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Sample records for planetary geochemical cycles

  1. DETECTING PLANETARY GEOCHEMICAL CYCLES ON EXOPLANETS: ATMOSPHERIC SIGNATURES AND THE CASE OF SO{sub 2}

    SciTech Connect

    Kaltenegger, L.; Sasselov, D.

    2010-01-10

    We study the spectrum of a planetary atmosphere to derive detectable features in low resolution of different global geochemical cycles on exoplanets-using the sulfur cycle as our example. We derive low-resolution detectable features for first generation space- and ground-based telescopes as a first step in comparative planetology. We assume that the surfaces and atmospheres of terrestrial exoplanets (Earth-like and super-Earths) will most often be dominated by a specific geochemical cycle. Here we concentrate on the sulfur cycle driven by outgassing of SO{sub 2} and H{sub 2}S followed by their transformation to other sulfur-bearing species, which is clearly distinguishable from the carbon cycle, which is driven by outgassing of CO{sub 2}. Due to increased volcanism, the sulfur cycle is potentially the dominant global geochemical cycle on dry super-Earths with active tectonics. We calculate planetary emission, reflection, and transmission spectrum from 0.4 mum to 40 mum with high and low resolution to assess detectable features using current and Archean Earth models with varying SO{sub 2} and H{sub 2}S concentrations to explore reducing and oxidizing habitable environments on rocky planets. We find specific spectral signatures that are observable with low resolution in a planetary atmosphere with high SO{sub 2} and H{sub 2}S concentration. Therefore, first generation space- and ground-based telescopes can test our understanding of geochemical cycles on rocky planets and potentially distinguish planetary environments dominated by the carbon and sulfur cycles.

  2. [Microbial geochemical calcium cycle].

    PubMed

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  3. Geochemical cycles of atmospheric gases

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Drever, J. I.

    1988-01-01

    The processes that control the atmosphere and atmospheric changes are reviewed. The geochemical cycles of water vapor, nitrogen, carbon dioxide, oxygen, and minor atmospheric constituents are examined. Changes in atmospheric chemistry with time are discussed using evidence from the rock record and analysis of the present atmosphere. The role of biological evolution in the history of the atmosphere and projected changes in the future atmosphere are considered.

  4. Geochemical cycles of atmospheric gases

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Drever, J. I.

    1988-01-01

    The processes that control the atmosphere and atmospheric changes are reviewed. The geochemical cycles of water vapor, nitrogen, carbon dioxide, oxygen, and minor atmospheric constituents are examined. Changes in atmospheric chemistry with time are discussed using evidence from the rock record and analysis of the present atmosphere. The role of biological evolution in the history of the atmosphere and projected changes in the future atmosphere are considered.

  5. Hydrologic Regulation of Global Geochemical Cycles

    NASA Astrophysics Data System (ADS)

    Maher, K.

    2015-12-01

    Earth's temperature is thought to be regulated by a negative feedback between atmospheric CO2 levels and chemical weathering of silicate rocks. However, direct evidence for the operation of this feedback over million-year timescales is difficult to obtain. For example, weathering fluxes over the last 20 million years of the Cenozoic Era, calculated using marine isotopic proxies (i.e. 87Sr/86Sr, δ7Li, and 187Os/188Os), appear inconsistent with past atmospheric CO2 levels and carbon mass balance. Similarly, observations from modern catchments suggest that chemical weathering fluxes are strongly correlated with erosion rates and only weakly correlated with temperature. As an alternative approach to evaluating the operation of a negative feedback, we use the major surface reservoirs of carbon to determine the imbalance in the geologic carbon cycle and the required silicate weathering flux over the Cenozoic. A miniscule (0.5-1%) increase in silicate weathering is necessary to explain the long-term decline in CO2 levels over the Cenozoic, providing evidence for a strong negative feedback between silicate weathering and climate. Rather than an appreciable increase in the silicate weathering flux, the long-term decrease in CO2levels may be due to an increase in the strength of the silicate weathering feedback. To explain the observed variations in the strength of the weathering feedback during the Cenozoic, we present a model for silicate weathering where hydrologic processes regulate climatic and tectonic forcings due to the presence of a thermodynamic limit to weathering fluxes. Climate regulation by silicate weathering is thus strongest when global topography is elevated, similar to today, and lowest when global topography is more subdued, allowing planetary temperatures to vary depending on the global distribution of topography and mountain belts. These results also motivate several key outstanding challenges in earth surface processes, including the need to

  6. Geochemical Cycling of Iodine Species in Soils

    SciTech Connect

    Hu, Q; Moran, J E; Blackwood, V

    2007-08-23

    Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine in soils is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we applied new analytical techniques to study the content and speciation of stable iodine in representative surface soils, and sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at numerous nuclear facilities in the United States, where anthropogenic {sup 129}I from prior nuclear fuel processing activities poses an environmental risk. The surface soil samples were chosen for their geographic locations (e.g., near the ocean or nuclear facilities) and for their differing physico-chemical characteristics (organic matter, texture, etc). Extracted solutions were analyzed by IC and ICP-MS methods to determine iodine concentrations and to examine iodine speciation (iodide, iodate, and organic iodine). In natural soils, iodine is mostly (nearly 90% of total iodine) present as organic species, while inorganic iodine becomes important (up to 50%) only in sediments with low organic matter. Results from laboratory column studies, aimed at examining transport of different iodine species, showed much greater retardation of 4-iodoaniline than iodide or iodate. Careful attention must be given to potential interconversion among species when interpreting the biogeochemical behavior of iodine in the environment. In addition to speciation, input concentration and residence time effects will influence the biogeochemical cycling of anthropogenic 129I deposited on surface soils.

  7. Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

  8. Chemical weathering rate laws and global geochemical cycles

    NASA Astrophysics Data System (ADS)

    Lasaga, Antonio C.; Soler, Josep M.; Ganor, Jiwchar; Burch, Timothy E.; Nagy, Kathryn L.

    1994-05-01

    In this paper, we discuss the recent kinetic work on water-rock interactions. Standard activity-activity diagrams are reinterpreted, using a mass transfer kinetic model and recent data on the relative rates of mineral reactions. The development of a fully integrated rate law is discussed, with special attention to the important effects of deviation from equilibrium on the rates of mineral-water reactions. The combined effects of temperature, pH, ionic strength, and saturation conditions on the overall dissolution and precipitation rates of minerals must be properly described before any seriously quantitative model of coupled fluid flow and chemical reaction can be undertaken. A rate law that integrates these effects is proposed. The functional dependence of the rate on ΔGr, the free energy change for the mineral reaction, is discussed, based on recent experimental work. An important result is the presence of a surface transition in the reaction mechanism leading to a very strong nonlinear dependence of the dissolution rates on ΔGr. The possible role of dislocation defects in this surface transition is discussed. The relation of global weathering rates and geochemical cycles to the recent experimental and theoretical water-rock kinetic work is explored. The temperature effect on the silica content of streams is reevaluated. The variation of silica concentration with runoff in the rivers of the world is quantified, using a coupled fluid flow and reaction model and the full rate law developed for a proto-granite system by the kinetic experiments. Implications of the water-rock kinetic data for the current geochemical cycles models are discussed with especial emphasis on the link between physical weathering and chemical weathering.

  9. Phosphorus geochemical cycling inferences from high frequency lake monitoring

    NASA Astrophysics Data System (ADS)

    Crockford, Lucy; Jordan, Philip; Taylor, David

    2013-04-01

    Freshwater bodies in Europe are required to return to good water quality status under the Water Framework Directive by 2015. A small inter-drumlin lake in the northeast of Ireland has been susceptible to eutrophic episodes and the presence of algal blooms during summer since annual monitoring began in 2002. While agricultural practice has been controlled by the implementation of the Nitrates Directive in 2006, the lake is failing to recover to good water quality status to meet with the Water Framework Directive objectives. Freshwaters in Ireland are regarded, in the main, as phosphorus (P) limited so identifying the sources of P possibly fuelling the algal blooms may provide an insight into how to improve water quality conditions. In a lake, these sources are divided between external catchment driven loads, as a result of farming and point sources, and P released from sediments made available to photic waters through internal lake mechanisms. High frequency sensors on data-sondes, installed on the lake in three locations, have provided chlorophyll a, redox potential, dissolved oxygen, temperature, pH, conductivity and turbidity data since March 2010. A data-sonde was installed in the hypolimnion to observe the change in lake conditions as P is released from lake sediments as a result of geochemical cycling with iron during anoxic periods. As compact high frequency sampling equipment for P analysis is still in its infancy for freshwaters, a proxy measurement of geochemical cycling in lakes would be useful to determine fully the extent of P contribution from sediments to the overall P load. Phosphorus was analysed once per month along with a number of other parameters and initial analysis of the high frequency data has shown changes in readings when known P release from lake sediments has occurred. Importantly, these data have shown when these P enriched hypolimnetic waters may be re-introduced to shallower waters in the photic zone, by changes in dissolved oxygen

  10. Examining Volcanic Terrains Using In Situ Geochemical Technologies; Implications for Planetary Field Geology

    NASA Technical Reports Server (NTRS)

    Young, K. E.; Bleacher, J. E.; Evans, C. A.; Rogers, A. D.; Ito, G.; Arzoumanian, Z.; Gendreau, K.

    2015-01-01

    Regardless of the target destination for the next manned planetary mission, the crew will require technology with which to select samples for return to Earth. The six Apollo lunar surface missions crews had only the tools to enable them to physically pick samples up off the surface or from a boulder and store those samples for return to the Lunar Module and eventually to Earth. Sample characterization was dependent upon visual inspection and relied upon their extensive geology training. In the four decades since Apollo however, great advances have been made in traditionally laboratory-based instrument technologies that enable miniaturization to a field-portable configuration. The implications of these advancements extend past traditional terrestrial field geology and into planetary surface exploration. With tools that will allow for real-time geochemical analysis, an astronaut can better develop a series of working hypotheses that are testable during surface science operations. One such technology is x-ray fluorescence (XRF). Traditionally used in a laboratory configuration, these instruments have now been developed and marketed commercially in a field-portable mode. We examine this technology in the context of geologic sample analysis and discuss current and future plans for instrument deployment. We also discuss the development of the Chromatic Mineral Identification and Surface Texture (CMIST) instrument at the NASA Goddard Space Flight Center (GSFC). Testing is taking place in conjunction with the RIS4E (Remote, In Situ, and Synchrotron Studies for Science and Exploration) SSERVI (Solar System Exploration and Research Virtual Institute) team activities, including field testing at Kilauea Volcano, HI..

  11. SINGR: A Single Scintillator Neutron and Gamma-Ray Spectrometer for Acquiring Rapid, Remote Geochemical Data on Future Planetary Science Missions

    NASA Astrophysics Data System (ADS)

    Hardgrove, C.; Prettyman, T.; Johnson, E.; Parsons, A.; Barnaby, H.; Christian, J.; Gupta, K.

    2016-10-01

    SINGR is a single scintillator detector coupled with a pulsed neutron generator that is currently being prototyped, modeled, developed and tested in order to acquire rapid geochemical data, hydrogen abundance and depth profiles on planetary missions.

  12. Planetary geochemical investigations using Raman and laser-induced breakdown spectroscopy.

    PubMed

    Clegg, Samuel M; Wiens, Roger; Misra, Anupam K; Sharma, Shiv K; Lambert, James; Bender, Steven; Newell, Raymond; Nowak-Lovato, Kristy; Smrekar, Sue; Dyar, M Darby; Maurice, Sylvestre

    2014-01-01

    An integrated Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) instrument is a valuable geoanalytical tool for future planetary missions to Mars, Venus, and elsewhere. The ChemCam instrument operating on the Mars Curiosity rover includes a remote LIBS instrument. An integrated Raman-LIBS spectrometer (RLS) based on the ChemCam architecture could be used as a reconnaissance tool for other contact instruments as well as a primary science instrument capable of quantitative mineralogical and geochemical analyses. Replacing one of the ChemCam spectrometers with a miniature transmission spectrometer enables a Raman spectroscopy mineralogical analysis to be performed, complementing the LIBS chemical analysis while retaining an overall architecture resembling ChemCam. A prototype transmission spectrometer was used to record Raman spectra under both Martian and Venus conditions. Two different high-pressure and high-temperature cells were used to collect the Raman and LIBS spectra to simulate surface conditions on Venus. The resulting LIBS spectra were used to generate a limited partial least squares Venus calibration model for the major elements. These experiments demonstrate the utility and feasibility of a combined RLS instrument.

  13. Geochemical Reservoirs and Timing of Sulfur Cycling on Mars

    NASA Astrophysics Data System (ADS)

    Gaillard, Fabrice; Michalski, Joseph; Berger, Gilles; McLennan, Scott M.; Scaillet, Bruno

    2013-01-01

    Sulfate-dominated sedimentary deposits are widespread on the surface of Mars, which contrasts with the rarity of carbonate deposits, and indicates surface waters with chemical features drastically different from those on Earth. While the Earth's surface chemistry and climate are intimately tied to the carbon cycle, it is the sulfur cycle that most strongly influences the Martian geosystems. The presence of sulfate minerals observed from orbit and in-situ via surface exploration within sedimentary rocks and unconsolidated regolith traces a history of post-Noachian aqueous processes mediated by sulfur. These materials likely formed in water-limited aqueous conditions compared to environments indicated by clay minerals and localized carbonates that formed in surface and subsurface settings on early Mars. Constraining the timing of sulfur delivery to the Martian exosphere, as well as volcanogenic H2O is therefore central, as it combines with volcanogenic sulfur to produce acidic fluids and ice. Here, we reassess and review the Martian geochemical reservoirs of sulfur from the innermost core, to the mantle, crust, and surficial sediments. The recognized occurrences and the mineralogical features of sedimentary sulfate deposits are synthesized and summarized. Existing models of formation of sedimentary sulfate are discussed and related to weathering processes and chemical conditions of surface waters. We also review existing models of sulfur content in the Martian mantle and analyze how volcanic activities may have transferred igneous sulfur into the exosphere and evaluate the mass transfers and speciation relationships between volcanic sulfur and sedimentary sulfates. The sedimentary clay-sulfate succession can be reconciled with a continuous volcanic eruption rate throughout the Noachian-Hesperian, but a process occurring around the mid-Noachian must have profoundly changed the composition of volcanic degassing. A hypothetical increase in the oxidation state or in

  14. Effects of the seasonal cycle on superrotation in planetary atmospheres

    SciTech Connect

    Mitchell, Jonathan L.; Vallis, Geoffrey K.; Potter, Samuel F.

    2014-05-20

    The dynamics of dry atmospheric general circulation model simulations forced by seasonally varying Newtonian relaxation are explored over a wide range of two control parameters and are compared with the large-scale circulation of Earth, Mars, and Titan in their relevant parameter regimes. Of the parameters that govern the behavior of the system, the thermal Rossby number (Ro) has previously been found to be important in governing the spontaneous transition from an Earth-like climatology of winds to a superrotating one with prograde equatorial winds, in the absence of a seasonal cycle. This case is somewhat unrealistic as it applies only if the planet has zero obliquity or if surface thermal inertia is very large. While Venus has nearly vanishing obliquity, Earth, Mars, and Titan (Saturn) all have obliquities of ∼25° and varying degrees of seasonality due to their differing thermal inertias and orbital periods. Motivated by this, we introduce a time-dependent Newtonian cooling to drive a seasonal cycle using idealized model forcing, and we define a second control parameter that mimics non-dimensional thermal inertia of planetary surfaces. We then perform and analyze simulations across the parameter range bracketed by Earth-like and Titan-like regimes, assess the impact on the spontaneous transition to superrotation, and compare Earth, Mars, and Titan to the model simulations in the relevant parameter regime. We find that a large seasonal cycle (small thermal inertia) prevents model atmospheres with large thermal Rossby numbers from developing superrotation by the influences of (1) cross-equatorial momentum advection by the Hadley circulation and (2) hemispherically asymmetric zonal-mean zonal winds that suppress instabilities leading to equatorial momentum convergence. We also demonstrate that baroclinic instabilities must be sufficiently weak to allow superrotation to develop. In the relevant parameter regimes, our seasonal model simulations compare favorably to

  15. Geochemical evidence for cryptic sulfur cycling in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Mills, Jennifer V.; Antler, Gilad; Turchyn, Alexandra V.

    2016-11-01

    Cryptic sulfur cycling is an enigmatic process in which sulfate is reduced to some lower-valence state sulfur species and subsequently quantitatively reoxidized; the rate and microbial energetics of this process and how prevalent it may be in the environment remain controversial. Here we investigate sulfur cycling in salt marsh sediments from Norfolk, England where we observe high ferrous iron concentrations with no depletion of sulfate or change in the sulfur isotope ratio of that sulfate, but a 5‰ increase in the oxygen isotope ratio in sulfate, indicating that sulfate has been through a reductive cycle replacing its oxygen atoms. This cryptic sulfur cycle was replicated in laboratory incubations using 18O-enriched water, demonstrating that the field results do not solely result from mixing processes in the natural environment. Numerical modeling of the laboratory incubations scaled to represent the salt marsh sediments suggests that the uptake rate of sulfate during this cryptic sulfur cycling is similar to the uptake rate of sulfate during the fastest microbial sulfate reduction that has been measured in the natural environment. The difference is that during cryptic sulfur cycling, all of the sulfur is subsequently reoxidized to sulfate. We discuss mechanisms for this pathway of sulfur cycling including the possible link to the subsurface iron cycle.

  16. Assessing the Role of Seafloor Weathering in Global Geochemical Cycling

    NASA Astrophysics Data System (ADS)

    Farahat, N. X.; Abbot, D. S.; Archer, D. E.

    2015-12-01

    Low-temperature alteration of the basaltic upper oceanic crust, known as seafloor weathering, has been proposed as a mechanism for long-term climate regulation similar to the continental climate-weathering negative feedback. Despite this potentially far-reaching impact of seafloor weathering on habitable planet evolution, existing modeling frameworks do not include the full scope of alteration reactions or recent findings of convective flow dynamics. We present a coupled fluid dynamic and geochemical numerical model of low-temperature, off-axis hydrothermal activity. This model is designed to explore the the seafloor weathering flux of carbon to the oceanic crust and its responsiveness to climate fluctuations. The model's ability to reproduce the seafloor weathering environment is evaluated by constructing numerical simulations for comparison with two low-temperature hydrothermal systems: A transect east of the Juan de Fuca Ridge and the southern Costa Rica Rift flank. We explore the sensitivity of carbon uptake by seafloor weathering on climate and geology by varying deep ocean temperature, seawater dissolved inorganic carbon, continental weathering inputs, and basaltic host rock in a suite of numerical experiments.

  17. Volatile cycling and the thermal evolution of planetary mantle

    NASA Astrophysics Data System (ADS)

    Sandu, Constantin

    The thermal histories of terrestrial planets are investigated using two parameterized mantle convection models for either Earth like planets and planets with no active plate tectonics. Using parameterized models of mantle convection, we performed computer simulations of planetary cooling and volatile cycling. The models estimate the amount of volatile in mantle reservoir, and calculate the outgassing and regassing rates. A linear model of volatile concentration-dependent is assumed for the activation energy of the solid-state creep in the mantle. The kinematic viscosity of the mantle is thus dynamically affected by the activation energy through a variable concentration in volatile. Mantle temperature and heat flux is calculated using a model derived from classic thermal boundary layer theory of a single layered mantle with temperature dependent viscosity. The rate of volatile exchanged between mantle and surface is calculated by balancing the amount of volatiles degassed in the atmosphere by volcanic and spreading related processes and the amount of volatiles recycled back in the mantle by the subduction process. In the cases that lack plate tectonics, the degassing efficiency is dramatically reduced and the regassing process is absent. The degassing effect is dependent on average spreading rate of tectonic plates and on the amount of volatile in the melt extract in the transition zone between mantle and upper boundary laver. The regassing effect is dependent on the subduction rate and on the amount of volatile present on a hydrated layer on top of the subducting slab. The degassing and regassing parameters are all related to the intensity of the convection in the mantle and to the surface temperature of the planet, and they are regulated by the amount of volatiles in reservoir. Comparative study with the previous models display significant differences and improve the versatility of the model. The optimum efficiency factors found are in the range of 0.01--0.06 for

  18. Long-term climate change and the geochemical cycle of carbon

    NASA Technical Reports Server (NTRS)

    Marshall, Hal G.; Walker, James C. G.; Kuhn, William R.

    1988-01-01

    The response of the coupled climate-geochemical system to changes in paleography is examined in terms of the biogeochemical carbon cycle. The simple, zonally averaged energy balance climate model combined with a geochemical carbon cycle model, which was developed to study climate changes, is described. The effects of latitudinal distributions of the continents on the carbon cycle are investigated, and the global silicate weathering rate as a function of latitude is measured. It is observed that a concentration of land area at high altitudes results in a high CO2 partial pressure and a high global average temperature, and for land at low latitudes a cold globe and ice are detected. It is noted that the CO2 greenhouse feedback effect is potentially strong and has a stabilizing effect on the climate system.

  19. Long-term climate change and the geochemical cycle of carbon

    NASA Technical Reports Server (NTRS)

    Marshall, Hal G.; Walker, James C. G.; Kuhn, William R.

    1988-01-01

    The response of the coupled climate-geochemical system to changes in paleography is examined in terms of the biogeochemical carbon cycle. The simple, zonally averaged energy balance climate model combined with a geochemical carbon cycle model, which was developed to study climate changes, is described. The effects of latitudinal distributions of the continents on the carbon cycle are investigated, and the global silicate weathering rate as a function of latitude is measured. It is observed that a concentration of land area at high altitudes results in a high CO2 partial pressure and a high global average temperature, and for land at low latitudes a cold globe and ice are detected. It is noted that the CO2 greenhouse feedback effect is potentially strong and has a stabilizing effect on the climate system.

  20. How life affects the geochemical cycle of carbon

    NASA Technical Reports Server (NTRS)

    Walker, James C. G.

    1992-01-01

    Developing a quantitative understanding of the biogeochemical cycles of carbon as they have worked throughout Earth history on various time scales, how they have been affected by biological evolution, and how changes in the carbon content of ocean and atmosphere may have affected climate and the evolution of life are the goals of the research. Theoretical simulations were developed that can be tuned to reproduce such data as exist and, once tuned, can be used to predict properties that have not yet been observed. This is an ongoing process, in which models and results are refined as new data and interpretations become available and as understanding of the global system improves. Results of the research are described in several papers which were published or submitted for publication. These papers are summarized. Future research plans are presented.

  1. Volcanic Metal Emissions and Implications for Geochemical Cycling and Mineralization

    NASA Astrophysics Data System (ADS)

    Edmonds, M.; Mather, T. A.

    2016-12-01

    Volcanoes emit substantial fluxes of metals to the atmosphere in volcanic gas plumes in the form of aerosol, adsorbed onto silicate particles and even in some cases as gases.. A huge database of metal emissions has been built over the preceding decades, which shows that volcanoes emit highly volatile metals into the atmosphere, such as As, Bi, Cd, Hg, Re, Se, Tl, among others. Understanding the cycling of metals through the Solid Earth system has importance for tackling a wide range of Earth Science problems, e.g. (1) the environmental impacts of metal emissions; (2) the sulfur and metal emissions of volcanic eruptions; (3) the behavior of metals during subduction and slab devolatilization; (4) the influence of redox on metal behavior in subduction zones; (5) the partitioning of metals between magmatic vapor, brines and melts; and (6) the relationships between volcanism and ore deposit formation. It is clear, when comparing the metal composition and flux in the gases and aerosols emitted from volcanoes, that they vary with tectonic setting. These differences allow insights into how the magmatic vapor was generated and how it interacted with melts and sulfides during magma differentiation and decompression. Hotspot volcanoes (e.g. Kilauea, Hawaii; volcanoes in Iceland) outgas a metal suite that mirrors the sulfide liquid-silicate melt partitioning behaviors reconstructed from experiments (as far as they are known), suggesting that the aqueous fluids (that will later be outgassed from the volcano) receive metals directly from oxidation of sulfide liquids during degassing and ascent of magmas towards the surface. At arc volcanoes, the gaseous fluxes of metals are typically much higher; and there are greater enrichments in elements that partition strongly into vapor or brine from silicate melts such as Cu, Au, Zn, Pb, W. We collate and present data on volcanic metal emissions from volcanoes worldwide and review the implications of the data array for metal cycling

  2. From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)

    NASA Astrophysics Data System (ADS)

    Cividini, D.; Lemarchand, D.; Chabaux, F.; Boutin, R.; Pierret, M.-C.

    2010-06-01

    There is a fast growing interest in understanding the coupling between mineralogical and biological processes responsible for the migration of elements through continental ecosystems. This issue has fundamental impacts at the soil/plant scale because it can explain the tight links between soil and plant development and at the watershed scale because it gives a direct access to the water quality. In the present study, we performed an extended investigation of the bio-geochemical cycle of boron, which is an element known to be suitable for investigating water/rock interactions and vegetation cycling. New B data are provided along the hydro-bio-geochemical continuum in a forest ecosystem (Strengbach basin, Vosges, France), from rainwaters down to the outlet of the basin including systematic analyses of throughfalls, soil solutions, springs and brooks scattered in the watershed. At the watershed scale, we evidence a relationship between the B isotopic composition of river waters and the weathering regime outlining a predominant control of the parent rock mineralogy on the B geochemical behavior. At the soil/plant scale, it appears that the B geochemical cycle is controlled by the vegetation cycling, which is characterized by an uncommon, easy to distinguish, B isotopic composition (δ 11B ranging from about +30‰ to +45‰). Each year the amount of B being involved in the vegetation cycle is about four times greater than that of B being exported out of the watershed. At 10 cm depth in soil, where the plant roots are expected to be the most active, we observe a marked seasonal oscillation of the B isotopic values, which is interpreted as resulting from the vegetation activity. A mass balance calculation based on the assumption that that 10B is preferentially accumulated in the biomass tends to indicate that the soil/plant system does not behave at steady state with respect to B. Because of the very distinct B isotopic signature of vegetation and minerals in soil, box

  3. The mid-term and long-term solar quasi-periodic cycles and the possible relationship with planetary motions

    NASA Astrophysics Data System (ADS)

    Tan, Baolin; Cheng, Zhuo

    2013-02-01

    This work investigates the solar quasi-periodic cycles with multi-timescales and the possible relationships with planetary motions. The solar cycles are derived from long-term observations of the relative sunspot number and microwave emission at frequency of 2.80 GHz. A series of solar quasi-periodic cycles with multi-timescales are registered. These cycles can be classified into three classes: (1) the strong PLC (PLC is defined as the solar cycle with a period very close to the ones of some planetary motions, named as planetary-like cycle) which is related strongly with planetary motions, including nine periodic modes with relatively short period ( P<12 yr), and related to the motions of the inner planets and of Jupiter; (2) the weak PLC, which is related weakly to planetary motions, including two periodic modes with relatively long period ( P>12 yr), and possibly related to the motions of outer planets; (3) the non-PLC, for which so far there has been found no clear evidence to show the relationship with any planetary motions. Among the planets, Jupiter plays a key role in most periodic modes due to its sidereal motion or spring tidal motions associated with other planets. Among planetary motions, the spring tidal motion of the inner planets and of Jupiter dominates the formation of most PLCs. The relationships between multi-timescale solar periodic modes and the planetary motions will help us to understand the essential nature and prediction of solar activities.

  4. Long-term climate change and the geochemical cycle of carbon.

    PubMed

    Marshall, H G; Walker, J C; Kuhn, W R

    1988-01-20

    We study the interactions between the geochemical cycles of carbon and long-term changes in climate. Climate change is studied with a simple, zonally averaged energy balance climate model that includes the greenhouse effect of carbon dioxide explicitly. The geochemical model balances the rate of consumption of carbon dioxide in silicate weathering against its release by volcanic and metamorphic processes. The silicate weathering rate is expressed locally as a function of temperature, carbon dioxide partial pressure, and runoff. The global weathering rate is calculated by integrating these quantities over the land area as a function of latitude. Carbon dioxide feedback stabilizes the climate system against a reduction in solar luminosity and may contribute to the preservation of equable climate on the early Earth, when solar luminosity was low. The system responds to reduced land area by increasing carbon dioxide partial pressure and warming the globe. Our model makes it possible to study the response of the system to changing latitudinal distribution of the continents. A concentration of land area at high latitudes leads to high carbon dioxide partial pressures and high global average temperature because weathering of high-latitude continents is slow. Conversely, concentration of the continents at low latitudes yields a cold globe and ice at low latitudes, a situation that appears to be representative of the late Precambrian glacial episode. This model is stable against ice albedo catastrophe even when the ice line occurs at low latitudes. In this it differs from energy balance models that lack the coupling to the geochemical cycle of carbon.

  5. A hybrid model of the CO2 geochemical cycle and its application to large impact events

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.; Pollack, J. B.; Toon, O. B.; Richardson, S. M.

    1986-01-01

    The effects of a large asteriod or comet impact on modern and ancient marine biospheres are analyzed. A hybrid model of the carbonate-silicate geochemical cycle, which is capable of calculating the concentrations of carbon dioxide in the atmosphere, ocean, and sedimentary rocks, is described. The differences between the Keir and Berger (1983) model and the hybrid model are discussed. Equilibrium solutions are derived for the preindustrial atmosphere/ocean system and for a system similar to that of the late Cretaceous Period. The model data reveal that globl darkening caused by a stratospheric dust veil could destroy the existing phytoplankton within a period of several weeks or months, nd the dissolution of atmospheric NO(x) compounds would lower the pH of ocean surface waters and release CO2 into the atmosphere. It is noted that the surface temperatures could be increased by several degrees and surface oceans would be uninhabitable for calcaerous organisms for approximately 20 years.

  6. Community Structure of Methane-Cycling Archaea in Different Geochemical Zones in Aarhus Bay, Denmark

    NASA Astrophysics Data System (ADS)

    Chen, X.; Lever, M. A.; Saunders, A. M.; Jørgensen, B. B.

    2014-12-01

    Methanogenesis and anaerobic oxidation of methane are dominant processes regulating methane cycle in the deep biosphere in marine environments, both of which are executed by microbes. The diversity of methane-cycling archaea has been intensively studied by exploring 16S ribosomal RNA gene and alpha subunit of methyl coenzyme M reductase gene (mcrA). In marine sediments, methanogens and methane-oxidizing archaea are mainly found in methane zone (MZ) and in sulfate-methane transition zone (SMTZ), respectively. However, methane-cycling archaea are also present in zones other than their usual residing geochemical zones. Next generation sequencing of mcrA genes from 5 gravity cores shows that both methanogens and methane-oxidizing archaeal group - ANME-1 are ubiquitous in all biogeochemical zones in Aarhus Bay. We will further discuss below questions: which methanogens and methanotrophs are present and active in the presence of sulfate, and which are restricted in SMTZ or MZ? How do activity and pathway of methanogenesis / methanotrophy change with depth and substrate availability?

  7. Planetary ecology

    SciTech Connect

    Caldwell, D.E.; Brierley, C.L.; Brierley, J.A.

    1984-01-01

    Over 100 top scientists contribute their knowledge to this study of the cycling of matter in our environment. It introduces the concept of biogeochemistry - an association of geochemical and biological forces which has led to a concept of planetary and biological co-evolution, and to a natural history ruled by inanimate and animate forces. Based on a symposium held in 1983, this volume compiled important research findings generated in 11 countries. It merges many scientific disciplines to promote an awareness that life is a universal, ubiquitous, and versatile geological force. Scientists working in microbiology, geology, atmospheric chemistry, paleoecology, geochemistry, soil chemistry, and environmental science will find data important to their work in this compendium.

  8. Parallel geochemical and metagenomic datasets reveal biogeochemical cycling in a hot spring ecosystem

    NASA Astrophysics Data System (ADS)

    Meyer-Dombard, D. R.; Swingley, W.; Raymond, J.; Shock, E.

    2012-12-01

    Environmental sequence data (2,321 16S rRNA clones and 470 megabases of "metagenome" sequence) were produced from biofilms at five sites in the outflow of "Bison Pool" (BP), an alkaline hot spring in the Lower Geyser Basin of Yellowstone National Park. The outflow of BP is characterized by decreasing temperature, increasing pH, increasing dissolved oxygen, decreasing total sulfide, and changing availability of biological nutrients. Microbial life along a 22 m gradient at BP transitions from a 92°C chemotrophic streamer biofilm community in the source pool to a 56°C phototrophic mat community. Coordinated analysis of the BP Environmental Genome and a complementary contextual geochemical dataset of ~75 parameters has revealed biogeochemical cycling and metabolic and microbial community shifts within a hot spring ecosystem (1). In the BP outflow, genes diagnostic for sulfide oxidation, attributed to Aquificales in the chemosynthetic zone and Deinococcus-Thermus at the photosynthetic fringe, decrease in total number downstream. Geochemical data indicate that biological sulfide oxidation, an energy-yielding process in BP, occurs over this same range. While the genetic capacity for sulfate reduction in Thermoproteales at high temperature was found, inorganic sulfate reduction is only minimally energy-yielding at BP suggesting limited activity of these genes. Presence of apr, sat, and dsr genes in the photosynthetic mats may indicate sulfate reduction in micro-niches at depth within the biofilms, perhaps in response to increased availability of organic solutes. Carbon fixation tactics shift downstream in BP as well, as evidenced by the presence of genes associated with specific pathways and carbon isotope ratios. Capacity for the rTCA cycle, attributed to Aquificales and Thermoproteales, and the acetyl co-A pathway are found throughout BP, but are most prevalent in highest temperature sites. At lower temperature sites, fewer total carbon fixation genes were observed

  9. Planetary Biology and Microbial Ecology: Molecular Ecology and the Global Nitrogen cycle

    NASA Technical Reports Server (NTRS)

    Nealson, Molly Stone (Editor); Nealson, Kenneth H. (Editor)

    1993-01-01

    This report summarizes the results of the Planetary Biology and Molecular Ecology's summer 1991 program, which was held at the Marine Biological Laboratory in Woods Hole, Massachusetts. The purpose of the interdisciplinary PBME program is to integrate, via lectures and laboratory work, the contributions of university and NASA scientists and student interns. The goals of the 1991 program were to examine several aspects of the biogeochemistry of the nitrogen cycle and to teach the application of modern methods of molecular genetics to field studies of organisms. Descriptions of the laboratory projects and protocols and abstracts and references of the lectures are presented.

  10. A geomorphic-geochemical framework for quantifying the cycling of sediment-associated contaminants in fluvial systems

    NASA Astrophysics Data System (ADS)

    Byrne, Patrick; Lopez-Tarazon, Jose; Williams, Richard

    2016-04-01

    Recent high-profile contamination events linked to extreme floods have underlined the persistent environmental risk posed by legacy metals stored in fluvial systems worldwide. While we understand that the fate of sediment-associated metals is largely determined by the dynamics of the fluvial transport system, we still lack a process-based understanding of the spatial and temporal mechanisms that affect the physical and geochemical transfer of metals through catchments. This interdisciplinary project will exploit advances in geomorphic and geochemical analyses to develop a methodological approach and conceptual framework to answer key questions related to the dynamics and timescales of metal cycling in fluvial systems. The approach will be tested in two reaches of the mining-impacted Afon Twymyn, Wales. The main objectives are: (i) quantify the physical transport of sediment and metals over a range of river flows and model sediment pathways; (ii) establish the geochemical mobility and speciation of sediment-associated metals and how this is modified through the sediment pathways. To achieve these objectives a geomorphic-geochemical combined methodology will be applied. It includes: (i) Aerial imagery that will be acquired from UAV surveys pre- and post-high flows and transformed into high-resolution DEMs using Structure-from-Motion; (ii) suspended sediment flux will be estimated indirectly by field calibration with a logging turbidimeter; (iii) 2D hydraulic and sediment transport model (Delft3D) will be used to quantify the transport of sediment and associated metals and to map the source, pathway and sink of contaminated sediment; (iv) soil and sediment samples (including suspended sediment) will be collected pre- and post-high flows for geochemical (concentration, speciation) and mineralogical (XRD, SEM) analyses; (v) finally, a geochemical model (Geochemists Workbench) will be developed to generate hypotheses that explain observed geochemical change as a function

  11. Plant Cuticle: A Geochemical and Biophysical Sensor of the Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Upchurch, G. R.; Marino, B. D.

    2007-12-01

    Plant cuticle--the decay-resistant outer layer of leaves and young stems---is the most abundant identificable component of the plant fossil record next to pollen and spores and occurs in both megafossils and phytodebris. Plant cuticles provide major information on past levels of atmospheric CO2 because of the inverse relationship between pCO2 and Stomatal Index in many modern species. Some geochemical studies have used partially decayed fossil leaf material (referred to as "plant cuticle") to reconstruct changes in atmospheric δ 13C by means of the strong correlation, in modern plants, between atmospheric δ 13C and that of plant tissue. However, the occurrence within the same piece of fossil tissue of different chemical compounds with different isotopic signatures limits the accuracy of reconstructions, because decay under anaerobic conditions distorts the original isotopic values. A standard histochemical test for plant cuticle---namely, high resistance to oxidation in chromium trioxide--- indicates the potential for isolating pure fractions of plant cuticle from the geologic record and using these fractions to reconstruct past changes in atmospheric δ 13C. Plant cuticle macerated in chromium trioxide is 3.5‰ more negative than whole tissue, an offset similar to that for other lipids and lignin. Preliminary isotopic analysis of fossil "cuticle" suggests that much, if not most, of the fossil "cuticle" reported in the geochemical literature may represent a mixture of cuticle, remnant cellulose, and other compounds. The offset between cuticle and whole tissue appears to be consistent for plants with C3, C4, and CAM photosynthesis, indicating that plant cuticle can be used to reconstruct the path of photosynthetic carbon fixation. Plant cuticle oxidized in chromium trioxide can be identified to genus and species through light microscopy and SEM, providing much greater taxonomic resolution for isotopic studies than is possible with bulk carbon and many biomarker

  12. A hybrid model of the CO2 geochemical cycle and its application to large impact events.

    PubMed

    Kasting, J F; Richardson, S M; Pollack, J B; Toon, O B

    1986-05-01

    A hybrid model of the carbonate-silicate geochemical cycle is presented which is capable of calculating the partitioning of carbon dioxide between the atmosphere, ocean, and sedimentary rocks. The ocean is subdivided into a shallow, mixed layer, which remains in equilibrium with the atmosphere, and a massive, deep layer which does not. Gradients in dissolved carbon content are established between the mixed layer and the deep ocean as a consequence of downward fluxes of fecal matter and of dead planktonic organisms. The dissolved carbon content and alkalinity of the ocean as a whole are controlled by weathering and metamorphism of sedimentary rocks. Equilibrium solutions are derived for the preindustrial atmosphere/ocean system and for a system that may be similar to that existing during the Late Cretaceous Period. The model is then used to determine how the modern and ancient marine biospheres might be affected by an oceanic impact of a large asteroid or comet. Such an event could perturb the carbon cycle in several different ways. Global darkening caused by stratospheric dust veil could destroy most of the existing phytoplankton in a period of several weeks to several months. At the same time, dissolution of atmospheric NOx compounds synthesized during the impact would lower the pH of ocean surface waters and release CO2 into the atmosphere. Both effects might be enhanced by an influx of CO2 released from upwelling of deep ocean water near the hot impact site, from oxidation of dead organic matter, and from the comet itself. The net result could be to raise surface temperatures by several degrees and to make the surface ocean uninhabitable by calcareous organisms for as much as 20 yrs (the time scale for mixing with deep ocean). It appears unlikely, however, that an impact could create a "Strangelove ocean," in which surface waters remained corrosive to calcium carbonate for thousands or tens of thousands of years. Thus, disruption of the carbon cycle by an impact

  13. Contrasting geochemical cycling of hafnium and neodymium in the central Baltic Sea

    NASA Astrophysics Data System (ADS)

    Chen, Tian-Yu; Stumpf, Roland; Frank, Martin; Bełdowski, Jacek; Staubwasser, Michael

    2013-12-01

    The central Baltic Sea is a marginal brackish basin which comprises anoxic bottom waters and is surrounded by geological source terrains with a wide variety of compositions and ages. This allows the investigation of water mass mixing using radiogenic isotope compositions of Nd and Hf as well as their geochemical cycling across varying redox conditions in the water column. In this study, we present the distribution of Nd and Hf concentrations and their isotopic compositions for 6 depth profiles and 3 surface water sites obtained during a cruise in the central Baltic Sea onboard the RV Oceania as a part of the international GEOTRACES program. The results obtained indicate that Nd isotopes effectively trace the mixing between more radiogenic saline waters from the south and unradiogenic fresh waters from the north, which helps to understand the reliability of Nd isotopes as water mass tracer in the open ocean. In surface waters, Nd shows higher concentrations and less radiogenic isotope compositions at the northern stations, which are progressively diluted and become more radiogenic to the south, consistent with the counterclockwise circulation pattern of central Baltic Sea surface waters. In contrast to the variable Nd concentrations, Hf shows much less variability. At the Gotland Deep station, the Nd concentrations of the euxinic waters are higher by a factor >10 than those of the overlying oxygen-depleted waters, whereas Hf only shows small concentration variations. This indicates faster removal of Hf from the water column than Nd. Moreover, the dissolved Hf isotope signatures document great variability but no consistent mixing trends. Our explanation is that Hf has a lower residence time than Nd, and also that the Hf isotope signatures of the sources are highly heterogeneous, which is attributed to their differing magmatic and tectonic histories as well as incongruent post-glacial weathering around the central Baltic Sea.

  14. Linking the climatic and geochemical controls on global soil carbon cycling

    NASA Astrophysics Data System (ADS)

    Doetterl, Sebastian; Stevens, Antoine; Six, Johan; Merckx, Roel; Van Oost, Kristof; Casanova Pinto, Manuel; Casanova-Katny, Angélica; Muñoz, Cristina; Boudin, Mathieu; Zagal Venegas, Erick; Boeckx, Pascal

    2015-04-01

    Climatic and geochemical parameters are regarded as the primary controls for soil organic carbon (SOC) storage and turnover. However, due to the difference in scale between climate and geochemical-related soil research, the interaction of these key factors for SOC dynamics have rarely been assessed. Across a large geochemical and climatic transect in similar biomes in Chile and the Antarctic Peninsula we show how abiotic geochemical soil features describing soil mineralogy and weathering pose a direct control on SOC stocks, concentration and turnover and are central to explaining soil C dynamics at larger scales. Precipitation and temperature had an only indirect control by regulating geochemistry. Soils with high SOC content have low specific potential CO2 respiration rates, but a large fraction of SOC that is stabilized via organo-mineral interactions. The opposite was observed for soils with low SOC content. The observed differences for topsoil SOC stocks along this transect of similar biomes but differing geo-climatic site conditions are of the same magnitude as differences observed for topsoil SOC stocks across all major global biomes. Using precipitation and a set of abiotic geochemical parameters describing soil mineralogy and weathering status led to predictions of high accuracy (R2 0.53-0.94) for different C response variables. Partial correlation analyses revealed that the strength of the correlation between climatic predictors and SOC response variables decreased by 51 - 83% when controlling for geochemical predictors. In contrast, controlling for climatic variables did not result in a strong decrease in the strength of the correlations of between most geochemical variables and SOC response variables. In summary, geochemical parameters describing soil mineralogy and weathering were found to be essential for accurate predictions of SOC stocks and potential CO2 respiration, while climatic factors were of minor importance as a direct control, but are

  15. SEDIMENT GEOCHEMICAL MODEL

    EPA Science Inventory

    Until recently, sediment geochemical models (diagenetic models) have been only able to explain sedimentary flux and concentration profiles for a few simplified geochemical cycles (e.g., nitrogen, carbon and sulfur). However with advances in numerical methods, increased accuracy ...

  16. SEDIMENT GEOCHEMICAL MODEL

    EPA Science Inventory

    Until recently, sediment geochemical models (diagenetic models) have been only able to explain sedimentary flux and concentration profiles for a few simplified geochemical cycles (e.g., nitrogen, carbon and sulfur). However with advances in numerical methods, increased accuracy ...

  17. Chemical footprint: a methodological framework for bridging life cycle assessment and planetary boundaries for chemical pollution.

