element content was inherited from both early <span class="hlt">meteorite</span> bombardment and later hydrothermal inputs from H2S fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940030922','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940030922"><span>Solar proton produced neon in shergottite <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>Garrison, D. H.; Rao, M. N.; Bogard, D. D.</p> <p>1994-01-01</p> <p>Cosmogenic radionuclides produced by near-surface, nuclear interactions of energetic solar protons (approx. 10-100 MeV) were reported in several lunar rocks and a very small <span class="hlt">meteorites</span>. We recently documented the existence and isotopic compositions of solar-produced (SCR) Ne in two lunar rocks. Here we present the first documented evidence for SCR Ne in a <span class="hlt">meteorite</span>, ALH77005, which was reported to contain SCR radionuclides. Examination of literature data for other shergottites suggests that they may also contain a SCR Ne component. The existence of SCR Ne in shergottites may be related to a <span class="hlt">Martian</span> origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6001O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6001O"><span>Mineralogical Composition of the Mexican Ordinary Chondrite Type <span class="hlt">Meteorite</span>: A Raman, Infrared and XRD <span class="hlt">Study</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ostrooumov, M.</p> <p>2016-08-01</p> <p>The Raman microprobe (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of seven mexican <span class="hlt">meteorites</span>: Aldama, Cosina, El Pozo, Escalon, Nuevo Mercurio,Pacula, Zapotitlan Salinas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940020426&hterms=bounded+variation&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbounded%2Bvariation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940020426&hterms=bounded+variation&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbounded%2Bvariation"><span><span class="hlt">Martian</span> mesoscale circulations induced by variations in surface optical and thermal characteristics: A numerical <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Siili, Tero; Savijarvi, H.</p> <p>1993-01-01</p> <p>According to Mariner 9 and Viking observations the surface albedo and the thermal inertia of Mars' surface vary substantially, and fairly large gradients also occur. The Syrtis Major region is bounded in the west by high-albedo cratered terrain and in the east by Isidis Planitia, a high-albedo plateau. Sinus Meridiani, centered at 0 degrees W 5 degrees S, is almost surrounded by higher albedo regions with sharp boundaries, and Acidalia Planitia, between 10 and 50 degrees W and north of 35 degrees N, has sharp albedo boundaries to the east and west. Observational and modeling <span class="hlt">studies</span>, e.g., on Australian dry salt lake coasts, have shown that discontinuities and gradients in surface properties can induce mesoscale circulations. We have used a version of the DMUH mesoscale model to simulate atmospheric circulations induced by variations in the reflectivity and in the thermal inertia of the <span class="hlt">martian</span> surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EPSC....8...50K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EPSC....8...50K"><span>AOTF near-IR spectrometers for <span class="hlt">study</span> of Lunar and <span class="hlt">Martian</span> surface composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korablev, O.; Kiselev, A.; Vyazovetskiy, N.; Fedorova, A.; Evdokimova, N.; Stepanov, A.; Titov, A.; Kalinnikov, Y.; Kuzmin, R. O.; Bazilevsky, A. T.; Bondarenko, A.; Moiseev, P.</p> <p>2013-09-01</p> <p>The series of the AOTF near-IR spectrometers is developed in Moscow Space Research Institute for <span class="hlt">study</span> of Lunar and <span class="hlt">Martian</span> surface composition in the vicinity of a lander or a rover. Lunar Infrared Spectrometer (LIS) is an experiment onboard Luna-Glob (launch in 2015) and Luna-Resurs (launch in 2017) Russian surface missions. The LIS is mounted on the mechanic arm of landing module in the field of view (45°) of stereo TV camera. Infrared Spectrometer for ExoMars (ISEM) is an experiment onboard ExoMars (launch in 2018) ESARoscosmos rover. The ISEM instrument is mounted on the rover's mast together with High Resolution camera (HRC). Spectrometers will provide measurements of selected surface area in the spectral range of 1.15-3.3 μm. The electrically commanded acousto-optic filter scans sequentially at a desired sampling, with random access, over the entire spectral range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010048879&hterms=Chemistry+organic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DChemistry%2Borganic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010048879&hterms=Chemistry+organic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DChemistry%2Borganic"><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> </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://adsabs.harvard.edu/abs/2009EGUGA..11.1292H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1292H"><span>Deception island, Antarctica: a terrestrial analogue for the <span class="hlt">study</span> and understanding of the <span class="hlt">martian</span> permafrost and subsurface glaciers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hernandez de Pablo, M. A.; Ramos, M.; Vieira, G.; Gilichinsky, D.; Gómez, F.; Molina, A.; Segovia, R.</p> <p>2009-04-01</p> <p>The existence of permafrost on Mars was widely <span class="hlt">studied</span> since Viking era and its presence is fundamental in the understanding of the water-cycle, the geological history of Mars, and the evolution of the <span class="hlt">martian</span> hydrosphere. Viking, MOC, THEMIS, HRSC and HiRISE images allowed increase our knowledge about the role of ice on the <span class="hlt">martian</span> landscapes. Polygonal terrains, glacial-like features, "basketball terrain" or pingos are some of the landforms that reveal the existence of frozen ice near the surface and in the ground forming the <span class="hlt">martian</span> permafrost on present, recent or ancient times. The field observations and analyses done by Phoenix mission seem to confirm the existence of the <span class="hlt">martian</span> permafrost hypothesized by the analyses of the images acquired by the previous missions to Mars. Moreover, the recent interpretations of the (RADAR) sensor on board of MRO mission also revealed that the surface of Mars seems to cover an important volume of ice forming glaciers covered by different materials. Here we propose the <span class="hlt">study</span> of the glaciers and permafrost of Deception Island (Antarctica) such as a terrestrial analogue of the glaciers and permafrost of Mars. This active volcanic island is an exceptional site to <span class="hlt">study</span> the permafrost since the climatic conditions maintain the surface covered by the ice and snow during the main part of the year. This characteristic allows the existence of an important permafrost layer also during the summer, and permanent glaciers in the higher part of the island. In addition, Deception Island is an active volcano. Some of the glaciers are covered by the ash and tephra what made difficult to distinguish between the covered glacier and the permafrost. The eruptive volcanic materials could have similar characteristics than some <span class="hlt">martian</span> regolith by lithology, granulometry and texture. In this way, the <span class="hlt">study</span> of the permafrost and glaciers in Deception Island could help to understand the <span class="hlt">martian</span> permafrost and glaciers at present. On the other hand</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890040112&hterms=Metamorphic+process&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DMetamorphic%2Bprocess','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890040112&hterms=Metamorphic+process&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DMetamorphic%2Bprocess"><span>Shock effects 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>Stoeffler, D.; Bischoff, A.; Buchwald, V.; Rubin, A. E.</p> <p>1988-01-01</p> <p>The impacts that can occur between objects on intersecting solar system orbits can generate shock-induced deformations and transformations, creating new mineral phases or melting old ones. These shock-metamorphic effects affect not only the petrography but the chemical and isotopic properties and the ages of primordial <span class="hlt">meteoritic</span> materials. A fuller understanding of shock metamorphism and breccia formation in <span class="hlt">meteorites</span> will be essential not only in the <span class="hlt">study</span> of early accretion, differentiation, and regolith-evolution processes, but in the characterization of the primordial composition of the accreted material itself.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P41F1983P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P41F1983P"><span>Synthesis of Seifertite and its Applications to 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>Page, M. E.; Ohtani, E.; Suzuki, A.; Asahara, Y.; Saxena, S.</p> <p>2013-12-01</p> <p>Seifertite is a high pressure polymorph of silica and a post-stishovite phase. The stable phase is observed at very high pressures around the core-mantle boundary, generally above 100 GPa. Despite this, the mineral is increasingly found in shocked <span class="hlt">meteorites</span>, both <span class="hlt">Martian</span> (1) (Sharp et al., 1999), and lunar (2) (Miyahara et al., 2013). It appears, then, that the occurrence of seifertite may indicate intensive shock events on Mars and the Moon. In direct contrast to this, recent high pressure <span class="hlt">studies</span> have shown metastable formation of seifertite from cristobalite, a high-temperature and low-pressure polymorph of silica, at high pressures of only 30 GPa (3) (Dubrovinski et al., 2001) or less (4) (Kubo et al., 2012). Thus, the formation conditions of seifertite in <span class="hlt">meteorites</span> are not well catalogued. Knowing this, experiments on the reaction kinetics of formation of seifertite from cristobalite are investigated. Synthesis experiments at 20 GPa and 600 C and 900 C were carried out for various heating duration using the Kawai type mutianvil apparatus. Formation of seifertite from cristobalite was observed, and seifertite was quenchable and recovered to ambient conditions. Present results suggest that the existence of seifertite does not indicate an intensive shock pressure above 100 GPa. Rather, it is as low as 20 GPa around 600 C. We intend to report a more detailed <span class="hlt">study</span> on reaction kinetics of seifertite from cristobalite at high pressures and temperatures, and will discuss new constraints on the impact conditions of some <span class="hlt">Martian</span> and lunar <span class="hlt">meteorites</span> from which seifertite was reported. (1) Sharp, T. G. et al. A Post-Stishovite SiO2 Polymorph in the <span class="hlt">Meteorite</span> Shergotty: Implications for Impact Events, Science, 284, 1511 (1999) (2) Miyahara, M. et al. Discovery of Seifertite in a Shocked Lunar <span class="hlt">Meteorite</span>, Nat Commun, 4, 1737 (2013) (3) Dubrovinsky, L. S. et al. Pressure-induced Transformations of Cristobalite, Chem Phys Lett, 333, 264 (2001) (4) Kubo, T. et al. Formation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRA..118.1972D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRA..118.1972D"><span>A statistical <span class="hlt">study</span> of proton precipitation onto the <span class="hlt">Martian</span> upper atmosphere: Mars Express observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DiéVal, C.; Stenberg, G.; Nilsson, H.; Barabash, S.