    PubMed

    Sala, Serenella; Goralczyk, Malgorzata

    2013-10-01

    The development and use of footprint methodologies for environmental assessment are increasingly important for both the scientific and political communities. Starting from the ecological footprint, developed at the beginning of the 1990s, several other footprints were defined, e.g., carbon and water footprint. These footprints-even though based on a different meaning of "footprint"-integrate life cycle thinking, and focus on some challenging environmental impacts including resource consumption, CO2 emission leading to climate change, and water consumption. However, they usually neglect relevant sources of impacts, as those related to the production and use of chemicals. This article presents and discusses the need and relevance of developing a methodology for assessing the chemical footprint, coupling a life cycle-based approach with methodologies developed in other contexts, such as ERA and sustainability science. Furthermore, different concepts underpin existing footprint and this could be the case also of chemical footprint. At least 2 different approaches and steps to chemical footprint could be envisaged, applicable at the micro- as well as at the meso- and macroscale. The first step (step 1) is related to the account of chemicals use and emissions along the life cycle of a product, sector, or entire economy, to assess potential impacts on ecosystems and human health. The second step (step 2) aims at assessing to which extent actual emission of chemicals harm the ecosystems above their capability to recover (carrying capacity of the system). The latter step might contribute to the wide discussion on planetary boundaries for chemical pollution: the thresholds that should not be surpassed to guarantee a sustainable use of chemicals from an environmental safety perspective. The definition of what the planetary boundaries for chemical pollution are and how the boundaries should be identified is an on-going scientific challenge for ecotoxicology and ecology. In

  18. Geochemical and hydrodynamic controls on arsenic and trace metal cycling in a seasonally stratified US sub-tropical reservoir

    SciTech Connect

    Brandenberger, Jill M.; Louchouarn, Patrick; Herbert, Bruce; Tissot, Philippe

    2004-10-01

    The phase distribution of trace metals and oxyanions was investigated within a South Texas watershed hosting a high density of surface uranium mine pits and tailings. The objectives of the study were to evaluate the potential impact of these old uranium mining sites on the watershed with particular emphasis on spatial and temporal changes in water quality of a reservoir that serves as the major source of freshwater to a population of {approx} 350,000 people in the region. A livestock pond, bordered by uranium mine tailings, was used as a model case-study site to evaluate the cycling of uranium mine-derived oxyanions under changing redox conditions. Although the pond showed seasonal thermal and chemical stratification, geochemical cycling of metals was limited to Co and Pb, which seemed to be mostly associated with redox cycling of Mn mineral phases, and U, which suggested reductive precipitation in the ponds hypolimnion. Uranium levels, however, were too low to support strong inputs from th e tailings into the water column of the pond. The strong relations observed between particulate Cr, Cs, V and Fe suggest that these metals are associated with a stable particulate phase (probably allochthonous aluminosilicates) enriched in unreactive iron. This observation is supported by a parallel relationship in sediments collected across a broad range of sediment depositional processed (and histories) in the basin. Arsenic, though selectively enriched in the ponds water column, remained stable and mostly in solution throughout the depth of the profile and showed no sign of geochemical cycling or interaction with Fe-rich particles. We found no evidence of anthropogenic impacts of U mines beyond the purely local scale. Arsenic does decrease in concentration downstream of uranium mining sites but its presence within the Nueces drainage basin is related to interactions between surface and ground waters with uranium-rich geological formations rather than long-scale transport of

  19. Synchronized Helicity Oscillations: A Link Between Planetary Tides and the Solar Cycle?

    NASA Astrophysics Data System (ADS)

    Stefani, F.; Giesecke, A.; Weber, N.; Weier, T.

    2016-10-01

    Recent years have seen an increased interest in the question of whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we examine which possible physical mechanism might link the weak planetary forces with solar dynamo action. We focus on the helicity oscillations that were recently found in simulations of the current-driven, kink-type Tayler instability, which is characterized by an m=1 azimuthal dependence. We show how these helicity oscillations may be resonantly excited by some m=2 perturbations that reflect a tidal oscillation. Specifically, we speculate that the tidal oscillation of 11.07 years induced by the Venus-Earth-Jupiter system may lead to a 1:1 resonant excitation of the oscillation of the α-effect. Finally, we recover a 22.14-year cycle of the solar dynamo in the framework of a reduced zero-dimensional α-Ω dynamo model.

  20. Evidence for Milankovitch periodicities in Cenomanian-Turonian lithologic and geochemical cycles, western interior U.S.A.

    USGS Publications Warehouse

    Sageman, B.B.; Rich, J.; Arthur, M.A.; Birchfield, G.E.; Dean, W.E.

    1997-01-01

    The limestone/marlstone bedding couplets of the Bridge Creek Limestone Member, Cenomanian-Turonian Greenhorn Formation, were analyzed by applying spectral techniques to high-resolution lithologic and geochemical data from a core. The results suggest that the Bridge Creek contains a complex record of orbital cyclicity. The dominant signal appears to be obliquity, but signals corresponding to precession and eccentricity were also observed. The development of the bedding couplets is interpreted to have resulted from a combination of factors, including insolation-controlled changes in higher-latitude precipitation leading to dilution/redox cycles, and in lower-latitude evaporation, leading to changes in surface water conditions and productivity cycles in the calcareous plankton. The data interpreted to reflect redox cycles appear to be more strongly influenced by obliquity, and show a weak precessional signal. In contrast, trends in the carbonate record show the opposite response. The complex bedding pattern observed in the Bridge Creek Limestone is interpreted to result from the competing influences of different orbital cycles expressed through different pathways of the depositional system, and was also affected by changes in sedimentation rates related to relative sea level fluctuations, aperiodic dilution by volcanic ash, and changes in organic-matter production and redox conditions related to a global "oceanic anoxic event". These factors complicate cycle analysis in the lower part of the member but leave a relatively undisturbed record in the upper Bridge Creek Limestone. Copyright ?? 1997, SEPM (Society for Sedimentary Geology).

  1. The geochemical record of the ancient nitrogen cycle, nitrogen isotopes, and metal cofactors.

    PubMed

    Godfrey, Linda V; Glass, Jennifer B

    2011-01-01

    The nitrogen (N) cycle is the only global biogeochemical cycle that is driven by biological functions involving the interaction of many microorganisms. The N cycle has evolved over geological time and its interaction with the oxygen cycle has had profound effects on the evolution and timing of Earth's atmosphere oxygenation (Falkowski and Godfrey, 2008). Almost every enzyme that microorganisms use to manipulate N contains redox-sensitive metals. Bioavailability of these metals has changed through time as a function of varying redox conditions, and likely influenced the biological underpinnings of the N cycle. It is possible to construct a record through geological time using N isotopes and metal concentrations in sediments to determine when the different stages of the N cycle evolved and the role metal availability played in the development of key enzymes. The same techniques are applicable to understanding the operation and changes in the N cycle through geological time. However, N and many of the redox-sensitive metals in some of their oxidation states are mobile and the isotopic composition or distribution can be altered by subsequent processes leading to erroneous conclusions. This chapter reviews the enzymology and metal cofactors of the N cycle and describes proper utilization of methods used to reconstruct evolution of the N cycle through time.

  2. The geochemical cycling of trace elements in a biogenic meromictic lake

    USGS Publications Warehouse

    Balistrieri, L.S.; Murray, J.W.; Paul, B.

    1994-01-01

    The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d-1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn). ?? 1994.

  3. The geochemical cycling of trace elements in a biogenic meromictic lake

    SciTech Connect

    Balistrieri, L.S.; Murray, J.W.; Paul, B. )

    1994-10-01

    The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d[sup [minus]1] and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

  4. Identifing CO2 bio-geochemical cycle for the ground-atmosphere system by artificial neural networks.

    NASA Astrophysics Data System (ADS)

    Paes, F. F.; Campos Velho, H. F.; Ramos, F. M.

    2012-04-01

    The estimation bio-geochemical cycle for the greenhouse gases is a relevant issue for atmospheric environment. This identification problem can be characterized an inverse problem. In the inverse analysis, an area source domain is considered, where the emission or absorption rate is assumed unknown. The identification problem is solved by using a supervised artificial neural network: multi-layer perceptron, with back-propagation scheme is employed to the learning process. For the numerical experiments, the forward problem is addressed by a source-receptor scheme, where a regressive Lagrangian model is applied to compute the transition matrix. The inverse problem methodology is tested with synthetic observational data, from six measurement points in the physical domain. The inversion is improved by including the wind field information, associated with the six concentration sensor measurements. The methodology is also applied with the satellite data.

  5. A study of the planetary waves generation and propagation in the MLT region during different phases of the solar cycle.

    NASA Astrophysics Data System (ADS)

    Koval, Andrey; Gavrilov, Nikolai; Pogoreltsev, Alexander; Shevchuk, Nikita

    2017-04-01

    One of the important factors of atmospheric dynamics and thermal regime at heights of mesosphere-lower thermosphere is energy and momentum transfer by atmospheric planetary waves. We perform numerical modeling of the atmospheric general circulation using improved general circulation model MUAM with 56 vertical levels. This model covers altitudes from the ground to 300 km. The MUAM includes parameterization schemes of stationary planetary waves (SPWs) and normal atmospheric modes (NAMs). To parameterize NAM sources in the MUAM, additional terms to the heat balance equation are used. These terms include sets of time-dependent sinusoidal components with zonal wavenumbers 1 and 2 and periods corresponding to simulated NAMs. We perform numerical simulation of global atmospheric circulation for the initial conditions corresponding to the years of solar cycle minima and maxima. We focus on the changes in amplitudes of SPWs and westward propagating NAMs in the atmosphere under different solar activity phases. In order to analyze the result of the numerical simulation we use calculation of planetary wave's refractivity indexes and Eliassen-Palm fluxes. It is shown that there are significant changes in SPW amplitudes for the different solar activity. SPWs better propagate into the thermosphere at solar cycle minima due to additional waveguides at altitude about 90 km. At the altitudes higher than 100 km SPW amplitudes at low latitudes and high latitudes of the Northern hemisphere may be stronger. Amplitudes of NAM are also in most cases stronger at solar minima.

  6. A geochemical and sedimentological perspective of the life cycle of Neapolis harbor (Naples, southern Italy)

    NASA Astrophysics Data System (ADS)

    Delile, H.; Goiran, J.-P.; Blichert-Toft, J.; Arnaud-Godet, F.; Romano, P.; Bravard, J.-P.

    2016-10-01

    Since the discovery of the ancient harbor of Naples in 2004 during construction work on an underground railway, geoarchaeological studies undertaken on the archaeological excavation have revealed the main stratigraphic and paleo-environmental levels of the harbor site near the Piazza Municipio. However, knowledge of the dynamics and paleo-environmental changes in the water column of the harbor, as well as the processes of transport and deposition of sediments that led to siltation and infilling of the harbor basin, has been lacking due to the absence of high-resolution data. To fill these gaps, we have undertaken a three-dimensional study (longitudinal, transverse and vertical) of the harbor deposits by carrying out geochemical and sedimentological analyses of four stratigraphic sections of the archaeological excavation. The results show that after a phase of relative calm during the first half of the 1st c. AD, siltation of the harbor progressed exponentially up to the 5th c. AD, when dredging operations were carried out to obtain a water level sufficient for the development of maritime and harbor activities. We attribute this acceleration of siltation to a combination of climatic, anthropic and volcanic factors. Volcanic activity was responsible for a high-energy, tsunami-type event during the eruption of Vesuvius in 79 AD. From the 5th c. AD onwards, the harbor basin of Neapolis does not appear to have been functional as evidenced by its transformation into a lagoon following coastal progradation. The last stage of infilling was the development of a flood-dominated fan delta under the combined influences of climatic cooling in the Early Medieval Cool Period and agro-pastoral activities in the catchment area of the harbor. Several generations of paleo-channels, containing flash flood deposits, as well as sheet wash from sheet floods, are indicative of high environmental instability in this period.

  7. Coupling of carbon and silicon geochemical cycles in rivers and lakes

    NASA Astrophysics Data System (ADS)

    Wang, Baoli; Liu, Cong-Qiang; Maberly, Stephen C.; Wang, Fushun; Hartmann, Jens

    2016-10-01

    Carbon (C) and silicon (Si) biogeochemical cycles are important factors in the regulation of atmospheric CO2 concentrations and hence climate change. Theoretically, these elements are linked by chemical weathering and organism stoichiometry, but this coupling has not been investigated in freshwaters. Here we compiled data from global rivers and lakes in the United States of America and the United Kingdom, in order to characterize the stoichiometry between the biogeochemical cycles of C and Si. In rivers this coupling is confirmed by a significant relationship between HCO3‑/Na+ and DSi/Na+, and DSi:HCO3‑ ratio can reflect the mineral source of chemical weathering. In lakes, however, these characteristic ratios of chemical weathering are altered by algal activity. The lacustrine Si:C atomic ratio is negative feedback regulation by phytoplankton, which may result in this ratio in algal assemblages similar to that in water column. And this regulation suggests lacustrine photosynthetic C fixation in this equilibrium state is quantitative and depends on the DSi concentration. These findings provide new insights into the role of freshwaters in global C and Si biogeochemical cycles.

  8. Coupling of carbon and silicon geochemical cycles in rivers and lakes

    PubMed Central

    Wang, Baoli; Liu, Cong-Qiang; Maberly, Stephen C.; Wang, Fushun; Hartmann, Jens

    2016-01-01

    Carbon (C) and silicon (Si) biogeochemical cycles are important factors in the regulation of atmospheric CO2 concentrations and hence climate change. Theoretically, these elements are linked by chemical weathering and organism stoichiometry, but this coupling has not been investigated in freshwaters. Here we compiled data from global rivers and lakes in the United States of America and the United Kingdom, in order to characterize the stoichiometry between the biogeochemical cycles of C and Si. In rivers this coupling is confirmed by a significant relationship between HCO3−/Na+ and DSi/Na+, and DSi:HCO3− ratio can reflect the mineral source of chemical weathering. In lakes, however, these characteristic ratios of chemical weathering are altered by algal activity. The lacustrine Si:C atomic ratio is negative feedback regulation by phytoplankton, which may result in this ratio in algal assemblages similar to that in water column. And this regulation suggests lacustrine photosynthetic C fixation in this equilibrium state is quantitative and depends on the DSi concentration. These findings provide new insights into the role of freshwaters in global C and Si biogeochemical cycles. PMID:27775007

  9. Hydrological sulfur cycling in the volcanic complex of Valles Caldera - geochemical and astrobiological implications for Mars

    NASA Astrophysics Data System (ADS)

    Szynkiewicz, A.; Borrok, D. M.; Vaniman, D. T.; Goff, F.

    2012-12-01

    Sulfate minerals on the Martian surface provide compelling evidence of past fluid movement, chemistry, and potential habitability. However, we are uncertain about the relative influence of concurrent volcanic sulfur emissions, aqueous sulfide weathering, and climate conditions on the sulfur cycle, and we poorly understand the hydrological cycle of sulfur transport on Mars. Therefore, the goal of our research is to describe and quantify the active and historical hydrological sulfur cycle in the Valles Caldera, a ≤ 1.25 Myr giant, circular, volcanic complex located in northern New Mexico, and to compare this to available data for the sulfur cycle on Mars. The rocks of Valles Caldera (e.g., rhyolite lavas and pyroclastic deposits, intracaldera sediments and breccias, pre-caldera dacite and andesite, etc.) show wide variations in S content from 0.003 up to 3.41 wt% in fresh to hydrothermally altered units, respectively (Goff et al. 2007). Additionally, an acid-sulfate hot spring system issues from the western flank of the resurgent dome inside Valles Caldera and significantly increases the sulfate concentrations in local springs (up to 3,000 mg/L; Szynkiewicz et al. 2012). Using historical USGS stream flow measurements and sulfate concentrations (1958 to 1990), we calculated that in average ~16.4 tons of dissolved sulfate is annually removed from this volcanic system via the hydrological cycle. Initial S isotope mass balance calculations indicate that ~70 % of the dissolved sulfate (~11.5 tons/year) is likely contributed by the acid-sulfate hot springs and ~30 % (~4.9 tons/year) comes from dissolution/oxidation of S-enriched bedrock and atmospheric wet deposition. Although the acid-sulfate hot spring system is an ideal habitat for microbial S metabolism, the preservation of S isotope biosignatures is poor in geological samples because of prevailing contributions of S species from magmatic sources. In the next step of our research, we will 1) quantify the present

  10. Geochemical Models of Water-Quality Changes During Aquifer Storage Recovery (ASR) Cycle Tests, Phase 1: Geochemical Models Using Existing Data

    DTIC Science & Technology

    2006-09-01

    reactions should proceed during storage, and these are simulated with inverse geochemical models: • Precipitation or dissolution of calcite , dolomite...hydro- gen sulfide from sulfate reduction. Minor mass changes result from ap- parent dissolution of calcite , dolomite, halite, and gypsum (Figure 5...dolomite, and gypsum solubilities, and phase mole- transfer val- ues. Calcite dissolution is indicated by positive phase-mole transfer values (Fig- ure

  11. Water-oxidation catalysis by manganese in a geochemical-like cycle

    NASA Astrophysics Data System (ADS)

    Hocking, Rosalie K.; Brimblecombe, Robin; Chang, Lan-Yun; Singh, Archana; Cheah, Mun Hon; Glover, Chris; Casey, William H.; Spiccia, Leone

    2011-06-01

    Water oxidation in all oxygenic photosynthetic organisms is catalysed by the Mn4CaO4 cluster of Photosystem II. This cluster has inspired the development of synthetic manganese catalysts for solar energy production. A photoelectrochemical device, made by impregnating a synthetic tetranuclear-manganese cluster into a Nafion matrix, has been shown to achieve efficient water oxidation catalysis. We report here in situ X-ray absorption spectroscopy and transmission electron microscopy studies that demonstrate that this cluster dissociates into Mn(II) compounds in the Nafion, which are then reoxidized to form dispersed nanoparticles of a disordered Mn(III/IV)-oxide phase. Cycling between the photoreduced product and this mineral-like solid is responsible for the observed photochemical water-oxidation catalysis. The original manganese cluster serves only as a precursor to the catalytically active material. The behaviour of Mn in Nafion therefore parallels its broader biogeochemistry, which is also dominated by cycles of oxidation into solid Mn(III/IV) oxides followed by photoreduction to Mn2+.

  12. The role of forced planetary waves in the annual cycle of the zonal mean circulation of the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Holton, J. R.; Wehrbein, W. M.

    1980-01-01

    A severely truncated semispectral numerical model is used to simulate the annual cycle of the zonally averaged circulation in the middle atmosphere (16-96 km). The model includes only a single zonal harmonic wave component which interacts with the mean flow; the circulation is driven by diabatic heating and by a specified perturbation in the topography of the lower boundary, which is taken to be the 100 mb surface. A comparison of the annual cycle simulated by this model with the results of an analogous two-dimensional model indicates that planetary waves have relatively little influence on the zonal mean temperature profiles and on the solstice mean zonal winds at high latitudes. The primary effects of the forced waves are in decelerating the mean winds at low latitudes in the winter hemisphere to produce a region of weak westerlies, and in generating final warmings at the spring equinoxes.

  13. Solar cycle dynamic of the Martian induced magnetosphere. Planetary ions acceleration zones and escape.

    NASA Astrophysics Data System (ADS)

    Fedorov, Andrey; Modolo, Ronan; Jarvinen, Riku; Barabash, Stas

    2016-10-01

    This work presents a massive statistical analysis of the ion flows in the Martian induced magnetosphere. We performed this analysis using Mars Express ion mass spectrometer data taken during 2008 - 2013 time interval. This data allows to make an enhanced study of the induced magnetosphere variations as a response of the solar activity level. Since Mars Express has no onboard magnetometer, we used the hybrid models of the Martian plasma environment to get a proper frame to make an adequate statistics of the magnetospheric response. In this paper we present a spatial distribution of the planetary plasma properties in the planetary wake as well as the ionosospheric escape as a function of the solar activity.

  14. Beyond Vmax and Km: How details of enzyme function influence geochemical cycles

    NASA Astrophysics Data System (ADS)

    Steen, A. D.

    2015-12-01

    Enzymes catalyze the vast majority of chemical reactions relevant to geomicrobiology. Studies of the activities of enzymes in environmental systems often report Vmax (the maximum possible rate of reaction; often proportional to the concentration of enzymes in the system) and sometimes Km (a measure of the affinity between enzymes and their substrates). However, enzyme studies - particularly those related to enzymes involved in organic carbon oxidation - are often limited to only those parameters, and a relatively limited and mixed set of enzymes. Here I will discuss some novel methods to assay and characterize the specific sets of enzymes that may be important to the carbon cycle in aquatic environments. First, kinetic experiments revealed the collective properties of the complex mixtures of extracellular peptidases that occur where microbial communities are diverse. Crystal structures combined with biochemical characterization of specific enzymes can yield more detailed information about key steps in organic carbon transformations. These new techniques have the potential to provide mechanistic grounding to geomicrobiological models.

  15. Seismic cycles recorded in late Quaternary calcite veins: Geochronological, geochemical and microstructural evidence

    NASA Astrophysics Data System (ADS)

    Uysal, I. Tonguç; Feng, Yue-xing; Zhao, Jian-xin; Bolhar, Robert; Işik, Veysel; Baublys, Kim A.; Yago, Anya; Golding, Suzanne D.

    2011-02-01

    Southwest Turkey is seismically active as a result of the Hellenic subduction process in the Eastern Mediterranean. We conducted high-resolution micro-sampling, high-precision U-series dating and microchemical analysis on an extensional vein system in a tectonically active but non-hydrothermal area. U/Th age data and microscopic observations provide evidence of repeated fracturing of a previously sealed crack system followed by a new increment of veining. Repeated injection of veinlets suggests that the vein system was formed by the crack-seal mechanism. Four major U/Th age groups for the emplacement of the vein system fall between 23.9 ± 0.2 ka and 23.2 ± 0.4 ka, 21.7 ± 0.4 ka and 19.2 ± 0.2 ka, 17.3 ± 0.1 ka and 16.2 ± 0.3 ka, and at 11.8 ± 0.2 ka. Stable and Sr isotope geochemistry of the calcite vein samples indicates that surface water interacting with the soil cover was the major component of the groundwater system from which the extensional veins precipitated. Trace element and O isotope data of the vein system are interpreted to reflect carbonate precipitation associated with seismic cycles involving fluids with different trace element compositions and CO 2 contents. Initial carbonate precipitation during a single seismic cycle occurred from CO 2-dominated fluids that were degassed from the original CO 2-water mixture. This was followed consecutively by carbonate precipitation from the remaining water, which was relatively impure with higher trace element contents. Millimetre to submillimetre-scale U-series dating in conjunction with geochemistry of carbonate veins related to active tectonism offers an innovative means of constraining the absolute timing of late Quaternary seismic and inter-seismic events.

  16. Empirical evidences for a planetary modulation of total solar irradiance and the TSI signature of the 1.09-year Earth-Jupiter conjunction cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola; Willson, Richard C.

    2013-11-01

    The time series of total solar irradiance (TSI) satellite observations since 1978 provided by ACRIM and PMOD TSI composites are studied. We find empirical evidence for planetary-induced forcing and modulation of solar activity. Power spectra and direct data pattern analysis reveal a clear signature of the 1.09-year Earth-Jupiter conjunction cycle, in particular during solar cycle 23 maximum. This appears to suggest that the Jupiter side of the Sun is slightly brighter during solar maxima. The effect is observed when the Earth crosses the Sun-Jupiter conjunction line every 1.09 years. Multiple spectral peaks are observed in the TSI records that are coherent with known planetary harmonics such as the spring, orbital and synodic periods among Mercury, Venus, Earth and Jupiter: the Mercury-Venus spring-tidal cycle (0.20 year); the Mercury orbital cycle (0.24 year); the Venus-Jupiter spring-tidal cycle (0.32 year); the Venus-Mercury synodic cycle (0.40 year); the Venus-Jupiter synodic cycle (0.65 year); and the Venus-Earth spring tidal cycle (0.80 year). Strong evidence is also found for a 0.5-year TSI cycle that could be driven by the Earth's crossing the solar equatorial plane twice a year and may indicate a latitudinal solar-luminosity asymmetry. Because both spring and synodic planetary cycles appear to be present and the amplitudes of their TSI signatures appear enhanced during sunspot cycle maxima, we conjecture that on annual and sub-annual scales both gravitational and electro-magnetic planet-sun interactions and internal non-linear feedbacks may be modulating solar activity. Gravitational tidal forces should mostly stress spring cycles while electro-magnetic forces could be linked to the solar wobbling dynamics, and would mostly stress the synodic cycles. The observed statistical coherence between the TSI records and the planetary harmonics is confirmed by three alternative tests.

  17. Geochemical cycling, mass balance, and Earth’s dynamic structure (Invited)

    NASA Astrophysics Data System (ADS)

    Allegre, C. J.

    2009-12-01

    The use of radiogenic tracers is now established as one of the standard methods (together with seismic tomography) to constrain Earth models. One of the advantages of radiogenic tracers is that they constrain not only present day structures, but also their historical evolution since the earliest time. A mandatory condition is to use not only one but all of the available isotopic systems, with their diverse cycling properties and different radioactive half-lives. Mass balances calculations are the basic tool which allows one to use quantitatively the various tracers. However, the inverse method approach, when applied to mass balance, is strongly non-linear, particularly for tracers with intermediate to short half lives. 142Nd, 82W, and 129Xe allows one to define a consistent model for the Present and past evolutions. Results point to a 3-layer model for the present mantle: an upper mantle with two layers separated by the 450 km discontinuity, and a lower mantle below the 670 km discontinuity. These layers all convect independently though none of them is fully isolated. They exchange matter and energy, not necessarily through the same process. For instance, most hotspots (though not all of them!) are boundary layer instabilities generated at the 670 km discontinuity, but there is important heat transfer from the lower mantle through megablobs. Recent results on the Hadean period are in agreement with core-mantle- atmosphere differentiation at 4444 My. The early crust was mostly anorthositic but has been recycled into the upper mantle within the first billion years. Formation of granitic continents started at 4300 My. 80% of their material was already present on the surface as acidic rocks by 2500 My. The reworking process involved in continental development increased continuously with time and today is the dominant process. Continents are now in a stage of steady state, with general addition of mantle and subducted continental material.

  18. Using planetary transits to estimate magnetic cycles lengths in Kepler stars

    NASA Astrophysics Data System (ADS)

    Estrela, Raissa; Valio, Adriana

    2017-10-01

    Observations of various solar-type stars along decades showed that they could have magnetic cycles, just like our Sun. These observations yield a relation between the rotation period P rot and the cycle length P cycle of these stars. Two distinct branches for the cycling stars were identified: active and inactive, classified according to stellar activity level and rotation rate. In this work, we determined the magnetic activity cycle for 6 active stars observed by the Kepler telescope. The method adopted here estimates the activity from the excess in the residuals of the transit light curves. This excess is obtained by subtracting a spotless model transit from the light curve, and then integrating over all the residuals during the transit. The presence of long term periodicity is estimated from the analysis of a Lomb-Scargle periodogram of the complete time series. Finally, we investigate the rotation-cycle period relation for the stars analysed here.

  19. Planetary resonances, bi-stable oscillation modes, and solar activity cycles

    NASA Technical Reports Server (NTRS)

    Sleeper, H. P., Jr.

    1972-01-01

    The natural resonance structure of the planets in the solar system yields resonance periods of 11.08 and 180 years. The 11.08 year period is due to resonance of the sidereal periods of the three inner planets. The 180-year period is due to synodic resonances of the four major planets. These periods are also observed in the sunspot time series. The 11-year sunspot cycles from 1 to 19 are separated into categories of positive and negative cycles, Mode 1 and Mode 2 cycles, and typical and anomalous cycles. Each category has a characteristic shape, magnitude, or duration, so that statistical prediction techniques are improved when a cycle can be classified in a given category. These categories provide evidence for bistable modes of solar oscillation. The next minimum is expected in 1977 and the next maximum in 1981 or later. These epoch values are 2.5 years later than those based on typical cycle characteristics.

  20. Impact of anaerobic oxidation of methane on the geochemical cycle of redox-sensitive elements at cold-seep sites of the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Hu, Yu; Feng, Dong; Liang, Qianyong; Xia, Zhen; Chen, Linying; Chen, Duofu

    2015-12-01

    Cold hydrocarbon seepage is a frequently observed phenomenon along continental margins worldwide. However, little is known about the impact of seeping fluids on the geochemical cycle of redox-sensitive elements. Pore waters from four gravity cores (D-8, D-5, D-7, and D-F) collected from cold-seep sites of the northern South China Sea were analyzed for SO42-, Mg2+, Ca2+, Sr2+, dissolved inorganic carbon (DIC), δ13CDIC, dissolved Fe, Mn, and trace elements (e.g. Mo, U). The sulfate concentration-depth profiles, δ13CDIC values and (ΔDIC+ΔCa2++ΔMg2+)/ΔSO42- ratios suggest that organoclastic sulfate reduction (OSR) is the dominant process in D-8 core. Besides OSR, anaerobic oxidation of methane (AOM) is partially responsible for depletion of sulfate at D-5 and D-7 cores. The sulfate consumption at D-F core is predominantly caused by AOM. The depth of sulfate-methane interface (SMI) and methane diffusive flux of D-F core are calculated to be ~7 m and 0.035 mol m-2 yr-1, respectively. The relatively shallow SMI and high methane flux at D-F core suggest the activity of gas seepage in this region. The concentrations of dissolved uranium (U) were inferred to decrease significantly within the iron reduction zone. It seems that AOM has limited influence on the U geochemical cycling. In contrast, a good correlation between the consumption of sulfate and the removal of molybdenum (Mo) suggests that AOM has a significantly influence on the geochemical cycle of Mo at cold seeps. Accordingly, cold seep environments may serve as an important potential sink in the marine geochemical cycle of Mo.

  1. Empirical evidences for a planetary modulation of total solar irradiance and the TSI signature of the 1.09-year Earth-Jupiter conjunction cycle (Invited)

    NASA Astrophysics Data System (ADS)

    Scafetta, N.; Willson, R. C.

    2013-12-01

    Abstract The time series of total solar irradiance (TSI) satellite observations since 1978 provided by ACRIM and PMOD TSI composites are studied. We find empirical evidence for planetary-induced forcing and modulation of solar activity. Power spectra and direct data pattern analysis reveal a clear signature of the 1.09-year Earth-Jupiter conjunction cycle, in particular during solar cycle 23 maximum. This appears to suggest that the Jupiter side of the Sun is slightly brighter during solar maxima. The effect is observed when the Earth crosses the Sun-Jupiter conjunction line every 1.09 years. Multiple spectral peaks are observed in the TSI records that are coherent with known planetary harmonics such as the spring, orbital and synodic periods among Mercury, Venus, Earth and Jupiter: the Mercury-Venus spring-tidal cycle (0.20 year); the Mercury orbital cycle (0.24 year); the Venus-Jupiter spring-tidal cycle (0.32 year); the Venus-Mercury synodic cycle (0.40 year); the Venus-Jupiter synodic cycle (0.65 year); and the Venus-Earth spring tidal cycle (0.80 year). Strong evidence is also found for a 0.5-year TSI cycle that could be driven by the Earth's crossing the solar equatorial plane twice a year and may indicate a latitudinal solar-luminosity asymmetry. Because both spring and synodic planetary cycles appear to be present and the amplitudes of their TSI signatures appear enhanced during sunspot cycle maxima, we conjecture that on annual and sub-annual scales both gravitational and electro-magnetic planet-sun interactions and internal non-linear feedbacks may be modulating solar activity. Gravitational tidal forces should mostly stress spring cycles while electro-magnetic forces could be linked to the solar wobbling dynamics, and would mostly stress the synodic cycles. The observed statistical coherence between the TSI records and the planetary harmonics is confirmed by three alternative tests. Top black: ACRIM TSI record (left) and its periodogram (black). Blue

  2. Geochemical cycling and depositional patterns across the northeast region of the Greenland Ice Sheet as determined from trace element chemistry

    NASA Astrophysics Data System (ADS)

    Wong, G. J.; Osterberg, E. C.; Courville, Z.; Hawley, R. L.; Lutz, E.; Overly, T. B.

    2012-12-01

    The Greenland Ice Sheet is both a repository of climate history and a major driver in Arctic and global climate. Between 1952 and 1955, Carl Benson led a series of traverses of the Greenland Ice Sheet (GIS), and characterized the GIS via mapping of the spatial distribution of annual net accumulation and classifying the diagenetic glacier facies (Benson, 1962). While polar ice sheets represent a unique archive of past atmospheric and climatic conditions, little information exists on large-scale geographical trends in trace element snow chemistry across GIS because of the remote, challenging location. In the spring of 2011, we undertook a 1120 km traverse of the GIS from Thule Air Base to Summit Station. Samples from 11 snow pits and 3 firn cores, dated by stable water isotopes, were analyzed and evaluated in seasonal resolution for their trace element content (23Na, 24Mg, 27Al, 32S, 39K, 44Ca, 47Ti, 51V, 52Cr, 55Mn, 56Fe, 59Co, 63Cu, 66Zn, 75As, 88Sr, 111Cd, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 208Pb, 209Bi, 238U). Here, we present an initial analysis of the spatial gradients of these trace elements and an interpretation of how their depositional patterns characterize the GIS. The seasonal trends coupled with spatial variability of certain trace elements establish the behavior of specific aerosols (e.g. dust, sea salt, pollution), which will be useful in quantifying geochemical cycling across the GIS and comparing characterizations with results from Benson's traverses. Benson, CS. 1962. Stratigraphic studies in the snow and firn of the Greenland Ice Sheet. SIPRE Research Report, 70, 89 pp.

  3. A vigorous activity cycle mimicking a planetary system in HD 200466

    NASA Astrophysics Data System (ADS)

    Carolo, E.; Desidera, S.; Gratton, R.; Martinez Fiorenzano, A. F.; Marzari, F.; Endl, M.; Mesa, D.; Barbieri, M.; Cecconi, M.; Claudi, R. U.; Cosentino, R.; Scuderi, S.

    2014-07-01

    Stellar activity can be a source of radial velocity (RV) noise and can reproduce periodic RV variations similar to those produced by an exoplanet. We present the vigorous activity cycle in the primary of the visual binary HD 200466, a system made of two almost identical solar-type stars with an apparent separation of 4.6 arcsec at a distance of 44 ± 2 pc. High precision RV over more than a decade, adaptive optics (AO) images, and abundances have been obtained for both components. A linear trend in the RV is found for the secondary. We assumed that it is due to the binary orbit and once coupled with the astrometric data, it strongly constrains the orbital solution of the binary at high eccentricities (e ~ 0.85) and quite small periastron of ~21 AU. If this orbital motion is subtracted from the primary radial velocity curve, a highly significant (false alarm probability <0.1%) period of about 1300 d is obtained, suggesting in a first analysis the presence of a giant planet, but it turned out to be due to the stellar activity cycle. Since our spectra do not include the Ca II resonance lines, we measured a chromospheric activity indicator based on the Hα line to study the correlation between activity cycles and long-term activity variations. While the bisector analysis of the line profile does not show a clear indication of activity, the correlation between the Hα line indicator and the RV measurements identify the presence of a strong activity cycle. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the Istituto Nazionale di Astrofisica (INAF) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Tables 5 and 6 are available in electronic form at http://www.aanda.org

  4. Ancient geochemical cycling in the Earth as inferred from Fe isotope studies of banded iron formations from the Transvaal Craton

    NASA Astrophysics Data System (ADS)

    Johnson, Clark; Beard, Brian; Beukes, Nicolas; Klein, Cornelis; O'Leary, Julie

    2002-11-01

    spectroscopic data. Some samples contain hematite and magnetite and have positive δ56Fe values; these seem best explained through production of high 56Fe/54Fe reservoirs by photosynthetic Fe oxidation. It is not yet clear if the low δ56Fe values measured for some oxides, as well as Fe carbonates, reflect biologic processes, or inorganic precipitation from low-δ56Fe ferrous-Fe-rich fluids. However, the present results demonstrate the great potential for Fe isotopes in tracing the geochemical cycling of Fe, and highlight the need for an extensive experimental program for determining equilibrium Fe isotope fractionation factors for minerals and fluids that are pertinent to sedimentary environments. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00410-002-0418-x.

  5. Comments on the BLAG model - The carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.

    1984-01-01

    A self-consistent method of determining initial conditions for the model presented by Berner, Lasaga, and Garrels (1983) (henceforth, the BLAG model) is derived, based on the assumption that the CO2 geochemical cycle was in steady state at t = -100 m.y. (million years). This initialization procedure leads to a dissolved magnesium concentration higher than that calculated by Berner, Lasaga, and Garrels and to a low ratio of dissolved calcium to bicarbonate prior to 60 m.y. ago. The latter prediction conflicts with the geologic record of evaporite deposits, which requires that this ratio remain greater than 0.5. The contradiction is probably caused by oversimplifications in the BLAG model, such as the neglect of the cycles of organic carbon and sulfur.

  6. Comments on the BLAG model: the carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.

    1984-01-01

    A self-consistent method of determining initial conditions for the model presented by Berner, Lasaga, and Garrels (1983) (henceforth, the BLAG model) is derived, based on the assumption that the CO2 geochemical cycle was in steady state at t = -100 my (million years). This initialization procedure leads to a dissolved magnesium concentration higher than that calculated by Berner, Lasaga, and Garrels and to a low ratio of dissolved calcium to bicarbonate prior to 60 my ago. The latter prediction conflicts with the geologic record of evaporite deposits, which requires that this ratio remain greater than 0.5. The contradiction is probably caused by oversimplifications in the BLAG model, such as the neglect of the cycles of organic carbon and sulfur.

  7. How Subduction Settings can Affect Planetary Nitrogen Cycle: An Experimental Insight

    NASA Astrophysics Data System (ADS)

    Cedeno, D. G.; Conceicao, R. V.; Wilbert de Souza, M. R.; Carniel, L. C.; Schmitz Quinteiro, R. V.

    2015-12-01

    Nitrogen is one of the main building blocks of life on Earth and its elemental cycle is deeply connected with organic matter and the biological system. It is known that nitrogen can be stored in mantellic phases (such as clinopyroxenes) or in metallic alloys under high pressures, meaning that Earth's mantle, and even the core, could be efficient nitrogen reservoirs. Probably, nitrogen is present in these deep Earth systems since the formation of our planet. Nevertheless, it is possible that superficial nitrogen can be reintroduced in the mantle through tectonic processes along Earth history. This is reinforced by d15N values in inclusions in diamonds and other deep mantle phases. We believe that subduction zones are efficient enough to transport nitrogen from surface to mantle. Clay minerals with high charge exchange capacity (CEC) are good candidates to convey nitrogen in subduction zones, especially when we take into account the similarities between K+ and NH4+. To simulate the high-pressure high-temperature conditions found in subduction zones, we performed a series of experiments with montmorillonite clay mineral undergone to high pressure and high temperature produced by a hydraulic press coupled with toroidal chambers, in pressures ranging from 2.5 to 7.7 GPa and temperatures up to 700oC. We used ex situ XRD analysis to accompany the main montmorillonite structural changes and FTIR analysis to determine quantitatively the presence of nitrogen. So far, our results show that the main structural transition in montmorillonite happens at ~350oC at room pressure and ~450oC at 2.5 and 4.0 GPa and consists in the transformation of an open clay structure to a closed mica structure (tobelite). FTIR data show the presence of nitrogen in all the analysed experiments. With the data obtained, we can presume that clay minerals carried in subduction zones can successfully transport nitrogen and other volatiles to the mantle. However, only cold subduction systems have the

  8. Microbial iron cycling in acidic geothermal springs of yellowstone national park: integrating molecular surveys, geochemical processes, and isolation of novel fe-active microorganisms.

    PubMed

    Kozubal, Mark A; Macur, Richard E; Jay, Zackary J; Beam, Jacob P; Malfatti, Stephanie A; Tringe, Susannah G; Kocar, Benjamin D; Borch, Thomas; Inskeep, William P

    2012-01-01

    Geochemical, molecular, and physiological analyses of microbial isolates were combined to study the geomicrobiology of acidic iron oxide mats in Yellowstone National Park. Nineteen sampling locations from 11 geothermal springs were studied ranging in temperature from 53 to 88°C and pH 2.4 to 3.6. All iron oxide mats exhibited high diversity of crenarchaeal sequences from the Sulfolobales, Thermoproteales, and Desulfurococcales. The predominant Sulfolobales sequences were highly similar to Metallosphaera yellowstonensis str. MK1, previously isolated from one of these sites. Other groups of archaea were consistently associated with different types of iron oxide mats, including undescribed members of the phyla Thaumarchaeota and Euryarchaeota. Bacterial sequences were dominated by relatives of Hydrogenobaculum spp. above 65-70°C, but increased in diversity below 60°C. Cultivation of relevant iron-oxidizing and iron-reducing microbial isolates included Sulfolobus str. MK3, Sulfobacillus str. MK2, Acidicaldus str. MK6, and a new candidate genus in the Sulfolobales referred to as Sulfolobales str. MK5. Strains MK3 and MK5 are capable of oxidizing ferrous iron autotrophically, while strain MK2 oxidizes iron mixotrophically. Similar rates of iron oxidation were measured for M. yellowstonensis str. MK1 and Sulfolobales str. MK5. Biomineralized phases of ferric iron varied among cultures and field sites, and included ferric oxyhydroxides, K-jarosite, goethite, hematite, and scorodite depending on geochemical conditions. Strains MK5 and MK6 are capable of reducing ferric iron under anaerobic conditions with complex carbon sources. The combination of geochemical and molecular data as well as physiological observations of isolates suggests that the community structure of acidic Fe mats is linked with Fe cycling across temperatures ranging from 53 to 88°C.

  9. Microbial Iron Cycling in Acidic Geothermal Springs of Yellowstone National Park: Integrating Molecular Surveys, Geochemical Processes, and Isolation of Novel Fe-Active Microorganisms

    PubMed Central

    Kozubal, Mark A.; Macur, Richard E.; Jay, Zackary J.; Beam, Jacob P.; Malfatti, Stephanie A.; Tringe, Susannah G.; Kocar, Benjamin D.; Borch, Thomas; Inskeep, William P.

    2012-01-01

    Geochemical, molecular, and physiological analyses of microbial isolates were combined to study the geomicrobiology of acidic iron oxide mats in Yellowstone National Park. Nineteen sampling locations from 11 geothermal springs were studied ranging in temperature from 53 to 88°C and pH 2.4 to 3.6. All iron oxide mats exhibited high diversity of crenarchaeal sequences from the Sulfolobales, Thermoproteales, and Desulfurococcales. The predominant Sulfolobales sequences were highly similar to Metallosphaera yellowstonensis str. MK1, previously isolated from one of these sites. Other groups of archaea were consistently associated with different types of iron oxide mats, including undescribed members of the phyla Thaumarchaeota and Euryarchaeota. Bacterial sequences were dominated by relatives of Hydrogenobaculum spp. above 65–70°C, but increased in diversity below 60°C. Cultivation of relevant iron-oxidizing and iron-reducing microbial isolates included Sulfolobus str. MK3, Sulfobacillus str. MK2, Acidicaldus str. MK6, and a new candidate genus in the Sulfolobales referred to as Sulfolobales str. MK5. Strains MK3 and MK5 are capable of oxidizing ferrous iron autotrophically, while strain MK2 oxidizes iron mixotrophically. Similar rates of iron oxidation were measured for M. yellowstonensis str. MK1 and Sulfolobales str. MK5. Biomineralized phases of ferric iron varied among cultures and field sites, and included ferric oxyhydroxides, K-jarosite, goethite, hematite, and scorodite depending on geochemical conditions. Strains MK5 and MK6 are capable of reducing ferric iron under anaerobic conditions with complex carbon sources. The combination of geochemical and molecular data as well as physiological observations of isolates suggests that the community structure of acidic Fe mats is linked with Fe cycling across temperatures ranging from 53 to 88°C. PMID:22470372

  10. The planetary waves dynamics and interannual course of meteorological parameters of the high latitude stratosphere and mesosphere of the Northern and Southern Hemispheres during the 20th and 21st solar cycles and different phases of QBO

    NASA Technical Reports Server (NTRS)

    Kidiyarova, V. G.; Fomina, N. N.

    1989-01-01

    The part of energy of the planetary waves which enters the stratosphere depends on conditions of planetary wave generation and propagation through the tropopause, and the part of planetary wave energy which enters the mesosphere depends on conditions of planetary wave propagation through the stratopause. An attempt is made to estimate connections between extratropical middle atmosphere temperature long term variations and portions of energy of planetary waves which enter the mesosphere and stratosphere during winter seasons in Northern and Southern Hemispheres. Interannual variations of temperatures at the 30 km and 70 km levels are investigated for the central winter months of the period 1970 to 1986. This period includes the descending branch of the 20th solar cycle and the whole 21st cycle. Calculations are made on the basis of measurements at Heiss Island and Molodezhnaya.

  11. Asphalt Volcanism as a Model to Understand the Geochemical Nature of Pitch Lake, a Planetary Analog for Titan and the Implications towards Methane Flux into Earth's Atmosphere.

    NASA Astrophysics Data System (ADS)

    Khan, A.

    2016-12-01

    Pitch Lake is located in the southwest peninsula of the island near La Brea in Trinidad and Tobago, covering an area of approximately 46 hectares. It was discovered in the year 1595 and is the largest of three natural asphalt lakes that exist on Earth. Pitch Lake is a large oval shaped reservoir composed of dominantly hydrocarbon compounds, but also includes minor amounts of clay and muddy water. It is a natural liquid asphalt desert, which is nourished by a form of petroleum consisting of mostly asphaltines from the surrounding oil-rich region. The hydrocarbons mix with mud and gases under high pressure during upward seepage, and the lighter portion evaporates or is volatilized, which produces a high-viscosity liquid asphalt residue. The residue on and near the surface is a hydrocarbon matrix, which poses extremely challenging environmental conditions to microorganisms characterized by an average low water activity in the range of 0.49 to 0.75, recalcitrant carbon substrates, and toxic chemical compounds. Nevertheless, an active microbial community of archaea and bacteria, many of them novel strains, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical analyses of minerals, done by our team, which revealed sulfates, sulfides, silicates, and metals, normally associated with deep-water hydrothermal vents leads to our new hypothetical model to describe the origins of Pitch Lake and its importance to atmospheric and earth sciences. Pitch Lake is likely the terrestrial equivalent of an offshore submarine asphalt volcano just as La Brea Tar Pits are in some ways an on-land version of the asphalt volcanoes discovered off shore of Santa Barbara by Valentine et al. in 2010. Asphalt volcanism possibly also creates the habitat for chemosynthetic life that is widespread in this lake, as reported by Schulze-Makuch et al. in 2011 and Meckenstock et al. in 2014.

  12. Geochemical cycles in sediments deposited on the slopes of the Guaymas and Carmen Basins of the Gulf of California over the last 180 years

    USGS Publications Warehouse

    Dean, W.; Pride, C.; Thunell, R.

    2004-01-01

    Sediments deposited on the slopes of the Guaymas and Carmen Basins in the central Gulf of California were recovered in two box cores. Q-mode factor analyses identified detrital-clastic, carbonate, and redox associations in the elemental composition of these sediments. The detrital-clastic fraction appears to contain two source components, a more mafic component presumably derived from the Sierra Madre Occidental along the west coast of Mexico, and a more felsic component most likely derived from sedimentary rocks (mostly sandstones) of the Colorado Plateau and delivered by the Colorado River. The sediments also contain significant siliceous biogenic components and minor calcareous biogenic components, but those components were not quantified in this study. Redox associations were identified in both cores based on relatively high concentrations of molybdenum, which is indicative of deposition under conditions of sulfate reduction. Decreases in concentrations of molybdenum in younger sediments suggest that the bottom waters of the Gulf have became more oxygenated over the last 100 years. Many geochemical components in both box cores exhibit distinct cyclicity with periodicities of 10-20 years. The most striking are 20-year cycles in the more mafic components (e.g., titanium), particularly in sediments deposited during the 19th century. In that century, the titanium cycles are in very good agreement with warm phases of the Pacific Decadal Oscillation, implying that at times of greater influx of titanium-rich volcanic debris, there were more El Nin??os and higher winter precipitation. The cycles are interpreted as due to greater and lesser riverine influx of volcanic rock debris from the Sierra Madre. There is also spectral evidence for periodicities of 4-8 and 8-16 years, suggesting that the delivery of detrital-clastic material is responding to some multiannual (ENSO?) forcing.

  13. Understanding past climatic and hydrological variability in the Mediterranean from Lake Prespa sediment isotope and geochemical record over the Last Glacial cycle

    NASA Astrophysics Data System (ADS)

    Leng, Melanie J.; Wagner, Bernd; Boehm, Anne; Panagiotopoulos, Konstantinos; Vane, Christopher H.; Snelling, Andrea; Haidon, Cheryl; Woodley, Ewan; Vogel, Hendrik; Zanchetta, Gianni; Baneschi, Ilaria

    2013-04-01

    Here we present stable isotope and geochemical data from Lake Prespa (Macedonia/Albania border) over the Last Glacial cycle (Marine Isotope Stages 5-1) and discuss past lake hydrology and climate (TIC, oxygen and carbon isotopes), as well as responses to climate of terrestrial and aquatic vegetation (TOC, Rock Eval pyrolysis, carbon isotopes, pollen). The Lake Prespa sediments broadly fall into 5 zones based on their sedimentology, geochemistry, palynology and the existing chronology. The Glacial sediments suggest low supply of carbon to the lake, but high summer productivity; intermittent siderite layers suggest that although the lake was likely to have mixed regularly leading to enhanced oxidation of organic matter, there must have been within sediment reducing conditions and methanogenesis. MIS 5 and 1 sediments suggest much more productivity, higher rates of organic material preservation possibly due to more limited mixing with longer periods of oxygen-depleted bottom waters. We also calculated lakewater δ18O from siderite (authigenic/Glacial) and calcite (endogenic/Holocene) and show much lower lakewater δ18O values in the Glacial when compared to the Holocene, suggesting the lake was less evaporative in the Glacial, probably as a consequence of cooler summers and longer winter ice cover. In the Holocene the oxygen isotope data suggests general humidity, with just 2 marked arid phases, features observed in other Eastern and Central Mediterranean lakes.

  14. The effects of diagenesis and dolomitization on Ca and Mg isotopes in marine platform carbonates: Implications for the geochemical cycles of Ca and Mg

    NASA Astrophysics Data System (ADS)

    Fantle, Matthew S.; Higgins, John

    2014-10-01

    The Ca, Mg, O, and C isotopic and trace elemental compositions of marine limestones and dolostones from ODP Site 1196A, which range in depth (∼58 to 627 mbsf) and in depositional age (∼5 and 23 Ma), are presented. The objectives of the study are to explore the potential for non-traditional isotope systems to fingerprint diagenesis, to quantify the extent to which geochemical proxies are altered during diagenesis, and to investigate the importance of diagenesis within the global Ca and Mg geochemical cycles. The data suggest that Ca, which has a relatively high solid to fluid mass ratio, can be isotopically altered during diagenesis. In addition, the alteration of Ca correlates with the alteration of Mg in such a way that both can serve as useful tools for deciphering diagenesis in ancient rocks. Bulk carbonate δ44Ca values vary between 0.60 and 1.31‰ (SRM-915a scale); the average limestone δ44Ca is 0.97 ± 0.24‰ (1SD), identical within error to the average dolostone (1.03 ± 0.15 1SD ‰). Magnesium isotopic compositions (δ26Mg, DSM-3 scale) range between -2.59‰ and -3.91‰, and limestones (-3.60 ± 0.25‰) and dolostones (-2.68 ± 0.07‰) are isotopically distinct. Carbon isotopic compositions (δ13C, PDB scale) vary between 0.86‰ and 2.47‰, with average limestone (1.96 ± 0.31‰) marginally offset relative to average dolostone (1.68 ± 0.57‰). The oxygen isotopic compositions (δ18O, PDB scale) of limestones (-1.22 ± 0.94‰) are substantially lower than the dolostones measured (2.72 ± 1.07‰). The isotopic data from 1196A suggest distinct and coherent trends in isotopic and elemental compositions that are interpreted in terms of diagenetic trajectories. Numerical modeling supports the contention that such trends can be interpreted as diagenetic, and suggests that the appropriate distribution coefficient (KMg) associated with limestone diagenesis is ∼1 to 5 × 10-3, distinctly lower than those values (>0.015) reported in laboratory

  15. Methane feedbacks to the global carbon cycle in a warming climate - combining microbial and geochemical perspectives. Methane feedbacks to the global ca

    NASA Astrophysics Data System (ADS)

    (Han) Dolman, Albertus J.; Dean, Joshua; Aerts, Rien; Blauw, Luke; Egger, Mathias; Jetten, Mike; de Jong, Anniek; Meisel, Ove; Rasigraf, Olivia; Roeckmann, Thomas; Slomp, Caroline; in't Zandt, Michiel; Middelburg, Jack

    2017-04-01

    Atmospheric methane (CH4) concentrations are increasing again following a brief plateau between 1999 and 2006. CH4 is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets are not well constrained, let alone potential future shifts in CH4 emissions. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, permafrost, marine and freshwater systems, and methane hydrates, through shifts in temperature and hydrology, vegetation and landscape disturbance, and sea level rise. Increased CH4 emissions from these systems will in turn induce further climate change, forming a positive climate feedback. Here we synthesize both biological and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines, something that has previously been missing at the global scale. We discuss environment-specific feedback processes (e.g. wetlands vs. methane hydrates), including the microbial, physical and geochemical inter-linkages and the timescales they operate on, to present the current state of knowledge on CH4 climate feedbacks in the immediate and distant future. We will discuss the important linkages between microbial activity and climate with the aim to better constrain the sensitivity of the CH4 cycle to the future climate change. From our synthesis, we determine that while higher emissions from wetlands will form the majority of the CH4 climate feedback up to 2100, beyond this timescale CH4 emissions from marine and freshwater systems and permafrost environments will be more important, alongside the potential for large CH4 emissions from destabilised methane hydrates. Our key findings highlight the current lack of understanding of whether CH4 consumption can counter balance CH4 production under future climate scenarios.

  16. Groundwater ecosystem resilience to organic contaminations: microbial and geochemical dynamics throughout the 5-year life cycle of a surrogate ethanol blend fuel plume.

    PubMed

    Ma, Jie; Nossa, Carlos W; Alvarez, Pedro J J

    2015-09-01

    The capacity of groundwater ecosystem to recover from contamination by organic chemicals is a vital concern for environmental scientists. A pilot-scale aquifer system was used to investigate the long-term dynamics of contaminants, groundwater geochemistry, and microbial community structure (by 16S rRNA gene pyrosequencing and quantitative real-time PCR) throughout the 5-year life cycle of a surrogate ethanol blend fuel plume (10% ethanol + 50 mg/L benzene + 50 mg/L toluene). Two-year continuous ethanol-blended release significantly changed the groundwater geochemistry (resulted in anaerobic, low pH, and organotrophic conditions) and increased bacterial and archaeal populations by 82- and 314-fold respectively. Various anaerobic heterotrophs (fermenters, acetogens, methanogens, and hydrocarbon degraders) were enriched. Two years after the release was shut off, all contaminants and their degradation byproducts disappeared and groundwater geochemistry completely restored to the pre-release states (aerobic, neutral pH, and oligotrophic). Bacterial and archaeal populations declined by 18- and 45-fold respectively (relative to the time of shut off). Microbial community structure reverted towards the pre-release states and alpha diversity indices rebounded, suggesting the resilience of microbial community to ethanol blend releases. We also found shifts from O2-sensitive methanogens (e.g., Methanobacterium) to methanogens that are not so sensitive to O2 (e.g., Methanosarcina and Methanocella), which is likely to contribute to the persistence of methanogens and methane generation following the source removal. Overall, the rapid disappearance of contaminants and their metabolites, rebound of geochemical footprints, and resilience of microbial community unequivocally document the natural capacity of groundwater ecosystem to attenuate and recover from a large volume of catastrophic spill of ethanol-based biofuel. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Biological and geochemical controls on diel dissolved inorganic carbon cycling in a low-order agricultural stream: Implications for reach scales and beyond

    USGS Publications Warehouse

    Tobias, C.; Böhlke, J.K.

    2011-01-01

    Movement of dissolved inorganic carbon (DIC) through the hydrologic cycle is an important component of global carbon budgets, but there is considerable uncertainty about the controls of DIC transmission from landscapes to streams, and through river networks to the oceans. In this study, diel measurements of DIC, ??13C-DIC, dissolved oxygen (O2), ??18O-O2, alkalinity, pH, and other parameters were used to assess the relative magnitudes of biological and geochemical controls on DIC cycling and flux in a nutrient-rich, net autotrophic stream. Rates of photosynthesis (P), respiration (R), groundwater discharge, air-water exchange of CO2, and carbonate precipitation/dissolution were quantified through a time-stepping chemical/isotope (12C and 13C, 16O and 18O) mass balance model. Groundwater was the major source of DIC to the stream. Primary production and carbonate precipitation were equally important sinks for DIC removed from the water column. The stream was always super-saturated with respect to carbonate minerals, but carbonate precipitation occurred mainly during the day when P increased pH. We estimated more than half (possibly 90%) of the carbonate precipitated during the day was retained in the reach under steady baseflow conditions. The amount of DIC removed from the overlying water through carbonate precipitation was similar to the amount of DIC generated from R. Air-water exchange of CO2 was always from the stream to the atmosphere, but was the smallest component of the DIC budget. Overall, the in-stream DIC reactions reduced the amount of CO2 evasion and the downstream flux of groundwater-derived DIC by about half relative to a hypothetical scenario with groundwater discharge only. Other streams with similar characteristics are widely distributed in the major river basins of North America. Data from USGS water quality monitoring networks from the 1960s to the 1990s indicated that 40% of 652 stream monitoring stations in the contiguous USA were at or above

  18. Biological and geochemical controls on diel dissolved inorganic carbon cycling in a low-order agricultural stream: implications for reach scales and beyond

    USGS Publications Warehouse

    Bohlke, Johnkarl F.; Tobias, Craig

    2011-01-01

    Movement of dissolved inorganic carbon (DIC) through the hydrologic cycle is an important component of global carbon budgets, but there is considerable uncertainty about the controls of DIC transmission from landscapes to streams, and through river networks to the oceans. In this study, diel measurements of DIC, d13C-DIC, dissolved oxygen (O2), d18O-O2, alkalinity, pH, and other parameters were used to assess the relative magnitudes of biological and geochemical controls on DIC cycling and flux in a nutrient-rich, net autotrophic stream. Rates of photosynthesis (P), respiration (R), groundwater discharge, air–water exchange of CO2, and carbonate precipitation/dissolution were quantified through a time-stepping chemical/isotope (12C and 13C, 16O and 18O) mass balance model. Groundwater was the major source of DIC to the stream. Primary production and carbonate precipitation were equally important sinks for DIC removed from the water column. The stream was always super-saturated with respect to carbonate minerals, but carbonate precipitation occurred mainly during the day when P increased pH. We estimated more than half (possibly 90%) of the carbonate precipitated during the day was retained in the reach under steady baseflow conditions. The amount of DIC removed from the overlying water through carbonate precipitation was similar to the amount of DIC generated from R. Air–water exchange of CO2 was always from the stream to the atmosphere, but was the smallest component of the DIC budget. Overall, the in-stream DIC reactions reduced the amount of CO2 evasion and the downstream flux of groundwater-derived DIC by about half relative to a hypothetical scenario with groundwater discharge only. Other streams with similar characteristics are widely distributed in the major river basins of North America. Data from USGS water quality monitoring networks from the 1960s to the 1990s indicated that 40% of 652 stream monitoring stations in the contiguous USA were at or above

  19. The HARPS search for southern extra-solar planets. XXX. Planetary systems around stars with solar-like magnetic cycles and short-term activity variation

    NASA Astrophysics Data System (ADS)

    Dumusque, X.; Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bouchy, F.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Naef, D.

    2011-11-01

    We present the discovery of four new long-period planets within the HARPS high-precision sample: HD 137388b (Msini = 0.22 MJ), HD 204941b (Msini = 0.27 MJ), HD 7199b (Msini = 0.29 MJ), HD 7449b (Msini = 1.04 MJ). A long-period companion, probably a second planet, is also found orbiting HD 7449. Planets around HD 137388, HD 204941, and HD 7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD 7449b. All these planets were discovered even though their hosting stars have clear signs of activity. Solar-like magnetic cycles, characterized by long-term activity variations, can be seen for HD 137388, HD 204941 and HD 7199, whereas the measurements of HD 7449 reveal a short-term activity variation, most probably induced by magnetic features on the stellar surface. We confirm that magnetic cycles induce a long-term radial velocity variation and propose a method to reduce considerably the associated noise. The procedure consists of fitting the activity index and applying the same solution to the radial velocities because a linear correlation between the activity index and the radial velocity is found. Tested on HD 137388, HD 204941, and HD 7199, this correction reduces considerably the stellar noise induced by magnetic cycles and allows us to derive precisely the orbital parameters of planetary companions. Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory (Chile), under programme IDs 072.C-0488 and 183.C-0972.Radial velocities (Tables 4-7) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A55

  20. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  1. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  2. A bibliography of planetary geology principal investigators and their associates, 1976-1978

    NASA Technical Reports Server (NTRS)

    1978-01-01

    This bibliography cites publications submitted by 484 principal investigators and their associates who were supported through NASA's Office of Space Sciences Planetary Geology Program. Subject classifications include: solar system formation, comets, and asteroids; planetary satellites, planetary interiors, geological and geochemical constraints on planetary evolution; impact crater studies, volcanism, eolian studies, fluvian studies, Mars geological mapping; Mercury geological mapping; planetary cartography; and instrument development and techniques. An author/editor index is provided.

  3. The Impact of Planetary-Scale Thermal Forcing and Small-Scale Topography on the Diurnal Cycle of Martian Surface Pressure

    NASA Astrophysics Data System (ADS)

    Wilson, R. J.; Murphy, J. R.

    2015-12-01

    The ongoing acquisition of high-precision surface pressure data in Gale crater by the MSL meteorology package motivates our investigation of how to interpret the observed diurnal variations in surface pressure in terms of seasonal changes in planetary-scale thermal forcing. We utilize a very high resolution Mars global circulation model (15 and 7.5 km resolution) that simulates diurnal variabilty at scales ranging from the crater scale to the planetary scale to address the issue of distinguishing the pressure signature of small-scale topographically-driven circulations from the global tide field. We define the latter as that resulting from a resynthesis of surface pressure using a compact set of tide modes derived from a space-time analysis of suitably normalized simulated surface pressure. This field includes the migrating tides, resonantly enhanced Kelvin waves and a small set of additional nonmigrating tides. The resulting residual pressure field is found to be highly localized and clearly influenced by topography. In particular, there are enhancements in the diurnal period tide amplitude of ~ 8-15 Pa in the majority of "small" scale craters. The enhancement in Gale crater is very similar to that found in a mesoscale model study by Tyler and Barnes [2013]. The phasing of the peak residual diurnal tide amplitude is invariably 6-8 am local solar time (LST) and is due to nighttime downlope/daytime upslope circulations. Slope wind effects are not simply localized to craters, but impact larger basin-like regions as well, including Hellas, Argyre, Isidis, and Solis Planum. A notable feature of the MSL pressure record is the seasonally-evolving appearance of sharply peaked features at 0800 and 2000 LST that reflect the presence of four and six hour harmonics. We find that these modes correspond to migrating (sun-synchronous) tides and the observed seasonal cycle can be well matched by models with suitably evolving radiative forcing by aerosols. In short, these tide

  4. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  5. Planetary maps

    USGS Publications Warehouse

    ,

    1992-01-01

    An important goal of the USGS planetary mapping program is to systematically map the geology of the Moon, Mars, Venus, and Mercury, and the satellites of the outer planets. These geologic maps are published in the USGS Miscellaneous Investigations (I) Series. Planetary maps on sale at the USGS include shaded-relief maps, topographic maps, geologic maps, and controlled photomosaics. Controlled photomosaics are assembled from two or more photographs or images using a network of points of known latitude and longitude. The images used for most of these planetary maps are electronic images, obtained from orbiting television cameras, various optical-mechanical systems. Photographic film was only used to map Earth's Moon.

  6. Inland Aquatic Resources and Biogeochemical Cycles

    NASA Technical Reports Server (NTRS)

    Melack, J. M.

    1984-01-01

    The biosphere is the entire planetary system that includes, sustains and is influenced by life. The central issue of the science of the biosphere is the extent to which the Earth's surface, atmosphere and hydrosphere is the result of biological rather than abiotic processes. Space science and technology accelerates the understanding of global biological processes by providing repetive synoptic observations on large spatial scales once the relationships between the processes and the remotely sensed quantities are established. Especially promising applications of space technology are the measurement of biological productivity and portions of geochemical cycles in aquatic ecosystems and the evaluation and management of the quality of freshwater resources.

  7. Inland aquatic resources and biogeochemical cycles

    SciTech Connect

    Melack, J.M.

    1984-08-01

    The biosphere is the entire planetary system that includes, sustains and is influenced by life. The central issue of the science of the biosphere is the extent to which the Earth's surface, atmosphere and hydrosphere is the result of biological rather than abiotic processes. Space science and technology accelerates the understanding of global biological processes by providing repetive synoptic observations on large spatial scales once the relationships between the processes and the remotely sensed quantities are established. Especially promising applications of space technology are the measurement of biological productivity and portions of geochemical cycles in aquatic ecosystems and the evaluation and management of the quality of freshwater resources.

  8. Planetary Magnetism

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  9. Planetary Interiors

    NASA Technical Reports Server (NTRS)

    Banerdt, W. Bruce; Abercrombie, Rachel; Keddie, Susan; Mizutani, Hitoshi; Nagihara, Seiichi; Nakamura, Yosio; Pike, W. Thomas

    1996-01-01

    This report identifies two main themes to guide planetary science in the next two decades: understanding planetary origins, and understanding the constitution and fundamental processes of the planets themselves. Within the latter theme, four specific goals related to interior measurements addressing the theme. These are: (1) Understanding the internal structure and dynamics of at least one solid body, other than the Earth or Moon, that is actively convecting, (2) Determine the characteristics of the magnetic fields of Mercury and the outer planets to provide insight into the generation of planetary magnetic fields, (3) Specify the nature and sources of stress that are responsible for the global tectonics of Mars, Venus, and several icy satellites of the outer planets, and (4) Advance significantly our understanding of crust-mantle structure for all the solid planets. These goals can be addressed almost exclusively by measurements made on the surfaces of planetary bodies.

  10. Planetary transmission

    SciTech Connect

    Nerstad, K.A.; Windish, W.E.

    1987-04-21

    A planetary transmission is described comprising: an input shaft; a first planetary gear set having a first sun gear driven by the input shaft, a first planet carrier serving as the output, a first ring gear, and first brake means for selectively holding the fist ring gear stationary; a second planetary gear set having a second sun gear driven by the input shaft, a second planet carrier connected for joint rotation to the first ring gear, a second ring gear, and second brake means for selectively holding the second ring gear stationary; a third planetary gear set having a third sun gear connected for joint rotation to the second planet carrier, a third planet carrier connected for joint rotation to the second ring gear, a third ring gear, and third brake means for selectively holding the third ring gear stationary; and clutch means for connecting the third sun gear to the input shaft and providing a direct drive mode of operation.

  11. Planetary volcanism

    SciTech Connect

    Cattermole, P.

    1989-01-01

    This book presents studies of the volcanic features of individual planets. Bring together the most recently acquired data on selected regions of individual planets and discusses in detail the volcanic processes at work. Begins with a discussion of theoretical considerations and a survey of volcanism on earth. Continues with a comparative approach to planetary volcanism, looking at the volcanic features of different planets. Draws conclusions about planetary development based on the characteristic volcanic features of the different planets.

  12. Planetary Mapping

    NASA Astrophysics Data System (ADS)

    Greeley, Ronald; Batson, Raymond M.

    2007-02-01

    Preface; List of contributors; 1. Introduction R. Greeley and R. M. Batson; 2. History of planetary cartography R. M. Batson, E. A. Whitaker and D. E. Wilhelms; 3. Cartography R. M. Batson; 4. Planetary nomenclature M. E. Strobell and H. Masursky; 5. Geodetic control M. E. Davies; 6. Topographic mapping S. S. C. Wu and F. J. Doyle; 7. Geologic mapping D. E. Wilhelms; Appendices R. M. Batson and J. L. Inge; Index.

  13. An Integrated Sedimentological and Geochemical Analysis through a Triassic Lacustrine Cycle and Lagerstätte in the Cow Branch Formation of the Dan River Basin, Virginia and North Carolina

    NASA Astrophysics Data System (ADS)

    Ritzer, S.; Gill, B. C.

    2016-12-01

    The Triassic Cow Branch Formation of the Dan River Basin is host to a world-class lagerstätte deposit of exceptionally preserved, soft-bodied insects, among other organisms. The lagerstätte occurs as a thin shale layer within a cyclic, lacustrine sedimentary succession, hypothesized to have been driven by Milankovitch climate forcing. The integrated sedimentological and geochemical investigation presented here suggests that the lagerstätte was deposited at the onset of a lake transgression, under intermittently anoxic and ferruginous conditions. Sedimentological evidence suggests a deepening of the lake followed by shoaling through a broad fining and subsequent coarsening of the grain sizes in the sedimentary units through the sequence. Despite relatively quartz-rich sediments sourced to the basin, silica content in the studied cycle is exceptionally low. The replacement of silica by the zeolite mineral analcime, coupled with evidence for primary dolomite precipitation suggests the paleolake was, at least periodically, alkaline. Geochemical evidence, including total organic carbon (TOC), pyrite sulfur and iron speciation data point to the presence of anoxic, ferruginous waters. At the lagerstätte interval, TOC content increases significantly, coinciding with the presence of darker, more laminated sedimentary lithofacies. At the interval of the highest TOC content, a spike in pyrite sulfur content occurs; likely the result of slowed sedimentation at lake high-stand. Overall pyrite sulfur content as well as organic carbon to pyrite sulfur ratios suggest however, that the lake water was consistently low in sulfur and the deep waters never became euxinic (anoxic, H2S-containing). The iron speciation data indicate that an active iron cycle was present and that the studied portion of the Cow Branch Formation was deposited under intermittent to persistent anoxic conditions, preserving the signal throughout the cycle. The integrated sedimentological and geochemical

  14. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  15. Planetary astronomy

    NASA Technical Reports Server (NTRS)

    Morrison, David; Hunten, Donald; Ahearn, Michael F.; Belton, Michael J. S.; Black, David; Brown, Robert A.; Brown, Robert Hamilton; Cochran, Anita L.; Cruikshank, Dale P.; Depater, Imke

    1991-01-01

    The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed.

  16. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1980-01-01

    Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io.

  17. Planetary Magnetism

    SciTech Connect

    Russell, C.T.

    1980-02-01

    Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io.

  18. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1980-01-01

    Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io.

  19. Global geochemical problems

    NASA Technical Reports Server (NTRS)

    Harriss, R. C.

    1980-01-01

    Application of remote sensing techniques to the solution of geochemical problems is considered with emphasis on the 'carbon-cycle'. The problem of carbon dioxide sinks and the areal extent of coral reefs are treated. In order to assess the problems cited it is suggested that remote sensing techniques be utilized to: (1)monitor globally the carbonate and bicarbonate concentrations in surface waters of the world ocean; (2)monitor the freshwater and oceanic biomass and associated dissolved organic carbon; (3) inventory the coral reef areas and types and the associated oceanographic climatic conditions; and (4)measure the heavy metal fluxes from forested and vegetated areas, from volcanos, from different types of crustal rocks, from soils, and from sea surfaces.

  20. Planetary Geomorphology.

    ERIC Educational Resources Information Center

    Baker, Victor R.

    1984-01-01

    Discusses various topics related to planetary geomorphology, including: research techniques; such geomorphic processes as impact, volcanic, degradational, eolian, and hillslope/mass movement processes; and channels and valleys. Indicates that the subject should be taught as a series of scientific questions rather than scientific results of…

  1. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  2. Planetary quarantine

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The overall objective is to identify those areas of future missions which will be impacted by planetary quarantine (PQ) constraints. The objective of the phase being described was to develop an approach for using decision theory in performing a PQ analysis for a Mariner Jupiter Uranus Mission and to compare it with the traditional approach used for other missions.

  3. Planetary radar

    NASA Technical Reports Server (NTRS)

    Taylor, R. M.

    1980-01-01

    The radar astronomy activities supported by the Deep Space Network during June, July, and August 1980 are reported. The planetary bodies observed were Venus, Mercury, and the asteroid Toro. Data were obtained at both S and X band, and the observations were considered successful.

  4. Planetary quarantine

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Developed methodologies and procedures for the reduction of microbial burden on an assembled spacecraft at the time of encapsulation or terminal sterilization are reported. This technology is required for reducing excessive microbial burden on spacecraft components for the purposes of either decreasing planetary contamination probabilities for an orbiter or minimizing the duration of a sterilization process for a lander.

  5. Planetary Geomorphology.

    ERIC Educational Resources Information Center

    Baker, Victor R.

    1984-01-01

    Discusses various topics related to planetary geomorphology, including: research techniques; such geomorphic processes as impact, volcanic, degradational, eolian, and hillslope/mass movement processes; and channels and valleys. Indicates that the subject should be taught as a series of scientific questions rather than scientific results of…

  6. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  7. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Tiscareno, Matthew S.

    Planetary rings are the only nearby astrophysical disks and the only disks that have been investigated by spacecraft (especially the Cassini spacecraft orbiting Saturn). Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 10- 7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close range and in real time in planetary rings.We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The A, B, and C rings of Saturn, plus the Cassini Division, comprise our solar system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are found both at Uranus (where they comprise the main rings entirely) and at Saturn (where they are embedded in the broad disk) and are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally confined arcs at Neptune, Saturn, and Jupiter. Finally, every known ring system includes a substantial component of diffuse dusty rings.Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of

  8. Planetary and synoptic-scale interactions during the life cycle of a mid-latitude blocking anticyclone over the North Atlantic

    NASA Technical Reports Server (NTRS)

    Smith, Phillip J.

    1995-01-01

    The formation of a blocking anticyclone over the North Atlantic has been examined over its entire life-CyCle using the Zwack-Okossi (Z-O) equation as the diagnostic tool. This blocking anticyclone occurred in late October and early November of 1985. The data used were provided by the NASA Goddard Laboratory for Atmospheres on a global 2.O degree latitude by 2.5 degree longitudinal grid. The horizontal distribution of the atmospheric forcing mechanisms that were important to 500 mb block formation, maintenance and decay were examined. A scale-partitioned form of the Z-O equation was then used to examine the relative importance of forcing on the planetary and synoptic scales, and their interactions. As seen in previous studies, the results presented here show that upper tropospheric anticyclonic vorticity advection was the most important contributor to block formation and maintenance. However, adiabatic warming, and vorticity tilting were also important at various times during the block lifetime. In association with precursor surface cyclogenesis, the 300 mb jet streak in the downstream (upstream) from a long-wave trough (ridge) amplified significantly. This strengthening of the jet streak enhanced the anti-cyclonic vorticity advection field that aided the amplification of a 500 mb short-wave ridge. Tile partitioned height tendency results demonstrate that the interactions between the planetary and sn,noptic-scale through vorticity advection was the most important contributor to block formation. Planetary-scale, synoptic-scale. and their interactions contributed weakly to the maintenance of the blocking anticyclone with the advection of synoptic-scale vorticity by the planetary-scale flow playing a more important role. Planetary-scale decay ofthe long-wave ridge contributed to the demise of this blocking event.

  9. Planetary systems in binaries

    NASA Astrophysics Data System (ADS)

    Takeda, Genya

    In this thesis we investigate the orbital evolution of planets in binaries. Unlike our own Solar System, at least one out of five planetary systems known to date is associated with additional stellar companions. Despite their large distances from the planetary systems, these stellar companions play an important role in significantly altering the planetary architecture over very long timescales. Most of the planets in binaries are found in hierarchical configurations in which a planet orbits around a component of a wide stellar binary. The evolution of such hierarchical triples has been analytically understood through the framework of the Kozai mechanism, in which the orbital eccentricity of a planet secularly grows through angular momentum exchange with the stellar companion. The aim of our first study is to investigate the global effect of stellar companions in exciting planetary eccentricities through the Kozai mechanism, using synthetic eccentricity distributions computed numerically from various initial assumptions motivated by observational studies. As inferred from observations and theoretical planet formation simulations, newly formed planetary systems are more likely to be oligarchic, containing multiple giant planets. However, the long-term evolution of gravitationally coupled planets perturbed by a stellar companion has been little understood in the previous studies. From a large ensemble of numerical integrations of double-planet systems in binaries, we have found that there are various evolutionary classes of multiple planets in binaries compared to simple hierarchical triple systems containing only one planet. Using the Kozai mechanism and the Laplace-Lagrange secular theory, we also provide analytic criteria that can readily predict the secular evolutionary behavior of a pair of planetary orbits in binaries. In the last part of this thesis we discuss an alternative channel of planetary migration induced by a combined effect of dissipative tidal forces

  10. Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Encrenaz, T.; Murdin, P.

    2000-11-01

    Planetary atmospheres are the external gaseous envelopes which surround the planets. In the case of the telluric planets, they represent only a negligible fraction of their mass, but they play an essential role in the energy balance between the surfaces and the Sun. In the case of the GIANT PLANETS, which are mostly gaseous, they account for a large fraction of their total mass and constitute the...

  11. Planetary quarantine

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Those areas of future missions which will be impacted by planetary quarantine (PQ) constraints were identified. The specific objectives for this reporting period were (1) to perform an analysis of the effects of PQ on an outer planet atmospheric probe, and (2) to prepare a quantitative illustration of spacecraft microbial reduction resulting from exposure to space environments. The Jupiter Orbiter Probe mission was used as a model for both of these efforts.

  12. Planetary Society

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Carl Sagan, Bruce Murray and Louis Friedman founded the non-profit Planetary Society in 1979 to advance the exploration of the solar system and to continue the search for extraterrestrial life. The Society has its headquarters in Pasadena, California, but is international in scope, with 100 000 members worldwide, making it the largest space interest group in the world. The Society funds a var...

  13. Planetary engineering

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Sagan, Carl

    1991-01-01

    Assuming commercial fusion power, heavy lift vehicles and major advances in genetic engineering, the authors survey possible late-21st century methods of working major transformations in planetary environments. Much more Earthlike climates may be produced on Mars by generating low freezing point greenhouse gases from indigenous materials; on Venus by biological conversion of CO2 to graphite, by canceling the greenhouse effect with high-altitude absorbing fine particles, or by a sunshield at the first Lagrangian point; and on Titan by greenhouses and/or fusion warming. However, in our present state of ignorance we cannot guarantee a stable endstate or exclude unanticipated climatic feedbacks or other unintended consequences. Moreover, as the authors illustrate by several examples, many conceivable modes of planetary engineering are so wasteful of scarce solar system resources and so destructive of important scientific information as to raise profound ethical issues, even if they were economically feasible, which they are not. Global warming on Earth may lead to calls for mitigation by planetary engineering, e.g., emplacement and replenishment of anti-greenhouse layers at high altitudes, or sunshields in space. But here especially we must be concerned about precision, stability, and inadvertent side-effects. The safest and most cost-effective means of countering global warming - beyond, e.g., improved energy efficiency, CFC bans and alternative energy sources - is the continuing reforestation of approximately 2 times 107 sq km of the Earth's surface. This can be accomplished with present technology and probably at the least cost.

  14. Planetary engineering

    NASA Astrophysics Data System (ADS)

    Pollack, James B.; Sagan, Carl

    Assuming commercial fusion power, heavy lift vehicles and major advances in genetic engineering, the authors survey possible late-21st century methods of working major transformations in planetary environments. Much more Earthlike climates may be produced on Mars by generating low freezing point greenhouse gases from indigenous materials; on Venus by biological conversion of CO2 to graphite, by canceling the greenhouse effect with high-altitude absorbing fine particles, or by a sunshield at the first Lagrangian point; and on Titan by greenhouses and/or fusion warming. However, in our present state of ignorance we cannot guarantee a stable endstate or exclude unanticipated climatic feedbacks or other unintended consequences. Moreover, as the authors illustrate by several examples, many conceivable modes of planetary engineering are so wasteful of scarce solar system resources and so destructive of important scientific information as to raise profound ethical issues, even if they were economically feasible, which they are not. Global warming on Earth may lead to calls for mitigation by planetary engineering, e.g., emplacement and replenishment of anti-greenhouse layers at high altitudes, or sunshields in space. But here especially we must be concerned about precision, stability, and inadvertent side-effects. The safest and most cost-effective means of countering global warming - beyond, e.g., improved energy efficiency, CFC bans and alternative energy sources - is the continuing reforestation of approximately 2 times 107 sq km of the Earth's surface. This can be accomplished with present technology and probably at the least cost.

  15. Geochemical ecosystem engineering by the mud shrimp Upogebia pugettensis (Crustacea: Thalassinidae) in Yaquina Bay, Oregon: density-dependent effects on organic matter remineralization and nutrient cycling

    EPA Science Inventory

    We investigated the effect of the thalassinid mud shrimp Upogebia pugettensis on organic matter and nutrient cycling on Idaho Flat, an intertidal flat in the Yaquina River estuary, Oregon. Field studies were conducted to measure carbon and nitrogen remineralization rates and bent...

  16. Geochemical ecosystem engineering by the mud shrimp Upogebia pugettensis (Crustacea: Thalassinidae) in Yaquina Bay, Oregon: density-dependent effects on organic matter remineralization and nutrient cycling

    EPA Science Inventory

    We investigated the effect of the thalassinid mud shrimp Upogebia pugettensis on organic matter and nutrient cycling on Idaho Flat, an intertidal flat in the Yaquina River estuary, Oregon. Field studies were conducted to measure carbon and nitrogen remineralization rates and bent...

  17. Planetary atlases

    NASA Technical Reports Server (NTRS)

    Batson, R. M.; Inge, J. L.; Morgan, H. F.

    1991-01-01

    Two kinds of planetary map atlases are in production. Atlases of the first kind contain reduced-scale versions of maps in hard-bound books with dimensions of 11 x 14 inches. These new atlases are intended to: (1) provide concise but comprehensive references to the geography of the planets needed by planetary scientists and others; and (2) allow inexpensive access to the planetary map dataset without requiring acquisition and examination of tens or hundreds of full-size map sheets. Two such atlases have been published and a third is in press. Work was begun of an Atlas of the Satellite of the Outer Planets. The second kind of atlas is a popular or semi-technical version designed for commercial publication and distribution. The first edition, The Atlas of the Solar System, is nearly ready for publication. New funding and contracting constraints now make it unlikely that the atlas can be published in the format originally planned. Currently, the possibility of publishing the maps through the U.S. Geological Survey as a series of folios in the I-map series is being explored. The maps are global views of each solid-surface body of the Solar System. Each map shows airbrushed relief, albedo, and, where available, topography. A set of simplified geologic maps is also included. All of the maps are on equal-area projections. Scales are 1:40,000,000 for the Earth and Venus; 1:2,000,000 for the Saturnian satellites Mimas and Enceladus and the Uranian satellite Miranda; 1:100,000 for the Martian satellites, Phobos and Deimos; and 1:10,000,000 for all other bodies.

  18. Planetary Volcanism

    NASA Technical Reports Server (NTRS)

    Antonenko, I.; Head, J. W.; Pieters, C. W.

    1998-01-01

    The final report consists of 10 journal articles concerning Planetary Volcanism. The articles discuss the following topics: (1) lunar stratigraphy; (2) cryptomare thickness measurements; (3) spherical harmonic spectra; (4) late stage activity of volcanoes on Venus; (5) stresses and calderas on Mars; (6) magma reservoir failure; (7) lunar mare basalt volcanism; (8) impact and volcanic glasses in the 79001/2 Core; (9) geology of the lunar regional dark mantle deposits; and (10) factors controlling the depths and sizes of magma reservoirs in Martian volcanoes.

  19. Planetary Dynamos

    NASA Technical Reports Server (NTRS)

    Busse, F. H.

    1985-01-01

    The MAGSAT-program has added significantly to our knowledge of planetary magnetism. The accuracy of observations has been improved such that a reliable extrapolation of the magnetic field to the core surface is now much more feasible than it has been before, and the prospect of further MAGSAT missions raises the expectation that the time dependence of the geomagnetic field will be known with similar accuracy in the future. In the research support it has been attempted to develop dynamo theory with these applications in mind.

  20. Planetary magnetospheres

    NASA Technical Reports Server (NTRS)

    Stern, D. P.; Ness, N. F.

    1981-01-01

    A concise overview is presented of our understanding of planetary magnetospheres (and in particular, of that of the Earth), as of the end of 1981. Emphasis is placed on processes of astrophysical interest, e.g., on particle acceleration, collision-free shocks, particle motion, parallel electric fields, magnetic merging, substorms, and large scale plasma flows. The general morphology and topology of the Earth's magnetosphere are discussed, and important results are given about the magnetospheres of Jupiter, Saturn and Mercury, including those derived from the Voyager 1 and 2 missions and those related to Jupiter's satellite Io. About 160 references are cited, including many reviews from which additional details can be obtained.

  1. Planetary astronomy

    NASA Technical Reports Server (NTRS)

    Smith, Harlan J.

    1991-01-01

    Lunar-based astronomy offers major prospects for solar system research in the coming century. In addition to active advocacy of both ground-based and Lunar-based astronomy, a workshop on the value of asteroids as a resource for man is being organized. The following subject areas are also covered: (1) astrophysics from the Moon (composition and structure of planetary atmospheres); (2) a decade of cost-reduction in Very Large Telescopes (the SST as prototype of special-purpose telescopes); and (3) a plan for development of lunar astronomy.

  2. Geochemistry and Isotope Stratigraphy (C, O, Sr, Nd, Cr) of the Ediacaran Sete Lagoas Cap Carbonate, Bambui Group, Brazil: Insights into Earth's Oceanic and Atmosphere Geochemical Cycles After a Snowball Glaciation.

    NASA Astrophysics Data System (ADS)

    Caxito, F.; Frei, R.; Uhlein, G. J.; Uhlein, A.

    2016-12-01

    We studied a basal Ediacaran cap carbonate profile pertaining to the base of the Bambuí Group (Sete Lagoas Formation) in the central portion of the São Francisco basin, east central Brazil. The section begins with a two-meter thick pink dolostone which grades upward into a reddish limestone. The basal dolostone preserves a drop of δ13C values from -3.8 to -4.2‰, and δ18O values from -4.5 to -5.1‰. The red laminated limestone yielded δ13C values averaging -5‰ for about 60 m up section. Above 60 m, the δ13C values shift abruptly to around -0.5‰. The section is capped by black calcarenites with positive δ13C (+0.9‰); these high [Sr] carbonates (>1000 ppm) yield 87Sr/86Sr around 0.7076. Overall, there is an upwards-decreasing trend of ɛNd(630 Ma) values, from -6.0 in the base to -7.2 towards the top, and also upwards-decreasing trends of trace metal concentrations, especially for Cr (10-4 ppm), Sc (4.3-1.7 ppm), Co (3.7-0.8 ppm), Cu (4-0.3 ppm), Zn (29-0.6 ppm), and Ti (80-10 ppm). δ53Cr values of the basal pink cap dolostone are about -0.3‰, with an upwards-increasing trend to about +0.2‰ at the topmost carbonates. Thus, the cap carbonate is characterized by upwards-decreasing trends of ɛNd(630 Ma) and trace metal concentrations and upwards-increasing trends of δ13C, δ18O and δ53Cr. These fluctuations can be interpreted to reflect increased continentally-derived input into the shallow seawater. The higher ɛNd(630 Ma) and trace metal contents, as well as negative δ13C and δ53Cr of the basal cap dolostone all point to a higher contribution of less-fractionated sources to seawater geochemical composition, probably due to the fact that oceanic geochemical cycles were not yet fully restored after isolation by ice caps from atmospheric and continental weathering inputs. Upwards, in the limestone section, decreasing ɛNd(630 Ma), increasing δ13C and increasingly positively fractionated δ53Cr values suggest a recovery of Earth

  3. Neutron-gamma techniques for planetary exploration

    NASA Technical Reports Server (NTRS)

    Johnson, R. G.; Evans, L. G.; Trombka, J. I.

    1979-01-01

    Chemical analysis of planetary surfaces is necessary for the understanding of the origin and evolutionary processes of the solar system. Orbital lunar geochemical experiments performed during the Apollo 15 and 16 demonstrated that even with a low neutron flux (fast and thermal), reliable results could be extracted. The possibility of using a compact 14 MeV neutron generator for geochemical analysis of planetary surfaces, comets and asteroids is currently studied. This method allows the determination of bulk chemical composition, even in the presence of an atmosphere. This would be possible on the surface of Venus, for example, where alternate methods such as sample return are impractical. This method can be used for continuous monitoring of elemental abundances from a roving vehicle, for example, on the surface of Mars.

  4. Planetary Astronomy

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1998-01-01

    This 1-year project was an augmentation grant to my NASA Planetary Astronomy grant. With the awarded funding, we accomplished the following tasks: (1) Conducted two NVK imaging runs in conjunction with the ILAW (International Lunar Atmosphere Week) Observing Campaigns in 1995 and 1997. In the first run, we obtained repeated imaging sequences of lunar Na D-line emission to better quantify the temporal variations detected in earlier runs. In the second run we obtained extremely high resolution (R=960.000) Na line profiles using the 4m AAT in Australia. These data are being analyzed under our new 3-year Planetary Astronomy grant. (2) Reduced, analyzed, and published our March 1995 spectroscopic dataset to detect (or set stringent upper limits on) Rb. Cs, Mg. Al. Fe, Ba, Ba. OH, and several other species. These results were reported in a talk at the LPSC and in two papers: (1) A Spectroscopic Survey of Metallic Abundances in the Lunar Atmosphere. and (2) A Search for Magnesium in the Lunar Atmosphere. Both reprints are attached. Wrote up an extensive, invited Reviews of Geophysics review article on advances in the study of the lunar atmosphere. This 70-page article, which is expected to appear in print in 1999, is also attached.