</p> <p>2013-05-01</p> <p>Due to the small size of the <span class="hlt">Martian</span> magnetic pile-up region, especially at the subsolar point, heated protons with high enough energy can penetrate the induced magnetosphere boundary without being backscattered, i.e., they precipitate. We present a statistical <span class="hlt">study</span> of the downgoing ~ keV proton fluxes measured in the <span class="hlt">Martian</span> ionosphere by the Analyzer of Space Plasma and Energetic Atoms experiment onboard the Mars Express spacecraft. We find that on the dayside, the events of proton penetration occur during 3% of the observation time; the precipitation is an intermittent phenomenon. The proton events carry on average ~0.2% of the incident solar wind flux. Therefore, the induced magnetosphere is an effective shield against the magnetosheath protons. The events are more frequent during fast solar wind conditions than during slow solar wind conditions. The sporadic proton penetration is thought to be caused by transient increases in the magnetosheath temperature. The precipitating flux is higher on the dayside than on the nightside, and its spatial deposition is controlled by the solar wind convective electric field. The largest crustal magnetic anomalies tend to decrease the proton precipitation in the southern hemisphere. The particle and energy fluxes vary in the range 104-106 cm-2 s-1 and 107-109 eVcm-2 s-1, respectively. The corresponding heating for the dayside atmosphere is on average negligible compared to the solar extreme ultraviolet heating, although the intermittent penetration may cause local ionization. The net precipitating proton particle flux input to the dayside ionosphere is estimated as 1.2 · 1021 s-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT........18G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT........18G"><span>From Magma Formation to Hydrothermal Alteration: an Integrated <span class="hlt">Study</span> of the <span class="hlt">Martian</span> Crust Using Thermodynamic Modeling of Geochemical Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Griffith, Laura Lee</p> <p></p> <p>Hydrothermal systems have undoubtedly occurred on Mars. These systems are of interest for a number of reasons. Hydrothermal alteration of host rocks can have effects on the atmosphere of the planet, the volatile budget, local hydrologic patterns, the rheology of the rocks, their ability to resist weathering, and even lower the melting temperature of crustal rocks. In addition, there is a connection between hydrothermal systems and the origin of life on earth that raises questions about life on Mars. The approach taken used theoretical geochemical modeling techniques to model hypothetical hydrothermal systems on Mars. The initial phase of the research involved understanding terrestrial systems that were used as analogs for <span class="hlt">Martian</span> systems. Compositions of Icelandic host rocks were used as input for extensive modeling calculations. These calculations investigated the roles of initial rock composition, fluid temperature, partial pressure of carbon dioxide in the fluid, water to rock ratio, and oxygen fugacity of the fluid on alteration assemblages. The second phase utilized the data available on the SNC <span class="hlt">meteorites</span> (they are suspected to come from Mars) as the basis for hydrothermal system modeling. The focus of this investigation was the variability of alteration assemblages that could be produced from the SNC <span class="hlt">meteorites</span>. The final investigation broadened the scope of possible substrates for hydrothermal systems by using theoretical geochemical modeling of igneous processes to produce likely Martial crustal rock compositions from a possible Martial mantle composition. A variety of variables (depth of initial melting, amount of initial melt, cooling rate during ascent, and depth of final emplacement) were examined to determine their effects on compositions of the calculated melts. Several rock compositions produced by the igneous modeling were used as input for hydrothermal modeling calculations. These calculations examined possible differences in alteration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.P13E..01G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.P13E..01G"><span>Laboratory <span class="hlt">Studies</span> of the Heterogeneous Uptake of Methane on <span class="hlt">Martian</span> Soil Analogs: Determination of Upper Limits of Reactivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gough, R. V.; Hatch, C. D.; Tolbert, M. A.</p> <p>2007-12-01</p> <p>In order to constrain possible methane sources on Mars, it is necessary to understand the type and magnitude of all possible methane sinks. We have performed laboratory experiments to determine the importance of heterogeneous uptake of methane on mineral surfaces analogous to <span class="hlt">Martian</span> surface material. The uptake of methane on sodium montmorillonite and Mars soil simulant JSC-1 (a palagonite) was <span class="hlt">studied</span> using a Knusden cell flow reactor capable of achieving <span class="hlt">Martian</span> temperature, pressure and relative humidity conditions. A quadrupole mass spectrometer was used to detect any decrease in methane flow due to heterogeneous uptake and infrared spectroscopy was used to detect any adsorbed species on the particles. Experiments were performed under <span class="hlt">Martian</span> temperatures (from 195 to 215 K), and under both dry conditions and 45% RH. As montmorillonite clay possesses unique swelling properties in the presence of water vapor, experiments were performed in which the clay was simultaneously exposed to water and methane, and also experiments in which the clay was equilibrated with water vapor prior to methane exposure. We found no methane uptake relative to an unreactive blank Si wafer on any of the <span class="hlt">Martian</span> soil analogs <span class="hlt">studied</span> under any conditions. These negative results place upper limits on the heterogeneous reactivity of methane on the <span class="hlt">Martian</span> surface. We have determined that the initial uptake coefficient of methane on palagonite is less than 3.66×10-10 (±1.41×10-11) and the initial uptake coefficient, γ0, of methane on montmorillonite is less than 7.52×10-10 (±2.56×10-11). These <span class="hlt">studies</span> demonstrate methane uptake by mineral surfaces is not expected to be a significant methane sink, as the process likely occurs on a time scale much longer than photolysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111064&hterms=Weathering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DWeathering','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111064&hterms=Weathering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DWeathering"><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('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('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/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://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://adsabs.harvard.edu/abs/2014cosp...40E1722K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1722K"><span>Meteor bodies entering the <span class="hlt">Martian</span> atmosphere: possible impact consequences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuznetsova, Daria; Gritsevich, Maria</p> <p></p> <p>The investigation of <span class="hlt">meteorite</span> production on Mars has attracted considerable attention during the recent years. The possible <span class="hlt">meteorite</span> showers are identified e.g. [1], and the estimates of <span class="hlt">meteorite</span> fluxes on Mars are found e.g. [2,3]. In this <span class="hlt">study</span>, we develop the theory describing a meteoroid entry into an atmosphere of a planet and apply our results to the <span class="hlt">Martian</span> atmosphere. We introduce two key dimensionless parameters, which are based on physical parameterization and have unique values for every single meteoroid case. This allows us to derive the condition for the <span class="hlt">meteorite</span> fall identification in a simple analytical form, which can be directly implemented for analysis and classification of the possible impact consequences. To describe the motion we use the classical equations of the model of meteor body deceleration [4,5]. The analytical dimensionless solution for the mass-velocity dependence and the height-velocity dependence can be expressed using two main parameters: (i) the ballistic coefficient alpha, which shows the ratio between the mass of the atmospheric column along the trajectory and the body's pre-entry mass, and (ii) the mass loss parameter beta, which is proportional to the ratio between the initial kinetic energy of the body and energy which is required to insure total mass loss of the body due to ablation and fragmentation [6-8]. To determine the possible consequences of impact for any given meteoroid, we use the <span class="hlt">meteorite</span>-fall condition: the terminal mass of the meteoroid should exceed or be equal to a certain chosen value. This condition can be written using the parameters alpha and beta, so the impact consequences are described by the position of the case-under-investigation point relatively to the boundary curve in the (alpha,beta) space. Following a number of <span class="hlt">studies</span> [9-11] we analyze the hypothesis that describes the possible evolution of <span class="hlt">Martian</span> atmospheric density until present. Based on the properties of the <span class="hlt">meteorites</span> recently found</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/2015E%26PSL.427..104B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.427..104B"><span>A Noachian source region for the "Black Beauty" <span class="hlt">meteorite</span>, and a source lithology for Mars surface hydrated dust?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, P.; Pommerol, A.; Zanda, B.; Remusat, L.; Lorand, J. P.; Göpel, C.; Hewins, R.; Pont, S.; Lewin, E.; Quirico, E.; Schmitt, B.; Montes-Hernandez, G.; Garenne, A.; Bonal, L.; Proux, O.; Hazemann, J. L.; Chevrier, V. F.</p> <p>2015-10-01</p> <p>The <span class="hlt">Martian</span> surface is covered by a fine-layer of oxidized dust responsible for its red color in the visible spectral range (Bibring et al., 2006; Morris et al., 2006). In the near infrared, the strongest spectral feature is located between 2.6 and 3.6 μm and is ubiquitously observed on the planet (Jouglet et al., 2007; Milliken et al., 2007). Although this absorption has been <span class="hlt">studied</span> for many decades, its exact attribution and its geological and climatic implications remain debated. We present new lines of evidence from laboratory experiments, orbital and landed missions data, and characterization of the unique <span class="hlt">Martian</span> <span class="hlt">meteorite</span> NWA 7533, all converging toward the prominent role of hydroxylated ferric minerals. <span class="hlt">Martian</span> breccias (so-called "Black Beauty" <span class="hlt">meteorite</span> NWA7034 and its paired stones NWA7533 and NWA 7455) are unique pieces of the <span class="hlt">Martian</span> surface that display abundant evidence of aqueous alteration that occurred on their parent planet (Agee et al., 2013). These dark stones are also unique in the fact that they arose from a near surface level in the Noachian southern hemisphere (Humayun et al., 2013). We used IR spectroscopy, Fe-XANES and petrography to identify the mineral hosts of hydrogen in NWA 7533 and compare them with observations of the <span class="hlt">Martian</span> surface and results of laboratory experiments. The spectrum of NWA 7533 does not show mafic mineral absorptions, making its definite identification difficult through NIR remote sensing mapping. However, its spectra are virtually consistent with a large fraction of the <span class="hlt">Martian</span> highlands. Abundant NWA 7034/7533 (and paired samples) lithologies might abound on Mars and might play a role in the dust production mechanism.