  5. Planetary Habitability

    NASA Technical Reports Server (NTRS)

    Kasting, James F.

    1997-01-01

    This grant was entitled 'Planetary Habitability' and the work performed under it related to elucidating the conditions that lead to habitable, i.e. Earth-like, planets. Below are listed publications for the past two and a half years that came out of this work. The main thrusts of the research involved: (1) showing under what conditions atmospheric O2 and O3 can be considered as evidence for life on a planet's surface; (2) determining whether CH4 may have played a role in warming early Mars; (3) studying the effect of varying UV levels on Earth-like planets around different types of stars to see whether this would pose a threat to habitability; and (4) studying the effect of chaotic obliquity variations on planetary climates and determining whether planets that experienced such variations might still be habitable. Several of these topics involve ongoing research that has been carried out under a new grant number, but which continues to be funded by NASA's Exobiology program.

  6. Evidence for a 17-year cycle in the IMF directions at 1 AU, in coronal hole variations, and in planetary magnetospheric modulations

    NASA Astrophysics Data System (ADS)

    Juckett, David A.

    1998-11-01

    A dominant 16-17yr cycle was observed in the net exposure times of the Earth to Toward and Away field directions of the interplanetary magnetic field (IMF). A cycle of the same frequency and phase was observed in the polarity of the long-term hemispheric differences in coronal hole distributions. This was determined from north/south differences in average Fexiv green line `quiet' regions at high- and mid-latitudes. It is argued that the 17-yr cycle is a fundamental oscillation of coronal hole topology, which is transferred to Earth via variations in the neutral sheet. A comparison of the 17-yr cycle to the 22-yr Hale cycle indicated that they are not identical, but rather, can mix to form a 75-yr cycle plus a 9-yr cycle. Evidence for the 75-yr cycle existed in the Earth's net exposure times to fields from the solar North and South, and in the long-term imbalance of solar quiet regions between the northern and southern hemispheres. The 9-yr cycle was manifested in the mid- to low- latitude Fexiv modulations and in solar wind velocity variations in the ecliptic. At Earth, evidence for a similar 17-yr cycle was observed in the horizontal magnetic field observations in a multitude of surface magnetic recording stations. In addition, the detection of a 17-yr cycle in the Huancayo neutron monitor cosmic ray series suggests that the effects of this cycle extend to the heliospheric boundaries. It is concluded that sufficient preliminary evidence exists to consider the hypothesis that the Sun contains a magnetic moment with an oscillatory cycle of 17years.

  7. Advanced planetary analyses. [for planetary mission planning

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The results are summarized of research accomplished during this period concerning planetary mission planning are summarized. The tasks reported include the cost estimations research, planetary missions handbook, and advanced planning activities.

  8. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1981-01-01

    A synoptic view of early and recent data on the planetary magnetism of Mercury, Venus, the moon, Mars, Jupiter, and Saturn is presented. The data on Mercury from Mariner 10 are synthesized with various other sources, while data for Venus obtained from 120 orbits of Pioneer Venus give the upper limit of the magnetic dipole. Explorer 35 Lunar Orbiter data provided the first evidence of lunar magnetization, but it was the Apollo subsatellite data that measured accurately the magnetic dipole of the moon. A complete magnetic survey of Mars is still needed, and only some preliminary data are given on the magnetic dipole of the planet. Figures on the magnetic dipoles of Jupiter and Saturn are also suggested. It is concluded that if the magnetic field data are to be used to infer the interior properties of the planets, good measures of the multiple harmonics in the field are needed, which may be obtained only through low altitude polar orbits.

  9. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1981-01-01

    A synoptic view of early and recent data on the planetary magnetism of Mercury, Venus, the moon, Mars, Jupiter, and Saturn is presented. The data on Mercury from Mariner 10 are synthesized with various other sources, while data for Venus obtained from 120 orbits of Pioneer Venus give the upper limit of the magnetic dipole. Explorer 35 Lunar Orbiter data provided the first evidence of lunar magnetization, but it was the Apollo subsatellite data that measured accurately the magnetic dipole of the moon. A complete magnetic survey of Mars is still needed, and only some preliminary data are given on the magnetic dipole of the planet. Figures on the magnetic dipoles of Jupiter and Saturn are also suggested. It is concluded that if the magnetic field data are to be used to infer the interior properties of the planets, good measures of the multiple harmonics in the field are needed, which may be obtained only through low altitude polar orbits.

  10. Laboratory simulation of organic geochemical processes.

    NASA Technical Reports Server (NTRS)

    Eglinton, G.

    1972-01-01

    Discussion of laboratory simulations that are important to organic geochemistry in that they provide direct evidence relating to geochemical cycles involving carbon. Reviewed processes and experiments include reactions occurring in the geosphere, particularly, short-term diagenesis of biolipids and organochlorine pesticides in estuarine muds, as well as maturation of organic matter in ancient sediments.

  11. Laboratory simulation of organic geochemical processes.

    NASA Technical Reports Server (NTRS)

    Eglinton, G.

    1972-01-01

    Discussion of laboratory simulations that are important to organic geochemistry in that they provide direct evidence relating to geochemical cycles involving carbon. Reviewed processes and experiments include reactions occurring in the geosphere, particularly, short-term diagenesis of biolipids and organochlorine pesticides in estuarine muds, as well as maturation of organic matter in ancient sediments.

  12. Significant achievements in the Planetary Geology Program. [geologic processes, comparative planetology, and solar system evolution

    NASA Technical Reports Server (NTRS)

    Head, J. W. (Editor)

    1978-01-01

    Developments reported at a meeting of principal investigators for NASA's planetology geology program are summarized. Topics covered include: constraints on solar system formation; asteriods, comets, and satellites; constraints on planetary interiors; volatiles and regoliths; instrument development techniques; planetary cartography; geological and geochemical constraints on planetary evolution; fluvial processes and channel formation; volcanic processes; Eolian processes; radar studies of planetary surfaces; cratering as a process, landform, and dating method; and the Tharsis region of Mars. Activities at a planetary geology field conference on Eolian processes are reported and techniques recommended for the presentation and analysis of crater size-frequency data are included.

  13. Planetary science at APL.

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.

    1999-12-01

    Planetary science at APL did not begin with the Near Earth Asteroid Rendezvous (NEAR) mission, although NEAR, as the first planetary mission ever implemented by a non-NASA center, is what brought the Laboratory into the main arena of planetary exploration. This is the story of how that happened, how planetary science developed at APL, and what lies ahead.

  14. Planetary Surface Instruments Workshop

    NASA Technical Reports Server (NTRS)

    Meyer, Charles (Editor); Treiman, Allan H. (Editor); Kostiuk, Theodor (Editor)

    1996-01-01

    This report on planetary surface investigations and planetary landers covers: (1) the precise chemical analysis of solids; (2) isotopes and evolved gas analyses; (3) planetary interiors; planetary atmospheres from within as measured by landers; (4) mineralogical examination of extraterrestrial bodies; (5) regoliths; and (6) field geology/processes.

  15. Planetary Seismology

    NASA Technical Reports Server (NTRS)

    Weber, Renee C.

    2015-01-01

    Of the many geophysical means that can be used to probe a planet's interior, seismology remains the most direct. In addition to Earth, seismometers have been installed on Venus, Mars, and the Moon. Given that the seismic data gathered on the Moon (now over 40 years ago) revolutionized our understanding of the Moon and are still being used today to produce new insight into the state of the lunar interior, it is no wonder that many future missions, both real and conceptual, plan to take seismometers to other planets. To best facilitate the return of high-quality data from these instruments, as well as to further our understanding of the dynamic processes that modify a planet's interior, various modeling approaches are used to quantify parameters such as the amount and distribution of seismicity, tidal deformation, and seismic structure of the terrestrial planets. In addition, recent advances in wavefield modeling have permitted a renewed look at seismic energy transmission and the effects of attenuation and scattering, as well as the presence and effect of a core, on recorded seismograms. In this talk I will discuss some of these methods and review the history of planetary seismology.

  16. Planetary nomenclature

    NASA Technical Reports Server (NTRS)

    Strobell, M. E.; Masursky, Harold

    1987-01-01

    In fiscal 1986, names were chosen for prominent features on the five previously known Uranian satellites and for features on the largest of the 10 satellites discovered by Voyager 2. The names of the five large satellites are taken mostly from Shakespeare, and most are spirits; therefore, Shakespearean and spirit themes were used to choose names for topographic features on the satellites. Crater names and most other feature names on Miranda, Oberon, and Titania are from Shakespeare; features on Ariel are named for bright spirits and those on Umbriel for dark, all taken from universal mythology. Preliminary coordinates for these features are derived from shaded relief maps of the satellites to be published in 1987. Orbital elements have been established for the 10 new satellites, and a paper describing this work is in progress; satellite positions are under review by Commission 16 of the IAU. The moon 1985 U1 is informally designated Puck. The nine small satellites discovered in 1986 are to be named for Shakespearean heroines; these names are to be listed in the 1987 edition of the Annual Gazetteer of Planetary Nomenclature.

  17. Planetary nomenclature

    NASA Astrophysics Data System (ADS)

    Strobell, M. E.; Masursky, Harold

    1987-05-01

    In fiscal 1986, names were chosen for prominent features on the five previously known Uranian satellites and for features on the largest of the 10 satellites discovered by Voyager 2. The names of the five large satellites are taken mostly from Shakespeare, and most are spirits; therefore, Shakespearean and spirit themes were used to choose names for topographic features on the satellites. Crater names and most other feature names on Miranda, Oberon, and Titania are from Shakespeare; features on Ariel are named for bright spirits and those on Umbriel for dark, all taken from universal mythology. Preliminary coordinates for these features are derived from shaded relief maps of the satellites to be published in 1987. Orbital elements have been established for the 10 new satellites, and a paper describing this work is in progress; satellite positions are under review by Commission 16 of the IAU. The moon 1985 U1 is informally designated Puck. The nine small satellites discovered in 1986 are to be named for Shakespearean heroines; these names are to be listed in the 1987 edition of the Annual Gazetteer of Planetary Nomenclature.

  18. Planetary Moon Cycler Trajectories

    NASA Technical Reports Server (NTRS)

    Russell, Ryan P.; Strange, Nathan J.

    2007-01-01

    Free-return cycler trajectories repeatedly shuttle a spacecraft between two bodies using little or no fuel. Here, the cycler architecture is proposed as a complementary and alternative method for designing planetary moon tours. Previously applied enumerative cycler search and optimization techniques are generalized and specifically implemented in the Jovian and Saturnian moon systems. In addition, the algorithms are tested for general use to find non-Earth heliocentric cyclers. Overall, hundreds of ideal model ballistic cycler geometries are found and several representative cases are documented and discussed. Many of the ideal model solutions are found to remain ballistic in a zero radius sphere of influence patched conic ephemeris model, and preliminary work in a high-fidelity fully integrated model demonstrates near-ballistic cycles for several example cases.

  19. Planetary Surface Instruments Workshop

    NASA Astrophysics Data System (ADS)

    Meyer, Charles; Treiman, Allanh; Kostiuk, Theodor,

    1996-01-01

    This report on planetary surface investigations an d planetary landers covers: (1) the precise chemic al analysis of solids; (2) isotopes and evolved ga s analyses; (3) planetary interiors; planetary atm ospheres from within as measured by landers; (4) m ineralogical examination of extraterrestrial bodie s; (5) regoliths; and (6) field geology/processes . For individual titles, see N96-34812 through N96-34819. (Derived from text.)

  20. Advances in planetary geology

    NASA Technical Reports Server (NTRS)

    Woronow, A. (Editor)

    1981-01-01

    This second issue in a new series intended to serve the planetary geology community with a form for quick and thorough communications includes (1) a catalog of terrestrial craterform structures for northern Europe; (2) abstracts of results of the Planetary Geology Program, and (3) a list of the photographic holdings of regional planetary image facilities.

  1. Geobiochemistry: Placing Biochemistry in Its Geochemical Context

    NASA Astrophysics Data System (ADS)

    Shock, E.; Boyer, G. M.; Canovas, P. A., III; Prasad, A.; Dick, J. M.

    2014-12-01

    Goals of geobiochemistry include simultaneously evaluating the relative stabilities of microbial cells and minerals, and predicting how the composition of biomolecules can change in response to the progress of geochemical reactions. Recent developments in theoretical geochemistry make it possible to predict standard thermodynamic properties of proteins, nucleotides, lipids, and many metabolites including the constituents of the citric acid cycle, at all temperatures and pressures where life is known to occur, and beyond. Combining these predictions with constraints from geochemical data makes it possible to assess the relative stabilities of biomolecules. Resulting independent predictions of the environmental occurrence of homologous proteins and lipid side-chains can be compared with observations from metagenomic and metalipidomic data to quantify geochemical driving forces that shape the composition of biomolecules. In addition, the energetic costs of generating biomolecules from within a diverse range of habitable environments can be evaluated in terms of prevailing geochemical variables. Comparisons of geochemical bioenergetic calculations across habitats leads to the generalization that the availability of H2 determines the cost of autotrophic biosynthesis relative to the aquatic environment external to microbial cells, and that pH, temperature, pressure, and availability of C, N, P, and S are typically secondary. Increasingly reduced conditions, which are determined by reactions of water with mineral surfaces and mineral assemblages, allow many biosynthetic reactions to shift from costing energy to releasing energy. Protein and lipid synthesis, as well as the reverse citric acid cycle, become energy-releasing processes under these conditions. The resulting energy balances that determine habitability contrast dramatically with assumptions derived from oxic surface conditions, such as those where human biochemistry operates.

  2. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Results of planetary advanced studies and planning support provided by Science Applications, Inc. staff members to Earth and Planetary Exploration Division, OSSA/NASA, for the period 1 February 1981 to 30 April 1982 are summarized. The scope of analyses includes cost estimation, planetary missions performance, solar system exploration committee support, Mars program planning, Galilean satellite mission concepts, and advanced propulsion data base. The work covers 80 man-months of research. Study reports and related publications are included in a bibliography section.

  3. SPACE AND PLANETARY ENVIRONMENTS

    DTIC Science & Technology

    PLANETARY ATMOSPHERES, PLUTO (PLANET), SATURN(PLANET), SOLAR RADIATION, SOLAR WIND, SPECTROGRAPHY, STARS, SUN, TERRAIN, GEOMAGNETISM, ULTRAVIOLET RADIATION, URANUS(PLANET), VAN ALLEN RADIATION BELT, VENUS(PLANET).

  4. Planetary geosciences, 1988

    NASA Technical Reports Server (NTRS)

    Zuber, Maria T. (Editor); Plescia, Jeff L. (Editor); James, Odette B. (Editor); Macpherson, Glenn (Editor)

    1989-01-01

    Research topics within the NASA Planetary Geosciences Program are presented. Activity in the fields of planetary geology, geophysics, materials, and geochemistry is covered. The investigator's current research efforts, the importance of that work in understanding a particular planetary geoscience problem, the context of that research, and the broader planetary geoscience effort is described. As an example, theoretical modelling of the stability of water ice within the Martian regolith, the applicability of that work to understanding Martian volatiles in general, and the geologic history of Mars is discussed.

  5. Geochemical modeling: a review

    SciTech Connect

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted.

  6. From Planetary Intelligence to Planetary Wisdom

    NASA Astrophysics Data System (ADS)

    Moser, S. C.

    2016-12-01

    "Planetary intelligence" - when understood as an input into the processes of "managing" Earth - hints at an instrumental understanding of scientific information. At minimum it is a call for useful data of political (and even military) value; at best it speaks to an ability to collect, integrate and apply such information. In this sense, 21st century society has more "intelligence" than any generation of humans before, begging the question whether just more or better "planetary intelligence" will do anything at all to move us off the path of planetary destruction (i.e., beyond planetary boundaries) that it has been on for decades if not centuries. Social scientists have argued that there are at least four shortcomings in this way of thinking that - if addressed - could open up 1) what is being researched; 2) what is considered socially robust knowledge; 3) how science interacts with policy-makers and other "planet managers"; and 4) what is being done in practice with the "intelligence" given to those positioned at the levers of change. To the extent "planetary management" continues to be approached from a scientistic paradigm alone, there is little hope that Earth's future will remain in a safe operating space in this or coming centuries.

  7. Seeking a geochemical identifier for authigenic carbonate

    PubMed Central

    Zhao, Ming-Yu; Zheng, Yong-Fei; Zhao, Yan-Yan

    2016-01-01

    Authigenic carbonate was recently invoked as a third major global carbon sink in addition to primary marine carbonate and organic carbon. Distinguishing the two carbonate sinks is fundamental to our understanding of Earth's carbon cycle and its role in regulating the evolution of atmospheric oxygen. Here, using microscale geochemical measurements of carbonates in Early Triassic strata, we show that the growth of authigenic carbonate follows a different trajectory from primary marine carbonate in a cross-plot of uranium concentration and carbon isotope composition. Thus, a combination of the two geochemical variables is able to distinguish between the two carbonate sinks. The temporal distribution of authigenic carbonates in the Early Triassic strata suggests that the increase in the extent of carbonate authigenesis acted as a negative feedback to the elevated atmospheric CO2 concentration. PMID:26947562

  8. Mathematical optimization of matter distribution for a planetary system configuration

    NASA Astrophysics Data System (ADS)

    Morozov, Yegor; Bukhtoyarov, Mikhail

    2016-07-01

    Planetary formation is mostly a random process. When the humanity reaches the point when it can transform planetary systems for the purpose of interstellar life expansion, the optimal distribution of matter in a planetary system will determine its population and expansive potential. Maximization of the planetary system carrying capacity and its potential for the interstellar life expansion depends on planetary sizes, orbits, rotation, chemical composition and other vital parameters. The distribution of planetesimals to achieve maximal carrying capacity of the planets during their life cycle, and maximal potential to inhabit other planetary systems must be calculated comprehensively. Moving much material from one planetary system to another is uneconomic because of the high amounts of energy and time required. Terraforming of the particular planets before the whole planetary system is configured might drastically decrease the potential habitability the whole system. Thus a planetary system is the basic unit for calculations to sustain maximal overall population and expand further. The mathematical model of optimization of matter distribution for a planetary system configuration includes the input observed parameters: the map of material orbiting in the planetary system with specified orbits, masses, sizes, and the chemical compound for each, and the optimized output parameters. The optimized output parameters are sizes, masses, the number of planets, their chemical compound, and masses of the satellites required to make tidal forces. Also the magnetic fields and planetary rotations are crucial, but they will be considered in further versions of this model. The optimization criteria is the maximal carrying capacity plus maximal expansive potential of the planetary system. The maximal carrying capacity means the availability of essential life ingredients on the planetary surface, and the maximal expansive potential means availability of uranium and metals to build

  9. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Results of planetary advanced studies and planning support are summarized. The scope of analyses includes cost estimation research, planetary mission performance, penetrator mission concepts for airless planets/satellites, geology orbiter payload adaptability, lunar mission performance, and advanced planning activities. Study reports and related publications are included in a bibliography section.

  10. Advances in Planetary Geology

    NASA Technical Reports Server (NTRS)

    Woronow, A. (Editor)

    1982-01-01

    Advances in Planetary Geology is a new series intended to serve the planetary geology community with a form for quick and thorough communications. There are no set lists of acceptable topics or formats, and submitted manuscripts will not undergo a formal review. All submissions should be in a camera ready form, preferably spaced, and submitted to the editor.

  11. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Results of planetary advanced studies and planning support are summarized. The scope of analyses includes cost estimation research, planetary mission performance, penetrator advanced studies, Mercury mission transport requirements, definition of super solar electric propulsion/solar sail mission discriminators, and advanced planning activities.

  12. Planetary Exploration in ESA

    NASA Technical Reports Server (NTRS)

    Schwehm, Gerhard H.

    2005-01-01

    A viewgraph presentation on planetary exploration in the European Space Agency is shown. The topics include: 1) History of the Solar System Material; 2) ROSETTA: The Comet Mission; 3) A New Name For The Lander: PHILAE; 4) The Rosetta Mission; 5) Lander: Design Characteristics; 6) SMART-1 Mission; 7) MARS Express VENUS Express; 8) Planetary Exploration in ESA The Future.

  13. Multistage Planetary Power Transmissions

    NASA Technical Reports Server (NTRS)

    Hadden, G. B.; Dyba, G. J.; Ragen, M. A.; Kleckner, R. J.; Sheynin, L.

    1986-01-01

    PLANETSYS simulates thermomechanical performance of multistage planetary performance of multistage planetary power transmission. Two versions of code developed, SKF version and NASA version. Major function of program: compute performance characteristics of planet bearing for any of six kinematic inversions. PLANETSYS solves heat-balance equations for either steadystate or transient thermal conditions, and produces temperature maps for mechanical system.

  14. Life cycles of transient planetary waves

    NASA Technical Reports Server (NTRS)

    Nathan, Terrence

    1993-01-01

    In recent years there has been an increasing effort devoted to understanding the physical and dynamical processes that govern the global-scale circulation of the atmosphere. This effort has been motivated, in part, from: (1) a wealth of new satellite data; (2) an urgent need to assess the potential impact of chlorofluorocarbons on our climate; (3) an inadequate understanding of the interactions between the troposphere and stratosphere and the role that such interactions play in short and long-term climate variability; and (4) the realization that addressing changes in our global climate requires understanding the interactions among various components of the earth system. The research currently being carried out represents an effort to address some of these issues by carrying out studies that combine radiation, ozone, seasonal thermal forcing and dynamics. Satellite and ground-based data that is already available is being used to construct basic states for our analytical and numerical models. Significant accomplishments from 1991-1992 are presented and include the following: ozone-dynamics interaction; (2) periodic local forcing and low frequency variability; and (3) steady forcing and low frequency variability.

  15. The Stability of Habitable Planetary Environments

    NASA Astrophysics Data System (ADS)

    Williams, Darren Mark

    1998-12-01

    The recent discoveries of extrasolar planets have generated widespread anticipation of detecting a life-supporting environment, such as an Earth-like planet or moon, around a nearby solar-type star. Future observations will enable life on such worlds to be detected remotely through the spectral identification of CH4 and O3 in their atmospheres. This thesis addresses the climatic and dynamic factors affecting whether an Earth-like biosphere might exist around another star and, hence, the likelihood that extraterrestrial life will be discovered in the foreseeable future. To remain habitable for billions of years, a planetary body must be large enough to form and retain an atmosphere. Earth's Moon (~0.01M⊕) does not satisfy this basic criterion. Objects with atmospheres must orbit their stars within the habitable zone (HZ) for liquid water to exist on their surfaces. Otherwise habitable worlds can have their climates destabilized by the slow brightening of their-stars as the age, or by chaotic variability of their orbits and obliquities over time. Earth's 23.5o-obliquity is presently stable, but the spin-stability of extrasolar Earths will depend on the masses and proximity of satellites and neighboring planets. Climates of planets with high obliquities are investigated using an energy-balance climate model. At high obliquity, Earth's climatic zonation is reversed so that the lower latitudes are permanently frozen and the poles are subjected to extraordinary swings in seasonal temperature. Planets within the outer HZs around their stars are less affected by obliquity because they develop dense-CO2 atmospheres as a result of the carbonate-silicate geochemical cycle. Efficient heat transport within such atmospheres reduce latitudinal temperature gradients and limit the amplitudes of seasonal temperature extremes. Geologic evidence for low-latitude glaciation during the Precambrian era suggests that the obliquity of early-Earth may have been much higher than it is

  16. Planetary data definition

    NASA Astrophysics Data System (ADS)

    1984-10-01

    Planetary data include all of those data which have resulted from measurements made by the instruments carried aboard planetary exploration spacecraft, and (for our purposes) exclude observations of Moon and Earth. The working, planetary data base is envisioned to contain not only these data, but also a wide range of supporting measurements such as calibration files, navigation parameters, spacecraft engineering states, and the various Earth-based and laboratory measurements which provide the planetary research scientist with historical and comparative data. No convention exists across the disciplines of the planetary community for defining or naming the various levels through which data pass in the progression from a sensed impulse at the spacecraft to a reduced, calibrated, and/or analyzed element in a planetary data set. Terms such as EDR (experiment data record), RDR (reduced data record), and SEDR (supplementary experiment data record) imply different meanings depending on the data set under consideration. The development of standard terminology for the general levels of planetary data is necessary.

  17. A geochemical study of acapulcoite and lodranite meteorites

    NASA Technical Reports Server (NTRS)

    Field, Stephen W.

    1993-01-01

    Lodranites and acapulcoites (primitive achondrites) are two classes of meteorites with geochemical signatures similar to chondrite meteorites. 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 study 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 meteorite suggest the rock is a metal rich acapulcoite and not a lodranite.

  18. Planetary Geophysics and Tectonics

    NASA Technical Reports Server (NTRS)

    Zuber, Maria

    2005-01-01

    The broad objective of this work is to improve understanding of the internal structures and thermal and stress histories of the solid planets by combining results from analytical and computational modeling, and geophysical data analysis of gravity, topography and tectonic surface structures. During the past year we performed two quite independent studies in the attempt to explain the Mariner 10 magnetic observations of Mercury. In the first we revisited the possibility of crustal remanence by studying the conditions under which one could break symmetry inherent in Runcorn's model of a uniformly magnetized shell to produce a remanent signal with a dipolar form. In the second we applied a thin shell dynamo model to evaluate the range of intensity/structure for which such a planetary configuration can produce a dipole field consistent with Mariner 10 results. In the next full proposal cycle we will: (1) develop numerical and analytical and models of thin shell dynamos to address the possible nature of Mercury s present-day magnetic field and the demise of Mars magnetic field; (2) study the effect of degree-1 mantle convection on a core dynamo as relevant to the early magnetic field of Mars; (3) develop models of how the deep mantles of terrestrial planets are perturbed by large impacts and address the consequences for mantle evolution; (4) study the structure, compensation, state of stress, and viscous relaxation of lunar basins, and address implications for the Moon s state of stress and thermal history by modeling and gravity/topography analysis; and (5) use a three-dimensional viscous relaxation model for a planet with generalized vertical viscosity distribution to study the degree-two components of the Moon's topography and gravity fields to constrain the primordial stress state and spatial heterogeneity of the crust and mantle.

  19. Planetary Magnetic Fields: Planetary Interiors and Habitability

    NASA Astrophysics Data System (ADS)

    Lazio, T. Joseph W.; Shkolnik, Evgenya; Hallinan, Gregg; Planetary Habitability Study Team

    2016-06-01

    The W. M. Keck Institute for Space Studies (KISS) sponsored the Planetary Magnetic Fields: Planetary Interiors and Habitability Study to review the state of knowledge of extrasolar planetary magnetic fields and the prospects for their detection. There were multiple motivations for this Study. Planetary-scale magnetic fields are a window to a planet's interior and provide shielding of the planet's atmosphere. The Earth, Mercury, Ganymede, and the giant planets of the solar system all contain internal dynamo currents that generate planetary-scale magnetic fields. In turn, these internal dynamo currents arise from differential rotation, convection, compositional dynamics, or a combination of these in objects' interiors. If coupled to an energy source, such as the incident kinetic or magnetic energy from the solar wind or an orbiting satellite, a planet's magnetic field can produce intense electron cyclotron masers in its magnetic polar regions. The most well known example of this process in the solar system is the Jovian decametric emission, but all of the giant planets and the Earth contain similar electron cyclotron masers within their magnetospheres. Extrapolated to extrasolar planets, the remote detection of the magnetic field of an extrasolar planet would provide a means of obtaining constraints on the thermal state, composition, and dynamics of its interior--all of which will be difficult to determine by other means--as well as improved understanding of the basic planetary dynamo process. This report presents the findings from the Study, including potential mission concepts that emerged and future work in both modeling and observations. There was also an identification of that radio wavelength observations would likely be key to making significant progress in this field. The entire Study program would not have been possible without the generous support of the W. M. Keck Foundation. We thank Michele Judd, Tom Prince, and the staff of the W. M. Keck Institute for

  20. Reconsideration of the planetary boundary for phosphorus

    NASA Astrophysics Data System (ADS)

    Carpenter, Stephen R.; Bennett, Elena M.

    2011-01-01

    Phosphorus (P) is a critical factor for food production, yet surface freshwaters and some coastal waters are highly sensitive to eutrophication by excess P. A planetary boundary, or upper tolerable limit, for P discharge to the oceans is thought to be ten times the pre-industrial rate, or more than three times the current rate. However this boundary does not take account of freshwater eutrophication. We analyzed the global P cycle to estimate planetary boundaries for freshwater eutrophication. Planetary boundaries were computed for the input of P to freshwaters, the input of P to terrestrial soil, and the mass of P in soil. Each boundary was computed for two water quality targets, 24 mg P m - 3, a typical target for lakes and reservoirs, and 160 mg m - 3, the approximate pre-industrial P concentration in the world's rivers. Planetary boundaries were also computed using three published estimates of current P flow to the sea. Current conditions exceed all planetary boundaries for P. Substantial differences between current conditions and planetary boundaries demonstrate the contrast between large amounts of P needed for food production and the high sensitivity of freshwaters to pollution by P runoff. At the same time, some regions of the world are P-deficient, and there are some indications that a global P shortage is possible in coming decades. More efficient recycling and retention of P within agricultural ecosystems could maintain or increase food production while reducing P pollution and improving water quality. Spatial heterogeneity in the global P cycle suggests that recycling of P in regions of excess and transfer of P to regions of deficiency could mitigate eutrophication, increase agricultural yield, and delay or avoid global P shortage.

  1. The search for signs of life on exoplanets at the interface of chemistry and planetary science.

    PubMed

    Seager, Sara; Bains, William

    2015-03-01

    The discovery of thousands of exoplanets in the last two decades that are so different from planets in our own solar system challenges many areas of traditional planetary science. However, ideas for how to detect signs of life in this mélange of planetary possibilities have lagged, and only in the last few years has modeling how signs of life might appear on genuinely alien worlds begun in earnest. Recent results have shown that the exciting frontier for biosignature gas ideas is not in the study of biology itself, which is inevitably rooted in Earth's geochemical and evolutionary specifics, but in the interface of chemistry and planetary physics.

  2. Remote geochemical experiment package for Discovery class missions

    NASA Technical Reports Server (NTRS)

    Clark, Pamela E.; Evans, Larry G.; Trombka, Jacob I.

    1994-01-01

    Remote sensing x-ray and gamma-ray spectrometers can be used to infer elemental composition on atmosphereless bodies, such as asteroids, the moon, and Mercury. The composition of the planetary body and variations in its surface chemistry are of fundamental importance in understanding the formation and dynamics of that body. Thus, for Discovery class missions, x-ray fluorescence (XRF), gamma-ray spectrometer (GRS), or a combined Geochemical Experiment Package (GEP) have been proposed. These instruments can meet the mission science objectives, while still meeting the weight, power, and cost constraints. These missions include the Near Earth Asteroid Rendezvous, the Main-belt Asteroid Rendezvous, and others such as HERMES (Mercury Orbiter). This paper presents the results of calculations done to assess the sensitivity of a combined instrument to obtain elemental compositions of planetary bodies with an uncertainty small enough to be scientifically useful.

  3. Lunar & Planetary Science, 11.

    ERIC Educational Resources Information Center

    Geotimes, 1980

    1980-01-01

    Presents a summary of each paper presented at the Lunar and Planetary Science Conference at the Johnson Space Center, Houston in March 1980. Topics relate to Venus, Jupiter, Mars, asteroids, meteorites, regoliths, achondrites, remote sensing, and cratering studies. (SA)

  4. Lunar & Planetary Science, 11.

    ERIC Educational Resources Information Center

    Geotimes, 1980

    1980-01-01

    Presents a summary of each paper presented at the Lunar and Planetary Science Conference at the Johnson Space Center, Houston in March 1980. Topics relate to Venus, Jupiter, Mars, asteroids, meteorites, regoliths, achondrites, remote sensing, and cratering studies. (SA)

  5. Lunar & Planetary Science Conference.

    ERIC Educational Resources Information Center

    Warner, Jeffrey L.; And Others

    1982-01-01

    Summaries of different topics discussed at the Lunar and Planetary Science Conference are presented to provide updated information to nonplanetologists. Some topics include Venus, isotopes, chondrites, creation science, cosmic dust, cratering, moons and rings, igneous rocks, and lunar soil. (DC)

  6. Lunar & Planetary Science Conference.

    ERIC Educational Resources Information Center

    Warner, Jeffrey L.; And Others

    1982-01-01

    Summaries of different topics discussed at the Lunar and Planetary Science Conference are presented to provide updated information to nonplanetologists. Some topics include Venus, isotopes, chondrites, creation science, cosmic dust, cratering, moons and rings, igneous rocks, and lunar soil. (DC)

  7. The Planetary Project

    NASA Astrophysics Data System (ADS)

    Pataki, Louis P.

    2016-06-01

    This poster presentation presents the Planetary Project, a multi-week simulated research experience for college non-science majors. Students work in research teams of three to investigate the properties of a fictitious planetary system (the “Planetary System”) created each semester by the instructor. The students write team and individual papers in which they use the available data to draw conclusions about planets, other objects or general properties of the Planetary System and in which they compare, contrast and explain the similarities between the objects in the Planetary System and comparable objects in the Solar System.Data about the orbital and physical properties of the planets in the Planetary System are released at the start of the project. Each week the teams request data from a changing pool of available data. For example, in week one pictures of the planets are available. Each team picks one planet and the data (pictures) on that planet are released only to that team. Different data are available in subsequent weeks. Occasionally a news release to all groups reports an unusual occurrence - e.g. the appearance of a comet.Each student acts as principal author for one of the group paper which must contain a description of the week’s data, conclusions derived from that data about the Planetary System and a comparison with the Solar System. Each students writes a final, individual paper on a topic of their choice dealing with the Planetary System in which they follow the same data, conclusion, comparison format. Students “publish” their papers on a class-only restricted website and present their discoveries in class talks. Data are released to all on the website as the related papers are “published.” Additional papers commenting on the published work and released data are encouraged.The successes and problems of the method are presented.

  8. Geochemical Speciation Mass Transfer

    SciTech Connect

    1985-12-01

    PHREEQC is designed to model geochemical reactions. Based on an ion association aqueous model, PHREEQC can calculate pH, redox potential, and mass transfer as a function of reaction progress. It can be used to describe geochemical processes for both far-field and near-field performance assessment and to evaluate data acquisition needs and test data. It can also calculate the composition of solutions in equilibrium with multiple phases. The data base, including elements, aqueous species, and mineral phases, is independent of the program and is completely user-definable. PHREEQC requires thermodynamic data for each solid, gaseous, or dissolved chemical species being modeled. The two data bases, PREPHR and DEQPAK7, supplied with PHREEQC are for testing purposes only and should not be applied to real problems without first being carefully examined. The conceptual model embodied in PHREEQC is the ion-association model of Pearson and Noronha. In this model a set of mass action equations are established for each ion pair (and controlling solid phases when making mass transfer calculations) along with a set of mass balance equations for each element considered. These sets of equations are coupled using activity coefficient values for each aqueous species and solved using a continued fraction approach for the mass balances combined with a modified Newton-Raphson technique for all other equations. The activity coefficient expressions in PHREEQC include the extended Debye-Huckel, WATEQ Debye-Huckel, and Davies equations from the original United States Geological Survey version of the program. The auxiliary preprocessor program PHTL, which is derived from EQTL, converts EQ3/6 thermodynamic data to PHREEQC format so that the two programs can be compared. PHREEQC can be used to determine solubility limits on the radionuclides present in the waste form. These solubility constraints may be input to the WAPPA leach model.

  9. Demographics of Planetary Science

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; White, S.

    2011-10-01

    A survey was sent out to university departments around the US that were thought to include faculty involved in planetary science research and/or offer planetary science undergraduate or graduate degrees. This is Part A of a study of the demographics of planetary science carried out by the American Institute of Physics (AIP) and sponsored by NASA's Planetary Science Division. Part B will be a survey of the planetary scientists with PhDs working in the US, to be carried out by the AIP in mid-2011. Starting on December 8th 2010 surveys were sent out by email to department chairs. A total of 48 departments responded between December 9th and April 8th . There is only U of Arizona that has a department that is called planetary sciences - the rest are combined with Earth sciences (14), astronomy (15), geology/geophysics (8), physics (7), atmospheric science (5), something else or combinations thereof. We present statistics from these 48 departments on faculty, researchers, graduate and undergraduate students.

  10. The Role of Planetary System Architecture in Planetary Habitability

    NASA Astrophysics Data System (ADS)

    Barnes, R.; Jackson, B.; Raymond, S.; Greenberg, R.

    2009-12-01

    Traditionally, the habitable zone is defined as the region around a star in which liquid water can be stable on a planetary surface. At first these calculations considered planets on circular orbits [1]. More recent investigations into nonzero orbital eccentricities found that the limits of the habitable zone should reflect the orbit-averaged flux a planet receives [2]. However, those studies assumed the potentially habitable planet is isolated. If additional planets are in the system, gravitational interactions between planets can cause eccentricity oscillations on timescales of 103 - 106 years. Furthermore, the known multi-planet systems (generally consisting of giant planets) appear to undergo large amplitude eccentricity oscillations [3]. If rocky exoplanets also experience such large variations, then the orbit-averaged flux may change significantly, impacting habitability. We show that plausible architectures of rocky planet systems can indeed lead to orbits with large eccentricity cycles. Moreover, some planets could cross either the inner or outer habitable zone boundaries due to these oscillations. We therefore suggest that the shape of actual habitable zones depends critically on the configuration (orbits and masses) of the entire planetary system. [1] Kasting, J.F. et al. 1993, Icarus, 101, 108. [2] Williams, D.M. & Pollard, D. 2002, I. J. AsBio, 2, 1. [3] Barnes, R., & Greenberg, R. 2006, Astrophys. J., 652, L53.

  11. Annual review of earth and planetary sciences. Vol. 21

    NASA Astrophysics Data System (ADS)

    Wetherill, George W.; Albee, Arden L.; Burke, Kevin C.

    Various papers on earth and planetary sciences are presented. The topics addressed include: petrology of the mantle transition zone, planetary lightning, sediment deposition from turbidity currents, oxygen isotopes in meteorites, acid rain, mantle and slab contribution in arc magmas, trends and patterns of phanerozoic ichnofabric, role of polar deep water formation in global climate change, matrices of carbonaceous chondrite meteorites, the role of fluids in accretion and erosion in subduction zones. Also discussed are: scaling of impact processes in planetary sciences, progress in the experimental study of seismic wave attenuation, the global methane cycle, terrestrial volcanism in space and time, Precambrian history of the West Australian cratons and adjacent orogens, understanding planetary rings, impact erosion of terrestrial planetary atmospheres.

  12. Environmental Applications of Geochemical Modeling

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Anderson, Greg

    2002-05-01

    This book discusses the application of geochemical models to environmental practice and studies, through the use of numerous case studies of real-world environmental problems, such as acid mine drainage, pit lake chemistry, nuclear waste disposal, and landfill leachates. In each example the authors clearly define the environmental threat in question; explain how geochemical modeling may help solve the problem posed; and advise the reader how to prepare input files for geochemical modeling codes and interpret the results in terms of meeting regulatory requirements.

  13. Planetary life: why and how?

    NASA Astrophysics Data System (ADS)

    Pratt, Andy; Kerr, William

    2012-07-01

    Understanding life in an astrobiological context requires that we understand why and how life emerged on earth. We report on the elaboration and preliminary testing of our recent model for the origin of life (Pratt, 2011). This model identifies key components, including availability of chemicals and geochemical energy sources, required for the emergence of planetary life. The model is based on the theory (Russell and Kanik, 2010) that life emerged as a mechanism for the dissipation of the intrinsic geochemical energy gradient of the planet. It proposes that life is founded on an ongoing chemical energy flux that can be harnessed more efficiently by autocatalytic networks of reactions than by direct chemical processes. Feedback and selection mechanisms are required to foster the apparently irreducible complexity found in cells. We posit that selective solubilisation in a hydrothermal flow system was a key mechanism that underpinned the emergence of life. Amongst other things, earthly cells are dependent on a combination of organic molecules, iron (for electron-transfer and catalysis) and phosphate (e.g. for digital information). Soluble aqueous systems that include all these components are constrained by precipitation chemistry (de Zwart et al., 2004). We propose that in situ abiological carbon fixation produced organic molecules that, in turn, led to more active carbon fixation catalysts and hence more efficient reduction of carbon oxides. By encapsulating free iron ions, these organic molecules also facilitated the solubilisation of phosphate species which thereby became integrated within this expanding autocatalytic network. We have evaluated the competitive solubility of phosphate species in the presence of iron and organic moieties to test this theory and provide evidence that this could act as positive feedback loop for a form of prebiological evolution that underpinned the emergence of complex cells. References, Pratt, A. J. (2011) Prebiological Evolution and

  14. Detectability of extrasolar planetary transits

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Scargle, J. D.; Hudson, H. S.

    1985-01-01

    Precise stellar photometry can be used to detect other planetary systems. However, the intrinsic variability of stellar luminosity imposes a fundamental limit on the sensitivity of this method. Based on recent precise solar observations made from the Solar Maximum Mission satellite, it appears that the detection of earth-sized planets will be marginal during periods of high stellar activity. However, with a suitable photometer larger planets should be readily detectable even in the presence of stellar activity equal to that of the sun at the peak of its sunspot cycle. The high precision, multiple-star photometric system required to detect planets in other stellar systems could be used to monitor flares, starspots, and global oscillations.

  15. Non-planetary Science from Planetary Missions

    NASA Astrophysics Data System (ADS)

    Elvis, M.; Rabe, K.; Daniels, K.

    2015-12-01

    Planetary science is naturally focussed on the issues of the origin and history of solar systems, especially our own. The implications of an early turbulent history of our solar system reach into many areas including the origin of Earth's oceans, of ores in the Earth's crust and possibly the seeding of life. There are however other areas of science that stand to be developed greatly by planetary missions, primarily to small solar system bodies. The physics of granular materials has been well-studied in Earth's gravity, but lacks a general theory. Because of the compacting effects of gravity, some experiments desired for testing these theories remain impossible on Earth. Studying the behavior of a micro-gravity rubble pile -- such as many asteroids are believed to be -- could provide a new route towards exploring general principles of granular physics. These same studies would also prove valuable for planning missions to sample these same bodies, as techniques for anchoring and deep sampling are difficult to plan in the absence of such knowledge. In materials physics, first-principles total-energy calculations for compounds of a given stoichiometry have identified metastable, or even stable, structures distinct from known structures obtained by synthesis under laboratory conditions. The conditions in the proto-planetary nebula, in the slowly cooling cores of planetesimals, and in the high speed collisions of planetesimals and their derivatives, are all conditions that cannot be achieved in the laboratory. Large samples from comets and asteroids offer the chance to find crystals with these as-yet unobserved structures as well as more exotic materials. Some of these could have unusual properties important for materials science. Meteorites give us a glimpse of these exotic materials, several dozen of which are known that are unique to meteorites. But samples retrieved directly from small bodies in space will not have been affected by atmospheric entry, warmth or

  16. Geochemical Evidence for a Terrestrial Magma Ocean

    NASA Technical Reports Server (NTRS)

    Agee, Carl B.

    1999-01-01

    The aftermath of phase separation and crystal-liquid fractionation in a magma ocean should leave a planet geochemically differentiated. Subsequent convective and other mixing processes may operate over time to obscure geochemical evidence of magma ocean differentiation. On the other hand, core formation is probably the most permanent, irreversible part of planetary differentiation. Hence the geochemical traces of core separation should be the most distinct remnants left behind in the mantle and crust, In the case of the Earth, core formation apparently coincided with a magma ocean that extended to a depth of approximately 1000 km. Evidence for this is found in high pressure element partitioning behavior of Ni and Co between liquid silicate and liquid iron alloy, and with the Ni-Co ratio and the abundance of Ni and Co in the Earth's upper mantle. A terrestrial magma ocean with a depth of 1000 km will solidify from the bottom up and first crystallize in the perovskite stability field. The largest effect of perovskite fractionation on major element distribution is to decrease the Si-Mg ratio in the silicate liquid and increase the Si-Mg ratio in the crystalline cumulate. Therefore, if a magma ocean with perovskite fractionation existed, then one could expect to observe an upper mantle with a lower than chondritic Si-Mg ratio. This is indeed observed in modern upper mantle peridotites. Although more experimental work is needed to fully understand the high-pressure behavior of trace element partitioning, it is likely that Hf is more compatible than Lu in perovskite-silicate liquid pairs. Thus, perovskite fractionation produces a molten mantle with a higher than chondritic Lu-Hf ratio. Arndt and Blichert-Toft measured Hf isotope compositions of Barberton komatiites that seem to require a source region with a long-lived, high Lu-Hf ratio. It is plausible that that these Barberton komatiites were generated within the majorite stability field by remelting a perovskite

  17. Nebular UV Absorption Lines in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet

    We propose to continue our Cycle 1 program of studying the Lyman and Werner bands of H_2, seen in absorption against the UV continua of planetary nebula central stars, which arise within neutral-molecular envelopes surrounding the ionized gas. These are the pump lines for a fluorescent cascade of near-infrared emission lines which are observed in many planetary nebulae. By observing the UV lines we can probe the chemical and thermal structure of the envelopes, as well as measure molecular column densities and clarify the excitation processes for the infrared lines. In Cycle 1 we were granted time for three targets, one of which was successfully observed shortly before submission of this proposal. Although the data were not yet available for examination, similar target observed by the project team revealed a rich set of H_2 circumstellar absorption features, demonstrating the feasibility of our program. FUSE spectra also include absorption features from atomic species such as O I and C II, which give rise to important far-infrared fine-structure cooling lines that likewise have been observed from planetary nebulae. In Cycle 2, we add as a secondary goal a search for nebular components of the O VI 032, 1038 AA absorption lines, which trace the presence of hot shocked gas, in nebulae with anomalously strong optical recombination lines of ions of oxygen and nitrogen. This will test a plausible hypothesis for the origin of this anomaly.