</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('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=19930055812&hterms=Lafayette&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DLafayette','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930055812&hterms=Lafayette&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DLafayette"><span>Preterrestrial aqueous alteration of the Lafayette (SNC) <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.; Barrett, Ruth A.; Gooding, James L.</p> <p>1993-01-01</p> <p>The structure and chemical composition of the Lafayette <span class="hlt">meteorite</span> were examined using several methods. The <span class="hlt">meteorite</span> contains abundant hydrous post-magnetic alteration material consisting of ferroan smectite clays, magnetite, and ferrihydrite. The textural relations, mineralogy, and composition of these materials were examined and their preterrestrial nature was documented. Olivine, pyroxene, and glass alteration are described and the bulk compositions of the alteration veinlets is discussed. Essential features of the geochemistry of the alteration processes are described. It is suggested that the alteration of the Lafayette <span class="hlt">meteorite</span> occurred during episodic infiltrations of small volumes of saline water. Constraints placed on water chemistry and water-rock interactions in the <span class="hlt">Martian</span> crust are outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12497188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12497188"><span>New approaches to the <span class="hlt">study</span> of Antarctic lithobiontic microorganisms and their inorganic traces, and their application in the detection of life in <span class="hlt">Martian</span> rocks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ascaso, C; Wierzchos, J</p> <p>2002-12-01</p> <p>Microbial life in the harsh conditions of Antarctica's cold desert may be considered an analogue of potential life on early Mars. In order to explore the development and survival of this epilithic and endolithic form of microbial life, our most sophisticated, state-of-the-art visualization technologies have to be used to their full potential. The <span class="hlt">study</span> of any ecosystem requires a knowledge of its components and the processes that take place within it. If we are to understand the structure and function of each component of the microecosystems that inhabit lithic substrates, we need to be able to quantify and identify the microorganisms present in each lithobiontic ecological niche and to accurately characterize the mineralogical features of these hidden microhabitats. Once we have established the techniques that will allow us to observe and identify these microorganisms and mineral substrates in situ, and have confirmed the presence of water, the following questions can be addressed: How are the microorganisms organized in the fissures or cavities? Which microorganisms are present and how many are there? Additional questions that logically follow include: What are the existing water relationships in the microhabitat and what effects do the microorganisms have on the mineral composition? Mechanical and chemical changes in minerals and mineralization of microbial cells can give rise to physical and/or chemical traces (biomarkers) and to microbial fossil formation. In this report, we describe the detection of chains of magnetite within the <span class="hlt">Martian</span> <span class="hlt">meteorite</span> ALH84001, as an example of the potential use of SEM-BSE in the search for plausible traces of life on early Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860022894','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860022894"><span><span class="hlt">Studies</span> on cosmogenic nuclides in <span class="hlt">meteorites</span> with regard to an application as potential depth indicators</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sarafin, R.; Herpers, U.; Englert, P.; Wieler, R.; Signer, P.; Bonani, G.; Hofmann, H. J.; Morenzoni, E.; Nessi, M.; Suter, M.</p> <p>1986-01-01</p> <p>Measurements of stable and radioactive spallation products in <span class="hlt">meteorites</span> allow to investigate their histories, especially with respect to the exposure to galactic cosmic ray particles and the pre-atmospheric size of the object. While the concentrations of spallation products lead to the determination of exposure and terrestrial ages, production rate ratios are characteristic for the location of the sample in the <span class="hlt">meteorite</span>. So, one of the aims of this investigation on <span class="hlt">meteorites</span> is to obtain depth indicators from suitable pairs of cosmogenic nuclides. Because of the different depth profiles for nuclide productions it is necessary to determine the concentrations of a larger number of spallation products in aliquots of a single small sample. Such same sample measurements of Be-10 and light noble gases were performed on 15 ordinary chondrites (7 H- and 8 L-chondrites. Be-10 was determined by accelerator mass spectrometry and the noble gases were measured by static mass spectrometry. The results are summarized and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HyInt.237...15G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HyInt.237...15G"><span>Comparative <span class="hlt">study</span> of Aliskerovo, Anyujskij, Sikhote-Alin and Sterlitamak iron <span class="hlt">meteorites</span> using Mössbauer spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goryunov, M. V.; Oshtrakh, M. I.; Chukin, A. V.; Grokhovsky, V. I.; Semionkin, V. A.</p> <p>2016-12-01</p> <p>A comparative <span class="hlt">study</span> of Sikhote-Alin IIAB, Anyujskij IIAB, Aliskerovo IIIE-an and Sterlitamak IIIAB iron <span class="hlt">meteorites</span> was carried out using Mössbauer spectroscopy with a high velocity resolution as well as using metallography, scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction. Different numbers of spectral components were found in the Mössbauer spectra of Sikhote-Alin IIAB and Anyujskij IIAB and in the spectra of Aliskerovo IIIE-an and Sterlitamak IIIAB iron <span class="hlt">meteorites</span>. The values of hyperfine field at the 57Fe nuclei obtained for spectral components were related to α-Fe(Ni, Co), α 2-Fe(Ni, Co) and γ-Fe(Ni, Co) phases with variations in Ni concentration.</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/1988EOSTr..69..616G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988EOSTr..69..616G"><span><span class="hlt">Meteorites</span> and Their Parent Planets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goodrich, Cyrena Anne</p> <p></p> <p>Harry Y. McSween's latest book, <span class="hlt">Meteorites</span> and Their Parent Planets, is not intended primarily as a textbook or a technical reference for the dedicated researcher in <span class="hlt">meteoritics</span>. Several up-to-date books along these lines already exist (<span class="hlt">Meteorites</span>: A Petrologic-Chemical Synthesis, by R. T. Dodd, Cambridge University Press, London, 1981; <span class="hlt">Meteorites</span>: Their Record of Early Solar System History, by J. T. Wasson, W. H. Freeman, San Francisco, Calif., 1985; <span class="hlt">Meteorites</span> and the Early Solar System, edited by J. F. Kerridge and M. Matthews, University of Arizona Press, Tucson, in press, 1988). Rather, it is intended as an introduction of the field of <span class="hlt">meteoritics</span> and the <span class="hlt">study</span> of the formation and evolution of the Solar System, and it is aimed at a broad spectrum of scientists and nonscientists.McSween has undertaken a difficult task. Many problems in <span class="hlt">meteoritics</span> require synthesis of information and lines of reasoning from such diverse and highly specialized areas of <span class="hlt">study</span> as celestial mechanics, astrophysics, cratering dynamics, spectrophotometry, igneous petrology, and isotope geochemistry. Hence these problems are often difficult for the student, or even the advanced researcher, to grasp and are rarely appreciated by the nonscientist. McSween, however, succeeds remarkably well in presenting this complex subject in a way that any curious, intelligent person can understand.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014acm..conf...95C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014acm..conf...95C"><span>Recent <span class="hlt">meteorite</span> falls in South Korea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, Y.; Kim, M.; Byun, Y.; Yi, H.; Chang, S.; Choi, J.; Sohn, J.; Moon, H.; Park, J.</p> <p>2014-07-01</p> <p>In the evening of March 9, 2014, a fireball falling from north to south was observed in South Korea. Multiple explosions were heard and multiple videos recorded in cars from various places, suggesting that the fireball was separated into several pieces. Immediately thereafter, a series of discovery reports about <span class="hlt">meteorites</span> from the southern part of South Korea followed and, as of today, three <span class="hlt">meteorites</span> were confirmed and one <span class="hlt">meteorite</span>, with a mass of about 20 kg, is pending. This discovery of a <span class="hlt">meteorite</span> in South Korea occurs for the first time in 70 years. The overall trajectory of the fireball matches the area where <span class="hlt">meteorites</span> were discovered. According to the preliminary analyses, the <span class="hlt">meteorite</span> is an ordinary chondrite. The origin of the <span class="hlt">meteorite</span> and its surface properties will be <span class="hlt">studied</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001515','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001515"><span><span class="hlt">Martian</span> seismicity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Phillips, Roger J.; Grimm, Robert E.</p> <p>1991-01-01</p> <p>The design and ultimate success of network seismology experiments on Mars depends on the present level of <span class="hlt">Martian</span> seismicity. Volcanic and tectonic landforms observed from imaging experiments show that Mars must have been a seismically active planet in the past and there is no reason to discount the notion that Mars is seismically active today but at a lower level of activity. Models are explored for present day Mars seismicity. Depending on the sensitivity and geometry of a seismic network and the attenuation and scattering properties of the interior, it appears that a reasonable number of <span class="hlt">Martian</span> seismic events would be detected over the period of a decade. The thermoelastic cooling mechanism as estimated is surely a lower bound, and a more refined estimate would take into account specifically the regional cooling of Tharsis and lead to a higher frequency of seismic events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770056178&hterms=American+Museum+Natural+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DAmerican%2BMuseum%2BNatural%2BHistory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770056178&hterms=American+Museum+Natural+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DAmerican%2BMuseum%2BNatural%2BHistory"><span><span class="hlt">Studies</span> of Brazilian <span class="hlt">meteorites</span>. III - Origin and history of the Angra dos Reis achondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prinz, M.; Keil, K.; Hlava, P. F.; Berkley, J. L.; Gomes, C. B.; Curvello, W. S.</p> <p>1977-01-01</p> <p>The mineral composition of the Angra dos Reis <span class="hlt">meteorite</span>, which fell in 1869, is described. This achondrite contains phases reported in a <span class="hlt">meteorite</span> for the first time. Petrofabric analysis shows that fassaite has a preferred orientation and lineation, which is interpreted as being due to cumulus processes, possibly the effect of post-depositional magmatic current flow or laminar flow of a crystalline mush. The mineral chemistry indicates crystallization from a highly silica-undersaturated melt at low pressure. Several aspects of the mineral composition are discussed with reference to the implications of crystallization conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090034382&hterms=Prokaryotes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DProkaryotes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090034382&hterms=Prokaryotes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DProkaryotes"><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('http://hdl.handle.net/2060/19900018247','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018247"><span>Carbon in primitive <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>Kerridge, John F.</p> <p>1990-01-01</p> <p>No <span class="hlt">meteorites</span> are truly primitive, in the sense of being pristine collections of interstellar grains or solar-nebular condensates. Nonetheless, some chrondritic <span class="hlt">meteorites</span> have been so little altered by secondary processing that they are commonly termed primitive and it is almost a definition of such chondrites that they contain significant quantities of carbon. Most of that carbon is of apparently local, i.e., solar-system, origin but a proportion that ranges from trace, in some cases, to minor, in others, is believed to be exotic, i.e., of circumstellar or interstellar origin, and it is upon such material that researchers focus here. The nature of the <span class="hlt">meteoritic</span> samples and the techniques used to analyse them are briefly discussed and the observational record is surveyed. Clearly, the <span class="hlt">study</span> of exotic carbon preserved in <span class="hlt">meteorites</span> has been informative about sites of nucleosynthesis, processes of nucleation and growth of grains in stellar outflows, grain survival in the interstellar medium, and many other topics of astrophysical significance. Much more work, particularly of an interdisciplinary nature remains to be done, however.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....5975R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....5975R"><span>Magnetic classification 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>Rochette, P.; Sagnotti, L.; Consolmagno, G.; Denise, M.; Folco, L.; Gattacceca, J.; Osete, M.; Pesonen, L.</p> <p>2003-04-01</p> <p>Magnetic susceptibility (X) provides a versatile rapid and non destructive way to quantify the amount of magnetic minerals (FeNi metal, magnetic oxides and sulfides) on large volume of material. As petrological <span class="hlt">studies</span> of <span class="hlt">meteorites</span> suggest that this parameter should be quite discriminant, we assembled a database of measurements on about 1200 stony <span class="hlt">meteorites</span> from various European collections: Helsinki, Madrid, Moscou, Paris, Prague, Roma, Siena, Vatican, and other smaller collections. From 1 to >20 pieces and 1 to >100 cc per <span class="hlt">meteorite</span> allow to define a representative mean value, using a large coil (8 cm) Kappabridge. For ordinary chondrites, it appears that weathering is responsible for a systematic bias toward low X for Antarctic (Frontier Mountain) and non Antarctic (mainly from Sahara) finds. Once only falls are considered a quite narrow range of X is observed for a given class, with no effect of petrological grade except for LL. This does not support suggested decrease of metal amount with metamorphism for L chondrites. High grade LLs (heated above 400°C) develop the weakly magnetic antitaenite-tetrataenite phases during slow cooling, explaining the difference with low grade taenite-bearing LLs. Once a few % of outliers are excluded, well defined means for H and L are observed with no overlap at 2 s.d.; this agrees with the lack of overlap on metal amount. For non ordinary chondrites and achondrites, weakly magnetic classes are HED, Aubrites and SNC (below LL), strongly ones are E (above H) and Ureilites (in the L-H range), while C chondrites are spread in the whole range, again with each class showing restricted variation. Outliers appeared to be in most cases either misclassified <span class="hlt">meteorites</span> or misindentified samples, based on petrographic and microprobe investigations of thin sections from outlying samples. It appears that systematic magnetic screening of large collections is an efficient way to detect erroneous sample identification, due to exchange with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2012M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2012M"><span>Siberian <span class="hlt">Meteorite</span> Chelyabinsk</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marov, Mikhail Ya.</p> <p></p> <p>On the February 15, 2013, in 9 (h) 20 (m) LT, a spectacular phenomenon - large <span class="hlt">meteorite</span> fall - was observed over Chelyabinsk city in Siberia, Russia. Basically, this rather routine astronomical event (though largest for the recent one hundred years) attracted great attention because occurred in the well populated area and affected environment and people. The phenomenon has been well documented and numerous fragments of the fall collected, the largest one excavated from Chebarcul lake amounting 560 kg. The <span class="hlt">meteorite</span> was called Chelyabinsk. It was observed as very bright bolide of 18 m in size which was exploded and mostly destroyed at the heights between 23 and 29 km and formed a powerful bow shock responsible for destructions when reaching the ground. Energy release at the explosion was estimated 300 to 500 Kt of TNT. The pieces collected brought evidence that Chelyabinsk is the stony <span class="hlt">meteorite</span> classified as typical ordinary chondrite of LL type of the 5th petrological class. Morphology and isotopic composition of the meteorite’s matter allowed us to reconstruct its history and to conclude that it represents a fragment of much larger asteroid-type body of the age close to the solar system origin and experienced a number of collisions, including the very early one during the first 30 million years after formation, which resulted to melted phase in the structure of the main matrix. The <span class="hlt">study</span> of <span class="hlt">meteorites</span> gives us unique opportunity to penetrate deep in the fundamental cosmochemical aspects of the solar system origin and also provide unique information concerning the processes of its thermal and dynamical early evolution. The new data contribute to the <span class="hlt">study</span>. Besides, Chelyabinsk <span class="hlt">meteorite</span> fall brought new important evidence that Earth is vulnerable to space hazards and raised warning how to protect our planet from asteroid-comet impacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890008997','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890008997"><span>Stable isotopic <span class="hlt">studies</span> of H,C,N,O and S in samples of <span class="hlt">Martian</span> origin</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.; Pillinger, C. T.</p> <p>1988-01-01</p> <p>The present day geochemical cycles of volatile elements through the various reservoirs on Earth are largely understood within the context of the planet's standing as a geologically and biologically evolved body. In terrestrial <span class="hlt">studies</span> stable isotope measurements of light elements (H, C, N, O and S) can be utilized to obtain insight into the conditions prevailing during formation of rocks of various types. Perhaps the most important problem which could be addressed by light element <span class="hlt">studies</span> of the sorts of specimen likely to be available from remote automatic sampling, would be the role of volatiles during evolution. Of fundamental importance here is the question of whether Mars was volatile rich or volatile poor. The only way to fully comprehend the effects of volatile cycling through the mantle crust and regolith atmosphere polar cap system of Mars, is by analyses of appropriate returned samples. In order to interpret the record of geological activity in <span class="hlt">Martian</span> samples it will be necessary to understand how the past, or present, surface environment may have acted to disturb the primary characteristics of the rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EM%26P..108..253K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EM%26P..108..253K"><span><span class="hlt">Martian</span> Case <span class="hlt">Study</span> of Multivariate Correlation and Regression with Planetary Datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karunatillake, Suniti; Gasnault, Olivier; Squyres, Steven W.; Keller, John M.; Janes, Daniel M.; Boynton, William; Newsom, Horton E.</p> <p>2012-06-01</p> <p>We synthesize multivariate correlation and regression methods to characterize unique relationships among compositional and physical properties of a planetary surface locally, regionally, and globally. <span class="hlt">Martian</span> data including elemental mass fractions, areal fractions of mineral types, and thermal inertia constitute our case <span class="hlt">study</span>. We incorporate techniques to address the effects of spatial autocorrelation and heteroscedasticity. We also utilize method and fit diagnostics. While the Mars Odyssey and Mars Global Surveyor missions provide the exploratory context in our discussion, our approach is applicable whenever the interrelationships of spatially binned data of continuous-valued planetary attributes are sought. For example, our regional-scale case <span class="hlt">study</span> reinforces the strength of the spatial correlation among K, Th, and the dominant mineralogic type within northern low albedo regions (surface type 2) of Mars. Recent chemical and mineralogic data from the MESSENGER mission at Mercury and Dawn at Vesta may be analyzed effectively with these hierarchical regression methods to constrain geochemical processes. Likewise, our algorithm could be applied locally with the wide variety of compositional data expected from the MSL mission at Gale Crater in general, and the ChemCam sampling grids in particular.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPSC....9..371I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPSC....9..371I"><span>AOTF near-IR spectrometers for <span class="hlt">study</span> of Lunar and <span class="hlt">Martian</span> surface composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, A.; Korablev, O.; Mantsevich, S.; Vyazovetskiy, N.; Fedorova, A.; Evdokimova, N.; Stepanov, A.; Titov, A.; Kalinnikov, Y.; Kuzmin, R.; Kiselev, A.; Bazilevsky, A.; Bondarenko, A.; Dokuchaev, I.; Moiseev, P.; Victorov, A.; Berezhnoy, A.; Skorov, Y.; Bisikalo, D.; Velikodsky, Y.</p> <p>2014-04-01</p> <p>The series of the AOTF near-IR spectrometers is developed in Moscow Space Research Institute for <span class="hlt">study</span> of Lunar and <span class="hlt">Martian</span> surface composition in the vicinity of a lander or a rover. Lunar Infrared Spectrometer (LIS) is an experiment onboard Luna-Glob (launch in 2017) and Luna- Resurs (launch in 2019) Russian surface missions. It's a pencil-beam spectrometer to be pointed by a robotic arm of the landing module. The instrument's field of view (FOV) of 1° is co-aligned with the FOV(45°) of a stereo TV camera. Infrared Spectrometer for ExoMars (ISEM) is an experiment onboard ExoMars (launch in 2018) ESARoscosmos rover. It's spectrometer based on LIS with required redesign for ExoMars mission. The ISEM instrument is mounted on the rover's mast coaligned with the FOV (5°) of High Resolution camera (HRC). Spectrometers and are intended for <span class="hlt">study</span> of the surface composition in the vicinity of the lander and rover. The spectrometers will provide measurements of selected surface areas in the spectral range of 1.15-3.3 μm. The spectral selection is provided by acoustooptic tunable filter (AOTF), which scans the spectral range sequentially. Electrical command of the AOTF allows selecting the spectral sampling, and permits a random access if needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DPS....4630405C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DPS....4630405C"><span>Measuring Fracture Properties of <span class="hlt">Meteorites</span>: 3D Scans and Disruption Experiments.