  18. Foundations of planetary quarantine.

    NASA Technical Reports Server (NTRS)

    Hall, L. B.; Lyle, R. G.

    1971-01-01

    Discussion of some of the problems in microbiology and engineering involved in the implementation of planetary quarantine. It is shown that the solutions require new knowledge in both disciplines for success at low cost in terms of both monetary outlay and man's further exploration of the planets. A related problem exists in that engineers are not accustomed to the wide variation of biological data and microbiologists must learn to work and think in more exact terms. Those responsible for formulating or influencing national and international policies must walk a tightrope with delicate balance between unnecessarily stringent requirements for planetary quarantine on the one hand and prevention of contamination on the other. The success of planetary quarantine measures can be assured only by rigorous measures, each checked, rechecked, and triple-checked to make sure that no errors have been made and that no factor has been overlooked.

  19. Planetary noble gases

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin

    1993-01-01

    An overview of the history and current status of research on planetary noble gases is presented. The discovery that neon and argon are vastly more abundant on Venus than on earth points to the solar wind rather than condensation as the fundamental process for placing noble gases in the atmospheres of the terrestrial planets; however, solar wind implantation may not be able to fully reproduce the observed gradient, nor does it obviously account for similar planetary Ne/Ar ratios and dissimilar planetary Ar/Kr ratios. More recent studies have emphasized escape rather than accretion. Hydrodynamic escape, which is fractionating, readily accounts for the difference between atmospheric neon and isotopically light mantle neon. Atmospheric cratering, which is nearly nonfractionating, can account for the extreme scarcity of nonradiogenic noble gases (and other volatiles) on Mars.

  20. Extrasolar planetary systems.

    NASA Technical Reports Server (NTRS)

    Huang, S.-S.

    1973-01-01

    The terms 'planet' and 'planet-like objects' are defined. The observational search for extrasolar planetary systems is described, as performable by earthbound optical telescopes, by space probes, by long baseline radio interferometry, and finally by inference from the reception of signals sent by intelligent beings in other worlds. It is shown that any planetary system must be preceded by a rotating disk of gas and dust around a central mass. A brief review of the theories of the formation of the solar system is given, along with a proposed scheme for classification of these theories. The evidence for magnetic activity in the early stages of stellar evolution is presented. The magnetic braking theories of solar and stellar rotation are discussed, and an estimate is made for the frequency of occurrence of planetary systems in the universe.

  1. Foundations of planetary quarantine.

    NASA Technical Reports Server (NTRS)

    Hall, L. B.; Lyle, R. G.

    1971-01-01

    Discussion of some of the problems in microbiology and engineering involved in the implementation of planetary quarantine. It is shown that the solutions require new knowledge in both disciplines for success at low cost in terms of both monetary outlay and man's further exploration of the planets. A related problem exists in that engineers are not accustomed to the wide variation of biological data and microbiologists must learn to work and think in more exact terms. Those responsible for formulating or influencing national and international policies must walk a tightrope with delicate balance between unnecessarily stringent requirements for planetary quarantine on the one hand and prevention of contamination on the other. The success of planetary quarantine measures can be assured only by rigorous measures, each checked, rechecked, and triple-checked to make sure that no errors have been made and that no factor has been overlooked.

  2. Airships for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Colozza, Anthony

    2004-01-01

    The feasibility of utilizing an airship for planetary atmospheric exploration was assessed. The environmental conditions of the planets and moons within our solar system were evaluated to determine their applicability for airship flight. A station-keeping mission of 50 days in length was used as the baseline mission. Airship sizing was performed utilizing both solar power and isotope power to meet the baseline mission goal at the selected planetary location. The results show that an isotope-powered airship is feasible within the lower atmosphere of Venus and Saturn s moon Titan.

  3. Planetary surface weathering

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1986-01-01

    The weathering of planetary surfaces is treated. Both physical and chemical weathering (reactions between minerals or mineraloids and planetary volatiles through oxidation, hydration, carbonation, or solution processes) are discussed. Venus, earth, and Mars all possess permanent atmospheres such that weathering should be expected to significantly affect their respective surfaces. In contrast, Mercury and the moon lack permanent atmospheres but conceivably could experience surface weathering in response to transient atmospheres generated by volcanic or impact cratering events. Weathering processes can be postulated for other rocky objects including Io, Titan, asteroids, and comets.

  4. Planetary science comes to Nantes

    NASA Astrophysics Data System (ADS)

    Massey, Robert

    2011-12-01

    MEETING REPORT Robert Massey reports on highlights of the first joint meeting of the European Planetary Science Congress (EPSC) and the AAS Division of Planetary Scientists (DPS) in Nantes in October.

  5. Online Planetary Science Courses at Athabasca University

    NASA Astrophysics Data System (ADS)

    Connors, M. G.; Bredeson, C.; Munyikwa, K.

    2014-12-01

    Athabasca University offers distance education courses in science, at freshman and higher levels. It has a number of geology courses, and recently opened a planetary science course as the first upper division astronomy course after many years of offering freshman astronomy. Astronomy 310, Planetary Science, focuses on the physics of the Solar System and allows the study of planetary astronomy in a deeper way than what is offered in a freshman course. With a mathematically based approach, it looks at the planets and smaller bodies such as meteoroids, asteroids and comets found in our own solar neighbourhood. It provides an understanding of the basic physics and equations needed for studies of planetary science and looks at the formation of the principal bodies in the Solar System. It investigates the interiors of planets and planetary surface phenomena such as cratering, volcanism and tectonics, and examines the atmospheres of planets, including how they originated and whether planets can keep an atmosphere. As a new course, it has grown rapidly.Geology 415, Earth's Origin and Early Evolution, explores the evidence for the various processes, events, and materials involved in the formation and evolution of Earth. The course provides an overview of objects in the Solar System, including the Sun, the planets, asteroids, comets, and meteoroids. Earth's place in the Solar System is examined and physical laws that govern the motion of objects in the universe are looked at. Various geochemical tools and techniques used by geologists to reveal and interpret the evidence for the formation and evolution of bodies in the Solar System as well as the age of Earth are also explored. After looking at lines of evidence used to reconstruct the evolution of the Solar System, processes involved in the formation of planets and stars are examined. The course concludes with a look at the origin and nature of Earth's internal structure. GEOL415 is a senior undergraduate course and enrols

  6. Conference on Planetary Volatiles

    NASA Technical Reports Server (NTRS)

    Hrametz, K.; Kofler, L.

    1982-01-01

    Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution were addressed.

  7. Planetary quarantine computer applications

    NASA Technical Reports Server (NTRS)

    Rafenstein, M.

    1973-01-01

    The computer programs are identified pertaining to planetary quarantine activities within the Project Engineering Division, both at the Air Force Eastern Test Range and on site at the Jet Propulsion Laboratory. A brief description of each program and program inputs are given and typical program outputs are shown.

  8. Advances in planetary geology

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A wide variety of topics on planetary geology are presented. Subjects include stratigraphy and geomorphology of Copernicus, the Mamers valle region, and other selected regions of Mars and the Moon. Crater density and distribution are discussed for Callisto and the lunar surface. Spectroscopic analysis is described for Europa and Ganymede.

  9. Conference on Planetary Volatiles

    NASA Technical Reports Server (NTRS)

    Pepin, R. O. (Compiler); Oconnell, R. (Compiler)

    1982-01-01

    Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution are addressed.

  10. Planetary Quarantine Activities

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The activities of the Planetary Quarantine Department at Sandia Laboratories during the period April 1965 through June 1972 are summarized. Included are the rationale, the methods, and the results of modeling and experimentation used in dry heat, radiation, thermoradiation, and chemical sterilization studies. Publications describing these activities and accounts of closely related research are also furnished.

  11. The Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Manaud, N.; Zender, J.; Heather, D.; Barthelemy, M.; Vazquez, J. L.; Trautner, R.; Ortiz, I.; Dowson, J.; Arviset, C.; Parilla, E.

    2007-08-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and shopping basket functionality. Besides data from the Giotto spacecraft and several ground-based cometary observations, the PSA contains data from the Mars Express, Smart-1 and Huygens spacecraft. In spring 2007 the PSA will provide the science and engineering data collected by Rosetta until July 2006 and data collected by Venus Express until November 2005. The main goal of the archive initiative is to contribute to the maximum scientific exploitation of the data. The PSA provides a broad range of query possibilities. User can search the database by targets, planetary features, observation geometry, dataset characteristics and time information. Primary emphasis of the archive is on long-term data and knowledge preservation. All data sets are peer reviewed and must undergo an additional PSA internal validation procedure. The PSA continuously discusses with the community and the instrument teams the definition of derived parameters useful for data identification via cross-discipline or cross-instrument searches. As the PSA supports the concept of users and groups, proprietary data are protected from unauthorized users. All data are compatible to the Planetary Data System Standard and the PSA staff work in close collaboration with the PDS.

  12. Asteroidal and planetary analysis

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1975-01-01

    Photometric, spectrophotometric, and radiometric investigations of asteroids and planets are reported. Profiles of the planetary disk were used to study the physical structure of the Uranus atmosphere, and thermal and photographic properties of Saturn rings were theoretically modelled. Ground-based Mars observations were made for long-term comparison with Mariner 9 results.

  13. Advanced planetary studies

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Eleven study tasks are described and key results are discussed for the following: advanced planning activity; cost estimation research; planetary missions performance handbooks-revisions; multiple discipline science assessment; asteroid workshop; galilean lander mission strategies; asteroid exploration study; ion drive transport capabilities; Mars strategy study; Venus surface sample return; and ion drive/solar sail assessment study.

  14. Contemporary Planetary Science.

    ERIC Educational Resources Information Center

    Belton, Michael J. S.; Levy, Eugene H.

    1982-01-01

    Presents an overview of planetary science and the United States program for exploration of the planets, examining the program's scientific objectives, its current activities, and the diversity of its methods. Also discusses the program's lack of continuity, especially in personnel. (Author/JN)

  15. Lunar and Planetary Science XXXV

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The 35th Lunar and Planetary Science Conference covered topics on Mars, planetary origins, planetary analog studies, education,chondrite studies, and meteorite composition. Over 1000 reports were presented at the conference in over 100 sessions. Each session, and presentations,was processed separately for the database.

  16. Planetary GIS interfaces and links with the Planetary Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Rossi, A. P.; Baumann, P.; Beccati, A.; Cecconi, B.; Erard, S.; Marmo, C.

    2014-04-01

    Planetary data with a strong geographic component constitute a large portion of all those collected over planets and moons [e.g. 1]. The variety of Solar System bodies imaged and their geometry is large and cartographic standards have been set [e.g. 2]. Linking and making broadly accessible the growing amount of data in planetary archives of the NASA Planetary Data System (PDS) [3, 4] and ESA Planetary Science Archive (PSA) [5], derived datasets from experiment teams, group and individual scientists is a tremendous challenge. In order to tackle this, Virtual Observatory (VO) techniques and tools applied to Planetary Science data have been developed [6, 7].

  17. The role of biology in planetary evolution: cyanobacterial primary production in low‐oxygen Proterozoic oceans

    PubMed Central

    Bryant, Donald A.; Macalady, Jennifer L.

    2016-01-01

    Summary Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well‐preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane‐derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O 2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co‐occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low‐oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic

  18. Biodegradation of hydrocarbons and biogeochemical sulfur cycling in the salt dome environment: Inferences from sulfur isotope and organic geochemical investigations of the Bahloul Formation at the Bou Grine Zn/Pb ore deposit, Tunisia

    NASA Astrophysics Data System (ADS)

    Bechtel, A.; Shieh, Y.-N.; Pervaz, M.; Püttmann, W.

    1996-08-01

    Combined organic geochemical and stable isotope (S) analyses of samples from the Cretaceous Bahloul Formation (Tunisia) provide insight to oil accumulation processes, biogeochemical alteration of hydrocarbons, microbial sulfate reduction, and mineral deposition at the flanks of the Triassic Jebel Lorbeus diapir, forming the Bou Grine Zn/Pb deposit. The sulfur isotopic composition of the metal sulfides correlates with the degree of biodegradation of hydrocarbons, with the base-metal content and with the proportion of aromatics in the organic extracts. The δ 34S-values are interpreted to reflect bacterial sulfate reduction in a more or less closed system rather than a thermogenic contribution. The extent of H 2S production by the activity of the sulfate-reducing bacteria probably was limited by the availability of sulfate, which in turn was governed by the permeability of the respective sedimentary sequence and by the distance to the anhydrite cap rock. Evidence is provided that biodegradation of hydrocarbons and microbial sulfate reduction contribute to the formation of the high-grade mineralization inside the Bahloul Formation at the contact with the salt dome cap rock. The metals probably were derived through leaching of deeper sedimentary sequences by hot hypersaline basinal brines, evolved by dissolution of salt at the flanks of the diapirs. These hot metalliferous brines are proposed to migrate up around the diapir, finally mixing with near-surface, sulfate-rich brines in the roof zone. When the fluids came in contact with the organic-rich sediments of the Bahloul Formation, the dissolved sulfate was reduced by the sulfate-reducing bacteria. Hydrocarbons generated or accumulated in the Bahloul Formation were utilized by sulfate reducers. The occurrence of high amounts of native sulfur in high-grade ore samples suggest that the production rate of H 2S by bacterial sulfate reduction exceeded its consumption by metal-sulfide precipitation. The supply of dissolved

  19. Robot manipulator technologies for planetary exploration

    NASA Astrophysics Data System (ADS)

    Das, Hari; Bao, Xiaoqi; Bar-Cohen, Yoseph; Bonitz, Robert; Lindemann, Randall A.; Maimone, Mark; Nesnas, Issa A.; Voorhees, Christopher J.

    1999-06-01

    NASA exploration missions to Mars, initiated by the Mars Pathfinder mission in July 1997, will continue over the next decade. The missions require challenging innovations in robot design and improvements in autonomy to meet ambitious objectives under tight budget and time constraints. The authors are developing design tools, component technologies and capabilities to address these needs for manipulation with robots for planetary exploration. The specific developments are: (1) a software analysis tool to reduce robot design iteration cycles and optimize on design solutions, (2) new piezoelectric ultrasonic motors for light-weight and high torque actuation in planetary environments, (3) use of advanced materials and structures for strong and light-weight robot arms and (4) intelligent camera-image coordinated autonomous control of robot arms for instrument placement and sample acquisition from a rover vehicle.

  20. Strongly Interacting Planetary Systems

    NASA Astrophysics Data System (ADS)

    Ford, Eric

    2017-01-01

    Both ground-based Doppler surveys and NASA's Kepler mission have discovered a diversity of planetary system architectures that challenge theories of planet formation. Systems of tightly-packed or near-resonant planets are particularly useful for constraining theories of orbital migration and the excitation of orbital eccentricities and inclinations. In particular, transit timing variations (TTVs) provide a powerful tool to characterize the masses and orbits of dozens of small planets, including many planets at orbital periods beyond the reach of both current Doppler surveys and photoevaporation-induced atmospheric loss. Dynamical modeling of these systems has identified some ``supper-puffy'' planets, i.e., low mass planets with surprisingly large radii and low densities. I will describe a few particularly interesting planetary systems and discuss the implications for the formation of planets ranging from gaseous super-Earth-size planets to rocky planets the size of Mars.

  1. Planetary gear unit

    SciTech Connect

    Takahashi, S.

    1986-10-07

    This patent describes a planetary gear unit for the transmission of a motor vehicle, comprising: a first planetary gear unit which includes a pinion shaft, a planet pinion rotatably mounted on the pinion shaft, a sun gear engaging the planet pinion, and an arm member supporting the pinion shaft and having an extending portion extending to a point adjacent the sun gear; a thrust washer contacting the arm member, the thrust washer having radiating conduit means formed on a contacting surface thereof so as to communicate an inner circumference of the extending portion of the arm member with the pinion shaft, the pinion shaft having a conduit formed therein so as to communicate with the radiating conduit means with an inner surface of the planet pinion wherein the radiating conduit means further comprises uniform spaced bevel surfaces and grooves in communication with the bevel surfaces.

  2. Geochemical evidence for active tropical serpentinization in the Santa Elena Ophiolite, Costa Rica: An analog of a humid early Earth?

    NASA Astrophysics Data System (ADS)

    Sánchez-Murillo, Ricardo; Gazel, Esteban; Schwarzenbach, Esther M.; Crespo-Medina, Melitza; Schrenk, Matthew O.; Boll, Jan; Gill, Ben C.

    2014-05-01

    Serpentinization is a planetary process that has important consequences on geochemical cycles, supporting microbial activity through the formation of H2 and CH4 and having the potential to sequester atmospheric CO2. We present geochemical evidence of active serpentinization in the Santa Elena Ophiolite, Costa Rica which is sustained by peridotites with a degree of serpentinization less than 50% with no evidence of an internal heat source. Average spring water temperatures are 29.1°C. Two hyperalkaline spring systems were discovered, with a spring fluid pH up to 11.18. The fluids are characterized by low Mg (1.0-5.9 mg/L) and K (1.0-5.5 mg/L) and relative high Ca (29-167 mg/L), Na (16-27 mg/L), Cl (26-29 mg/L), hydroxide (41-63 mg/L), and carbonate (31-49 mg/L). Active CH4 (24.3% v/v) vents coupled with carbonate deposits (δ13CCO2 =-27 to -14‰; δ18OCO2 =-17 to - 6‰) also provide evidence for active serpentinization and carbonation. Isotope ratios of the alkaline fluids (δ18O = -7.9‰, δ2H = -51.4‰) and groundwater (δ18O = -7.6‰; δ2H = -48.0‰) suggests that, during base flow recession, springs are fed by groundwater circulation. Methanogenic Archaea, which comprises a relatively high percentage of the 16S rRNA gene tag sequences, suggests that biological methanogenesis may play a significant role in the system. Santa Elena's extreme varying weather results in a scenario that could be of significant importance for (a) improving the knowledge of conditions on a humid early Earth or Mars that had periodic changes in water supply, (b) revealing new insights on serpentinizing solute transport, and (c) modeling hydrogeochemical responses as a function of recharge.

  3. Planetary seismology and interiors

    NASA Technical Reports Server (NTRS)

    Toksoz, M. N.

    1979-01-01

    This report briefly summarizes knowledge gained in the area of planetary seismology in the period 1969-1979. Attention is given to the seismic instruments, the seismic environment (noise, characteristics of seismic wave propagation, etc.), and the seismicity of the moon and Mars as determined by the Apollo missions and Viking Lander experiments, respectively. The models of internal structures of the terrestrial planets are discussed, with the earth used for reference.

  4. NASA Planetary Rover Program

    NASA Technical Reports Server (NTRS)

    Lavery, David; Bedard, Roger J., Jr.

    1991-01-01

    The NASA Planetary Rover Project was initiated in 1989. The emphasis of the work to date has been on development of autonomous navigation technology within the context of a high mobility wheeled vehicle at the JPL and an innovative legged locomotion concept at Carnegie Mellon University. The status and accomplishments of these two efforts are discussed. First, however, background information is given on the three rover types required for the Space Exploration Initiative (SEI) whose objective is a manned mission to Mars.

  5. Galactic planetary science

    PubMed Central

    Tinetti, Giovanna

    2014-01-01

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets—mainly radial velocity and transit—or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even ‘just’ in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current ‘understanding’. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy. PMID:24664916

  6. Galactic planetary science.

    PubMed

    Tinetti, Giovanna

    2014-04-28

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets--mainly radial velocity and transit--or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even 'just' in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current 'understanding'. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy.

  7. Planetary gear train

    SciTech Connect

    Hiraiwa, K.

    1988-10-04

    A planetary gear train is described comprising: an input member; an output member; a first planetary gear set including a first sun gear, a first ring gear, and a first pinion carrier rotatably supporting first planet pinions; a secondary planetary gear set including a second sun gear, and second ring gear and a second pinion carrier rotatably supporting second planet pinions; first drive means for connecting the input member with the first ring gear; second drive means for connecting the input member with the first sun gear; third drive means for constantly connecting the first sun gear with the second sun gear and establishing a force transmitting positive drive from the first sun gear to the second sun gear, whereby the first sun gear rotates at a speed different from the second sun gear; first brake means for braking the second sun gear; second brake means for braking the second pinion carrier; fourth drive means for connecting the second ring gear with the output member and providing a first speed ratio therebetween; and fifth drive means for connecting the first pinion carrier with the output member and providing a second speed ratio therebetween, the second speed ratio being different from the first speed ratio.

  8. Planetary System Physics

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    2002-01-01

    Contents include a summary of publications followed by their abstracts titeled: 1. On microlensing rates and optical depth toward the Galactic center. 2. Newly discovered brown dwarfs not seen in microlensing timescale frequency distribution? 3. Origin and evolution of the natural satellites. 4. Probing the structure of the galaxy with microlensing. 5. Tides, Encyclopedia of Astronomy and Astrophysics. 6. The Puzzle of the Titan-Hyperion 4:3 Orbital Resonance. 7. On the Validity of the Coagulation Equation and the Nature of Runaway Growth. 8. Making Hyperion. 9. The MESSENGER mission to Mercury: Scientific objectives and implementation. 10. A Survey of Numerical Solutions to the Coagulation. 11. Probability of detecting a planetary companion during a microlensing event. 12. Dynamics and origin of the 2:l orbital resonances of the GJ876 planets. 13. Planetary Interior Structure Revealed by Spin Dynamics. 14. A primordial origin of the Laplace relation among the Galilean Satellites. 15. A procedure for determining the nature of Mercury's core. 16. Secular evolution of hierarchical planetary systems. 17. Tidally induced volcanism. 18. Extrasolar planets and mean motion resonances. 19. Comparison of a ground-based microlensing search for planets with a search from space.

  9. Halos around planetary nebulae

    NASA Technical Reports Server (NTRS)

    Jewitt, D. C.; Danielson, G. E.; Kupferman, P. N.

    1986-01-01

    Preliminary results of a CCD survey designed to detect and investigate faint halos around planetary nebulae are reported. A TI 800 x 800 pixel CCD was used to take deep exposures of 44 planetary nebulae. The exposures were obtained through an H-alpha filter at the Cassegrain focus of the Palomar 1.5 m telescope. Spatial resolutions of 1 to 2 arcsec were obtained across 400 arcsec wide fields. The images, which are in many cases considerably deeper than any previously taken, reveal numerous planetary nebula halos. About two-thirds of the studied nebulae possess extensive outer halos, here defined as any extended emission beyond the 10 percent isophote. Ionized sulphur electron density measurements show that in some nebulae, the mass in the halo is comparable to the mass contained in the primary H II region. The data have been used to place constraints on the mode of origin of the halos. It is likely that the halos originate either by dynamical separation of a single ejected shell of gas or by the ejection of two or more such shells from the central star. It is possible but less likely that the halos are caused by excitation of the preplanetary stellar wind and improbable that the halos represent reflection nebulae.

  10. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  11. Evaluating Handheld X-Ray Fluorescence (XRF) Technology in Planetary Exploration: Demonstrating Instrument Stability and Understanding Analytical Constraints and Limits for Basaltic Rocks

    NASA Technical Reports Server (NTRS)

    Young, K. E.; Hodges, K. V.; Evans, C. A.

    2012-01-01

    While large-footprint X-ray fluorescence (XRF) instruments are reliable providers of elemental information about geologic samples, handheld XRF instruments are currently being developed that enable the collection of geochemical data in the field in short time periods (approx.60 seconds) [1]. These detectors are lightweight (1.3kg) and can provide elemental abundances of major rock forming elements heavier than Na. While handheld XRF detectors were originally developed for use in mining, we are working with commercially available instruments as prototypes to explore how portable XRF technology may enable planetary field science [2,3,4]. If an astronaut or robotic explorer visited another planetary surface, the ability to obtain and evaluate geochemical data in real-time would be invaluable, especially in the high-grading of samples to determine which should be returned to Earth. We present our results on the evaluation of handheld XRF technology as a geochemical tool in the context of planetary exploration.

  12. Cosmological Effects in Planetary Science

    NASA Technical Reports Server (NTRS)

    Blume, H. J.; Wilson, T. L.

    2010-01-01

    In an earlier discussion of the planetary flyby anomaly, a preliminary assessment of cosmological effects upon planetary orbits exhibiting the flyby anomaly was made. A more comprehensive investigation has since been published, although it was directed at the Pioneer anomaly and possible effects of universal rotation. The general subject of Solar System anomalies will be examined here from the point of view of planetary science.

  13. Universal planetary tectonics (supertectonics)

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2009-04-01

    Universal planetary tectonics (supertectonics) G. Kochemasov IGEM of the Russian Academy of Sciences, Moscow, Russia, kochem.36@mail.ru The wave planetology [1-3 & others] proceeds from the following: "planetary structures are made by orbits and rotations". A uniform reason makes uniform structures. Inertia-gravity waves arising in planetary bodies due to their movements in Keplerian elliptical orbits with periodically changing accelerations warp these bodies in such way that they acquire polyhedron shapes (after interference of standing waves of four directions). Strong Newtonian gravity makes bodies larger than ~400 to 500 km in diameter globular and polyhedra are rarely seen. Only geomorphologic, geologic and geophysical mapping can develop these hidden structures. But small bodies, normally less than ~ 300 to 400 km in diameter, often show parts of the polyhedra, rarely fully developed forms (the asteroid Steins and satellite Amalthea present rather perfect forms of "diamond"). Depending on warping wavelengths (they make harmonics) various Plato's figures superimposed on each other can be distinguished. The fundamental wave 1 produces a tetrahedron, intrinsically dichotomic figure in which a vertex (contraction) always is opposed to a face (expansion). From the recent examples the best is the saturnian northern hexagon (a face) opposed to the southern hurricane (a vertex). The first overtone wave 2 is responsible for creation of structural octahedra. Whole ‘diamonds" and their parts are known [4, 5]. Other overtones produce less developed (because of smaller wave amplitudes) planetary shapes complicating main forms. Thus, the first common structural peculiarity of planetary bodies is their polyhedron nature. Not less important is the second common structural peculiarity. As all globular or smaller more or less isometric bodies rotate, they have an angular momentum. It is inevitably different in tropic and extra-tropic belts having uneven radii or distances to

  14. Thermal Modeling on Planetary Regoliths

    NASA Technical Reports Server (NTRS)

    Hale, A. S.; Hapke, B.W.

    2002-01-01

    The thermal region of the spectrum is one of special interest in planetary science as it is the only region where planetary emission is significant. Studying how planetary surfaces emit in the thermal infrared can tell us about their physical makeup and chemical composition, as well as their temperature profile with depth. This abstract will discuss a model of thermal energy transfer in planetary regoliths on airless bodies which includes both conductive and radiative processes while including the time dependence of the solar input function.

  15. Thermal Modeling on Planetary Regoliths

    NASA Technical Reports Server (NTRS)

    Hale, A. S.; Hapke, B.W.

    2002-01-01

    The thermal region of the spectrum is one of special interest in planetary science as it is the only region where planetary emission is significant. Studying how planetary surfaces emit in the thermal infrared can tell us about their physical makeup and chemical composition, as well as their temperature profile with depth. This abstract will discuss a model of thermal energy transfer in planetary regoliths on airless bodies which includes both conductive and radiative processes while including the time dependence of the solar input function.

  16. Scientific and technical services for development of planetary quarantine measures for automated spacecraft

    NASA Technical Reports Server (NTRS)

    Bacon, E. J.

    1972-01-01

    The progress is reported for all 13 tasks of the program to develop planetary quarantine measures. Results of analyses of the following are included: activities of the SSB, Viking sterilization cycle, Jovian parameters, and review of the Martian data.

  17. Leveraging Knowledge: Impact on Low Cost Planetary Mission Design.

    ERIC Educational Resources Information Center

    Momjian, Jennifer

    This paper discusses innovations developed by the Jet Propulsion Laboratory (JPL) librarians to reduce the information query cycle time for teams planning low-cost, planetary missions. The first section provides background on JPL and its library. The second section addresses the virtual information environment, including issues of access, content,…

  18. Dynamics of planetary rings

    NASA Astrophysics Data System (ADS)

    Araki, S.

    1991-02-01

    The modeling of the dynamics of particle collisions within planetary rings is discussed. Particles in the rings collide with one another because they have small random motions in addition to their orbital velocity. The orbital speed is roughly 10 km/s, while the random motions have an average speed of about a tenth of a millimeter per second. As a result, the particle collisions are very gentle. Numerical analysis and simulation of the ring dynamics, performed with the aid of a supercomputer, is outlined.

  19. Planetary cratering mechanics

    NASA Technical Reports Server (NTRS)

    Okeefe, John D.; Ahrens, Thomas J.

    1992-01-01

    To obtain a quantitative understanding of the cratering process over a broad range of conditions, we have numerically computed the evolution of impact induced flow fields and calculated the time histories of the major measures of crater geometry (e.g., depth diameter, lip height ...) for variations in planetary gravity (0 to 10 exp 9 cm/sq seconds), material strength (0 to 140 kbar), thermodynamic properties, and impactor radius (0.05 to 5000 km). These results were fit into the framework of the scaling relations of Holsapple and Schmidt (1987). We describe the impact process in terms of four regimes: (1) penetration; (2) inertial; (3) terminal; and (4) relaxation.

  20. Planetary entry experiments

    NASA Technical Reports Server (NTRS)

    Craig, Roger A.

    1994-01-01

    The final report summarizes the results from three research areas: (1) window design for the radiometric measurement of the forebody radiative heating experienced by atmospheric entry spaceraft; (2) survey of the current understanding of chemical species on selected solar system bodies and assess the importance of measurements with regard to vehicle environment and with regard to understanding of planetary atmospheres with emphasis on Venus, Mars, and Titan; and (3) measure and analyze the radiation (VUV to near-IR) from the shock heated gas cap of a blunt body in an Ames arc Jet wind-tunnel facility.

  1. Robotic Planetary Drill Tests

    NASA Technical Reports Server (NTRS)

    Glass, Brian J.; Thompson, S.; Paulsen, G.

    2010-01-01

    Several proposed or planned planetary science missions to Mars and other Solar System bodies over the next decade require subsurface access by drilling. This paper discusses the problems of remote robotic drilling, an automation and control architecture based loosely on observed human behaviors in drilling on Earth, and an overview of robotic drilling field test results using this architecture since 2005. Both rotary-drag and rotary-percussive drills are targeted. A hybrid diagnostic approach incorporates heuristics, model-based reasoning and vibration monitoring with neural nets. Ongoing work leads to flight-ready drilling software.

  2. Planetary Spatial Analyst

    NASA Technical Reports Server (NTRS)

    Keely, Leslie

    2008-01-01

    This is a status report for the project entitled Planetary Spatial Analyst (PSA). This report covers activities from the project inception on October 1, 2007 to June 1, 2008. Originally a three year proposal, PSA was awarded funding for one year and required a revised work statement and budget. At the time of this writing the project is well on track both for completion of work as well as budget. The revised project focused on two objectives: build a solid connection with the target community and implement a prototype software application that provides 3D visualization and spatial analysis technologies for that community. Progress has been made for both of these objectives.

  3. Volcanoes. A planetary perspective.

    NASA Astrophysics Data System (ADS)

    Francis, P.

    In this book, the author gives an account of the familiar violent aspects of volcanoes and the various forms that eruptions can take. He explores why volcanoes exist at all, why volcanoes occur where they do, and how examples of major historical eruptions can be interpreted in terms of physical processes. Throughout he attempts to place volcanism in a planetary perspective, exploring the pre-eminent role of submarine volcanism on Earth and the stunning range of volcanic phenomena revealed by spacecraft exploration of the solar system.

  4. Planetary geological processes

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly M. C.; Solomonidou, Anezina

    2014-11-01

    In this introduction to planetary geology, we review the major geologic processes affecting the solid bodies of the solar system, namely volcanism, tectonism, impact cratering, and erosion. We illustrate the interplay of these processes in different worlds, briefly reviewing how they affect the surfaces of the Earth's Moon, Mercury, Venus and Mars, then focusing on two very different worlds: Jupiter's moon Io, the most volcanically active object in the solar system, and Saturn's moon Titan, where the interaction between a dense atmosphere and the surface make for remarkably earth-like landscapes despite the great differences in surface temperature and composition.

  5. Chemical kinetics and modeling of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    1990-01-01

    A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.

  6. The final fate of planetary systems

    NASA Astrophysics Data System (ADS)

    Gaensicke, Boris

    2015-12-01

    The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly

  7. Planetary image conversion task

    NASA Technical Reports Server (NTRS)

    Martin, M. D.; Stanley, C. L.; Laughlin, G.

    1985-01-01

    The Planetary Image Conversion Task group processed 12,500 magnetic tapes containing raw imaging data from JPL planetary missions and produced an image data base in consistent format on 1200 fully packed 6250-bpi tapes. The output tapes will remain at JPL. A copy of the entire tape set was delivered to US Geological Survey, Flagstaff, Ariz. A secondary task converted computer datalogs, which had been stored in project specific MARK IV File Management System data types and structures, to flat-file, text format that is processable on any modern computer system. The conversion processing took place at JPL's Image Processing Laboratory on an IBM 370-158 with existing software modified slightly to meet the needs of the conversion task. More than 99% of the original digital image data was successfully recovered by the conversion task. However, processing data tapes recorded before 1975 was destructive. This discovery is of critical importance to facilities responsible for maintaining digital archives since normal periodic random sampling techniques would be unlikely to detect this phenomenon, and entire data sets could be wiped out in the act of generating seemingly positive sampling results. Reccomended follow-on activities are also included.

  8. Planetary Ringmoon Systems

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.; Morrison, David (Technical Monitor)

    1994-01-01

    The last decade has seen an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Much of the structure revealed was thoroughly puzzling and fired the imagination of workers in a variety of disciplines. Consequently, we have also seen steady progress in our understanding of these systems as our intuitions (and our computers) catch up with the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron to-several-meter size particles which comprise ring systems (refs 1-5). The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems and families of regular satellites are invariably found together, and there is an emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system.

  9. Planetary protection: lessons learned

    NASA Astrophysics Data System (ADS)

    Perek, L.

    Planetary protection is a very wide subject because of the variety of physical conditions on individual planets and their moons. At present, we have good photographs or imagery, as well as other evidence, from most planets and from a selection of their moons. The most important factor is the presence or absence of any form of life. Material samples are available from the Moon and possibly, in the form of a few meteorites, from Mars. The danger of contamination has been recognized in the past and it became clear that some measures would have to be taken. The adoption of measures will have to be universal in mssions to planets and their moons because for an undesirablei contamination to occur, one failed measure of protection may be enough. The question is, if we can learn from experience gained in the last forty years in adopting laws, rules or unbinding recommendations for space activities. Several examples will be discussed, such as the amount of knowledge at a time when international treaties on space law were adopted, the consequences of the failed discussion at the United Nations on the definition of outer space, or of the break-up of Cosmos 954. Special attention will be devoted to the ongoing discussion of space debris in the UN Committee on the Peaceful Uses of Outer Space and its relevance for planetary protection, to the general compliance with the Registration Convention and to the experience gained with the recommendation to re-orbit geostationary satellites.

  10. Planetary protection: lessons learned

    NASA Astrophysics Data System (ADS)

    Perek, L.

    2004-01-01

    Planetary protection is a very wide subject because of the variety of physical conditions on individual planets and their moons. At present, we have good photographs or imagery, as well as other evidence, from most planets and from a selection of their moons. The most important factor is the presence or absence of any form of life. Material samples are available from the Moon and possibly, in the form of a few meteorites, from Mars. The danger of contamination has been recognized in the past and it became clear that some measures would have to be taken. The adoption of measures will have to be universal in missions to planets and their moons because for an undesirable contamination to occur, one failed measure of protection may be enough. The question is, if we can learn from experience gained in the last forty years in adopting laws, rules or unbinding recommendations for space activities. Several examples will be discussed, such as the amount of knowledge at a time when international treaties on space law were adopted, the consequences of the failed discussion at the United Nations on the definition of outer space, or of the break-up of Cosmos 954. Special attention will be devoted to the ongoing discussion of space debris in the UN Committee on the Peaceful Uses of Outer Space and its relevance for planetary protection, to the general compliance with the Registration Convention and to the experience gained with the recommendation to re-orbit geostationary satellites.

  11. Online Planetary Science Courses at Athabasca University

    NASA Astrophysics Data System (ADS)

    Connors, Martin; Munyikwa, Ken; Bredeson, Christy

    2016-01-01

    Athabasca University offers distance education courses in science, at freshman and higher levels. It has a number of geology and astronomy courses, and recently opened a planetary science course as the first upper division astronomy course after many years of offering freshman astronomy. Astronomy 310, Planetary Science, focuses on process in the Solar System on bodies other than Earth. This process-oriented course uses W. F. Hartmann's "Moons and Planets" as its textbook. It primarily approaches the subject from an astronomy and physics perspective. Geology 415, Earth's Origin and Early Evolution, is based on the same textbook, but explores the evidence for the various processes, events, and materials involved in the formation and evolution of Earth. The course provides an overview of objects in the Solar System, including the Sun, the planets, asteroids, comets, and meteoroids. Earth's place in the solar system is examined and physical laws that govern the motion of objects in the universe are looked at. Various geochemical tools and techniques used by geologists to reveal and interpret the evidence for the formation and evolution of bodies in the solar system as well as the age of earth are also explored. After looking at lines of evidence used to reconstruct the evolution of the solar system, processes involved in the formation of planets and stars are examined. The course concludes with a look at the origin and nature of Earth's internal structure. GEOL415 is a senior undergraduate course and enrols about 15-30 students annually. The courses are delivered online via Moodle and student evaluation is conducted through assignments and invigilated examinations.

  12. Planetary Cores Flows Driven by Mantle Libration

    NASA Astrophysics Data System (ADS)

    Noir, J.; Aurnou, J.; Wicht, J.

    2007-12-01

    We investigate, via a set of laboratory and numerical experiments, the flow induced inside a spherical fluid cavity by torsional oscillation of the outer shell. Our goal is to produce models of libration-driven flows within planetary cores and subsurface oceans. Such models will improve our understanding of a number of planetary bodies including Mercury, Europa, Io, Callisto, Ganymede and the Earth's Moon. Here we focus on the case of a spherical shell with either a small inner core or no inner core; moderate planetary rotation rate (Ekman number E = 10- 4); and libration frequency equal to the planetary rotation frequency ("synchronous libration"). We vary only the non-dimensional amplitude of libration α, defined as α=Δ φ (2 π flib) / Ømega, where Δ φ is the total angular displacement, flib is the libration frequency and Ømega is the background angular rotation rate. Different core flow regimes are observed as α is increased. For a small amplitude of libration (α \\ll 1)), the oscillatory motion of the outer boundary drives laminar flows that are well described as inertial modes and waves. For α ~ 0.5, azimuthal roll instabilities periodically develop and decay along the outer shell boundary during each libration cycle. These instabilities tend to develop when the outer shell is decelerating and decay when it is accelerating. By further increasing α, the flow pattern transitions from axisymmetric rolls (m=0) to wavy rolls (m ≠ 0), and then to turbulent flow. Extrapolating our present results to Mercury suggests that mantle libration can drive large-scale instabilities in its liquid metal core. The authors wish to the thank NASA's PG&G and PME Programs for reasearch funding under grant #NNG0697G.

  13. From Geochemistry to Biochemistry: Simulating Prebiotic Chemistry Driven by Geochemical Gradients in Alkaline Hydrothermal Vents

    NASA Astrophysics Data System (ADS)

    Barge, Laurie

    2016-07-01

    Planetary water-rock interfaces generate energy in the form of redox, pH, and thermal gradients, and these disequilibria are particularly focused in hydrothermal vent systems where the reducing, heated hydrothermal fluid feeds back into the more oxidizing ocean. Alkaline hydrothermal vents have been proposed as a likely location for the origin of life on the early Earth due to various factors: including the hydrothermal pH / Eh gradients that resemble the ubiquitous electrical / proton gradients in biology, the catalytic hydrothermal precipitates that resemble inorganic catalysts in enzymes, and the presence of electron donors and acceptors in hydrothermal systems (e.g. H2 + CH4 and CO2) that are thought to have been utilized in the earliest metabolisms. Of particular importance for the emergence of metabolism are the mineral "chimneys" that precipitate at the vent fluid / seawater interface. Hydrothermal chimneys are flow-through chemical reactors that form porous and permeable inorganic membranes transecting geochemical gradients; in some ways similar to biological membranes that transect proton / ion gradients and harness these disequilibria to drive metabolism. These emergent chimney structures in the far-from-equilibrium system of the alkaline vent have many properties of interest to the origin of life that can be simulated in the laboratory: for example, they can generate electrical energy and drive redox reactions, and produce catalytic minerals (in particular the metal sulfides and iron oxyhydroxides - "green rust") that can facilitate chemical reactions towards proto-metabolic cycles and biosynthesis. Many of the factors prompting interest in alkaline hydrothermal vents on Earth may also have been present on early Mars, or even presently within icy worlds such as Europa or Enceladus - thus, understanding the disequilibria and resulting prebiotic chemistry in these systems can be of great use in assessing the potential for other environments in the Solar

  14. Europlanet Research Infrastructure: Planetary Simulation Facilities

    NASA Astrophysics Data System (ADS)

    Davies, G. R.; Mason, N. J.; Green, S.; Gómez, F.; Prieto, O.; Helbert, J.; Colangeli, L.; Srama, R.; Grande, M.; Merrison, J.

    2008-09-01

    physical properties of ice samples formed under planetary conditions to assess how rheology varies with pressure and temperature and grain size to gain a far better understanding of how tectonics may operate on icy moons. Hot planetary surfaces simulation chamber at DLR The planetary simulation chamber is to study the behaviour of planetary analogue materials on the surface of hot (airless) bodies in the solar system. Samples can be heated up to temperatures of 500°C simulating conditions found on the surface of Mercury and Venus. This enables highly accurate thermal emission measurements using the integrated infrared spectrometer and calibrated sources. Thermal gradients can be applied to samples to simulate diurnal thermal cycles and examine thermal stresses in materials. The chamber can be placed under vacuum or purged with gas. In addition, to the high temperature chamber a number of further planetary simulation chambers are available equipped with LIBS and Raman-spectroscopy equipment. Dust analogue simulation chamber at INAF/OACN This facility produces and characterises dust analogues (arc discharge, laser ablation, grinding of minerals, ices) in a variety of simulation chambers under variable pressure (10-6 - 10-3 mbar), temperature (80 - 330 K) and gas composition. Dust and analogues are characterised by a variety of Spectroscopic (absorption, transmission, diffuse-specular reflectance) and imaging techniques (SEM) and can be subjected to thermal annealing, ion bombardment and UV irradiation. Dust accelerator facility at Max Planck Institüt Nuclear Physics, Heidelberg. This facility allows the investigation of hypervelocity dust impacts onto various materials. Dust grain materials from nano to micron sizes are accelerated using a 2 MV Vande- Graaff to velocities between 1 and 60 km/s comparable to the planetary rings of the giant gas planets and impact ejecta processes on the surface of small bodies (asteroids, comets) as well as moons and planetary surfaces

  15. Fourier spectroscopy and planetary research

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.; Kunde, V. G.

    1974-01-01

    The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, the Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered and the prospects and limitations of FTS for planetary research in the forthcoming years are discussed.

  16. Circumstellar disks and planetary formation

    NASA Astrophysics Data System (ADS)

    Huélamo, N.

    2017-03-01

    Circumstellar disks are very common around young intermediate-, low-mass stars, and brown dwarfs. They are the cradle of planetary systems, although the mechanism to form planets is still unknown. In this text I review some advances in the field of circumstellar disks and planetary formation coming from observations.