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cotto-Figueroa, Desireé; Asphaug, Erik; Morris, Melissa A.; Garvie, Laurence</p> <p>2014-11-01</p> <p>The Arizona State University (ASU) Center for <span class="hlt">Meteorite</span> <span class="hlt">Studies</span> (CMS) houses over 30,000 specimens that represent almost every known <span class="hlt">meteorite</span> type. A number of these are available for fragmentation experiments in small samples, but in most cases non-destructive experiments are desired in order to determine the fundamental mechanical properties of <span class="hlt">meteorites</span>, and by extension, the Near-Earth Asteroids (NEAs) and other planetary bodies they derive from. We present results from an ongoing suite of measurements and experiments, featuring automated 3D topographic scans of a comprehensive suite of <span class="hlt">meteorites</span> in the CMS collection, basic mechanical <span class="hlt">studies</span>, and culminating in catastrophic fragmentation of four representative <span class="hlt">meteorites</span>: Tamdakht (H5), Allende (CV3), Northwest Africa 869 (L3-6) and Chelyabinsk (LL5). Results will include high-resolution 3D color-shape models of <span class="hlt">meteorites</span>, including specimens such as the 349g oriented and fusion crusted <span class="hlt">Martian</span> (shergottite) Tissint, and the delicately fusion crusted and oriented 131g Whetstone Mountains (H5) ordinary chondrite. The 3D color-shape models will allow us to obtain basic physical properties (such as volume to derive density) and to derive fractal dimensions of fractured surfaces. Fractal dimension is closely related to the internal structural heterogeneity and fragmentation of the material, to macroscopic optical properties, and to rubble friction and cohesion. Freshly fractured surfaces of fragments that will result from catastrophic hypervelocity impact experiments will be subsequently scanned and analyzed in order to determine whether fractal dimension is preserved or if it changes with surface maturation.</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('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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790043915&hterms=nutrients+cancer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dnutrients%2Bcancer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790043915&hterms=nutrients+cancer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dnutrients%2Bcancer"><span>The response of selected terrestrial organisms to the <span class="hlt">Martian</span> environment - A modeling <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kuhn, W. R.; Rogers, S. R.; Macelroy, R. D.</p> <p>1979-01-01</p> <p>An energy balance model has been developed to investigate how the <span class="hlt">Martian</span> atmospheric environment could influence a community of photosynthetic microorganisms with properties similar to those of a cyanophyte (blue-green algal mat) and a lichen. Surface moisture and soil nutrients are assumed to be available. The model was developed to approximate equatorial equinox conditions and includes parameters for solar and thermal radiation, convective and conductive energy transport, and evaporative cooling. Calculations include the diurnal variation of organism temperature and transpiration and photosynthetic rates. The influences of different wind speeds and organism size and resistivity are also <span class="hlt">studied</span>. The temperature of organisms in mats less than a few millimeters thick will not differ from the ground temperature by more than 10 K. Water loss is actually retarded at higher wind speeds, since the organism temperature is lowered, thus reducing the saturation vapor pressure. Typical photosynthetic rates lead to the production of 1 millionth to 100 billionths mole O2 per sq cm/day.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...820..127T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...820..127T"><span>Mechanistic <span class="hlt">Studies</span> on the Radiolytic Decomposition of Perchlorates 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>Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.</p> <p>2016-04-01</p> <p>Perchlorates—inorganic compounds carrying the perchlorate ion ({{ClO}}4{}-)—were discovered at the north polar landing site of the Phoenix spacecraft and at the southern equatorial landing site of the Curiosity Rover within the <span class="hlt">Martian</span> soil at levels of 0.4-0.6 wt%. This <span class="hlt">study</span> explores in laboratory experiments the temperature-dependent decomposition mechanisms of hydrated perchlorates—namely magnesium perchlorate hexahydrate (Mg(ClO4)2·6H2O)—and provides yields of the oxygen-bearing species formed in these processes at Mars-relevant surface temperatures from 165 to 310 K in the presence of galactic cosmic-ray particles (GCRs). Our experiments reveal that the response of the perchlorates to the energetic electrons is dictated by the destruction of the perchlorate ion ({{ClO}}4{}-) and the inherent formation of chlorates ({{ClO}}3{}-) plus atomic oxygen (O). Isotopic substitution experiments reveal that the oxygen is released solely from the perchlorate ion and not from the water of hydration (H2O). As the mass spectrometer detects only molecular oxygen (O2) and no atomic oxygen (O), atomic oxygen recombines to molecular oxygen within the perchlorates, with the overall yield of molecular oxygen increasing as the temperature drops from 260 to 160 K. Absolute destruction rates and formation yields of oxygen are provided for the planetary modeling community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008A%26A...484..547E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008A%26A...484..547E"><span>A <span class="hlt">study</span> of the <span class="hlt">Martian</span> water vapor over Hellas using OMEGA and PFS aboard Mars Express</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Encrenaz, T.; Fouchet, T.; Melchiorri, R.; Drossart, P.; Gondet, B.; Langevin, Y.; Bibring, J.-P.; Forget, F.; Maltagliati, L.; Titov, D.; Formisano, V.</p> <p>2008-06-01</p> <p>We used the OMEGA imaging spectrometer aboard Mars Express to <span class="hlt">study</span> the evolution of the water vapor abundance over the Hellas basin, as a function of the seasonal cycle. The H2O column density is found to range from very low values (between southern fall and winter) up to more than 15 pr-μm during southern spring and summer. The general behavior is consistent with the expected seasonal cycle of water vapor on Mars, as previously observed by TES and modeled. In particular, the maximum water vapor content is observed around the southern solstice, and is significantly less than its northern couterpart. However, there is a noticeable discrepancy around the northern spring equinox (Ls = 330-60°), where the observed H2O column densities are significantly lower than the values predicted by the GCM. Our data show an abrupt enhancement of the water vapor column density (from 3 to 16 pr-μm) on a timescale of 3 days, for Ls = 251-254°. Such an increase, not predicted by the GCM, was also occasionally observed by TES over Hellas during previous <span class="hlt">martian</span> years at the same season; however, its origin remains to be understood.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AN....334..936G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AN....334..936G"><span>A statistical dynamical <span class="hlt">study</span> of <span class="hlt">meteorite</span> impactors: A case <span class="hlt">study</span> based on parameters derived from the Bosumtwi impact event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galiazzo, M. A.; Bazsó, Á.; Huber, M. S.; Losiak, A.; Dvorak, R.; Koeberl, C.</p> <p>2013-11-01</p> <p>The <span class="hlt">study</span> of <span class="hlt">meteorite</span> craters on Earth provides information about the dynamic evolution of bodies within the Solar System. the Bosumtwi crater is a well <span class="hlt">studied</span>, 10.5 km in diameter, ca. 1.07 Myr old impact structure located in Ghana. (Koeberl et al., 1997a). The impactor was ˜ 1 km in diameter, an ordinary chondrite and struck the Earth with an angle between 30o and 45o (Artemieva et al., 2004) from the horizontal. We have used a two phase backward integration to constrain the most probable parent region of the impactor. We find that the most likely source region is a high inclination object from the Middle Main Belt.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07834&hterms=fingerprint&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D20%26Ntt%3Dfingerprint','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07834&hterms=fingerprint&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D20%26Ntt%3Dfingerprint"><span><span class="hlt">Martian</span> Fingerprints</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 9 April 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows patterned ground on the <span class="hlt">martian</span> northern plains. The circular features are buried meteor impact craters; the small dark dots associated with them are boulders. The dark feature at left center is a wind streak. <p/> <i>Location near</i>: 75.1oN, 303.0oW <i>Image width</i>: 3 km (1.9 mi) <i>Illumination from</i>: lower left <i>Season</i>: Northern Summer</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('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('https://ntrs.nasa.gov/search.jsp?R=19930022746&hterms=john+morris&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djohn%2Bmorris','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022746&hterms=john+morris&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djohn%2Bmorris"><span><span class="hlt">Martian</span> weathering/alteration scenarios from spectral <span class="hlt">studies</span> of ferric and ferrous minerals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bell, James F., III; Adams, John B.; Morris, Richard V.</p> <p>1992-01-01</p> <p>We review the major aspects of our current knowledge of <span class="hlt">martian</span> ferric and ferrous mineralogy based on the available ground-based telescopic and spacecraft data. What we know and what we don't know are used to constrain various weathering/alteration models and to identify key future measurements and techniques that can distinguish between these models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140006563','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140006563"><span><span class="hlt">Martian</span> Cryogenic Carbonate Formation: Stable Isotope Variations Observed in Laboratory <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>Socki, Richard A.; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K. Jr.</p> <p>2014-01-01</p> <p>The history of water on Mars is tied to the formation of carbonates through atmospheric CO2 and its control of the climate history of the planet. Carbonate mineral formation under modern <span class="hlt">martian</span> atmospheric conditions could be a critical factor in controlling the <span class="hlt">martian</span> climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the <span class="hlt">martian</span> surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms easily from freezing solutions when carbon dioxide degasses quickly from Ca-bicarbonate-rich water, a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lake beds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. A series of laboratory experiments were conducted that simulated cryogenic carbonate formation on Mars in order to understand their isotopic systematics. The results indicate that carbonates grown under <span class="hlt">martian</span> conditions show variable enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values.