  17. Reports of planetary astronomy, 1991

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A collection is presented of summaries designed to provide information about scientific research projects conducted in the Planetary Astronomy Program in 1990 and 1991, and to facilitate communication and coordination among concerned scientists and interested persons in universities, government, and industry. Highlights of recent accomplishments in planetary astronomy are included.

  18. Lunar and Planetary Science XXXIV

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The 34th Lunar and Planetary Science Conference was held March 17-21, 2003. Topics included planetary exploration, crater research on Mars, Earth, Moon, and other planets or satellites, imaging techniques and image analysis, age determination, albedo studies, petrographic studies, isotope composition studies, instrument design, sampling methods, landform analysis, asteroids, impact analysis, impact melts, and related research.

  19. The Birth of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1997-01-01

    Models of planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large- enough to gravitationally trap substantial quantities of gas. Another potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  20. The International Planetary Data Alliance

    NASA Astrophysics Data System (ADS)

    Sarkissian, A.; Crichton, D. J.; Hughes, J. S.; Heather, D.; Martinez, S.; Beebe, R.; Neakrase, L. D. V.; Yamamoto, Y.; Capria, M. T.; Krishna, B. G.

    2013-09-01

    The International Planetary Data Alliance (IPDA) is an international collaboration of space agencies with a mission of providing access to scientific data returned from solar system missions archived at international data centers. In order to improve access and share scientific data, the IPDA was founded to develop data and software standards. The IPDA has focused on promoting standards that drive common methods for collecting and describing planetary science data. An initial starting point for developing such a standard has been the internationalization of NASA's Planetary Data System (PDS) standard, which has become the de-facto archival data standard. Given the demands of supporting more capable and international missions and collaborations, the Planetary Data System, in partnership with the IPDA, has embarked on developing a next generation data standard and system called PDS4. Significant progress has been made on PDS4 and early adopters are beginning to use the emerging standard on new planetary science missions.

  1. The Birth of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1997-01-01

    Models of planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large- enough to gravitationally trap substantial quantities of gas. Another potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  2. Planetary Doppler Imaging

    NASA Astrophysics Data System (ADS)

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  3. Derivation of a planetary ionospheric storm index

    NASA Astrophysics Data System (ADS)

    Gulyaeva, T. L.; Stanislawska, I.

    2008-09-01

    The planetary ionospheric storm index, Wp, is deduced from the numerical global ionospheric GPS-IONEX maps of the vertical total electron content, TEC, for more than half a solar cycle, 1999-2008. The TEC values are extracted from the 600 grid points of the map at latitudes 60° N to 60° S with a step of 5° and longitudes 0° to 345° E with a step of 15° providing the data for 00:00 to 23:00 h of local time. The local effects of the solar radiant energy are filtered out by normalizing of the TEC in terms of the solar zenith angle χ at a particular time and the local noon value χ0. The degree of perturbation, DTEC, is computed as log of TEC relative to quiet reference median for 27 days prior to the day of observation. The W-index map is generated by segmentation of DTEC with the relevant thresholds specified earlier for foF2 so that 1 or -1 stands for the quiet state, 2 or -2 for the moderate disturbance, 3 or -3 for the moderate ionospheric storm, and 4 or -4 for intense ionospheric storm at each grid point of the map. The planetary ionospheric storm Wp index is obtained from the W-index map as a latitudinal average of the distance between maximum positive and minimum negative W-index weighted by the latitude/longitude extent of the extreme values on the map. The threshold Wp exceeding 4.0 index units and the peak value Wpmax≥6.0 specify the duration and the power of the planetary ionosphere-plasmasphere storm. It is shown that the occurrence of the Wp storms is growing with the phase of the solar cycle being twice as much as the number of the magnetospheric storms with Dst≤-100 nT and Ap≥100 nT.

  4. Planetary habitability: lessons learned from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Preston, Louisa J.; Dartnell, Lewis R.

    2014-01-01

    Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known ones which require greater study, are incorporated to inform on the astrobiological potential of Venus, Mars, Europa, Enceladus and Titan. For example, the possibility of an aerial habitable zone on Venus has been hypothesized based on studies of life at high-altitudes in the terrestrial atmosphere. We also demonstrate why many different terrestrial analogue sites are required to satisfactorily assess the habitability of the changing environmental conditions throughout Martian history, and recommend particular sites for different epochs or potential niches. Finally, habitable zones within the aqueous environments of the icy moons of Europa and Enceladus and potentially in the hydrocarbon lakes of Titan are discussed and suitable analogue sites proposed. It is clear from this review that a number of terrestrial analogue sites can be applied to multiple planetary bodies, thereby increasing their value for astrobiological exploration. For each analogue site considered here, we summarize the pertinent physiochemical environmental features they offer and critically assess the fidelity with which

  5. An integral approach to investigate planetary cores

    NASA Astrophysics Data System (ADS)

    Fei, Y.

    2012-12-01

    shockwave compression to determine density, sound velocity, and melting of core materials up to liquid outer core conditions. The integration of the static and dynamic compression data provides an extensive dataset over a wide pressure and temperature range that is necessary for establishing a comprehensive model of the planetary cores, providing the best fit to the geophysical, cosmochemial, and geochemical observations.

  6. Seasonal constraints on inferred planetary heat content

    NASA Astrophysics Data System (ADS)

    McKinnon, Karen A.; Huybers, Peter

    2016-10-01

    Planetary heating can be quantified using top of the atmosphere energy fluxes or through monitoring the heat content of the Earth system. It has been difficult, however, to compare the two methods with each other because of biases in satellite measurements and incomplete spatial coverage of ocean observations. Here we focus on the the seasonal cycle whose amplitude is large relative to satellite biases and observational errors. The seasonal budget can be closed through inferring contributions from high-latitude oceans and marginal seas using the covariance structure of National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM1). In contrast, if these regions are approximated as the average across well-observed regions, the amplitude of the seasonal cycle is overestimated relative to satellite constraints. Analysis of the same CESM1 simulation indicates that complete measurement of the upper ocean would increase the magnitude and precision of interannual trend estimates in ocean heating more than fully measuring the deep ocean.

  7. Planetary exploration sensor systems

    NASA Technical Reports Server (NTRS)

    Saunders, R. S.

    1981-01-01

    Most of the instruments that have been used in planetary exploration have been either spectrometers or imaging devices. Instruments of these types are being developed for the Galileo and VOIR (Venus Orbiting Imaging Radar) missions. Galileo will take advantage of new CCD (charge-coupled device) technology, and VOIR will use techniques of synthetic aperture radar developed for Seasat. For determining the macrostructure of mineral resources, the best approach is believed to involve acoustic imaging, essentially a seismic data processing technique. Determinations of microstructure would require a light microscope and an electron microscope. For determining the nature and form of volatiles, a differential scanning calorimeter could be used. To determine the mineral composition, an electron beam microprobe with X-ray fluorescence and spectroscopy would be used.

  8. Future planetary television cameras

    NASA Technical Reports Server (NTRS)

    Norris, D. D.; Landauer, F. P.

    1976-01-01

    The evolution of planetary slow-scan vidicon cameras started with the exploratory flyby mission to Mars in 1965, and has continued through the planned launch of the Mariner Jupiter/Saturn 1977 Mission. To date, the camera performance has been constrained by limited spacecraft capabilities rather than driven by desires of experimenters. The paper traces this evolution for a generation of camera using charge-coupled device (CCD) sensors, which have greater capability within spacecraft weight and power constraints. Projections are given of scientific objectives for the CCD cameras, and it is shown how these objectives will drive the camera performance, data rates, on-board processing, pointing accuracy, and other spacecraft system parameters.

  9. Photochemistry in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Graedel, T. E.

    1981-01-01

    Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.

  10. Rheology of planetary ices

    SciTech Connect

    Durham, W.B.; Kirby, S.H.; Stern, L.A.

    1996-04-24

    The brittle and ductile rheology of ices of water, ammonia, methane, and other volatiles, in combination with rock particles and each other, have a primary influence of the evolution and ongoing tectonics of icy moons of the outer solar system. Laboratory experiments help constrain the rheology of solar system ices. Standard experimental techniques can be used because the physical conditions under which most solar system ices exist are within reach of conventional rock mechanics testing machines, adapted to the low subsolidus temperatures of the materials in question. The purpose of this review is to summarize the results of a decade-long experimental deformation program and to provide some background in deformation physics in order to lend some appreciation to the application of these measurements to the planetary setting.

  11. Planetary Space Weather

    NASA Astrophysics Data System (ADS)

    Grande, M.

    2012-04-01

    Invited Talk - Space weather at other planets While discussion of space weather effects has so far largely been confined to the near-Earth environment, there are significant present and future applications to the locations beyond, and to other planets. Most obviously, perhaps, are the radiation hazards experienced by astronauts on the way to, and on the surface of, the Moon and Mars. Indeed, the environment experienced by planetary spacecraft in transit and at their destinations is of course critical to their design and successful operation. The case of forthcoming missions to Jupiter and Europa is an exreme example. Moreover, such craft can provide information which in turn increases our understanding of geospace. Indeed, space weather may be a significant factor in the habitability of other solar system and extrasolar planets, and the ability of life to travel between them.

  12. Formation of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates.

  13. Historical Planetary Astronomy

    NASA Astrophysics Data System (ADS)

    Hockey, T. A.

    1995-12-01

    Historical planetary astronomy refers to attempts to use archival physical descriptions and depictions of the Moon and planets to help solve modern problems in planetary science. These data are usually qualitative in nature, most often coming to us in the form of telescopic observers' reports and drawings made in the seventeenth, eighteenth, and nineteenth centuries. For this reason, such data must be treated differently from more-modern photographic and digital imagery. Most useful historical records come from the telescopic (but pre-photographic) era. However, the eyewitness account, in the year 1178, of what may have been a large, crater-producing impact on the Moon, dates as the earliest historical datum applied to lunar science. The studies of lunar transient phenomena (LTPs), and of the "ashen light" on Venus, also benefit from a body of historical records. Other examples that I will discuss include attempts to determine if a periodicity exists in the appearance of major dust storms on Mars and attempts to understand the seeming periodicity of the appearance of large, white spots in the northern latitudes of Saturn. I also will discuss my own attempts to use the historical record to search for past jovian features similar to those produced by the collision of comet P/Shoemaker-Levy 9 and Jupiter in 1994. I will conclude by listing a number of "filters" through which historical data necessarily pass before becoming of use to modern astronomers. These considerations are: 1) resolution, 2) instrumentation, 3) observing conditions, 4) observing technique, 5) observers' experience, 6) observers' purpose, 7) language, and 8) observer objectivity. Recognition of them is necessary to assess the quality of historical records and their applicability to a given astronomical problem. These "filters" will be illustrated by applying them to the example problems described above.

  14. Photochemistry of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Yung, Y. L.

    2005-12-01

    The Space Age started half a century ago. Today, with the completion of a fairly detailed study of the planets of the Solar System, we have begun studying exoplanets (or extrasolar planets). The overriding question in is to ask whether an exoplanet is habitable and harbors life, and if so, what the biosignatures ought to be. This forces us to confront the fundamental question of what controls the composition of an atmosphere. The composition of a planetary atmosphere reflects a balance between thermodynamic equilibrium chemistry (as in the interior of giant planets) and photochemistry (as in the atmosphere of Mars). The terrestrial atmosphere has additional influence from life (biochemistry). The bulk of photochemistry in planetary atmospheres is driven by UV radiation. Photosynthesis may be considered an extension of photochemistry by inventing a molecule (chlorophyll) that can harvest visible light. Perhaps the most remarkable feature of photochemistry is catalytic chemistry, the ability of trace amounts of gases to profoundly affect the composition of the atmosphere. Notable examples include HOx (H, OH and HO2) chemistry on Mars and chlorine chemistry on Earth and Venus. Another remarkable feature of photochemistry is organic synthesis in the outer solar system. The best example is the atmosphere of Titan. Photolysis of methane results in the synthesis of more complex hydrocarbons. The hydrocarbon chemistry inevitably leads to the formation of high molecular weight products, giving rise to aerosols when the ambient atmosphere is cool enough for them to condense. These results are supported by the findings of the recent Cassini mission. Lastly, photochemistry leaves a distinctive isotopic signature that can be used to trace back the evolutionary history of the atmosphere. Examples include nitrogen isotopes on Mars and sulfur isotopes on Earth. Returning to the question of biosignatures on an exoplanet, our Solar System experience tells us to look for speciation

  15. Deciphering Kepler's Planetary Systems

    NASA Astrophysics Data System (ADS)

    Lithwick, Yoram

    The theory for how planetary systems form and achieve their final configuration remains highly uncertain. Until now, theories could only be tested against a single system -- the solar system. The Kepler mission, with its abundance of planetary systems, will likely prove to be a Rosetta stone. However, much remains to be deciphered. To help realize the potential of the Kepler mission, we propose to pursue the complementary tasks of characterizing the properties of the Kepler systems and developing theories to explain these properties: 1) Characterizing Kepler systems. We will characterize these planets using the transit-time-variation (TTV) signatures obtained by the mission. We have recently derived a simple expression for the TTV, and used it to derive the masses and eccentricities of a couple dozen Kepler planets. We will extend that work by applying it to many more planets, and by deriving higher-order TTV effects that will allow us to obtain more accurate measurements by breaking degeneracies. We will also use the TTV signals, as well as other observables, to infer the intrinsic orbital architecture of Kepler planets. This will form the basis for the following study. 2) Assembling Kepler systems. Informed by our above analysis, we will try to uncover how the Kepler planets were assembled onto their current orbits. Our recent work on the resonant repulsion mechanism suggests that the final assembly was shaped by a dissipative process, and we will explore that mechanism further. We will also run simulations to test the conjecture that planetesimals were the dissipative agent responsible for final assembly -- just as they are thought to be responsible for the assembly of the planets in the outer solar system

  16. Planetary heat flow measurements.

    PubMed

    Hagermann, Axel

    2005-12-15

    The year 2005 marks the 35th anniversary of the Apollo 13 mission, probably the most successful failure in the history of manned spaceflight. Naturally, Apollo 13's scientific payload is far less known than the spectacular accident and subsequent rescue of its crew. Among other instruments, it carried the first instrument designed to measure the flux of heat on a planetary body other than Earth. The year 2005 also should have marked the launch of the Japanese LUNAR-A mission, and ESA's Rosetta mission is slowly approaching comet Churyumov-Gerasimenko. Both missions carry penetrators to study the heat flow from their target bodies. What is so interesting about planetary heat flow? What can we learn from it and how do we measure it?Not only the Sun, but all planets in the Solar System are essentially heat engines. Various heat sources or heat reservoirs drive intrinsic and surface processes, causing 'dead balls of rock, ice or gas' to evolve dynamically over time, driving convection that powers tectonic processes and spawns magnetic fields. The heat flow constrains models of the thermal evolution of a planet and also its composition because it provides an upper limit for the bulk abundance of radioactive elements. On Earth, the global variation of heat flow also reflects the tectonic activity: heat flow increases towards the young ocean ridges, whereas it is rather low on the old continental shields. It is not surprising that surface heat flow measurements, or even estimates, where performed, contributed greatly to our understanding of what happens inside the planets. In this article, I will review the results and the methods used in past heat flow measurements and speculate on the targets and design of future experiments.

  17. HUBBLE'S PLANETARY NEBULA GALLERY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [Top left] - IC 3568 lies in the constellation Camelopardalis at a distance of about 9,000 light-years, and has a diameter of about 0.4 light-years (or about 800 times the diameter of our solar system). It is an example of a round planetary nebula. Note the bright inner shell and fainter, smooth, circular outer envelope. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Top center] - NGC 6826's eye-like appearance is marred by two sets of blood-red 'fliers' that lie horizontally across the image. The surrounding faint green 'white' of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the center of the green oval) drives a fast wind into older material, forming a hot interior bubble which pushes the older gas ahead of it to form a bright rim. (The star is one of the brightest stars in any planetary.) NGC 6826 is 2,200 light- years away in the constellation Cygnus. The Hubble telescope observation was taken Jan. 27, 1996 with the Wide Field and Planetary Camera 2. Credits: Bruce Balick (University of Washington), Jason Alexander (University of Washington), Arsen Hajian (U.S. Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence, Italy), Patrizio Patriarchi (Arcetri Observatory, Italy) and NASA [Top right ] - NGC 3918 is in the constellation Centaurus and is about 3,000 light-years from us. Its diameter is about 0.3 light-year. It shows a roughly spherical outer envelope but an elongated inner balloon inflated by a fast wind from the hot central star, which is starting to break out of the spherical envelope at the top and bottom of the image. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Bottom left] - Hubble 5 is a striking example of a 'butterfly' or bipolar (two-lobed) nebula. The heat generated by fast winds causes

  18. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  19. HUBBLE'S PLANETARY NEBULA GALLERY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [Top left] - IC 3568 lies in the constellation Camelopardalis at a distance of about 9,000 light-years, and has a diameter of about 0.4 light-years (or about 800 times the diameter of our solar system). It is an example of a round planetary nebula. Note the bright inner shell and fainter, smooth, circular outer envelope. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Top center] - NGC 6826's eye-like appearance is marred by two sets of blood-red 'fliers' that lie horizontally across the image. The surrounding faint green 'white' of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the center of the green oval) drives a fast wind into older material, forming a hot interior bubble which pushes the older gas ahead of it to form a bright rim. (The star is one of the brightest stars in any planetary.) NGC 6826 is 2,200 light- years away in the constellation Cygnus. The Hubble telescope observation was taken Jan. 27, 1996 with the Wide Field and Planetary Camera 2. Credits: Bruce Balick (University of Washington), Jason Alexander (University of Washington), Arsen Hajian (U.S. Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence, Italy), Patrizio Patriarchi (Arcetri Observatory, Italy) and NASA [Top right ] - NGC 3918 is in the constellation Centaurus and is about 3,000 light-years from us. Its diameter is about 0.3 light-year. It shows a roughly spherical outer envelope but an elongated inner balloon inflated by a fast wind from the hot central star, which is starting to break out of the spherical envelope at the top and bottom of the image. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Bottom left] - Hubble 5 is a striking example of a 'butterfly' or bipolar (two-lobed) nebula. The heat generated by fast winds causes

  20. Geochemical Interpretation of Collision Volcanism

    NASA Astrophysics Data System (ADS)

    Pearce, Julian

    2014-05-01

    Collision volcanism can be defined as volcanism that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision volcanics are easily misinterpreted as being of volcanic arc, extensional or mantle plume origin. There are many types of collision volcanic province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision volcanism resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision volcanism. The latter can be subdivided into orogenic volcanism, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision volcanism is preceded by normal arc volcanism and followed by normal intraplate volcanism. Identification and interpretation of collision volcanism in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision volcanism is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of

  1. Planetary Landscape Geography

    NASA Astrophysics Data System (ADS)

    Hargitai, H.

    INTRODUCTION Landscape is one of the most often used category in physical ge- ography. The term "landshap" was introduced by Dutch painters in the 15-16th cen- tury. [1] The elements that build up a landscape (or environment) on Earth consists of natural (biogenic and abiogenic - lithologic, atmospheric, hydrologic) and artificial (antropogenic) factors. Landscape is a complex system of these different elements. The same lithology makes different landscapes under different climatic conditions. If the same conditions are present, the same landscape type will appear. Landscapes build up a hierarchic system and cover the whole surface. On Earth, landscapes can be classified and qualified according to their characteristics: relief forms (morphology), and its potential economic value. Aesthetic and subjective parameters can also be considered. Using the data from landers and data from orbiters we can now classify planetary landscapes (these can be used as geologic mapping units as well). By looking at a unknown landscape, we can determine the processes that created it and its development history. This was the case in the Pathfinder/Sojourner panoramas. [2]. DISCUSSION Planetary landscape evolution. We can draw a raw landscape develop- ment history by adding the different landscape building elements to each other. This has a strong connection with the planet's thermal evolution (age of the planet or the present surface materials) and with orbital parameters (distance from the central star, orbit excentricity etc). This way we can build a complex system in which we use differ- ent evolutional stages of lithologic, atmospheric, hydrologic and biogenic conditions which determine the given - Solar System or exoplanetary - landscape. Landscape elements. "Simple" landscapes can be found on asteroids: no linear horizon is present (not differentiated body, only impact structures), no atmosphere (therefore no atmospheric scattering - black sky as part of the landscape) and no

  2. The search for signs of life on exoplanets at the interface of chemistry and planetary science

    PubMed Central

    Seager, Sara; Bains, William

    2015-01-01

    The discovery of thousands of exoplanets in the last two decades that are so different from planets in our own solar system challenges many areas of traditional planetary science. However, ideas for how to detect signs of life in this mélange of planetary possibilities have lagged, and only in the last few years has modeling how signs of life might appear on genuinely alien worlds begun in earnest. Recent results have shown that the exciting frontier for biosignature gas ideas is not in the study of biology itself, which is inevitably rooted in Earth’s geochemical and evolutionary specifics, but in the interface of chemistry and planetary physics. PMID:26601153

  3. Spatial Query for Planetary Data

    NASA Technical Reports Server (NTRS)

    Shams, Khawaja S.; Crockett, Thomas M.; Powell, Mark W.; Joswig, Joseph C.; Fox, Jason M.

    2011-01-01

    Science investigators need to quickly and effectively assess past observations of specific locations on a planetary surface. This innovation involves a location-based search technology that was adapted and applied to planetary science data to support a spatial query capability for mission operations software. High-performance location-based searching requires the use of spatial data structures for database organization. Spatial data structures are designed to organize datasets based on their coordinates in a way that is optimized for location-based retrieval. The particular spatial data structure that was adapted for planetary data search is the R+ tree.

  4. Stratospheric Observatory for Infrared Astornomy and Planetary Science

    NASA Astrophysics Data System (ADS)

    Reach, William T.; SOFIA Sciece Mission Operations

    2016-10-01

    The Stratospheric Observatory for Infrared Astronomy enables observations at far-infrared wavelengths, including the range 30-300 microns that is nearly completely obscured from the ground. By flying in the stratosphere above 95% of atmospheric water vapor, access is opened to photometric, spectroscopic, and polarimetric observations of Solar System targets spanning small bodies through major planets. Extrasolar planetary systems can be observed through their debris disks or transits, and forming planetary systems through protoplanetary disks, protostellar envelopes, and molecular cloud cores. SOFIA operates out of Southern California most of the year. For the summer of 2016, we deployed to New Zealand with 3 scientific instruments. The HAWC+ far-infrared photopolarimeter was recently flown and is in commissioning, and two projects are in Phase A study to downselect to one new facility instrument. The Cycle 5 observing proposal results are anticipated to be be released by the time of this DPS meeting, and successful planetary proposals will be advertised.

  5. Lunar and Planetary Science XXXV: Origin of Planetary Systems

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session"Origin of Planetary Systems" presented the following reports:Planetary Formation in the the Gamma Cephei System by Core:Accretion; Accretion and Heating of Particles by Supersonic Planetesimals; Planetesimal Accretion in Close Binary Systems; Collisions, Gas Flow, and the Formation of Planetesimals; Hydrodynamic Escape of a Proto-Atmosphere Just After a Giant Impact; X-Ray Flare Induced Shock Waves and Chondrule Formation in Upper Solar Nebula; and Making Water Worlds: The Role of 26Al.

  6. Global geochemical cycles of carbon, sulfur and oxygen

    NASA Technical Reports Server (NTRS)

    Walker, J. C.

    1986-01-01

    Time resolved data on the carbon isotopic composition of carbonate minerals and the sulfur isotopic composition or sulfate minerals show a strong negative correlation during the Cretaceous. Carbonate minerals are isotopically heavy during this period while sulfate minerals are isotopically light. The implication is that carbon is being transferred from the oxidized, carbonate reservoir to the reservoir of isotopically light reduced organic carbon in sedimentary rocks while sulfur is being transferred from the reservoir of isotopically light sedimentary sulfide to the oxidized, sulfate reservoir. These apparently oppositely directed changes in the oxidation state of average sedimentary carbon and sulfur are surprising because of a well-established and easy to understand correlation between the concentrations of reduced organic carbon and sulfide minerals in sedimentary rocks. Rocks rich in reduced carbon are also rich in reduced sulfur. The isotopic and concentration data can be reconciled by a model which invokes a significant flux of hydrothermal sulfide to the deep sea, at least during the Cretaceous.

  7. Perchlorate and Superfund Response to Uncertainty and the Geochemical Cycle

    NASA Astrophysics Data System (ADS)

    Mayer, K. P.

    2007-12-01

    Perchlorate, a chemical that had been known both in nature and through synthesis since the nineteenth century, only emerged into the limelight as an environmental contaminant in 1997. US EPA's Superfund Program became involved in perchlorate issues in the late 1980s and early 1990s due to the chemical's presence mixed with other contaminants at cleanup sites. Relying largely on pharmaceutical studies primarily from the 1950s and 1960s, EPA scientists in 1992 made a provisional estimate of toxicity and estimated that about 4 micrograms per liter (parts per billion or ppb) in drinking water would be protective. "Uncertainty factors" were incorporated to address for several identified information gaps. Results of new animal and human studies funded by the Defense Department and industry in the late 1990s shifted the concern from affects on adults with unhealthy thyroids to the potential developmental health risks to infants and children. EPA's January, 2002, draft toxicity assessment was referred to a committee of the National Research Council. In January, 2005, this committee recommended a "reference dose" based primarily on human clinical data. Many decisions remain on interpretation of the scientific recommendations for regulatory applications. After California's 1997 development of an analytical method to detect perchlorate in water to 4 ppb, EPA and state officials quickly discovered this chemical at 10 Superfund sites in the Pacific Southwest Region and at more than 30 other locations in California, Arizona and Nevada. Even before current research on the potential for natural sources of this anion, reported detections of perchlorate were investigated with reasonable care and appropriate skepticism. A brief overview of the search for likely sources of perchlorate detected in California water supplies is presented from a regional Superfund perspective. Some are clearly anthropogenic and others may be unrelated to industrial or disposal practices. Currently, there is no Federal standard for perchlorate. In March, 2004, California established Public Health Goal of 6 ppb in drinking water and a drinking water standard may be promulgated by November 2007. Seven other states have advisory levels ranging from 1 to 51 ppb.

  8. Influence of late Cenozoic mountain building on ocean geochemical cycles

    NASA Astrophysics Data System (ADS)

    Raymo, Maureen E.; Ruddiman, William F.; Froelich, Philip N.

    1988-07-01

    In a steady-state ocean, input fluxes of dissolved salts to the sea must be balanced in mass and isotopic value by output fluxes. For the elements strontium, calcium, and carbon, rivers provide the primary input, whereas marine biogenic sedimentation dominates removal. Dissolved fluxes in rivers are related to rates of continental weathering, which in turn are strongly dependent on rates of uplift. The largest dissolved fluxes today arise in the Himalayan and Andean mountain ranges and the Tibetan Plateau. During the past 5 m.y., uplift rates in these areas have increased significantly; this suggests that weathering rates and river fluxes may have increased also. The oceanic records of carbonate sedimentation, level of the calcite compensation depth, and δ13C and δ87Sr in biogenic sediments are consistent with a global increase in river fluxes since the late Miocene. The cooling of global climate over the past few million years may be linked to a decrease in atmospheric CO2 driven by enhanced continental weathering in these tectonically active regions.

  9. Planetary cratering mechanics

    NASA Astrophysics Data System (ADS)

    O'Keefe, John D.; Ahrens, Thomas J.

    1993-09-01

    The objective of this study was to obtain a quantitative understanding of the cratering process over a broad range of conditions. Our approach was to numerically compute the evolution of impact induced flow fields and calculate the time histories of the key measures of crater geometry (e.g., depth, diameter, lip height) for variations in planetary gravity (0 to 109 cm/s2), material strength (0 to 2400 kbar), and impactor radius (0.05 to 5000 km). These results were used to establish the values of the open parameters in the scaling laws of Holsapple and Schmidt (1987). We describe the impact process in terms of four regimes: (1) penetration, (2) inertial, (3) terminal, and (4) relaxation. During the penetration regime, the depth of impactor penetration grows linearly for dimensionless times τ=(Ut/a)<5.1. Here, U is projectile velocity, t is time, and a is projectile radius. In the inertial regime, τ>5.1, the crater grows at a slower rate until it is arrested by either strength or gravitational forces. In this regime, the increase of crater depth, d, and diameter, D, normalized by projectile radius is given by d/a=1.3 (Ut/a)0.36 and D/a=2.0(Ut/a)0.36. For strength-dominated craters, growth stops at the end of the inertial regime, which occurs at τ=0.33 (Yeff/ρU2)-0.78, where Yeff is the effective planetary crustal strength. The effective strength can be reduced from the ambient strength by fracturing and shear band melting (e.g., formation of pseudo-tachylites). In gravity-dominated craters, growth stops when the gravitational forces dominate over the inertial forces, which occurs at τ=0.92 (ga/U2)-0.61. In the strength and gravity regimes, the maximum depth of penetration is dp/a=0.84 (Y/ρ U2)-0.28 and dp/a=1.2 (ga/U2)-0.22, respectively. The transition from simple bowl-shaped craters to complex-shaped craters occurs when gravity starts to dominate over strength in the cratering process. The diameter for this transition to occur is given by Dt=9.0 Y/ρg, and

  10. Dust in Planetary Systems

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Graps, A.

    2007-01-01

    The workshop 'Dust in Planetary Systems' was held in Kauai'i/Hawaii from September 26 to 30, 2005, following the tradition of holding meetings in the field of Interplanetary Dust Research at regular intervals of a few years. The series of meetings started in Honolulu, Hawaii (USA) in 1967, followed by Heidelberg (Germany) in 1975, Ottawa (Canada) in 1979, Marseilles (France) in 1984, Kyoto (Japan) in 1990, Gainesville, Florida (USA) in 1995, with the last being held in Canterbury, (U.K.) in 2000. The Kauai'i workshop in 2005 was attended by 150 scientists from 20 countries who actively discussed recent progress made through remote observations from the ground and from space, in-situ measurements, as well as from theory and laboratory experiments. Since the last meeting in Canterbury, numerous space missions provided significant progress in various fields of cosmic dust research. For studies of comet nuclei, scientists in our field were involved in three space missions. In 2001, the Deep Space 1 spacecraft flew by comet Borelly. In 2004, Stardust flew by comet Wild 2, with many exciting results from the Stardust return capsule still to come. In 2005, the Deep Impact probe collided with comet Tempel 1. In addition, the comet dust community made large strides forward when Rosetta was launched to begin its 10-year voyage towards comet Churyumov-Gerasimenkov. Saturn's environment also provides a natural laboratory for cosmic dust researchers. The Saturn ring system with its spokes has been the prime motivator for dusty plasma studies since the time of the Voyager spacecraft twenty years ago. The Cassini spacecraft in orbit around Saturn since 2004 is well-placed to not only continue those studies, but to start new studies provided by Saturn's enigmatic moon Enceladus. Jupiter's dusty environment has not been neglected by spacecraft in these last five years either. While the Galileo mission was terminated in 2003 after the spacecraft's 7-year orbital tour about Jupiter

  11. Planetary Geophysics and Tectonics

    NASA Technical Reports Server (NTRS)

    Parmentier, E. M.

    1997-01-01

    Research supported by grant NAGW-1928 has addressed a variety of problems related to planetary evolution. One important focus has been on questions related to the role of chemical buoyancy in planetary evolution with application to both Venus and the Moon. We have developed a model for the evolution of the Moon (Hess and Parmentier, 1995) in which dense, highly radioactive, late stage magma ocean cumulates sink forming a core. This core heats the overlying, chemically layered mantle giving rise to a heated, chemically well-mixed layer that thickens with time. This Mixed layer eventually becomes hot enough and thick enough that its top begins to melt at a pressure low enough that melt is buoyant, thus creating mare basalts from a high pressure source of the correct composition and at an appropriate time in lunar evolution. In work completed during the last year, numerical experiments on convection in a chemically stably stratified fluid layer heated from below have been completed. These results show us how to calculate the evolution of a mixed layer in the Moon, depending on the heat production in the ilmenite- cumulate core and the chemical stratification of the overlying mantle. Chemical stratification of the mantle after its initial differentiation is would trap heat in the deep interior and prevent the rapid rise of plumes with accompanying volcanism. This trapping of heat in the interior can explain the thickness of the lunar lithosphere as a function of time as well as the magmatic evolution. We show that heat transported to the base of the lithosphere at a rate determined by current estimates of radioactivity in the Moon would not satisfy constraints on elastic lithosphere thickness from tectonic feature associated with basin loading. Trapping heat at depth by a chemically stratified mantle may also explain the absence of global compressional features on the surface that previous models predict for an initially hot lunar interior. For Venus, we developed a

  12. Formation of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Stars are observed to be forming within cold regions of the galaxy called molecular clouds. A clump of gas and dust within a molecular cloud can collapse into a rotationally- supported disk orbiting the pre s sure -supported star. Such a disk has the same initial elemental composition as the growing star. At sufficient distances from the central star, it is cool enough for approx. 1 - 2% of this material to be in solid form, either remnant interstellar grains or condensates formed within the disk. During the infall stage, the disk is very active and probably highly turbulent. When the infall slows substantially or stops, the disk becomes more quiescent. The dust grows from micron-sized dust to kilometer-sized planetesimals by physical collisions, possibly aided by collective gravity. The dynamics of larger solid bodies within protoplanetary disks are better characterized. The primary perturbations on the orbits of kilometer-sized and larger planetesimals in protoplanetary disks are mutual gravitational interactions and physical collisions. These interactions lead to accretion (and in some cases erosion and fragmentation) of planetesimals. The most massive planets have the largest gravitationally-enhanced collision cross-sections, and accrete almost everything with which they collide. The size distribution of solid bodies becomes quite skewed, with a few large bodies growing much faster than the rest of the swarm, until they have accumulated most of the small bodies within their gravitational reach. Slower growth continues (at least for solid, earth-like planets) as the eccentricities of planetary embryos are pumped up by long-range mutual gravitational perturbations. As planetary masses increase, they become more efficient at stirring random velocities of neighboring bodies. If sufficiently massive and dense planets exist far enough from the star, they can eject material into interstellar space. In most models, giant planets begin their growth like terrestrial

  13. Formation of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Stars are observed to be forming within cold regions of the galaxy called molecular clouds. A clump of gas and dust within a molecular cloud can collapse into a rotationally- supported disk orbiting the pre s sure -supported star. Such a disk has the same initial elemental composition as the growing star. At sufficient distances from the central star, it is cool enough for approx. 1 - 2% of this material to be in solid form, either remnant interstellar grains or condensates formed within the disk. During the infall stage, the disk is very active and probably highly turbulent. When the infall slows substantially or stops, the disk becomes more quiescent. The dust grows from micron-sized dust to kilometer-sized planetesimals by physical collisions, possibly aided by collective gravity. The dynamics of larger solid bodies within protoplanetary disks are better characterized. The primary perturbations on the orbits of kilometer-sized and larger planetesimals in protoplanetary disks are mutual gravitational interactions and physical collisions. These interactions lead to accretion (and in some cases erosion and fragmentation) of planetesimals. The most massive planets have the largest gravitationally-enhanced collision cross-sections, and accrete almost everything with which they collide. The size distribution of solid bodies becomes quite skewed, with a few large bodies growing much faster than the rest of the swarm, until they have accumulated most of the small bodies within their gravitational reach. Slower growth continues (at least for solid, earth-like planets) as the eccentricities of planetary embryos are pumped up by long-range mutual gravitational perturbations. As planetary masses increase, they become more efficient at stirring random velocities of neighboring bodies. If sufficiently massive and dense planets exist far enough from the star, they can eject material into interstellar space. In most models, giant planets begin their growth like terrestrial

  14. Secular Resonances In Planetary Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    2006-06-01

    Secular effects introduce very low frequencies in planetary systems. The consequences are quite varied. They include mundane effects on the planetary ephemerides and on Earthly seasons, but also more esoteric effects such as apsidal alignment or anti-alignment, fine-splitting of mean motion resonances, broadening of chaotic zones, and dramatic orbital instabilities. Secular effects may shape the overall architecture of mature planetary systems by determining the long term stability of major and minor planetary bodies. This talk will be partly tutorial and partly a review of secular resonance phenomena here in the solar system and elsewhere in extra-solar systems. I acknowledge research support from NASA-Origins of Solar Systems and NASA-Outer Planets research programs.

  15. Integration of planetary protection activities

    NASA Technical Reports Server (NTRS)

    Race, Margaret S.

    1995-01-01

    For decades, NASA has been concerned about the protection of planets and other solar system bodies from biological contamination. Its policies regarding biological contamination control for outbound and inbound planetary spacecraft have evolved to focus on three important areas: (1) the preservation of celestial objects and the space environment; (2) protection of Earth from extraterrestrial hazards; and (3) ensuring the integrity of its scientific investigations. Over the years as new information has been obtained from planetary exploration and research, planetary protection parameters and policies have been modified accordingly. The overall focus of research under this cooperative agreement has been to provide information about non-scientific and societal factors related to planetary protection and use it in the planning and implementation phases of future Mars sample return missions.

  16. Mini Planetary System Artist Concept

    NASA Image and Video Library

    2012-01-11

    This artist concept, based on data from NASA Kepler mission and ground-based telescopes, depicts an itsy bitsy planetary system -- so compact, in fact, that it more like Jupiter and its moons than a star and its planets.

  17. Planetary Scientist Profile: Noah Petro

    NASA Image and Video Library

    Noah Petro is a NASA planetary geologist who studies the surface of airless bodies in space, primarily focusing on the moon. In this video profile, Noah talks about how he was inspired to become a ...

  18. Planetary science: Eris under scrutiny

    NASA Astrophysics Data System (ADS)

    Gulbis, Amanda

    2011-10-01

    A stellar occultation by the dwarf planet Eris provides a new estimate of its size. It also reveals a surprisingly bright planetary surface, which could indicate the relatively recent condensation of a putative atmosphere. See Letter p.493

  19. Magnetic Helicity and Planetary Dynamos

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    2012-01-01

    A model planetary dynamo based on the Boussinesq approximation along with homogeneous boundary conditions is considered. A statistical theory describing a large-scale MHD dynamo is found, in which magnetic helicity is the critical parameter

  20. Reaching Water: Planetary Deep Drilling

    NASA Astrophysics Data System (ADS)

    Glass, B.; Bergman, D.; Davis, R.; Hoftun, C.; Lee, P.; Johansen, B.

    2017-02-01

    Deeper drilling to 100m depths is easy on Earth, but an extreme challenge on other solar system bodies. Deeper planetary subsurface access into ocean worlds or to the Mars cryosphere is possible with new drilling concepts.

  1. Planetary geosciences, 1989-1990

    NASA Technical Reports Server (NTRS)

    Zuber, Maria T. (Editor); James, Odette B. (Editor); Lunine, Jonathan I. (Editor); Macpherson, Glenn J. (Editor); Phillips, Roger J. (Editor)

    1992-01-01

    NASA's Planetary Geosciences Programs (the Planetary Geology and Geophysics and the Planetary Material and Geochemistry Programs) provide support and an organizational framework for scientific research on solid bodies of the solar system. These research and analysis programs support scientific research aimed at increasing our understanding of the physical, chemical, and dynamic nature of the solid bodies of the solar system: the Moon, the terrestrial planets, the satellites of the outer planets, the rings, the asteroids, and the comets. This research is conducted using a variety of methods: laboratory experiments, theoretical approaches, data analysis, and Earth analog techniques. Through research supported by these programs, we are expanding our understanding of the origin and evolution of the solar system. This document is intended to provide an overview of the more significant scientific findings and discoveries made this year by scientists supported by the Planetary Geosciences Program. To a large degree, these results and discoveries are the measure of success of the programs.

  2. TAPIR--Finnish national geochemical baseline database.

    PubMed

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  3. The Importance of Planetary Rotation Period for Ocean Heat Transport

    PubMed Central

    Stevens, D.; Joshi, M.

    2014-01-01

    Abstract The climate and, hence, potential habitability of a planet crucially depends on how its atmospheric and ocean circulation transports heat from warmer to cooler regions. However, previous studies of planetary climate have concentrated on modeling the dynamics of atmospheres, while dramatically simplifying the treatment of oceans, which neglects or misrepresents the effect of the ocean in the total heat transport. Even the majority of studies with a dynamic ocean have used a simple so-called aquaplanet that has no continental barriers, which is a configuration that dramatically changes the ocean dynamics. Here, the significance of the response of poleward ocean heat transport to planetary rotation period is shown with a simple meridional barrier—the simplest representation of any continental configuration. The poleward ocean heat transport increases significantly as the planetary rotation period is increased. The peak heat transport more than doubles when the rotation period is increased by a factor of ten. There are also significant changes to ocean temperature at depth, with implications for the carbon cycle. There is strong agreement between the model results and a scale analysis of the governing equations. This result highlights the importance of both planetary rotation period and the ocean circulation when considering planetary habitability. Key Words: Exoplanet—Oceans—Rotation—Climate—Habitability. Astrobiology 14, 645–650. PMID:25041658

  4. The importance of planetary rotation period for ocean heat transport.

    PubMed

    Cullum, J; Stevens, D; Joshi, M

    2014-08-01

    The climate and, hence, potential habitability of a planet crucially depends on how its atmospheric and ocean circulation transports heat from warmer to cooler regions. However, previous studies of planetary climate have concentrated on modeling the dynamics of atmospheres, while dramatically simplifying the treatment of oceans, which neglects or misrepresents the effect of the ocean in the total heat transport. Even the majority of studies with a dynamic ocean have used a simple so-called aquaplanet that has no continental barriers, which is a configuration that dramatically changes the ocean dynamics. Here, the significance of the response of poleward ocean heat transport to planetary rotation period is shown with a simple meridional barrier--the simplest representation of any continental configuration. The poleward ocean heat transport increases significantly as the planetary rotation period is increased. The peak heat transport more than doubles when the rotation period is increased by a factor of ten. There are also significant changes to ocean temperature at depth, with implications for the carbon cycle. There is strong agreement between the model results and a scale analysis of the governing equations. This result highlights the importance of both planetary rotation period and the ocean circulation when considering planetary habitability.

  5. Impact of lunar and planetary missions on the space station

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The impacts upon the growth space station of several advanced planetary missions and a populated lunar base are examined. Planetary missions examined include sample returns from Mars, the Comet Kopff, the main belt asteroid Ceres, a Mercury orbiter, and a saturn orbiter with multiple Titan probes. A manned lunar base build-up scenario is defined, encompassing preliminary lunar surveys, ten years of construction, and establishment of a permanent 18 person facility with the capability to produce oxygen propellant. The spacecraft mass departing from the space station, mission Delta V requirements, and scheduled departure date for each payload outbound from low Earth orbit are determined for both the planetary missions and for the lunar base build-up. Large aerobraked orbital transfer vehicles (OTV's) are used. Two 42 metric ton propellant capacity OTV's are required for each the the 68 lunar sorties of the base build-up scenario. The two most difficult planetary missions (Kopff and Ceres) also require two of these OTV's. An expendable lunar lander and ascent stage and a reusable lunar lander which uses lunar produced oxygen are sized to deliver 18 metric tons to the lunar surface. For the lunar base, the Space Station must hangar at least two non-pressurized OTV's, store 100 metric tons of cryogens, and support an average of 14 OTV launch, return, and refurbishment cycles per year. Planetary sample return missions require a dedicated quarantine module.

  6. Planetary Interior in the Laboratory

    SciTech Connect

    Chau, R; Bastea, M; Mitchell, A C; Minich, R W; Nellis, W J

    2003-01-31

    In the three years of this project, we have provided a complete database of the electrical conductivity of planetary materials to 180 GPa. The electrical conductivities of these planetary materials now provide a basis for future modeling of planets taking into account full magnetohydrodynamics. By using a full magnetohydrodynamics simulation, the magnetic fields of the planets can then be taken into account. Moreover, the electrical conductivities of the planetary materials have given us insight into the structure and nature of these dense fluids. We showed that simple monoatomic fluids such as hydrogen, nitrogen, and oxygen at planetary interior conditions undergo a common metallization process which can be explained on a simple basis of their radial charge density distributions. This model also shows that the metallization process is actually rather common and likely to take place in a number of materials such as carbon monoxide which is also present within planetary objects. On the other hand, we have also showed that a simple two component fluid like water and methane take on much different behaviors than say nitrogen due to the chemical interactions within these systems. The dynamics of an even more complex system, ''synthetic Uranus'' are still being analyzed but suggest that on some levels the behavior is very simple, i.e. the electrical conductivity is essentially the same as water, but the local dynamics are very complex. This project has shed much light on the nature of electrical transport within planetary interiors but also has shown that understanding chemical processes in the complex fluids within planetary interiors to be very important. Understanding those local interactions and processes is required to gain further insight into planetary interiors.

  7. Planetary Data Workshop, Part 1

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The community of planetary scientists addresses two general problems regarding planetary science data: (1) important data sets are being permanently lost; and (2) utilization is constrainted by difficulties in locating and accessing science data and supporting information necessary for its use. A means to correct the problems, provide science and functional requirements for a systematic and phased approach, and suggest technologies and standards appropriate to the solution were explored.