</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('https://ntrs.nasa.gov/search.jsp?R=PIA05759&hterms=meteorite+hit+earth&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmeteorite%2Bhit%2Bearth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05759&hterms=meteorite+hit+earth&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmeteorite%2Bhit%2Bearth"><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('http://adsabs.harvard.edu/abs/2010EGUGA..12.3368S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.3368S"><span><span class="hlt">Study</span> of H2O and CO in <span class="hlt">Martian</span> atmosphere with PFS/MEX data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sindoni, Giuseppe; Formisano, Vittorio</p> <p>2010-05-01</p> <p>In the history of the Mars exploration its atmosphere and planetary climatology has from time aroused particular interest. In the <span class="hlt">study</span> of the minor gas abundance in the <span class="hlt">Martian</span> CO2 atmosphere, the water vapour assumes particular importance, both because it is the most variable trace gas, and because it is involved in several processes characterizing the planetary atmosphere. The water vapour photolysis regulates the <span class="hlt">Martian</span> atmosphere photochemistry, and so it is strictly bounded to the carbon monoxide. The CO <span class="hlt">study</span> is very important for the so called "atmosphere stability problem" (the whole CO2 atmosphere should be destroyed in 6000 years by photolysis), solved by the theoretical modelling involving photochemical reactions in which the H2O and the CO gases are main characters. The Planetary Fourier Spectrometer (PFS) on board of ESA Mars Express (MEX) mission can probe the Mars atmosphere in the infrared spectral range between 200 and 2000 cm-1 (5-50 μm) with the Long wavelength channel (LWC) and between 1700 and 8000 cm-1 (1.2-5.8 μm) with the Short wavelength channel (SWC). Although there are several H2O and CO absorption bands in the spectral range covered by PFS, we chose to use the 3845 cm-1 (2.6 μm) band for the water vapour and the 4235 cm-1 (2.36 μm) band for the CO analysis, because these ranges are less affected by instrumental problems respect to other ones. The gaseous abundances are retrieved by using a particular algorithm developed for this purpose. The analysis procedure is based on the best fit between the measured averaged spectrum and a synthetic one appositely generated in each step of the fitting loop. The averaged water vapour mixing ratio results to be about 130 ppm, while the averaged carbon monoxide mixing ratio results to be about 1000 ppm, but with strong seasonal variations at high latitudes. The seasonal water vapour map reproduces very well the known seasonal water cycle. In the northern summer the water vapour and CO show a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IAUGA..2257523G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2257523G"><span>Fireball data analysis: bridging the gap between small solar system bodies and <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>Gritsevich, Maria; Moreno-Ibáñez, Manuel; Kuznetsova, Daria; Bouquet, Alexis; Trigo-Rodríguez, Josep; Peltoniemi, Jouni; Koschny, Detlef</p> <p>2015-08-01</p> <p>One of the important steps in identification of <span class="hlt">meteorite</span>-producing fireballs and prediction of impact threat to Earth raised by potentially hazardous asteroids is the understanding and modeling of processes accompanying the object’s entry into the terrestrial atmosphere (Gritsevich et al., 2012). Such knowledge enables characterization, simulation and classification of possible impact consequences with further reommendation for potential <span class="hlt">meteorite</span> searches. Using dimensionless expressions, which involve the pre-atmospheric meteoroid parameters, we have built physically based parametrisation to describe changes in mass, height, velocity and luminosity of the object along its atmospheric path (Gritsevich and Koschny, 2011; Bouquet et al., 2014). The developed model is suitable to estimate a number of crucial unknown values including shape change coefficient, ablation rate, and surviving <span class="hlt">meteorite</span> mass. It is also applicable to predict the terminal height of the luminous flight and therefore, duration of the fireball (Moreno-Ibáñez et al., 2015). Besides the model description, we demonstrate its application using the wide range of observational data from <span class="hlt">meteorite</span>-producing fireballs appearing annually (such as Košice) to larger scale impacts (such as Chelyabinsk, Sikhote-Alin and Tunguska).REFERENCESBouquet A., Baratoux D., Vaubaillon J., Gritsevich M.I., Mimoun D., Mousis O., Bouley S. (2014): Planetary and Space Science, 103, 238-249, http://dx.doi.org/10.1016/j.pss.2014.09.001Gritsevich M., Koschny D. (2011): Icarus, 212(2), 877-884, http://dx.doi.org/10.1016/j.icarus.2011.01.033Gritsevich M.I., Stulov V.P., Turchak L.I. (2012): Cosmic Research, 50(1), 56-64, http://dx.doi.org/10.1134/S0010952512010017Moreno-Ibáñez M., Gritsevich M., Trigo-Rodríguez J.M. (2015): Icarus, 250, 544-552, http://dx.doi.org/10.1016/j.icarus.2014.12.027</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MNRAS.436.2818M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MNRAS.436.2818M"><span>The Geminid meteoroid stream as a potential <span class="hlt">meteorite</span> dropper: a case <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Madiedo, José M.; Trigo-Rodríguez, Josep M.; Castro-Tirado, Alberto J.; Ortiz, José L.; Cabrera-Caño, Jesús</p> <p>2013-12-01</p> <p>A Geminid fireball with an absolute magnitude of -13 was observed over the south of Spain on 2009 December 15. This extraordinarily bright event (the brightest Geminid ever recorded by our team) was imaged from two meteor observing stations operated by the SPanish Meteor Network (SPMN). The bolide exhibited fast and quasi-periodic variations in brightness, a behaviour typically associated with the rotation of the parent meteoroid. The inferred tensile strength of this particle was found to be significantly higher than the typical values obtained for Geminid meteoroids. The fireball penetrated in the atmosphere till a final height of about 25 km above the ground level and a non-zero terminal mass was calculated at the ending point of the luminous trajectory. In this way, the observational evidence points to the existence of a population of meteoroids in the higher end of the Geminid mass distribution capable of producing <span class="hlt">meteorites</span>. From the relative chemical abundances inferred from the emission spectrum of this bolide we conclude that the Geminid-forming materials are similar to some primitive carbonaceous chondrite groups. Then, we conclude that in <span class="hlt">meteorite</span> collections from cold deserts, capable of preserving <span class="hlt">meteorites</span> of a few tens of grams, some rare groups of carbonaceous chondrites could be coming from the Geminid parent body: (3200) Phaeton.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AsBio..16..703M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AsBio..16..703M"><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="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940028688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940028688"><span>Thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels and valleys using Termoskan data: New results</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Betts, B. H.; Murray, B. C.</p> <p>1993-01-01</p> <p>The Termoskan instrument onboard the Phobos '88 spacecraft acquired the highest-spatial-resolution thermal data ever obtained for Mars. Included in the thermal images are 2 km/pixel midday observations of several major channel and valley systems, including significant portions of Shalbatana Vallis, Ravi Vallis, Al-Qahira Vallis, Ma'adim Vallis, the channel connecting Valles Marineris with Hydraotes Chaos, and channel material in Eos Chasma. Termoskan also observed small portions of the southern beginnings of Simud, Tiu, and Ares Valles and some channel material in Gangis Chasma. Simultaneous broad band visible data were obtained for all but Ma'adim Vallis. We find that most of the channels and valleys have higher inertias than their surroundings, consistent with Viking IRTM-based thermal <span class="hlt">studies</span> of <span class="hlt">Martian</span> channels. We see for the first time that thermal inertia boundaries closely match all flat channel floor boundaries. Combining Termoskan thermal data, relative observations from Termoskan visible channel data, Viking absolute bolometric albedos, and a thermal model of the Mars surface, we have derived lower bounds on channel thermal inertias. Lower bounds on typical channel thermal inertias range from 8.4 to 12.5 (10(exp -3) cal cm(exp -2) s(exp -1/2)K(exp -1)) (352 to 523 in SI units). Lower bounds on inertia differences with the surrounding heavily cratered plains range from 1.1 to 3.5 (46 to 147 in SI units). Atmospheric and geometric effects are not sufficient to cause the inertia enhancements. We agree with previous researchers that localized, dark, high inertia areas within channels are likely eolian in nature. However, the Temloskan data show that eolian deposits do not fill the channels, nor are they responsible for the overall thermal inertia enhancement. Thermal homogeneity and strong correlation of thermal boundaries with the channel floor boundaries lead us to favor noneolian overall explanations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999PhDT.........1W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999PhDT.........1W"><span>A Mossbauer spectroscopic <span class="hlt">study</span> of iron-rich deposits of hydrothermal springs as <span class="hlt">Martian</span> analogues</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wade, Manson Lashawn</p> <p>1999-09-01</p> <p>In this work, results are reported of Mössbauer analysis focused on a suite of samples collected systematically along the outflow channel from an iron- rich hydrothermal vent mound in the Chocolate Pots area of Yellowstone National Park in the context of Mars exploration. Similar hydrothermal spring systems may well have been present on an early Mars and could have harbored primitive life. Mössbauer spectroscopy was chosen as the primary investigative technique in this <span class="hlt">study</span> because of its ability to discriminate among the iron-bearing minerals in these samples. Those on the surface and near the vent are identified as predominantly ferrihydrite, Fe5HO8 ˙ 4H2O or 5Fe2O3 ˙ 9H2O. Subsurface samples, which seem to have been altered by either inorganic and/or biological processes, exhibit spectral signatures that include nontronite [(Ca,Na) 0.66Fe3+S<inf loc='pre'>4i7.34 Al0.66O20(OH) 4,nH2O], in the smectite clay mineral group, hematite (α-Fe 3+2O3), small- particle/nanophase goethite (α-Fe 3+OOH), and siderite (Fe2+CO3) . Evidence is presented that all these minerals, including those with the nanophase property, can have multi-billion year residence times and thus survive from their possible production in a putative early <span class="hlt">Martian</span> hydrothermal environment to present day. Mössbauer spectroscopy will be a planned component of the instrument suite included on the 2001 Mars Surveyor Athena Rover mission. It is hoped that this work will aid in the use of this instrument, in the service of exobiology, and in helping to identify hydrothermal sediments and samples suitable for subsequent return to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040085669','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040085669"><span>The Polar Regions and <span class="hlt">Martian</span> Climate: <span class="hlt">Studies</span> with a Global Climate Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, R. J.; Richardson, M. I.; Smith, M. D.