  8. The Charging of Planetary Rings

    NASA Astrophysics Data System (ADS)

    Graps, Amara L.; Horanyi, M.; Havnes, O.; Gruen, E.

    2008-09-01

    Planetary rings have an undeniable aesthetic appeal, resulting in media icons of ringed planets as descriptive of the planetary sciences field as a whole. Such far-reaching symbolism might not be misplaced, however, because planetary rings represent a fundamental class of planetary structure that invites interdisciplinary investigations from specialists in dust, gravitational, plasma, collisional, and radiative transfer physics, due to: its sub-micron to meters-sized particles, its immersion in the planet's magnetic field, its embedded moonlets and its close proximity to the ringed planet's ionosphere and innermost moons. As such, planetary rings are a metaphoric bridge through a wide range of planetary physical processes. Processes to charge ring particles have different relative dynamical effects, dependent upon the rings' particle sizes, and the ring's plasma, magnetic and gravitational environments. This presentation will review what is known about the charging parameters and processes of planetary rings, in particular the sum of the individual currents from the time-varying charge dQ/dt, of the planetary ring particle. The individual currents depend on the environmental plasma conditions: number density, flow speed, temperature, and mass for the currents: electron and ion capture from the plasma, ion currents to a moving grain, photoelectron emission, secondary electron emission, thermionic effects, with stochastic charging influencing all of the above. Since rings are an ensemble of particles, ("cloud" Ring), we will define an ensemble, and consider the above currents, including those for the smallest ring particles, the dust particles, to arrive at a table giving charge potential and other relevant parameters.

  9. Planetary waves in rotating ionosphere

    SciTech Connect

    Khantadze, A. G.; Jandieri, V. G.; Jandieri, G. V.

    2008-06-15

    The problem of propagation of ultralong planetary waves in the Earth's upper atmosphere is considered. A new exact solution to the MHD equations for the ionosphere is obtained in spherical coordinates with allowance for the geomagnetic field and Earth's rotation. A general dispersion relation is derived for planetary waves in the ionospheric E and F regions, and the characteristic features of their propagation in a weakly ionized ionospheric plasma are discussed.

  10. Planetary Photojournal Home Page Graphic

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image is an unannotated version of the Planetary Photojournal Home Page graphic. This digital collage contains a highly stylized rendition of our solar system and points beyond. As this graphic was intended to be used as a navigation aid in searching for data within the Photojournal, certain artistic embellishments have been added (color, location, etc.). Several data sets from various planetary and astronomy missions were combined to create this image.

  11. The formation of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Sparks, W. M.

    1973-01-01

    A hydrodynamic model of a star consisting of a helium shell and a hydrogen-rich shell overlying a hard core is proposed in order to find out what causes the ejection of stellar mass with low velocities that form planetary nebulae. Observations indicate that a planetary nebula is composed of hydrogen-rich material, while the remaining remnant of the star is of helium or heavier material.

  12. Migrating microbes and planetary protection.

    PubMed

    Nicholson, Wayne L; Schuerger, Andrew C; Race, Margaret S

    2009-09-01

    Since the dawn of the space age, humans have wrestled with concerns about planetary cross-contamination. Spacecraft launched from Earth can transport hitchhiker microbes to new worlds on both robotic and crewed vehicles. As plans proceed for future life detection and human exploration missions, planetary protection considerations are again uppermost on the agendas of mission planners, and microbiologists have an important role to play.

  13. Planetary Seismometers: An Overview

    NASA Astrophysics Data System (ADS)

    Knapmeyer, M.; Akito, A.; Bampasidis, G.; Banerdt, W. B.; Coustenis, A.; Fouch, M. J.; Garnero, E. J.; Khavroshkin, O.; Kobayashi, N.; Moussas, X.; Pike, W. T.; Seidensticker, K. J.; Solomonidou, A.; Yu, H.; Zakharov, A.

    2012-04-01

    Seismometers were part of lander payloads since the launch of Ranger 3 in early 1962, which was the first attempt to deliver scientific instruments to the surface of another celestial body. Since then, active and passive seismic experiments were conducted with great success on the Moon, and to a lesser extent on Mars and Venus. Proposals have been made or are in preparation for new experiments with single instruments or instrument networks on Venus, Moon, Mars, Phobos, Titan, Europa, and other bodies. One instrument (CASSE, sensitive for acoustic frequencies >= 30Hz) is currently flying to comet 67P/Churyumov-Gerasimenko on board of the Rosetta Mission. We give an overview of seismometers for use in planetary missions, including instruments of past and future missions. The focus is on the current developments as represented by the authors of the presentation. These encompass a Micro-Electromechanic System, several piezoelectric transducers that are able to resist strong decelerations, as well as new developments based on laser-interferometric sensing or hydrodynamic flow of electrolytic liquids.

  14. Planetary Vital Signs

    NASA Astrophysics Data System (ADS)

    Kennel, Charles; Briggs, Stephen; Victor, David

    2016-07-01

    The climate is beginning to behave in unusual ways. The global temperature reached unprecedented highs in 2015 and 2016, which led climatologists to predict an enormous El Nino that would cure California's record drought. It did not happen the way they expected. That tells us just how unreliable temperature has become as an indicator of important aspects of climate change. The world needs to go beyond global temperature to a set of planetary vital signs. Politicians should not over focus policy on one indicator. They need to look at the balance of evidence. A coalition of scientists and policy makers should start to develop vital signs at once, since they should be ready at the entry into force of the Paris Agreement in 2020. But vital signs are only the beginning. The world needs to learn how to use the vast knowledge we will be acquiring about climate change and its impacts. Is it not time to use all the tools at hand- observations from space and ground networks; demographic, economic and societal measures; big data statistical techniques; and numerical models-to inform politicians, managers, and the public of the evolving risks of climate change at global, regional, and local scales? Should we not think in advance of an always-on social and information network that provides decision-ready knowledge to those who hold the responsibility to act, wherever they are, at times of their choosing?

  15. Lunar and planetary studies

    NASA Technical Reports Server (NTRS)

    Muhleman, Duane O.; Goldreich, P.; Ingersoll, A. P.; Westphal, J. A.

    1988-01-01

    This grant supports the core program in planetary astronomy at Caltech. The research includes observations in the IR, sub-mm, mm and cm wavelengths at national and Caltech observatories with a strong emphasis on integrating the observations with spacecraft data and with models of atmospheric structure, dynamics and chemistry. Muhleman's group made extensive observations of Saturn, Uranus and Neptune which are being interpreted in terms of deep atmospheric structures which are obvious in the 2 and 6 cm maps of Saturn and Uranus. The microwave measurements are one of the few sources of information below the 2 bar level. Goldreich is investigating the dynamics of narrow rings with postdoctoral fellow, Pierre-Yves Longaretti. Their work has focused on the role of collisional stresses on the precession of the rings, since the Voyager radio science results imply that the previous model based on the ring's self-gravity is not the entire story. In addition Borderies, Goldreich and Tremaine have completed an investigation of the dynamics of the Encke division in Saturn's A ring.

  16. Extrasolar Planetary Transits

    NASA Astrophysics Data System (ADS)

    Cameron, Andrew Collier

    An extrasolar planet will transit the visible hemisphere of its host star if its orbital plane lies sufficiently close to the observer's line of sight. The resulting periodic dips in stellar flux reveal key system parameters, including the density of the host star and, if radial-velocity observations are available, the surface gravitational acceleration of the planet. In this chapter I present the essential methodology for modelling the time-dependent flux variation during a transit, and its use in determining the posterior probability distribution for the physical parameters of the system. Large-scale searches for transiting systems are an efficient way of discovering planets whose bulk densities, and hence compositions, can be accessed if their masses can also be determined. I present algorithms for detrending large ensembles of light curves, for searching for transit-like signals among them. I also discuss methods for identifying diluted stellar eclipsing binaries mimicking planetary transit signals, and validation of transit candidates too faint for radial-velocity follow-up. I review the use of time-resolved spectrophotometry and high-resolution spectroscopy during transits to identify the molecular constituents of exoplanetary atmospheres.

  17. How much are Planetary Waves in the lower Ionosphere persistent?

    NASA Astrophysics Data System (ADS)

    Loastovicka, J.; Krizan, P.; Novotna, D.

    The transient planetary waves in the atmosphere and ionosphere seem to occur in the form of bursts of a couple of waves with limited persistence. To study persistence of planetary wave events in the lower ionosphere, data from two radio paths from Central Europe are used, Luxembourg - Panská Ves (f = 6.09 MHz, feq = 2.1-2.2 MHz) and Deutschlandfunk - Panská Ves (f = 1539 kHz, feq = 650-700 kHz). The absorption along the former radio paths is formed very predominantly at altitudes of about 90-100 km, whereas the latter is formed mostly at altitudes of about 85-90 km. The persistence of planetary wave type oscillations is studied in three period bands centred at 5, 10 and 16 days with the use of the wavelet transform. Waves with period (T) near 5 days reveal a typical persistence of wave events around 5 cycles. Waves with T = 10 days are less persistent with a typical persistence of 3-4 cycles. The typical persistence of waves T = 16 days is no more than 3 cycles. In terms of number of cycles, the persistence of oscillations evidently decreases with increasing period. On the other hand, in terms of number of days, the persistence seems rather to increase with increasing period.

  18. Planetary Science with the Stratospheric Observatory for Infrared Astronomy (SOFIA)

    NASA Astrophysics Data System (ADS)

    Backman, Dana E.; Reach, William T.

    2015-11-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is currently conducting the third annual Cycle of guest investigator observing programs. Programs selected for the fourth Cycle (2016) were announced in October. The planetary science community has made a significant showing in all proposal Cycles, comprising approximately 15% of the time awarded in Cycles 1-3. SOFIA offers observers access to the complete infrared spectrum, with much less atmospheric absorption than from even the finest ground-based telescope sites. New capabilities include high-resolution spectroscopy in the mid-infrared with the Echelon-Cross-Echelle Spectrograph (EXES) that allows spectroscopy of molecules from narrow stratospheric lines of planetary atmospheres, plus imaging spectroscopy with the Field Imaging Far-Infrared Line Spectrometer (FIFI-LS) capable, for example, of simultaneous observations in 9 spatial pixels in each of two far-infrared spectral lines. Also, the FLITECAM near-IR and FORCAST mid-IR cameras include grisms that allow moderate-resolution spectral imaging at wavelengths inaccessible from the ground, and HIPO and FPI+ high-speed photometric imagers are capable of high-S/N measurements of stellar occultations and exoplanet transits. Planetary science targets observed to date include comets ISON and PanSTARRS, main belt asteroids, Mars, Jupiter, Neptune, Pluto, Europa, exoplanets, and debris disks. This poster will showcase science highlights, give details regarding the SOFIA observatory and instrument capabilities, and present observing program statistics.

  19. Planetary Geologic Mapping Handbook - 2009

    NASA Technical Reports Server (NTRS)

    Tanaka, K. L.; Skinner, J. A.; Hare, T. M.

    2009-01-01

    Geologic maps present, in an historical context, fundamental syntheses of interpretations of the materials, landforms, structures, and processes that characterize planetary surfaces and shallow subsurfaces (e.g., Varnes, 1974). Such maps also provide a contextual framework for summarizing and evaluating thematic research for a given region or body. In planetary exploration, for example, geologic maps are used for specialized investigations such as targeting regions of interest for data collection and for characterizing sites for landed missions. Whereas most modern terrestrial geologic maps are constructed from regional views provided by remote sensing data and supplemented in detail by field-based observations and measurements, planetary maps have been largely based on analyses of orbital photography. For planetary bodies in particular, geologic maps commonly represent a snapshot of a surface, because they are based on available information at a time when new data are still being acquired. Thus the field of planetary geologic mapping has been evolving rapidly to embrace the use of new data and modern technology and to accommodate the growing needs of planetary exploration. Planetary geologic maps have been published by the U.S. Geological Survey (USGS) since 1962 (Hackman, 1962). Over this time, numerous maps of several planetary bodies have been prepared at a variety of scales and projections using the best available image and topographic bases. Early geologic map bases commonly consisted of hand-mosaicked photographs or airbrushed shaded-relief views and geologic linework was manually drafted using mylar bases and ink drafting pens. Map publishing required a tedious process of scribing, color peel-coat preparation, typesetting, and photo-laboratory work. Beginning in the 1990s, inexpensive computing, display capability and user-friendly illustration software allowed maps to be drawn using digital tools rather than pen and ink, and mylar bases became obsolete

  20. Proceedings of the workshop on geochemical modeling

    SciTech Connect

    Not Available

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices.

  1. NASA Planetary Science Summer School: Preparing the Next Generation of Planetary Mission Leaders

    NASA Astrophysics Data System (ADS)

    Lowes, L. L.; Budney, C. J.; Sohus, A.; Wheeler, T.; Urban, A.; NASA Planetary Science Summer School Team

    2011-12-01

    Sponsored by NASA's Planetary Science Division, and managed by the Jet Propulsion Laboratory, the Planetary Science Summer School prepares the next generation of engineers and scientists to participate in future solar system exploration missions. Participants learn the mission life cycle, roles of scientists and engineers in a mission environment, mission design interconnectedness and trade-offs, and the importance of teamwork. For this professional development opportunity, applicants are sought who have a strong interest and experience in careers in planetary exploration, and who are science and engineering post-docs, recent PhDs, and doctoral students, and faculty teaching such students. Disciplines include planetary science, geoscience, geophysics, environmental science, aerospace engineering, mechanical engineering, and materials science. Participants are selected through a competitive review process, with selections based on the strength of the application and advisor's recommendation letter. Under the mentorship of a lead engineer (Dr. Charles Budney), students select, design, and develop a mission concept in response to the NASA New Frontiers Announcement of Opportunity. They develop their mission in the JPL Advanced Projects Design Team (Team X) environment, which is a cross-functional multidisciplinary team of professional engineers that utilizes concurrent engineering methodologies to complete rapid design, analysis and evaluation of mission concept designs. About 36 students participate each year, divided into two summer sessions. In advance of an intensive week-long session in the Project Design Center at JPL, students select the mission and science goals during a series of six weekly WebEx/telecons, and develop a preliminary suite of instrumentation and a science traceability matrix. Students assume both a science team and a mission development role with JPL Team X mentors. Once at JPL, students participate in a series of Team X project design sessions

  2. The OpenPlanetary initiative

    NASA Astrophysics Data System (ADS)

    Manaud, Nicolas; Rossi, Angelo Pio; Hare, Trent; Aye, Michael; Galluzzi, Valentina; van Gasselt, Stephan; Martinez, Santa; McAuliffe, Jonathan; Million, Chase; Nass, Andrea; Zinzi, Angelo

    2016-10-01

    "Open" has become attached to several concepts: science, data, and software are some of the most obvious. It is already common practice within the planetary science community to share spacecraft missions data freely and openly [1]. However, this is not historically the case for software tools, source code, and derived data sets, which are often reproduced independently by multiple individuals and groups. Sharing data, tools and overall knowledge would increase scientific return and benefits [e.g. 2], and recent projects and initiatives are helping toward this goal [e.g. 3,4,5,6].OpenPlanetary is a bottom-up initiative to address the need of the planetary science community for sharing ideas and collaborating on common planetary research and data analysis problems, new challenges, and opportunities. It started from an initial participants effort to stay connected and share information related to and beyond the ESA's first Planetary GIS Workshop [7]. It then continued during the 2nd (US) Planetary Data Workshop [8], and aggregated more people.Our objective is to build an online distributed framework enabling open collaborations within the planetary science community. We aim to co-create, curate and publish resource materials and data sets; to organise online events, to support community-based projects development; and to offer a real-time communication channel at and between conferences and workshops.We will present our current framework and resources, developing projects and ideas, and solicit for feedback and participation. OpenPlanetary is intended for research and education professionals: scientists, engineers, designers, teachers and students, as well as the general public that includes enthusiasts and citizen scientists. All are welcome to join and contribute at openplanetary.co[1] International Planetary Data Alliance, planetarydata.org. [2] Nosek et al (2015), dx.doi.org/10.1126/science.aab2374. [3] Erard S. et al. (2016), EGU2016-17527. [4] Proposal for a PDS

  3. Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Ksanfomaliti, L. V.

    2000-11-01

    The discovery of planetary systems around alien stars is an outstanding achievement of recent years. The idea that the Solar System may be representative of planetary systems in the Galaxy in general develops upon the knowledge, current until the last decade of the 20th century, that it is the only object of its kind. Studies of the known planets gave rise to a certain stereotype in theoretical research. Therefore, the discovery of exoplanets, which are so different from objects of the Solar System, alters our basic notions concerning the physics and very criteria of normal planets. A substantial factor in the history of the Solar System was the formation of Jupiter. Two waves of meteorite bombardment played an important role in that history. Ultimately there arose a stable low-entropy state of the Solar System, in which Jupiter and the other giants in stable orbits protect the inner planets from impacts by dangerous celestial objects, reducing this danger by many orders of magnitude. There are even variants of the anthropic principle maintaining that life on Earth owes its genesis and development to Jupiter. Some 20 companions more or less similar to Jupiter in mass and a few ``infrared dwarfs,'' have been found among the 500 solar-type stars belonging to the main sequence. Approximately half of the exoplanets discovered are of the ``hot-Jupiter'' type. These are giants, sometimes of a mass several times that of Jupiter, in very low orbits and with periods of 3-14 days. All of their parent stars are enriched with heavy elements, [Fe/H] = 0.1-0.2. This may indicate that the process of exoplanet formation depends on the chemical composition of the protoplanetary disk. The very existence of exoplanets of the hot-Jupiter type considered in the context of new theoretical work comes up against the problem of the formation of Jupiter in its real orbit. All the exoplanets in orbits with a semimajor axis of more than 0.15-0.20 astronomical units (AU) have orbital

  4. NASA Planetary Visualization Tool

    NASA Astrophysics Data System (ADS)

    Hogan, P.; Kim, R.

    2004-12-01

    NASA World Wind allows one to zoom from satellite altitude into any place on Earth, leveraging the combination of high resolution LandSat imagery and SRTM elevation data to experience Earth in visually rich 3D, just as if they were really there. NASA World Wind combines LandSat 7 imagery with Shuttle Radar Topography Mission (SRTM) elevation data, for a dramatic view of the Earth at eye level. Users can literally fly across the world's terrain from any location in any direction. Particular focus was put into the ease of usability so people of all ages can enjoy World Wind. All one needs to control World Wind is a two button mouse. Additional guides and features can be accessed though a simplified menu. Navigation is automated with single clicks of a mouse as well as the ability to type in any location and automatically zoom to it. NASA World Wind was designed to run on recent PC hardware with the same technology used by today's 3D video games. NASA World Wind delivers the NASA Blue Marble, spectacular true-color imagery of the entire Earth at 1-kilometer-per-pixel. Using NASA World Wind, you can continue to zoom past Blue Marble resolution to seamlessly experience the extremely detailed mosaic of LandSat 7 data at an impressive 15-meters-per-pixel resolution. NASA World Wind also delivers other color bands such as the infrared spectrum. The NASA Scientific Visualization Studio at Goddard Space Flight Center (GSFC) has produced a set of visually intense animations that demonstrate a variety of subjects such as hurricane dynamics and seasonal changes across the globe. NASA World Wind takes these animations and plays them directly on the world. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) produces a set of time relevant planetary imagery that's updated every day. MODIS catalogs fires, floods, dust, smoke, storms and volcanic activity. NASA World Wind produces an easily customized view of this information and marks them directly on the globe. When one

  5. Directed energy planetary defense

    NASA Astrophysics Data System (ADS)

    Lubin, Philip; Hughes, Gary B.; Bible, Johanna; Bublitz, Jesse; Arriola, Josh; Motta, Caio; Suen, Jon; Johansson, Isabella; Riley, Jordan; Sarvian, Nilou; Clayton-Warwick, Deborah; Wu, Jane; Milich, Andrew; Oleson, Mitch; Pryor, Mark; Krogen, Peter; Kangas, Miikka

    2013-09-01

    Asteroids and comets that cross Earth's orbit pose a credible risk of impact, with potentially severe disturbances to Earth and society. Numerous risk mitigation strategies have been described, most involving dedicated missions to a threatening object. We propose an orbital planetary defense system capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation. We call the system DE-STAR for Directed Energy System for Targeting of Asteroids and exploRation. DE-STAR is a modular phased array of kilowatt class lasers powered by photovoltaic's. Modular design allows for incremental development, test, and initial deployment, lowering cost, minimizing risk, and allowing for technological co-development, leading eventually to an orbiting structure that would be developed in stages with both technological and target milestones. The main objective of DE-STAR is to use the focused directed energy to raise the surface spot temperature to ~3,000K, allowing direct vaporization of all known substances. In the process of heating the surface ejecting evaporated material a large reaction force would alter the asteroid's orbit. The baseline system is a DE-STAR 3 or 4 (1-10km array) depending on the degree of protection desired. A DE-STAR 4 allows for asteroid engagement starting beyond 1AU with a spot temperature sufficient to completely evaporate up to 500-m diameter asteroids in one year. Small asteroids and comets can be diverted/evaporated with a DESTAR 2 (100m) while space debris is vaporized with a DE-STAR 1 (10m).

  6. Planetary Transmission Diagnostics

    NASA Technical Reports Server (NTRS)

    Lewicki, David G. (Technical Monitor); Samuel, Paul D.; Conroy, Joseph K.; Pines, Darryll J.

    2004-01-01

    This report presents a methodology for detecting and diagnosing gear faults in the planetary stage of a helicopter transmission. This diagnostic technique is based on the constrained adaptive lifting algorithm. The lifting scheme, developed by Wim Sweldens of Bell Labs, is a time domain, prediction-error realization of the wavelet transform that allows for greater flexibility in the construction of wavelet bases. Classic lifting analyzes a given signal using wavelets derived from a single fundamental basis function. A number of researchers have proposed techniques for adding adaptivity to the lifting scheme, allowing the transform to choose from a set of fundamental bases the basis that best fits the signal. This characteristic is desirable for gear diagnostics as it allows the technique to tailor itself to a specific transmission by selecting a set of wavelets that best represent vibration signals obtained while the gearbox is operating under healthy-state conditions. However, constraints on certain basis characteristics are necessary to enhance the detection of local wave-form changes caused by certain types of gear damage. The proposed methodology analyzes individual tooth-mesh waveforms from a healthy-state gearbox vibration signal that was generated using the vibration separation (synchronous signal-averaging) algorithm. Each waveform is separated into analysis domains using zeros of its slope and curvature. The bases selected in each analysis domain are chosen to minimize the prediction error, and constrained to have the same-sign local slope and curvature as the original signal. The resulting set of bases is used to analyze future-state vibration signals and the lifting prediction error is inspected. The constraints allow the transform to effectively adapt to global amplitude changes, yielding small prediction errors. However, local wave-form changes associated with certain types of gear damage are poorly adapted, causing a significant change in the

  7. Geochemical data synthesis and analysis

    NASA Technical Reports Server (NTRS)

    Philpotts, J. A.

    1979-01-01

    Data obtained at the Goddard Flight Center were collected for the purpose of completing analyses started at Goddard in order to maximize the scientific yield of the geochemistry program which was terminated in 1977. The major analytical task undertaken was to complete Gd analyses on a large number of samples already analyzed by mass spectrometry for other rare earth element abundances at Goddard. Gd values are important for pinning down the central part of the geochemically significant rare earth abundance pattern and are especially useful in the high precision definition of the utilitarian Eu anomaly. Isotope-dilution Gd abundances were obtained for 39 samples. The data are for 27 partition-coefficient samples, six Apollo 15 and 16 breccia samples, four terrestrial impactities, and associated rock standards.

  8. Geochemical challenge to earthquake prediction.

    PubMed

    Wakita, H

    1996-04-30

    The current status of geochemical and groundwater observations for earthquake prediction in Japan is described. The development of the observations is discussed in relation to the progress of the earthquake prediction program in Japan. Three major findings obtained from our recent studies are outlined. (i) Long-term radon observation data over 18 years at the SKE (Suikoen) well indicate that the anomalous radon change before the 1978 Izu-Oshima-kinkai earthquake can with high probability be attributed to precursory changes. (ii) It is proposed that certain sensitive wells exist which have the potential to detect precursory changes. (iii) The appearance and nonappearance of coseismic radon drops at the KSM (Kashima) well reflect changes in the regional stress state of an observation area. In addition, some preliminary results of chemical changes of groundwater prior to the 1995 Kobe (Hyogo-ken nanbu) earthquake are presented.

  9. Geochemical challenge to earthquake prediction.

    PubMed Central

    Wakita, H

    1996-01-01

    The current status of geochemical and groundwater observations for earthquake prediction in Japan is described. The development of the observations is discussed in relation to the progress of the earthquake prediction program in Japan. Three major findings obtained from our recent studies are outlined. (i) Long-term radon observation data over 18 years at the SKE (Suikoen) well indicate that the anomalous radon change before the 1978 Izu-Oshima-kinkai earthquake can with high probability be attributed to precursory changes. (ii) It is proposed that certain sensitive wells exist which have the potential to detect precursory changes. (iii) The appearance and nonappearance of coseismic radon drops at the KSM (Kashima) well reflect changes in the regional stress state of an observation area. In addition, some preliminary results of chemical changes of groundwater prior to the 1995 Kobe (Hyogo-ken nanbu) earthquake are presented. PMID:11607665

  10. PHREEQC. Geochemical Speciation Mass Transfer

    SciTech Connect

    Parkhurst, D.L.

    1995-01-01

    PHREEQC is designed to model geochemical reactions. Based on an ion association aqueous model, PHREEQC can calculate pH, redox potential, and mass transfer as a function of reaction progress. It can be used to describe geochemical processes for both far-field and near-field performance assessment and to evaluate data acquisition needs and test data. It can also calculate the composition of solutions in equilibrium with multiple phases. The data base, including elements, aqueous species, and mineral phases, is independent of the program and is completely user-definable. PHREEQC requires thermodynamic data for each solid, gaseous, or dissolved chemical species being modeled. The two data bases, PREPHR and DEQPAK7, supplied with PHREEQC are for testing purposes only and should not be applied to real problems without first being carefully examined. The conceptual model embodied in PHREEQC is the ion-association model of Pearson and Noronha. In this model a set of mass action equations are established for each ion pair (and controlling solid phases when making mass transfer calculations) along with a set of mass balance equations for each element considered. These sets of equations are coupled using activity coefficient values for each aqueous species and solved using a continued fraction approach for the mass balances combined with a modified Newton-Raphson technique for all other equations. The activity coefficient expressions in PHREEQC include the extended Debye-Huckel, WATEQ Debye-Huckel, and Davies equations from the original United States Geological Survey version of the program. The auxiliary preprocessor program PHTL, which is derived from EQTL, converts EQ3/6 thermodynamic data to PHREEQC format so that the two programs can be compared. PHREEQC can be used to determine solubility limits on the radionuclides present in the waste form. These solubility constraints may be input to the WAPPA leach model.

  11. The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans.

    PubMed

    Hamilton, Trinity L; Bryant, Donald A; Macalady, Jennifer L

    2016-02-01

    Understanding the role of biology in planetary evolution remains an outstanding challenge to geobiologists. Progress towards unravelling this puzzle for Earth is hindered by the scarcity of well-preserved rocks from the Archean (4.0 to 2.5 Gyr ago) and Proterozoic (2.5 to 0.5 Gyr ago) Eons. In addition, the microscopic life that dominated Earth's biota for most of its history left a poor fossil record, consisting primarily of lithified microbial mats, rare microbial body fossils and membrane-derived hydrocarbon molecules that are still challenging to interpret. However, it is clear from the sulfur isotope record and other geochemical proxies that the production of oxygen or oxidizing power radically changed Earth's surface and atmosphere during the Proterozoic Eon, pushing it away from the more reducing conditions prevalent during the Archean. In addition to ancient rocks, our reconstruction of Earth's redox evolution is informed by our knowledge of biogeochemical cycles catalysed by extant biota. The emergence of oxygenic photosynthesis in ancient cyanobacteria represents one of the most impressive microbial innovations in Earth's history, and oxygenic photosynthesis is the largest source of O2 in the atmosphere today. Thus the study of microbial metabolisms and evolution provides an important link between extant biota and the clues from the geologic record. Here, we consider the physiology of cyanobacteria (the only microorganisms capable of oxygenic photosynthesis), their co-occurrence with anoxygenic phototrophs in a variety of environments and their persistence in low-oxygen environments, including in water columns as well as mats, throughout much of Earth's history. We examine insights gained from both the rock record and cyanobacteria presently living in early Earth analogue ecosystems and synthesize current knowledge of these ancient microbial mediators in planetary redox evolution. Our analysis supports the hypothesis that anoxygenic photosynthesis

  12. Stellar Ablation of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.; Horwitz, J. L.

    2007-01-01

    We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.

  13. Stellar Ablation of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.; Horwitz, J. L.

    2007-01-01

    We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.

  14. The fragility of planetary systems

    NASA Astrophysics Data System (ADS)

    Portegies Zwart, S. F.; Jílková, Lucie

    2015-07-01

    We specify the range to which perturbations penetrate a planetesimal system. Such perturbations can originate from massive planets or from encounters with other stars. The latter can have an origin in the star cluster in which the planetary system was born, or from random encounters once the planetary system has escaped its parental cluster. The probability of a random encounter, either in a star cluster or in the Galactic field depends on the local stellar density, the velocity dispersion and the time spend in that environment. By adopting order of magnitude estimates, we argue that the majority of planetary systems born in open clusters will have a Parking zone, in which planetesimals are affected by encounters in their parental star cluster but remain unperturbed after the star has left the cluster. Objects found in this range of semimajor axis and eccentricity preserve the memory of the encounter that last affected their orbits, and they can therefore be used to reconstruct this encounter. Planetary systems born in a denser environment, such as in a globular cluster are unlikely to have a Parking zone. We further argue that some planetary systems may have a Frozen zone, in which orbits are not affected either by the more inner massive planets or by external influences. Objects discovered in this zone will have preserved information about their formation in their orbital parameters.

  15. Interstellar Transfer of Planetary Microbiota

    NASA Astrophysics Data System (ADS)

    Wallis, Max K.; Wickramasinghe, N. C.

    Panspermia theories require the transport of micro-organisms in a viable form from one astronomical location to another. The evidence of material ejection from planetary surfaces, of dynamical orbit evolution and of potential survival on landing is setting a firm basis for interplanetary panspermia. Pathways for interstellar panspermia are less clear. We compare the direct route, whereby life-bearing planetary ejecta exit the solar system and risk radiation hazards en route to nearby stellar systems, and an indirect route whereby ejecta hitch a ride within the shielded environment of comets of the Edgeworth- Kuiper Belt that are subsequently expelled from the solar system. We identify solutions to the delivery problem. Delivery to fully-fledged planetary systems of either the direct ejecta or the ejecta borne by comets depends on dynamical capture and is of very low efficiency. However, delivery into a proto-planetary disc of an early solar-type nebula and into pre-stellar molecular clouds is effective, because the solid grains efficiently sputter the incoming material in hypervelocity collisions. The total mass of terrestrial fertile material delivered to nearby pre-stellar systems as the solar system moves through the galaxy is from kilogrammes up to a tonne. Subject to further study of bio-viability under irradiation and fragmenting collisions, a few kg of original grains and sputtered fragments could be sufficient to seed the planetary system with a wide range of solar system micro-organisms.

  16. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.

    1971-01-01

    The development of new types of detectors for analysis of planetary atmospheres is discussed. Initially, the interest was in detectors for use under partial vacuum conditions. The program has been extended to include detectors for use at one atmosphere and adsorption system for control and separation of gases. Results to date have included detectors for O2 and H2 under partial vacuum conditions. Experiments on detectors for use at high pressures began in 1966, and systems for CO, H2, and O2, were reported. Electrically controlled adsorbent was developed. It was demonstrated that under proper conditions a thin film of semiconductor material could be electrically cycled to adsorb and desorb a specific gas. This work was extended to obtain quantitative data on the use of semiconductors as controllable adsorbents.

  17. High performances imaging systems for planetary landers

    NASA Astrophysics Data System (ADS)

    Josset, J.-L.; Beauvivre, S.

    2003-04-01

    Each planetary mission brings its specific needs and environmental conditions: high temperature and radiations for Mercury, shock, thermal cycles and low temperature operation for Mars, long vacuum cruise phase and very low temperature for comet nucleus. Nevertheless, all the missions share the same interests in term of low mass, low power and harsh environmental conditions. When a mission includes a lander, mass optimization is even more critical for the benefit of the overall science return. SPACE-X has developed high-performances imaging systems for Rosetta Lander and MarsExpress Lander. Future imaging systems for new exploration missions have to consider the promising micro-nano-technology developments in terms of miniaturisation, low power, wireless capabilities, etc.

  18. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.; Summerton, J. E.; Kirchner, J. D.; Allred, J. B.

    1974-01-01

    The development of new types of detectors for analysis of planetary atmospheres is discussed. Initially, the interest was in detectors for use under partial vacuum conditions; recently, the program has been extended to include detectors for use at one atmosphere and adsorption systems for control and separation of gases. Results to date have included detector for O2 and H2 under partial vacuum conditions. Experiments on detectors for use at high pressures began in 1966; and systems for CO, H2, and O2 were reported in 1967 and 1968. In 1968 studies began on an electrically controlled adsorbent. It was demonstrated that under proper conditions a thin film of semiconductor material could be electrically cycled to absorb and desorb a specific gas. This work was extended to obtain quantitative data on the use of semiconductors as controllable adsorbents.

  19. Use of Geochemical Indices in Environmental Assessment of Soil; the Predictable and the Predictably Unpredictable

    NASA Astrophysics Data System (ADS)

    Mikkonen, Hannah; Clarke, Bradley; van de Graaff, Robert; Reichman, Suzie

    2016-04-01

    application of geochemical indices without an understanding of site specific conditions could result in significant underestimation of anthropogenic impacts to soil and potential risks to the environment. The reliability and application of geochemical indices for estimation of background concentrations will be discussed, including comment on statistical limitations, (such as management of censored results and the behaviour of composition data) and miss-use/miss-interpretation of geochemical indices within the environmental assessment industry, including inferences of causation based on empirical relationships. HAMON, R. E., MCLAUGHLIN, M. J., GILKES, R. J., RATE, A. W., ZARCINAS, B., ROBERTSON, A., COZENS, G., RADFORD, N. & BETTENAY, L. 2004. Geochemical indices allow estimation of heavy metal background concentrations in soils. Global Biogeochemical Cycles, 18, GB1014. MYERS, J. & THORBJORNSEN, K. 2004. Identifying Metals Contamination in Soil: A Geochemical Approach. Soil & Sediment Contamination, 13, 1-16.

  20. The Planetary Archive

    NASA Astrophysics Data System (ADS)

    Penteado, Paulo F.; Trilling, David; Szalay, Alexander; Budavári, Tamás; Fuentes, César

    2014-11-01

    We are building the first system that will allow efficient data mining in the astronomical archives for observations of Solar System Bodies. While the Virtual Observatory has enabled data-intensive research making use of large collections of observations across multiple archives, Planetary Science has largely been denied this opportunity: most astronomical data services are built based on sky positions, and moving objects are often filtered out.To identify serendipitous observations of Solar System objects, we ingest the archive metadata. The coverage of each image in an archive is a volume in a 3D space (RA,Dec,time), which we can represent efficiently through a hierarchical triangular mesh (HTM) for the spatial dimensions, plus a contiguous time interval. In this space, an asteroid occupies a curve, which we determine integrating its orbit into the past. Thus when an asteroid trajectory intercepts the volume of an archived image, we have a possible observation of that body. Our pipeline then looks in the archive's catalog for a source with the corresponding coordinates, to retrieve its photometry. All these matches are stored into a database, which can be queried by object identifier.This database consists of archived observations of known Solar System objects. This means that it grows not only from the ingestion of new images, but also from the growth in the number of known objects. As new bodies are discovered, our pipeline can find archived observations where they could have been recorded, providing colors for these newly-found objects. This growth becomes more relevant with the new generation of wide-field surveys, particularly LSST.We also present one use case of our prototype archive: after ingesting the metadata for SDSS, 2MASS and GALEX, we were able to identify serendipitous observations of Solar System bodies in these 3 archives. Cross-matching these occurrences provided us with colors from the UV to the IR, a much wider spectral range than that

  1. Planetary Image Geometry Library

    NASA Technical Reports Server (NTRS)

    Deen, Robert C.; Pariser, Oleg

    2010-01-01

    The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A

  2. Packed Planetary Systems

    NASA Astrophysics Data System (ADS)

    Barnes, R.; Greenberg, R.

    2005-08-01

    Planetary systems display a wide range of appearances, with apparently arbitrary values of semi-major axis, eccentricity, etc. We reduce the complexity of orbital configurations to a single value, δ , which is a measure of how close, over secular timescales ( ˜10,000 orbits), two consecutive planets come to each other. We measure this distance relative to the sum of the radii of their Hill spheres, sometimes referred to as mutual Hill radii (MHR). We determine the closest approach distance by numerically integrating the entire system on coplanar orbits, using minimum masses. For non-resonant systems, close approach occurs during apsidal alignment, either parallel or anti-parallel. For resonant pairs the distance at conjunction determines the closest approach distance. Previous analytic work found that planets on circular orbits were assuredly unstable if they came within 3.5 MHR (i.e. Gladman 1993; Chambers, Wetherill & Boss 1996). We find that most known pairs of jovian planets (including those in our solar system) come within 3.5 -- 7 MHR of each other. We also find that several systems are unstable (their closest approach distance is less than 3.5 MHR). These systems, if they are real, probably exist in an observationally permitted location somewhat different from the current best fit. In these cases, the planets' closest approach distance will most likely also be slightly larger than 3.5 MHR. Most pairs beyond 7 MHR probably experienced post-formation migration (i.e. tidal circularization, inward scattering of small bodies) which moved them further apart. This result is even more remarkable since we have used the minimum masses; most likely the systems are inclined to the line of sight, making the Hill spheres larger, and shrinking δ . This dense packing may reflect a tendency for planets to form as close together as they can without being dynamically unstable. This result further implies there may be a large number of smaller, currently undetectable

  3. The complex planetary synchronization structure of the solar system

    NASA Astrophysics Data System (ADS)

    Scafetta, N.

    2014-01-01

    The complex planetary synchronization structure of the solar system, which since Pythagoras of Samos (ca. 570-495 BC) is known as the music of the spheres, is briefly reviewed from the Renaissance up to contemporary research. Copernicus' heliocentric model from 1543 suggested that the planets of our solar system form a kind of mutually ordered and quasi-synchronized system. From 1596 to 1619 Kepler formulated preliminary mathematical relations of approximate commensurabilities among the planets, which were later reformulated in the Titius-Bode rule (1766-1772), which successfully predicted the orbital position of Ceres and Uranus. Following the discovery of the ~ 11 yr sunspot cycle, in 1859 Wolf suggested that the observed solar variability could be approximately synchronized with the orbital movements of Venus, Earth, Jupiter and Saturn. Modern research has further confirmed that (1) the planetary orbital periods can be approximately deduced from a simple system of resonant frequencies; (2) the solar system oscillates with a specific set of gravitational frequencies, and many of them (e.g., within the range between 3 yr and 100 yr) can be approximately constructed as harmonics of a base period of ~ 178.38 yr; and (3) solar and climate records are also characterized by planetary harmonics from the monthly to the millennial timescales. This short review concludes with an emphasis on the contribution of the author's research on the empirical evidences and physical modeling of both solar and climate variability based on astronomical harmonics. The general conclusion is that the solar system works as a resonator characterized by a specific harmonic planetary structure that also synchronizes the Sun's activity and the Earth's climate. The special issue Pattern in solar variability, their planetary origin and terrestrial impacts (Mörner et al., 2013) further develops the ideas about the planetary-solar-terrestrial interaction with the personal contribution of 10

  4. NASA Planetary Science Summer School: Preparing the Next Generation of Planetary Mission Leaders

    NASA Astrophysics Data System (ADS)

    Budney, C. J.; Lowes, L. L.; Sohus, A.; Wheeler, T.; Wessen, A.; Scalice, D.

    2010-12-01

    Sponsored by NASA’s Planetary Science Division, and managed by the Jet Propulsion Laboratory, the Planetary Science Summer School prepares the next generation of engineers and scientists to participate in future solar system exploration missions. Participants learn the mission life cycle, roles of scientists and engineers in a mission environment, mission design interconnectedness and trade-offs, and the importance of teamwork. For this professional development opportunity, applicants are sought who have a strong interest and experience in careers in planetary exploration, and who are science and engineering post-docs, recent PhDs, and doctoral students, and faculty teaching such students. Disciplines include planetary science, geoscience, geophysics, environmental science, aerospace engineering, mechanical engineering, and materials science. Participants are selected through a competitive review process, with selections based on the strength of the application and advisor’s recommendation letter. Under the mentorship of a lead engineer (Dr. Charles Budney), students select, design, and develop a mission concept in response to the NASA New Frontiers Announcement of Opportunity. They develop their mission in the JPL Advanced Projects Design Team (Team X) environment, which is a cross-functional multidisciplinary team of professional engineers that utilizes concurrent engineering methodologies to complete rapid design, analysis and evaluation of mission concept designs. About 36 students participate each year, divided into two summer sessions. In advance of an intensive week-long session in the Project Design Center at JPL, students select the mission and science goals during a series of six weekly WebEx/telecons, and develop a preliminary suite of instrumentation and a science traceability matrix. Students assume both a science team and a mission development role with JPL Team X mentors. Once at JPL, students participate in a series of Team X project design

  5. Variational Principle for Planetary Interiors

    NASA Astrophysics Data System (ADS)

    Zeng, Li; Jacobsen, Stein B.

    2016-09-01

    In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equations into one, which provides us some insight into the problem. From this principle, a universal mass-radius relation, an estimate of the error propagation from the equation of state to the mass-radius relation, and a form of the virial theorem applicable to planetary interiors are derived.

  6. Dynamical Evolution of Planetary Embryos

    NASA Technical Reports Server (NTRS)

    Wetherill, George W.

    2002-01-01

    During the past decade, progress has been made by relating the 'standard model' for the formation of planetary systems to computational and observational advances. A significant contribution to this has been provided by this grant. The consequence of this is that the rigor of the physical modeling has improved considerably. This has identified discrepancies between the predictions of the standard model and recent observations of extrasolar planets. In some cases, the discrepancies can be resolved by recognition of the stochastic nature of the planetary formation process, leading to variations in the final state of a planetary system. In other cases, it seems more likely that there are major deficiencies in the standard model, requiring our identifying variations to the model that are not so strongly constrained to our Solar System.

  7. Planetary systems in star clusters .

    NASA Astrophysics Data System (ADS)

    Kouwenhoven, M. B. N.; Shu, Qi; Cai, Maxwell Xu; Spurzem, Rainer

    Thousands of confirmed and candidate exoplanets have been identified in recent years. Consequently, theoretical research on the formation and dynamical evolution of planetary systems has seen a boost, and the processes of planet-planet scattering, secular evolution, and interaction between planets and gas/debris disks have been well-studied. Almost all of this work has focused on the formation and evolution of isolated planetary systems, and neglect the effect of external influences, such as the gravitational interaction with neighbouring stars. Most stars, however, form in clustered environments that either quickly disperse, or evolve into open clusters. Under these conditions, young planetary systems experience frequent close encounters with other stars, at least during the first 106-107 years, which affects planets orbiting at any period range, as well as their debris structures.

  8. International Agreement on Planetary Protection

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The maintenance of a NASA policy, is consistent with international agreements. The planetary protection policy management in OSS, with Field Center support. The advice from internal and external advisory groups (NRC, NAC/Planetary Protection Task Force). The technology research and standards development in bioload characterization. The technology research and development in bioload reduction/sterilization. This presentation focuses on: forward contamination - research on the potential for Earth life to exist on other bodies, improved strategies for planetary navigation and collision avoidance, and improved procedures for sterile spacecraft assembly, cleaning and/or sterilization; and backward contamination - development of sample transfer and container sealing technologies for Earth return, improvement in sample return landing target assessment and navigation strategy, planning for sample hazard determination requirements and procedures, safety certification, (liaison to NEO Program Office for compositional data on small bodies), facility planning for sample recovery system, quarantine, and long-term curation of 4 returned samples.