</p> <p>2003-01-01</p> <p>Much of the interest in the polar regions centers on the fact that they likely contain the best record of <span class="hlt">Martian</span> climate change on time scales from years to eons. This expectation is based upon the observed occurrence of weathering product deposits and volatile reservoirs that are coupled to the climate. Interpretation and understanding of these records requires understanding of the mechanisms that involve the exchange of dust, water, and carbon dioxide between the surface and atmosphere, and the atmospheric redistribution of these species. We will summarize our use of the GFDL Mars general circulation model (MGCM), to exploration aspects of the interaction between the global climate and the polar regions. For example, our <span class="hlt">studies</span> have shown that while the northern polar cap is the dominant seasonal source for water, it can act as a net annual source or sink for water, depending upon the cap temperatures and the bulk humidity of the atmosphere. This behavior regulates the annual and global average humidity of the atmosphere, as the cap acts as a sink if the atmosphere is too wet and a source if it is too dry. We will then focus our presentation on the ability of the MGCM to simulate the observed diurnal variations of surface temperature. We are particularly interested in assessing the influence of dust aerosol and water ice clouds on simulated surface temperature and the comparison with observations. Surface thermal inertia and albedo are critical boundary inputs for MGCM simulations. Thermal inertia is also of intrinsic interest as it may be related to properties of the surface such as particle size and surface character.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009P%26SS...57..454V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009P%26SS...57..454V"><span>Beta-carotene—A possible biomarker in the <span class="hlt">Martian</span> evaporitic environment: Raman micro-spectroscopic <span class="hlt">study</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vítek, Petr; Osterrothová, Kateřina; Jehlička, Jan</p> <p>2009-04-01</p> <p>Due to the discovery of the evaporitic environment on the <span class="hlt">Martian</span> surface, there is a reasonable possibility that evaporites served (or still serve) as habitats for microbial life if ever present on Mars. At the very least, if no signatures of extant life exist within these rocks, it may sustain molecular remnants as evidence for living organisms in the past. β-Carotene, among other carotenoids, could be such a suitable biomarker. In this <span class="hlt">study</span>, Raman micro-spectroscopy was tested as a nondestructive method of determining the presence of β-carotene in experimentally prepared evaporitic matrices. Samples prepared by mixing β-carotene with powdered gypsum (CaSO 4·2H 2O), halite (NaCl) and epsomite (MgSO 4·7H 2O) were analyzed using a 785 nm excitation source. Various concentrations of β-carotene in the matrices were investigated to determine the lowest β-carotene content detectable by Raman micro-spectroscopy. Mixtures were also measured with a laser beam permeating the crystals of gypsum and epsomite in order to evaluate the possibility of identifying β-carotene inside the mineral matrix. We were able to obtain a clear β-carotene signal at the 10 mg kg -1 concentration level - the number of registered β-carotene Raman bands differed depending on the particular mineral matrix. Spectral signatures of β-carotene were detected even when analyzing samples containing 1 mg kg -1 of this molecule. The 10-100 mg kg -1 of β-carotene in mineral matrices (halite, epsomite) was detected when analyzed through the monocrystal of gypsum and epsomite, respectively. These results will aid both in-situ analyses on Mars and sample analyses on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT.........8C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT.........8C"><span>Spectral reflectance <span class="hlt">studies</span> and optical surface alteration in the search for links between <span class="hlt">meteorites</span> and asteroids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, Beth Ellen</p> <p>1993-01-01</p> <p>The ordinary chondrites (OC's) are the most numerous and most ancient of <span class="hlt">meteorites</span>, but as yet their Solar System source region has not been identified. Meteoriticists have scrutinized these <span class="hlt">meteorites</span> for clues as to the origin and evolution of the Solar System. They are among the most chemically primitive <span class="hlt">meteorites</span> known, having been relatively unprocessed since their formation 4.6 billion years ago. The textures they preserve are records of prevailing conditions during the formation of the planets. There is a long history to the search for the ordinary chondrite parent bodies. Dynamical modelling indicates that they are most likely to be from the main asteroid belt at 2.5 AU. This happens to be where the S-type asteroids are located, and hence the 'OC <span class="hlt">meteorite-S</span> Type asteroid controversy' arises. S-type asteroid reflectance spectra indicate surface compositions of olivine, pyroxene, and Fe,Ni metal. These are also the minerals that compose the ordinary chondrites, and so a genetic link is indicated. The subject of this dissertation is the connection, or lack thereof, between the ordinary chondrites and the S-type asteroids. To begin the investigations, Chapter two is a report on laboratory experiments which were performed in an attempt to simulate the optical surfaces or ordinary chondrite patent bodies to see if the optical properties of the S-type asteroids could be manufactured. The next chapter is a three-parameter analysis of the main spectral features which were found to be most altered by the experiments in Chapter two. Chapter four is an examination of the first spacecraft images of an S-type asteroid, 951 Gaspra, with possible mineralogic implications. Chapter five is a presentation of a new infrared telescopic survey of the S-type asteroids. Specifically, we investigate the suggestion that the OC parent-bodies may be found among the smaller main-belt asteroids. Finally, in Chapter six, an analysis of the compositions of S-type asteroids is performed</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('http://adsabs.harvard.edu/abs/2013HyInt.222...91C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013HyInt.222...91C"><span>An 57Fe Mössbauer <span class="hlt">study</span> of three Australian L5 ordinary-chondrite <span class="hlt">meteorites</span>: dating Kinclaven-001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cadogan, J. M.; Rebbouh, L.; Mills, J. V. J.; Bland, P. A.</p> <p>2013-12-01</p> <p>Three L5-type ordinary chondrite <span class="hlt">meteorites</span> recovered from the Nullarbor Region of Western Australia were <span class="hlt">studied</span> by 57Fe Mössbauer spectroscopy: Kinclaven-001, Camel Donga-007 and Gunnadorah-002. The relative amounts of the various Fe-bearing phases including the primary minerals (Olivine, Pyroxene, Troilite and Fe-Ni metal) and the ferric alteration products (Goethite, Maghemite/Magnetite) were obtained to determine the percentage of iron converted to Fe3 + by weathering processes. These data allow us to estimate the terrestrial age of Kinclaven-001 at 1,700 ± 1,300 yrs.</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/2015P%26SS..118...54A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..118...54A"><span>Impact history of the Chelyabinsk <span class="hlt">meteorite</span>: Electron microprobe and LA-ICP-MS <span class="hlt">study</span> of sulfides and metals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andronikov, A. V.; Andronikova, I. E.; Hill, D. H.</p> <p>2015-12-01</p> <p>Electron microprobe and LA-ICP-MS <span class="hlt">study</span> of sulfides and metals from two fragments of the LL5 Chelyabinsk <span class="hlt">meteorite</span> were conducted. The fragments are impact breccias, one fragment contains both chondritic and shock vein lithologies, and the other contains shock-darkened chondritic clasts and vesicular impact melts. The chondritic lithology and shock veins display very similar opaque mineral compositions. The mineral compositions in the impact-melt breccias are distinctly different. The brecciated state of the Chelyabinsk <span class="hlt">meteorite</span> suggests strong involvement of shock-related processes during the evolution of the parent body. Multiple heavy impact events occurred on the parent asteroid and on the Chelyabinsk meteoroid itself over the time period from ca. 4.5 Ga until ca. 1.2 Ma. The shock veins were produced in situ on the parent body. The impact-melt breccias could have formed because of the dramatic impact to the parent LL-chondrite body that could be partly disintegrated. The fragment containing shock-darkened chondritic clasts and vesicular impact melt lithologies preserves a record of melting, volatilization, partial degassing, and quenching of the molten material. The abundance and size (up to 1 mm) of the vesicles suggest that the impact melt must have been buried at some depth after formation. After impact and subsequent melting occurred, the impact-induced pressure on the shallow asteroid interior was released that caused "boiling" of volatiles and generation of S-rich bubbles. Such an impact excavated down to depths of the body generating multiple fragments with complicated histories. These fragments reaccumulated into a gravitational aggregate and formed the parental meteoroid for the Chelyabinsk <span class="hlt">meteorite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019358','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019358"><span>Thermoluminescence of Antarctic <span class="hlt">meteorites</span>: A rapid screening technique for terrestrial age estimation, pairing <span class="hlt">studies</span> and identification of specimens with unusual prefall histories</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sutton, S. R.; Walker, R. M.</p> <p>1986-01-01</p> <p>Thermoluminescence (TL) is a promising technique for rapid screening of the large numbers of Antarctic <span class="hlt">meteorites</span>, permitting identification of interesting specimens that can then be <span class="hlt">studied</span> in detail by other, more definite techniques. Specifically, TL permits determination of rough terrestrial age, identification of potential paired groups and location of specimens with unusual pre-fall histories. <span class="hlt">Meteorites</span> with long terrestrial ages are particularly valuable for <span class="hlt">studying</span> transport and weathering mechanisms. Pairing <span class="hlt">studies</span> are possible because TL variations among <span class="hlt">meteorites</span> are large compared to variations within individual objects, especially for natural TL. Available TL data for several L3 fragments, three of which were paired by other techniques, are presented as an example of the use of TL parameters in pairing <span class="hlt">studies</span>. Additional TL measurements, specifically a blind test, are recommended to satisfactorily establish the reliability of this pairing property. The TL measurements also identify fragments with unusual pre-fall histories, such an near-Sun orbits.</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> </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://adsabs.harvard.edu/abs/2015EPSC...10..215P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..215P"><span>A high resolution <span class="hlt">study</span> of the <span class="hlt">Martian</span> water cycle with a global climate model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pottier, A.; Montmessin, F.; Forget, F.; Navarro, T.; Millour, E.; Madeleine, J.-B.; Spiga, A.</p> <p>2015-10-01</p> <p>The <span class="hlt">martian</span> water cycle's main source is the northern polar cap. Running high resolution models, up to 360° per 180°, help better resolve this ice cap, and better mimic the gradual retreat of the seasonal cap. Atmospheric circulation is also better resolved. Water vapor advection and the subsequent formation of clouds quite differ when we compare these brand new high resolution simulations and the usual lower resolution ones at 64 per 48 grid points.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110012697','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110012697"><span>Stabile Chlorine Isotope <span class="hlt">Study</span> of <span class="hlt">Martian</span> Shergottites and Nakhlites; Whole Rock and Acid Leachates and Residues</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.</p> <p>2011-01-01</p> <p>We have established a precise analytical technique for stable chlorine isotope measurements of tiny planetary materials by TIMS (Thermal Ionization Mass Spectrometry) [1], for which the results are basically consistent with the IRMS tech-nique (gas source mass spectrometry) [2,3,4]. We present here results for <span class="hlt">Martian</span> shergottites and nakhlites; whole rocks, HNO3-leachates and residues, and discuss the chlorine isotope evolution of planetary Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.452..123W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.452..123W"><span>Spectroscopic <span class="hlt">study</span> of perchlorates and other oxygen chlorides in a <span class="hlt">Martian</span> environmental chamber</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Zhongchen; Wang, Alian; Ling, Zongcheng</p> <p>2016-10-01</p> <p> generation from chloride salts, as a potential mechanism to form oxygen chlorides during <span class="hlt">Martian</span> dust storm. The results of the current <span class="hlt">study</span> will be used for in situ simultaneous identification of the Cl O4- and other intermediate oxygen chloride products generated during a dynamic ESD experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06760&hterms=clovis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclovis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06760&hterms=clovis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclovis"><span>Contrasting <span class="hlt">Martian</span> Terrains</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/> NASA's Mars Exploration Rover Spirit captured this interesting view of <span class="hlt">martian</span> topography just below the 'West Spur' portion of the 'Columbia Hills' on sol 208 (Aug. 2, 2004). The view is looking southwest. The rover's wheel tracks show the contrast between soft <span class="hlt">martian</span> soil and the harder 'Clovis' rock outcrop, which scientists are now <span class="hlt">studying</span>. <p/> The angle of the horizon indicates the tilt of the rover to be about 20 degrees. On the horizon is a small peak informally named 'Grissom Hill,' about 15 kilometers (9.3 miles) away. To the right of the peak is the edge of a 2-kilometer-wide (1.2-mile-wide) crater. A few weeks ago, Spirit stopped to conduct scientific <span class="hlt">studies</span> of rocks in 'Hank's Hollow,' located on the right side of the image approximately one-third of the way down from the top. This photo was taken with Spirit's right rear hazard-avoidance camera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6119C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6119C"><span><span class="hlt">Meteorite</span> Falls in Morocco</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chennaoui Aoudjehane, H.</p> <p>2016-08-01</p> <p>The number of <span class="hlt">meteorite</span> falls reported in Morocco since 2000 is highest than any other place compared to the other countries in the world, that call into question the efficiency of the randomly <span class="hlt">meteorite</span> falls on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=yAN-wjGKzx0','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=yAN-wjGKzx0"><span>Searching for <span class="hlt">Meteorites</span></span></a></p> <p><a target="_blank" href="http://www.nasa.gov/multimedia/videogallery/index.html">NASA Video Gallery</a></p> <p></p> <p></p> <p>This lesson combines a series of activities to provide students with an understanding of how <span class="hlt">meteorites</span> can unlock answers to the early history of the solar system and how <span class="hlt">meteorites</span> and their big ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890034476&hterms=hinton+richard&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dhinton%252C%2Brichard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890034476&hterms=hinton+richard&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dhinton%252C%2Brichard"><span>A chemical and isotopic <span class="hlt">study</span> of hibonite-rich refractory inclusions in primitive <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>Hinton, Richard W.; Davis, Andrew M.; Scatena-Wachel, Debra E.; Grossman, Lawrence; Draus, Ronald J.</p> <p>1988-01-01</p> <p>Isotopic and chemical analyses of hibonite-rich inclusions from a number of primitive <span class="hlt">meteorites</span> and, in some cases, of coexisting minerals from carbonaceous and ordinary chondrites, were carried out using ion microprobe (IP). The results of the IP analyses were compared with literature data obtained by INAA and electron microprobe analysis. Results showed that the trace element patterns of the hibonite inclusions analyzed have a number of feautures in common. The results are discussed with reference to the possible chemical processes operating early in the history of the solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988GeCoA..52.2573H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988GeCoA..52.2573H"><span>A chemical and isotopic <span class="hlt">study</span> of hibonite-rich refractory inclusions in 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>Hinton, Richard W.; Davis, Andrew M.; Scatena-Wachel, Debra E.; Grossman, Lawrence; Draus, Ronald J.</p> <p>1988-11-01</p> <p>Isotopic and chemical analyses of hibonite-rich inclusions from a number of primitive <span class="hlt">meteorites</span> and, in some cases, of coexisting minerals from carbonaceous and ordinary chondrites, were carried out using ion microprobe (IP). The results of the IP analyses were compared with literature data obtained by INAA and electron microprobe analysis. Results showed that the trace element patterns of the hibonite inclusions analyzed have a number of feautures in common. The results are discussed with reference to the possible chemical processes operating early in the history of the solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870038383&hterms=mercury+Hg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmercury%2BHg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870038383&hterms=mercury+Hg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmercury%2BHg"><span>Mass spectrometric <span class="hlt">study</span> of the mercury isotopes in the 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>Nier, A. O.; Schlutter, D. J.</p> <p>1986-01-01</p> <p>Isotopic abundance ratios for mercury were determined by mass spectrometry in six samples of bulk material and in one sample of chondrules from the Allende <span class="hlt">meteorite</span>. A primary purpose of the work was to attempt to verify the anomalous ratios reported for Hg-196/Hg-202 by neutron activation. Measurements were made on the mercury released at temperatures of 250, 450, 600 C, and in some cases, higher temperatures. The precision of the measurements was such that if an anomaly of the magnitude reported exists, it should have been seen. The isotopic abundance ratios for the other mercury isotopes were also measured. Within the errors of measurement these agreed with normal terrestrial values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/543108','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/543108"><span>Genesis of presolar diamonds: Comparative high-resolution transmission electron microscopy <span class="hlt">study</span> of <span class="hlt">meteoritic</span> and terrestrial nano-diamonds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Daulton, T.L. |; Eisenhour, D.D.; Buseck, P.R.</p> <p>1996-12-01</p> <p>Nano-diamonds isolated from acid dissolution residues of primitive carbonaceous <span class="hlt">meteorites</span> (Allende and Murchison) were <span class="hlt">studied</span> using high-resolution transmission electron microscopy. To discriminate among their most likely formation mechanisms, high-pressure shock-induced metamorphism or low-pressure vapor condensation. the microstructures of presolar diamond crystallites were compared to those of (terrestrial) synthesized nano-diamonds. The synthesized diamonds used for comparison in this <span class="hlt">study</span> were produced by high-pressure shock waves generated in controlled detonations and by direct nucleation and homoepitaxial growth from the vapor phase in low-pressure chemical vapor deposition (CVD)-type processes. Microstructural features were identified that appear unique to shock metamorphism and to nucleation from the vapor phase, respectively. A comparison of these features to the microstructures found in presolar diamonds indicates that the predominant mechanism for presolar diamond formation is a vapor deposition process, suggesting a circumstellar condensation origin. A new presolar grain component has also been identified in the <span class="hlt">meteoritic</span> residues, the (2H) hexagonal polytype of diamond (lonsdaleite). 93 refs., 17 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990109991&hterms=search+extraterrestrial+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsearch%2Bextraterrestrial%2Blife','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990109991&hterms=search+extraterrestrial+life&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsearch%2Bextraterrestrial%2Blife"><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('https://ntrs.nasa.gov/search.jsp?R=20000110466&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHydrothermal%2Bvents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000110466&hterms=Hydrothermal+vents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHydrothermal%2Bvents"><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('http://adsabs.harvard.edu/abs/1985GeCoA..49..397N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeCoA..49..397N"><span>A major revision of iron <span class="hlt">meteorite</span> cooling rates - an experimental <span class="hlt">study</span> of the growth of the Widmanstaetten pattern</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Narayan, C.; Goldstein, J. I.</p> <p>1985-02-01</p> <p>Intragranular kamacite has been experimentally grown in Fe-Ni-P alloys containing between 5 and 10 percent by weight Ni and between 0 and 1.0 percent by weight P. The nucleation and growth process of these precipitates is <span class="hlt">studied</span> using analytical electron microscopy techniques. A numerical model is developed to simulate the growth of intragranular kamacite in Fe-Ni-P alloys based on the experimental results, and this model is used to revise the existing cooling rate estimates of iron <span class="hlt">meteorites</span> from observed Widmanstaetten patterns. It is found that heterogeneous sites like phospides are necessary for the nucleation of intragranular kamacite in the Fe-Ni-P system, and that kamacite size depends largely on the bulk Ni content and the cooling rate and to a lesser extent on the P concentration. The cooling rates predicted by the new model are two orders of magnitude greater than those previously estimated. To accommodate the new rates, <span class="hlt">meteorite</span> parent bodies need only be a few kilometers in diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21930423','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21930423"><span>Mineralogical composition of the <span class="hlt">meteorite</span> El Pozo (Mexico): a Raman, infrared and XRD <span class="hlt">study</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ostrooumov, Mikhail; Hernández-Bernal, Maria del Sol</p> <p>2011-12-01</