  9. Robotic vehicles for planetary exploration

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian; Matthies, Larry; Gennery, Donald; Cooper, Brian; Nguyen, Tam; Litwin, Todd; Mishkin, Andrew; Stone, Henry

    1992-01-01

    A program to develop planetary rover technology is underway at the Jet Propulsion Laboratory (JPL) under sponsorship of the National Aeronautics and Space Administration. Developmental systems with the necessary sensing, computing, power, and mobility resources to demonstrate realistic forms of control for various missions have been developed, and initial testing has been completed. These testbed systems and the associated navigation techniques used are described. Particular emphasis is placed on three technologies: Computer-Aided Remote Driving (CARD), Semiautonomous Navigation (SAN), and behavior control. It is concluded that, through the development and evaluation of such technologies, research at JPL has expanded the set of viable planetary rover mission possibilities beyond the limits of remotely teleoperated systems such as Lunakhod. These are potentially applicable to exploration of all the solid planetary surfaces in the solar system, including Mars, Venus, and the moons of the gas giant planets.

  10. Atomic hydrogen in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Schneider, Stephen E.; Silverglate, Peter R.; Altschuler, Daniel R.; Giovanardi, Carlo

    1987-01-01

    The authors searched for neutral atomic hydrogen associated with 22 planetary nebulae and three evolved stars in the 21 cm line at the Arecibo Observatory. Objects whose radial velocities permitted discrimination from Galactic H I were chosen for observation. Hydrogen was detected in absorption from IC 4997. From the measurements new low limits are derived to the mass of atomic hydrogen associated with the undetected nebulae. Radio continuum observations were also made of several of the nebulae at 12.6 cm. The authors reexamine previous measurements of H I in planetary nebulae, and present the data on a consistent footing. The question of planetary nebula distances is considered at length. Finally, implications of the H I measurements for nebular evolution are discussed and it is suggested that atomic hydrogen seen in absorption was expelled from the progenitor star during the final 1000 yr prior to the onset of ionization.

  11. International Agreement on Planetary Protection

    NASA Astrophysics Data System (ADS)

    2000-10-01

    The maintenance of a NASA policy, is consistent with international agreements. The planetary protection policy management in OSS, with Field Center support. The advice from internal and external advisory groups (NRC, NAC/Planetary Protection Task Force). The technology research and standards development in bioload characterization. The technology research and development in bioload reduction/sterilization. This presentation focuses on: forward contamination - research on the potential for Earth life to exist on other bodies, improved strategies for planetary navigation and collision avoidance, and improved procedures for sterile spacecraft assembly, cleaning and/or sterilization; and backward contamination - development of sample transfer and container sealing technologies for Earth return, improvement in sample return landing target assessment and navigation strategy, planning for sample hazard determination requirements and procedures, safety certification, (liaison to NEO Program Office for compositional data on small bodies), facility planning for sample recovery system, quarantine, and long-term curation of 4 returned samples.

  12. From Planetary Mapping to Map Production: Planetary Cartography as integral discipline in Planetary Sciences

    NASA Astrophysics Data System (ADS)

    Nass, Andrea; van Gasselt, Stephan; Hargitai, Hendrik; Hare, Trent; Manaud, Nicolas; Karachevtseva, Irina; Kersten, Elke; Roatsch, Thomas; Wählisch, Marita; Kereszturi, Akos

    2016-04-01

    Cartography is one of the most important communication channels between users of spatial information and laymen as well as the open public alike. This applies to all known real-world objects located either here on Earth or on any other object in our Solar System. In planetary sciences, however, the main use of cartography resides in a concept called planetary mapping with all its various attached meanings: it can be (1) systematic spacecraft observation from orbit, i.e. the retrieval of physical information, (2) the interpretation of discrete planetary surface units and their abstraction, or it can be (3) planetary cartography sensu strictu, i.e., the technical and artistic creation of map products. As the concept of planetary mapping covers a wide range of different information and knowledge levels, aims associated with the concept of mapping consequently range from a technical and engineering focus to a scientific distillation process. Among others, scientific centers focusing on planetary cartography are the United State Geological Survey (USGS, Flagstaff), the Moscow State University of Geodesy and Cartography (MIIGAiK, Moscow), Eötvös Loránd University (ELTE, Hungary), and the German Aerospace Center (DLR, Berlin). The International Astronomical Union (IAU), the Commission Planetary Cartography within International Cartographic Association (ICA), the Open Geospatial Consortium (OGC), the WG IV/8 Planetary Mapping and Spatial Databases within International Society for Photogrammetry and Remote Sensing (ISPRS) and a range of other institutions contribute on definition frameworks in planetary cartography. Classical cartography is nowadays often (mis-)understood as a tool mainly rather than a scientific discipline and an art of communication. Consequently, concepts of information systems, mapping tools and cartographic frameworks are used interchangeably, and cartographic workflows and visualization of spatial information in thematic maps have often been

  13. Quantitative Studies in Planetary Volcanism

    NASA Technical Reports Server (NTRS)

    Baloga, Stephen M.

    2001-01-01

    Scientific research was conducted on volcanic processes on Mars, Venus, Io, the moon, and the Earth. The achievements led to scientific advances in the understanding of volcanic plumes, lava flow emplacements, coronae, and regoliths on the solid surfaces. This research led to multiple publications on each of the main topics of the proposal. Research was also presented at the annual Lunar and Planetary Science Conference at Houston. Typically, this grant contributed to 3-4 presentations each year. This grant demonstrated, numerous times, the usefulness of NASA mission data for advancing the understanding of volcanic processes on other planetary surfaces and the Earth.

  14. NASA Regional Planetary Image Facility

    NASA Technical Reports Server (NTRS)

    Arvidson, Raymond E.

    2001-01-01

    The Regional Planetary Image Facility (RPIF) provided access to data from NASA planetary missions and expert assistance about the data sets and how to order subsets of the collections. This ensures that the benefit/cost of acquiring the data is maximized by widespread dissemination and use of the observations and resultant collections. The RPIF provided education and outreach functions that ranged from providing data and information to teachers, involving small groups of highly motivated students in its activities, to public lectures and tours. These activities maximized dissemination of results and data to the educational and public communities.

  15. NASA Regional Planetary Image Facility

    NASA Technical Reports Server (NTRS)

    Arvidson, Raymond E.

    2001-01-01

    The Regional Planetary Image Facility (RPIF) provided access to data from NASA planetary missions and expert assistance about the data sets and how to order subsets of the collections. This ensures that the benefit/cost of acquiring the data is maximized by widespread dissemination and use of the observations and resultant collections. The RPIF provided education and outreach functions that ranged from providing data and information to teachers, involving small groups of highly motivated students in its activities, to public lectures and tours. These activities maximized dissemination of results and data to the educational and public communities.

  16. Shock modelling of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Cuesta, L.; Phillips, J. P.; Mampaso, A.

    1994-06-01

    The kinematics of Planetary Nebulae are analyzed in terms of the solutions to the equations of hydrodynamic equilibrium developed by J. Canto. We apply our analysis to the Planetary Nebulae NGC 6905 and NGC 6537. A detailed spectroscopic study of these objects reveals the existence of high nuclear velocities, together with complex kinematic structures and unusual emission line intensities. Shock ionization clearly plays a key role in these nebulae. Remarkably good agreement is obtained when comparing the synthetic maps and spectra resulting from the shock solutions with the observational data.

  17. Density in a Planetary Exosphere

    NASA Technical Reports Server (NTRS)

    Herring, Jackson; Kyle, Herbert L.

    1961-01-01

    A discussion of the Opik-Singer theory of the density of a planetary exosphere is presented. Their density formula permits the calculation of the depth of the exosphere. Since the correctness of their derivation of the basic formula for the density distribution has been questioned, an alternate method based directly on Liouville's theorem is given. It is concluded that the Opik-Singer formula seems valid for the ballistic component of the exosphere; but for a complete description of the planetary exosphere, the ionized and bound-orbit components must also be included.

  18. Division Iii: Planetary Systems Sciences

    NASA Astrophysics Data System (ADS)

    Meech, Karen; Valsecchi, Giovanni; Bowell, Edward L.; Bockelee-Morvan, Dominique; Boss, Alan; Cellino, Alberto; Consolmagno, Guy; Fernandez, Julio; Irvine, William; Lazzaro, Daniela; Michel, Patrick; Noll, Keith; Schulz, Rita; Watanabe, Jun-ichi; Yoshikawa, Makoto; Zhu, Jin

    2012-04-01

    Division III, with 1126 members, is the third largest of the 12 IAU Divisions, focusing on subject matter related to the physical study of interplanetary dust, comets, minor planets, satellites, planets, planetary systems and astrobiology. Within the Division are very active working groups that are responsible for planetary system and small body nomenclature, as well as a newly created working group on Near Earth Objects which was established order to investigate the requirements for international ground-and/or space-based NEO surveys to characterize 90% of all NEOs with diameters >40m in order to establish a permanent international NEO Early Warning System.

  19. Lunar and Planetary Science XXXV: Mars Volcanology and Tectonics

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Reports from the session, "Mars Volcanology and Tectonics" include:Martian Shield Volcanoes; Estimating the Rheology of Basaltic Lava Flows; A Model for Variable Levee Formation Rates in an Active Lava Flow; Deflections in Lava Flow Directions Relative to Topography in the Tharsis Region: Indicators of Post-Flow Tectonic Motion; Fractal Variation with Changing Line Length: A Potential Problem for Planetary Lava Flow Identification; Burfellshraun:A Terrestrial Analogue to Recent Volcanism on Mars; Lava Domes of the Arcadia Region of Mars; Comparison of Plains Volcanism in the Tempe Terra Region of Mars to the Eastern Snake River Plains, Idaho with Implications for Geochemical Constraints; Vent Geology of Low-Shield Volcanoes from the Central Snake River Plain, Idaho: Lessons for Mars and the Moon; Field and Geochemical Study of Table Legs Butte and Quaking Aspen Butte, Eastern Snake River Plain, Idaho: An Analog to the Morphology of Small Shield Volcanoes on Mars; Variability in Morphology and Thermophysical Properties of Pitted Cones in Acidalia Planitia and Cydonia Mensae; A Volcano Composed of Light-colored Layered Deposits on the Floor of Valles Marineris; Analysis of Alba Patera Flows: A Comparison of Similarities and Differences Geomorphologic Studies of a Very Long Lava Flow in Tharsis, Mars; Radar Backscatter Characteristics of Basaltic Flow Fields: Results for Mauna Ulu, Kilauea Volcano, Hawaii;and Preliminary Lava Tube-fed Flow Abundance Mapping on Olympus Mons.

  20. Lunar and Planetary Science XXXV: Mars Volcanology and Tectonics

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Reports from the session, "Mars Volcanology and Tectonics" include:Martian Shield Volcanoes; Estimating the Rheology of Basaltic Lava Flows; A Model for Variable Levee Formation Rates in an Active Lava Flow; Deflections in Lava Flow Directions Relative to Topography in the Tharsis Region: Indicators of Post-Flow Tectonic Motion; Fractal Variation with Changing Line Length: A Potential Problem for Planetary Lava Flow Identification; Burfellshraun:A Terrestrial Analogue to Recent Volcanism on Mars; Lava Domes of the Arcadia Region of Mars; Comparison of Plains Volcanism in the Tempe Terra Region of Mars to the Eastern Snake River Plains, Idaho with Implications for Geochemical Constraints; Vent Geology of Low-Shield Volcanoes from the Central Snake River Plain, Idaho: Lessons for Mars and the Moon; Field and Geochemical Study of Table Legs Butte and Quaking Aspen Butte, Eastern Snake River Plain, Idaho: An Analog to the Morphology of Small Shield Volcanoes on Mars; Variability in Morphology and Thermophysical Properties of Pitted Cones in Acidalia Planitia and Cydonia Mensae; A Volcano Composed of Light-colored Layered Deposits on the Floor of Valles Marineris; Analysis of Alba Patera Flows: A Comparison of Similarities and Differences Geomorphologic Studies of a Very Long Lava Flow in Tharsis, Mars; Radar Backscatter Characteristics of Basaltic Flow Fields: Results for Mauna Ulu, Kilauea Volcano, Hawaii;and Preliminary Lava Tube-fed Flow Abundance Mapping on Olympus Mons.

  1. Collected radiochemical and geochemical procedures

    SciTech Connect

    Kleinberg, J

    1990-05-01

    This revision of LA-1721, 4th Ed., Collected Radiochemical Procedures, reflects the activities of two groups in the Isotope and Nuclear Chemistry Division of the Los Alamos National Laboratory: INC-11, Nuclear and radiochemistry; and INC-7, Isotope Geochemistry. The procedures fall into five categories: I. Separation of Radionuclides from Uranium, Fission-Product Solutions, and Nuclear Debris; II. Separation of Products from Irradiated Targets; III. Preparation of Samples for Mass Spectrometric Analysis; IV. Dissolution Procedures; and V. Geochemical Procedures. With one exception, the first category of procedures is ordered by the positions of the elements in the Periodic Table, with separate parts on the Representative Elements (the A groups); the d-Transition Elements (the B groups and the Transition Triads); and the Lanthanides (Rare Earths) and Actinides (the 4f- and 5f-Transition Elements). The members of Group IIIB-- scandium, yttrium, and lanthanum--are included with the lanthanides, elements they resemble closely in chemistry and with which they occur in nature. The procedures dealing with the isolation of products from irradiated targets are arranged by target element.

  2. Improving Performance in Planetary Ultraviolet Spectrographs

    NASA Astrophysics Data System (ADS)

    Davis, M. W.; Gladstone, G. R.; Retherford, K. D.

    2016-10-01

    Four planetary ultraviolet spectrographs by SwRI have successfully operated on different planetary missions. Two more will operate aboard the JUICE and Europa missions with advancements to allow operations in the Jovian environment.

  3. Planetary Nomenclature: An Overview and Update

    NASA Astrophysics Data System (ADS)

    Gaither, T.; Hayward, R. K.; Blue, J.; Gaddis, L.; Schulz, R.; Aksnes, K.; Burba, G.; Consolmagno, G.; Lopes, R. M. C.; Masson, P.; Sheehan, W.; Smith, B. A.; Williams, G.; Wood, C.

    2017-06-01

    This contribution is an update for the planetary science community on the status of planetary nomenclature, its purpose and rules, the process for submitting name requests, and the IAU approval process.

  4. Planetary quarantine. Space research and technology

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Planetary quarantine strategies for advanced spacecraft consider effects of satellite encounter, Jupiter atmosphere entry, space radiation, and cleaning and decontamination techniques on microbiological growth probability. Analytical restructuring is developed for microbial burden prediction and planetary contamination.

  5. Tunable Laser Spectrometers for Planetary Science

    NASA Astrophysics Data System (ADS)

    Webster, C. R.; Flesch, G. J.; Forouhar, S.; Christensen, L. E.; Briggs, R.; Keymeulen, D.; Blacksberg, J.; Alerstam, E.; Mahaffy, P. R.

    2016-10-01

    Tunable laser spectrometers enjoy a wide range of applications in scientific research, medicine, industry, Earth and planetary space missions. We will describe instruments for planetary probes, aircraft, balloon, landers and CubeSats.

  6. Activities at the Lunar and Planetary Institute

    NASA Technical Reports Server (NTRS)

    Burke, K.

    1984-01-01

    The scientific and administrative activities of the Lunar and Planetary Institute are summarized. Recent research relating to geophysics, planetary geology, the origin of the Earth and Moon, the lunar surface, Mars, meteorites, and image processing techniques is discussed.

  7. International Infrastructure for Planetary Sciences: Universal Planetary Database Development Project 'the International Planetary Data Alliance'

    NASA Astrophysics Data System (ADS)

    Kasaba, Yasumasa; Crichton, D.; Capria, M. T.; Beebe, R.; Zender, J.

    2009-09-01

    The International Planetary Data Alliance (IPDA), formed under COSPAR in 2008, is a joint international effort to enable global access and exchange of high quality planetary science data, and to establish archive standards that make it easier to share data across international boundaries. In June - July 2009, we held the 4th Steering Committee meeting. Thanks to the many players from several agencies and institutions in the world, we got fruitful results in 6 projects: (1) Inter-operable Planetary Data Access Protocol (PDAP) implementations [led by J. Salgado@ESA], (2) Small bodies interoperability [led by I. Shinohara@JAXA & N. Hirata@U. Aizu], (3) PDAP assessment [led by Y. Yamamoto@JAXA], (4) Architecture and standards definition [led by D. Crichton@NASA], (5) Information model and data dictionary [led by S. Hughes@NASA], and (6) Venus Express Interoperability [led by N. Chanover@NMSU]. The projects demonstrated the feasibility of sharing data and emphasized the importance of developing common data standards to ensure world-wide access to international planetary archives. The Venus Express Interoperability project leveraged standards and technology efforts from both the Planetary Data System (PDS) and IPDA in order to deliver a new capability for data sharing between NASA/PDS and ESA/PSA. This project demonstrated a model and framework for linking compliant planetary archive systems for future international missions. The next step for IPDA, during the 2009-2010 period, will be to work with NASA/PDS to review and participate in an upgrade of its standards to improve both the consistency of the standards to build compliant international archives as well as improve long-term usability of the science data products. This paper presents the achievements and plans, which will be summarized in the paper which will appear in 'Space Research Today' in December 2009.

  8. Lunar and Planetary Surface Dynamics and Early History

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This document, submitted as part of this proposal renewal represents the Final Report required by NASA for Grant NAGS-9442. It should be emphasized that, while this work statement in the original proposal outlined anticipated directions of our research, the specific activities we carried out during this period differed slightly from those proposed, capitalizing on new unexpected results and new advances in analytical capability. The thrust of all the work we completed were completely within the stated research goals of the proposal and significantly advanced our knowledge of planetary processes and our understanding of the early solar system. The following summary outlines our achievements in the different areas of research. These include: A) Early solar system processes and time scales using I-Xe chronometry; B) The Active Capture of Volatiles: A new mechanism for the capture of heavy noble gases, possible implications for phase Q and planetary heavy noble gases; C) Separation of Xe-L from Xe-H: Physically selective experiments; D) Abundances of Presolar grains; E) Studies of Neon and Helium from single interstellar SiC and graphite grains; F) Pre-compaction exposure of meteoritic grains and chondrules; G) Geochemically Measured Half-Lives: Double beta-decay of Te and Ba isotopes; H) Noble gases in stratospheric interplanetary dust particles; I) New Analytical Instrument.

  9. Planetary gear train ring gear and support structure investigation

    NASA Astrophysics Data System (ADS)

    Valco, Mark J.

    1992-01-01

    Most helicopter transmissions utilize a planetary gear train as the final speed reduction stage. Due to weight constraints these transmissions have high power-to-weight ratios and relatively flexible structures. This investigation addresses the analysis of planetary gear trains with the ring gear mounted on a flexible support structure. The approach utilizes recent advances in automated contact methods for nonlinear finite element analysis. Rather than using a line of action spring to model gear pair mesh stiffness, finite element models of complete gears are developed, and the elastic gear members are engaged and rolled through mesh. The procedure includes detailed gear tooth geometry with profile modifications. A nonlinear approach is required due to large displacements associated with gear rotation and nonlinear boundary conditions associated with the gear tooth surface contact. The updated Lagrangian formulation and the MARC K-4.1 automated contact features are applied in the analysis. The ring gear support structure is modeled by an elastic foundation linking the ring gear to a rigid support. Calculation of gear pair deflections, stresses, transmission error, and mesh stiffness through the gear meshing cycle are demonstrated for external and internal spur gear pairs and a planetary gear train. Issues relating to the accuracy of the nonlinear finite element contact method, gear mesh stiffness, transmission error, and the planetary gear train elastic support structure are discussed.

  10. The National Geochemical Survey; database and documentation

    USGS Publications Warehouse

    ,

    2004-01-01

    The USGS, in collaboration with other federal and state government agencies, industry, and academia, is conducting the National Geochemical Survey (NGS) to produce a body of geochemical data for the United States based primarily on stream sediments, analyzed using a consistent set of methods. These data will compose a complete, national-scale geochemical coverage of the US, and will enable construction of geochemical maps, refine estimates of baseline concentrations of chemical elements in the sampled media, and provide context for a wide variety of studies in the geological and environmental sciences. The goal of the NGS is to analyze at least one stream-sediment sample in every 289 km2 area by a single set of analytical methods across the entire nation, with other solid sample media substituted where necessary. The NGS incorporates geochemical data from a variety of sources, including existing analyses in USGS databases, reanalyses of samples in USGS archives, and analyses of newly collected samples. At the present time, the NGS includes data covering ~71% of the land area of the US, including samples in all 50 states. This version of the online report provides complete access to NGS data, describes the history of the project, the methodology used, and presents preliminary geochemical maps for all analyzed elements. Future editions of this and other related reports will include the results of analysis of variance studies, as well as interpretive products related to the NGS data.

  11. Thermochemical cycles

    NASA Technical Reports Server (NTRS)

    Funk, J. E.; Soliman, M. A.; Carty, R. H.; Conger, W. L.; Cox, K. E.; Lawson, D.

    1975-01-01

    The thermochemical production of hydrogen is described along with the HYDRGN computer program which attempts to rate the various thermochemical cycles. Specific thermochemical cycles discussed include: iron sulfur cycle; iron chloride cycle; and hybrid sulfuric acid cycle.

  12. Influence Of Subsurface Biosphere On Geochemical Fluxes From Diffuse Hydrothermal Fluids: Direct Measurement Of Subsurface Hydrogen Oxidation

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Germanovich, L. N.; Lilley, M. D.; Genc, G.; DiPerna, C. J.; Bradley, A. S.; Olson, E. J.; Girguis, P. R.

    2011-12-01

    After decades of research on hydrothermal vent biogeochemistry, quantification of low-temperature diffusive geochemical fluxes remains elusive and limits our ability to place constraints on their role in global geochemical cycles. Quantifying the relative differences in geochemical composition, in particular of energy-rich compounds such as H2 and CH4, between focused high-temperature and diffuse low-temperature hydrothermal fluids can allow the estimation of metabolic rates in the underlying subsurface biosphere. Towards shortening the gap in our understanding of geochemical and microbial dynamics of the subsurface biosphere, we deployed an in situ mass spectrometer (ISMS) and low flow meter to quantify biologically relevant volatiles in a wide range of flow regimes and temperatures. Here we present coupled in situ chemical analyses and flow measurements that enable quantification of geochemical fluxes from a diversity of diffuse and focused vents along the Juan de Fuca Ridge hydrothermal system. We show that geochemical flux from diffuse vents can equal or exceed that emanating from hot, focused vents. Notably, hydrogen concentrations in fluids emerging from diffuse vents are 50% to 80% lower than predicted. We attribute the loss of hydrogen in diffuse vent fluids to microbial consumption in the subsurface, and suggest that subsurface microbial communities can significantly influence hydrothermal geochemical fluxes to the deep ocean.

  13. Reports of planetary astronomy - 1991

    NASA Technical Reports Server (NTRS)

    Rahe, Jurgen (Editor)

    1993-01-01

    This publication provides information about currently funded scientific research projects conducted in the Planetary Astronomy Program during 1991, and consists of two main sections. The first section gives a summary of research objectives, past accomplishments, and projected future investigations, as submitted by each principal investigator. In the second section, recent scientifically significant accomplishments within the Program are highlighted.

  14. Isotopic analysis of planetary solids

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Neuland, M.; Meyer, S.; Wurz, P.

    2013-09-01

    Isotopic analysis of planetary surfaces is of considerable interest for planetology. Studies of isotope composition can deliver information on radio-isotope chronology of planetary soil/regolith, an insight to processes that altered planetary surface (space weathering) or on possible biogenic processes that occurred or still occur on the planet. Mass spectrometry is a well-suited method that delivers accurate and precise isotope composition. Among other instruments (LAZMA and LAMS), the miniature laser ablation/ionisation mass analyser, LMS developed in Bern for in situ space research can be used to measure the elemental and isotopic composition of planetary solids. LMS support mass spectrometric investigation with a mass resolution of m/Δm≈500-1500, dynamic range of at least 8 decades and detection sensitivity of ~10 ppb. Current studies of various solid materials and standard reference materials show that isotope composition can be conducted with an accuracy and precision at per mill level if the isotope concentration exceeds 10-100 ppm. Implications of the studies for in situ application are discussed.

  15. Photometric calibration of planetary photographs

    NASA Technical Reports Server (NTRS)

    Beebe, R. F.

    1976-01-01

    The basic data and approach for calibrating photographic plates obtained with the 61 cm telescope at the Tortugas Mountain Station of New Mexico State University are summarized. Since this is the fundamental calibration of planetary data it is of use to all in-house users as well as other individuals who use the data.

  16. Lunar and Planetary Science XXXI

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This CD-ROM presents papers presented to the Thirty-first Lunar and Planetary Science Conference, March 13-17, 2000, Houston, Texas. Eighty-one conference sessions, and over one thousand extended abstracts are included. Abstracts cover topics such as Martian surface properties and geology, meteoritic composition, Martian landing sites and roving vehicles, planned Mars Sample Return Missions, and general astrobiology.

  17. Virtual reality and planetary exploration

    NASA Technical Reports Server (NTRS)

    Mcgreevy, Michael W.

    1992-01-01

    Exploring planetary environments is central to NASA's missions and goals. A new computing technology called Virtual Reality has much to offer in support of planetary exploration. This technology augments and extends human presence within computer-generated and remote spatial environments. Historically, NASA has been a leader in many of the fundamental concepts and technologies that comprise Virtual Reality. Indeed, Ames Research Center has a central role in the development of this rapidly emerging approach to using computers. This ground breaking work has inspired researchers in academia, industry, and the military. Further, NASA's leadership in this technology has spun off new businesses, has caught the attention of the international business community, and has generated several years of positive international media coverage. In the future, Virtual Reality technology will enable greatly improved human-machine interactions for more productive planetary surface exploration. Perhaps more importantly, Virtual Reality technology will democratize the experience of planetary exploration and thereby broaden understanding of, and support for, this historic enterprise.

  18. Virtual reality and planetary exploration

    NASA Technical Reports Server (NTRS)

    Mcgreevy, Michael W.

    1992-01-01

    Exploring planetary environments is central to NASA's missions and goals. A new computing technology called Virtual Reality has much to offer in support of planetary exploration. This technology augments and extends human presence within computer-generated and remote spatial environments. Historically, NASA has been a leader in many of the fundamental concepts and technologies that comprise Virtual Reality. Indeed, Ames Research Center has a central role in the development of this rapidly emerging approach to using computers. This ground breaking work has inspired researchers in academia, industry, and the military. Further, NASA's leadership in this technology has spun off new businesses, has caught the attention of the international business community, and has generated several years of positive international media coverage. In the future, Virtual Reality technology will enable greatly improved human-machine interactions for more productive planetary surface exploration. Perhaps more importantly, Virtual Reality technology will democratize the experience of planetary exploration and thereby broaden understanding of, and support for, this historic enterprise.

  19. Lunar and Planetary Science XXXI

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This CD-ROM presents papers presented to the Thirty-first Lunar and Planetary Science Conference, March 13-17, 2000, Houston, Texas. Eighty-one conference sessions, and over one thousand extended abstracts are included. Abstracts cover topics such as Martian surface properties and geology, meteoritic composition, Martian landing sites and roving vehicles, planned Mars Sample Return Missions, and general astrobiology.

  20. Investigations of planetary ring phenomena

    NASA Technical Reports Server (NTRS)

    Burns, Joseph A.

    1987-01-01

    Faint planetary rings, their dynamical behavior and physical properties, were the main focus of the research efforts. The motion of weakly-charged dust through the gravitational and magnetic fields of Jupiter were examined. Several topics concerning features of Saturn's rings were addressed. The origin and fate of the Uranian ring dust is presently being studied.

  1. Virtual reality and planetary exploration

    NASA Astrophysics Data System (ADS)

    McGreevy, Michael W.

    Exploring planetary environments is central to NASA's missions and goals. A new computing technology called Virtual Reality has much to offer in support of planetary exploration. This technology augments and extends human presence within computer-generated and remote spatial environments. Historically, NASA has been a leader in many of the fundamental concepts and technologies that comprise Virtual Reality. Indeed, Ames Research Center has a central role in the development of this rapidly emerging approach to using computers. This ground breaking work has inspired researchers in academia, industry, and the military. Further, NASA's leadership in this technology has spun off new businesses, has caught the attention of the international business community, and has generated several years of positive international media coverage. In the future, Virtual Reality technology will enable greatly improved human-machine interactions for more productive planetary surface exploration. Perhaps more importantly, Virtual Reality technology will democratize the experience of planetary exploration and thereby broaden understanding of, and support for, this historic enterprise.

  2. Lunar and Planetary Science XXXII

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This CD-ROM publication contains the extended abstracts that were accepted for presentation at the 32nd Lunar and Planetary Science Conference held at Houston, TX, March 12-16, 2001. The papers are presented in PDF format and are indexed by author, keyword, meteorite, program and samples for quick reference.

  3. Reports of planetary astronomy, 1989

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This is a compilation of abstracts of reports from Principal Investigators funded through NASA's Planetary Astronomy Office. It provides a summarization of work conducted in this program in 1989. Each report contains a brief statement on the strategy of investigation and lists significant accomplishments within the area of the author's funded grant or contract, plans for future work, and publications.

  4. Priority Planetary Science Missions Identified

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-03-01

    The U.S. National Research Council's (NRC) planetary science decadal survey report, released on 7 March, lays out a grand vision for priority planetary science missions for 2013-2022 within a tightly constrained fiscal environment. The cost-conscious report, issued by NRC's Committee on the Planetary Science Decadal Survey, identifies high-priority flagship missions, recommends a number of potential midsized missions, and indicates support for some smaller missions. The report states that the highest-priority flagship mission for the decade is the Mars Astrobiology Explorer-Cacher (MAX-C)—the first of three components of a NASA/European Space Agency Mars sample return campaign—provided that the mission scope can be reduced so that MAX-C costs no more than $2.5 billion. The currently estimated mission cost of $3.5 billion “would take up a disproportionate near-term share of the overall budget for NASA's Planetary Science Division,” the report notes.

  5. Interstellar transfer of planetary microbiota

    NASA Astrophysics Data System (ADS)

    Wallis, Max K.; Wickramasinghe, N. C.

    2004-02-01

    Panspermia theories require the transport of micro-organisms in a viable form from one astronomical location to another. The evidence of material ejection from planetary surfaces, of dynamical orbit evolution and of potential survival on landing is setting a firm basis for interplanetary panspermia. Pathways for interstellar panspermia are less clear. We compare the direct route, whereby life-bearing planetary ejecta exit the Solar system and risk radiation hazards en route to nearby stellar systems, and an indirect route whereby ejecta hitch a ride within the shielded environment of comets of the Edgeworth-Kuiper Belt that are subsequently expelled from the Solar system. We identify solutions to the delivery problem. Delivery to fully fledged planetary systems of either the direct ejecta or the ejecta borne by comets depends on dynamical capture and is of very low efficiency. However, delivery into a protoplanetary disc of an early solar-type nebula and into pre-stellar molecular clouds is effective, because the solid grains efficiently sputter the incoming material in hypervelocity collisions. The total mass of terrestrial fertile material delivered to nearby pre-stellar systems as the Solar system moves through the Galaxy is from kilograms up to a tonne. Subject to further study of bio-viability under irradiation and fragmenting collisions, a few kg of original grains and sputtered fragments could be sufficient to seed the planetary system with a wide range of Solar system micro-organisms.

  6. Simulating Planetary Dynamics in a Laboratory Setting

    NASA Astrophysics Data System (ADS)

    Kumar, Mohi

    2013-04-01

    The technological feats of rovers on planets and the stunning images that these and other space missions return from celestial bodies in the solar system tend to dominate public perception of what it means to be a planetary scientist. However, many planetary scientists are also involved with experimental planetary science research in the laboratory.

  7. The global sulfur cycle

    NASA Technical Reports Server (NTRS)

    Sagan, D. (Editor)

    1985-01-01

    The results of the planetary biology microbial ecology's 1984 Summer Research Program, which examined various aspects of the global sulfur cycle are summarized. Ways in which sulfur flows through the many living and chemical species that inhabit the surface of the Earth were investigated. Major topics studied include: (1) sulfur cycling and metabolism of phototropic and filamentous sulfur bacteria; (2) sulfur reduction in sediments of marine and evaporite environments; (3) recent cyanobacterial mats; (4) microanalysis of community metabolism in proximity to the photic zone in potential stromatolites; and (5) formation and activity of microbial biofilms on metal sulfides and other mineral surfaces. Relationships between the global sulfur cycle and the understanding of the early evolution of the Earth and biosphere and current processes that affect global habitability are stressed.

  8. Hyperspectral Image Analysis in Planetary Science and Astronomy

    NASA Astrophysics Data System (ADS)

    Merenyi, Erzsebet

    2014-01-01

    Hyperspectral images (spectral signatures acquired in hundreds of narrow, contiguous band passes on a regular spatial grid over a target area) have long been utilized in planetary astronomy for remote geochemical analyses. Typical hyperspectral imagery spans the visible to near-and-thermal-infrared wavelengths with 5-20 nm (λ/Δλ > 100) resolution, sufficient to resolve the discriminating spectral features of (near-)surface compounds. Compared with broad-band, multi-spectral imagery, hyperspectral data brings a phase change in the complexity of spectral patterns and the cluster structure and richness of the data space, and consequently in the analysis challenges for tasks like clustering, classification, regression, and parameter inference. Many traditional favorite techniques do not meet these challenges if one’s aim is to fully exploit the rich, intricate information captured by the sensor, ensure discovery of surprising small anomalies, and more. In stellar astronomy, where Ångström resolution is typical, the data complexity can grow even higher. With the advent of 21st century observatories such as ALMA, high spatial and spectral resolution image cubes with thousands of bands are extending into new and wider wavelength domains, adding impetus to develop and deploy increasingly powerful and efficient knowledge extraction techniques. In this talk I will highlight applications of brain-like machine learning, specifically advanced forms of neural maps that mimic analogous behaviors in natural neural maps in brains (for example, preferential attention to rare signals, to enhance discovery of small clusters). I will present examples of information extraction from hyperspectral data in planetary astronomy, and point out advantages over more traditional techniques, for “precision” data mining, discovery of small anomalies in the face of highly irregular cluster structure, accurate inference of non-linearly entangled latent parameters, or non-linear dimension

  9. Geochemical processes at mineral surfaces

    SciTech Connect

    Davis, J.A.; Hayes, K.F.

    1986-01-01

    This volume includes 32 papers which were presented at a symposium on geochemical processes at mineral-water interfaces in 1985 and which bring to bear on this area a very wide range of expertise. The discontinuities in properties which occur at the mineral-water interface have profound effects on the movement of naturally occurring ions. Weathering and precipitation processes control the concentrations and speciation of ions in natural waters and the movements of these within the hydrosphere; both classes of processes take place at mineral-water interfaces. After an introductory overview, the book is divided into seven major sections, each dealing with one of the aspects of the processes occurring at the mineral-water interface. Five papers deal with the physical properties of the mineral-water interface; these represent a well-balanced mix of experimental and theoretical (mathematical modeling) work. Adsorption phenomena are dealt with in another five papers; these are largely experimental in character. Ion-exchange processes are discussed in four papers, one of which addresses the use of relaxation methods to study ion exchange kinetics at the microscopic level. Spectroscopic techniques (including electron-spin resonance and Moessbauer spectroscopy) are utilized in four papers. Chemical reactions, mainly redox processes, at mineral-water interfaces are treated in four papers, one of which deals with non-biological organic reactions. Solid-solution formation and equilibria are the subjects of another set of four articles, and the last group of papers deals with the processes involved in precipitation and dissolution, including weathering.

  10. Organic geochemical constraints on paleoelevation

    NASA Astrophysics Data System (ADS)

    Polissar, P. J.; Rowley, D. B.; Currie, B. S.; Freeman, K. H.

    2012-12-01

    The elevation history of the land surface is an important factor in the interpretation of past tectonic, climate and ecological processes. However, quantitative estimates of paleoelevation are difficult to produce and new techniques are needed. Organic geochemical approaches to quantifying paleoelevations provide a new perspective on this difficult task. The hydrogen isotopic composition of organic biomarker molecules synthesized by plants and algae is systematically related to the water used for growth. Organic molecules in ancient sediments can provide values for the isotopic composition of this water and thus elevation, provided the relationship between elevation and isotopic values is known. Molecular hydrogen isotope ratios from Cenozoic lake sediments on the Tibetan Plateau demonstrate the utility of a biomarker approach. Terrestrial plant-wax D/H values on Neogene sediments from the Namling-Oiyug Basin provide new paleoelevation estimates that compare well with previous studies. Plant wax D/H ratios paired with lacustrine carbonate oxygen isotope values from the Lunpola and Hoh-Xil basins illustrate how paired isotope systems can unravel the isotopic composition of precipitation from evaporative enrichment of lake waters. A potentially fruitful avenue for future research is illustrated by D/H analyses on older sediments from the Namling-Oiyug Basin. These sediments—like many that could be useful for paleoaltimetry—have experienced significant burial and heating. As temperatures approach the oil window it becomes possible to exchange hydrogen in both the extractable organic molecules (bitumen) and the insoluble organic residue (kerogen). The extent to which this exchange alters the original isotopic composition will determine the usefulness of D/H analyses on thermally mature organic matter. The potential payoff and pitfalls of D/H analyses on heated sediments is illustrated with thermally immature and mature samples from the Namling-Oiyug Basin.

  11. Geochemical Origin of Biological Molecules

    NASA Astrophysics Data System (ADS)

    Bassez, Marie-Paule

    2013-04-01

    A model for the geochemical origin of biological molecules is presented. Rocks such as peridotites and basalts, which contain ferromagnesian minerals, evolve in the presence of water. Their hydrolysis is an exothermic reaction which generates heat and a release of H2 and of minerals with modified structures. The hydrogen reacts with the CO2 embedded inside the rock or with the CO2 of the environment to form CO in an hydrothermal process. With the N2 of the environment, and with an activation source arising from cosmic radiation, ferromagnesian rocks might evolve towards the abiotic formation of biological molecules, such as peptide like macromolecules which produce amino acids after acid hydrolysis. The reactions concerned are described. The production of hydrothermal CO is discussed in geological sites containing ferromagnesian silicate minerals and the low intensity of the Earth's magnetic field during Paleoarchaean Era is also discussed. It is concluded that excitation sources arising from cosmic radiation were much more abundant during Paleoarchaean Era and that macromolecular structures of biological relevance might consequently form during Archaean Eon, as a product of the chemical evolution of the rocks and of their mineral contents. This synthesis of abiotically formed biological molecules is consecutively discussed for meteorites and other planets such as Mars. This model for the geochemical origin of biological molecules has first been proposed in 2008 in the context of reactions involving catalysers such as kaolinite [Bassez 2008a] and then presented in conferences and articles [Bassez 2008b, 2009, 2012; Bassez et al. 2009a to 2012b]. BASSEZ M.P. 2008a Synthèse prébiotique dans les conditions hydrothermales, CNRIUT'08, Lyon 29-30/05/2008, Conf. and open access article:http://liris.cnrs.fr/~cnriut08/actes/ 29 mai 11h-12h40. BASSEZ M.P. 2008b Prebiotic synthesis under hydrothermal conditions, ISSOL'08, P2-6, Firenze-Italy, 24-29/08/2008. Poster at the

  12. Mineralogical and geochemical anomalous data of the K-T boundary samples

    NASA Technical Reports Server (NTRS)

    Miura, Y.; Shibya, G.; Imai, M.; Takaoka, N.; Saito, S.

    1988-01-01

    Cretaceous-Tertiary boundary problem has been discussed previously from the geological research, mainly by fossil changes. Although geochemical bulk data of Ir anomaly suggest the extraterrestrial origin of the K-T boundary, the exact formation process discussed mainly by mineralogical and geochemical study has been started recently, together with noble gas contents. The K-T boundary sample at Kawaruppu River, Hokkaido was collected, in order to compare with the typical K-T boundary samples of Bubbio, Italy, Stevns Klint, Denmark, and El Kef, Tunisia. The experimental data of the silicas and calcites in these K-T boundary samples were obtained from the X-ray unit-cell dimension (i.e., density), ESR signal and total linear absorption coefficient, as well as He and Ne contents. The K-T boundary samples are usually complex mixture of the terrestrial activities after the K-T boundary event. The mineralogical and geochemical anomalous data indicate special terrestrial atmosphere at the K-T boundary formation probably induced by asteroid impact, followed the many various terrestrial activities (especially the strong role of sea-water mixture, compared with terrestrial highland impact and impact craters in the other earth-type planetary bodies).

  13. Lunar and Planetary Science XXXV: Origin of Planetary Systems

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session titled Origin of Planetary Systems" included the following reports:Convective Cooling of Protoplanetary Disks and Rapid Giant Planet Formation; When Push Comes to Shove: Gap-opening, Disk Clearing and the In Situ Formation of Giant Planets; Late Injection of Radionuclides into Solar Nebula Analogs in Orion; Growth of Dust Particles and Accumulation of Centimeter-sized Objects in the Vicinity of a Pressure enhanced Region of a Solar Nebula; Fast, Repeatable Clumping of Solid Particles in Microgravity ; Chondrule Formation by Current Sheets in Protoplanetary Disks; Radial Migration of Phyllosilicates in the Solar Nebula; Accretion of the Outer Planets: Oligarchy or Monarchy?; Resonant Capture of Irregular Satellites by a Protoplanet ; On the Final Mass of Giant Planets ; Predicting the Atmospheric Composition of Extrasolar Giant Planets; Overturn of Unstably Stratified Fluids: Implications for the Early Evolution of Planetary Mantles; and The Evolution of an Impact-generated Partially-vaporized Circumplanetary Disk.

  14. Nature and Composition of Planetary Surficial Deposits and Their Relationship to Planetary Crusts

    NASA Astrophysics Data System (ADS)

    McLennan, S. M.

    2010-12-01

    Planetary soils constitute micron to meter sized debris blankets covering all or parts of the surfaces of many planetary bodies. Recent results from the Martian surface, by the MER rovers and Phoenix lander, the Huygens probe at Titan and perhaps even the NEAR mission to asteroid 433 Eros suggest a continuum between classic planetary soils, such as those on the Moon, and conventional sediments, such as those on Earth. Controls on this variation are governed by complex interactions related to (1) impact and volcanic history, (2) presence and nature of atmospheres (and thus climate), (3) occurrence, composition and physical state of near-surface volatiles (e.g., water, methane), and (4) presence and nature of crustal tectonics, crustal evolution, and so forth. The Moon represents one extreme where surficial deposits result almost exclusively from impact processes. Absence of water and air restrict further reworking or transport on a significant scale after initial deposition. Disruption and mixing of lunar soils takes place but is related to impact gardening operating on relatively local scales and largely in a vertical sense; alteration is restricted to space weathering. The effect is that lunar soils are compositionally variable and match the composition of the crust in the vicinity of where they form. Thus lunar soils in the highlands are fundamentally different in composition than those on maria. Earth provides the other extreme where the highly dynamic geochemical and geophysical nature of the surface precludes preservation of classic planetary soils, although analogs may exist in ejecta blankets and eolian loess. Instead, a complex suite of sedimentary deposits form in response to chemical and physical weathering, erosion, transport and deposition by a variety of mechanisms involving water, wind, ice and biology. Although there is substantial sedimentary lithological differentiation (e.g., shales, sands, carbonates, evaporites), greatly influenced by the

  15. Low-density geochemical mapping and the robustness of geochemical patterns

    USGS Publications Warehouse

    Smith, D.B.; Reimann, C.

    2008-01-01

    Geochemical mapping of entire continents and, ultimately, the world is still a challenge for applied geochemists. At sample densities traditionally used for geochemical exploration (1 site per 1-25 km2), geochemical mapping of whole continents is logistically extremely demanding and tremendously expensive. The first low-density geochemical surveys (1 site per 200 km2) were carried out during the late 1960s in Africa. Later surveys conducted in various parts of the world had sample densities ranging from 1 site per 300 km2 to 1 site per 18 000 km2. Although these surveys were deemed successful by the investigators in defining variations in background element content on a regional scale, the scientific community was sceptical that low-density geochemical mapping was possible and would provide useful information. The main area of criticism centred around the concern that at such low sample densities the resulting maps would not be robust, i.e. if the same area were resampled and remapped, different geochemical patterns would emerge. Different examples from the USA, Europe, China and Africa demonstrate that low-density geochemical mapping will result in stable and robust geochemical patterns at the continental scale. Such maps are urgently needed for a wide variety of applications. ?? 2008 AAG/ Geological Society of London.

  16. Lunar and Planetary Science XXXV: Origin of Planetary Systems

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Origin of Planetary Systems" included the following reports: (12753) Povenmire - Standard Comparison Small Main Belt Asteroid?; Gravitational Frequencies of Extra-Solar Planets; 'Jumping Jupiters' in Binary Star Systems; Hermes, Asteroid 2002 SY50 and the Northern Cetids - No Link Found!; What Kind of Accretion Model is Required for the Solar System; and Use of an Orbital Phase Curve of Extrasolar Planet for Specification of its Mass.

  17. Planetary landscape: a new synthesis

    NASA Astrophysics Data System (ADS)

    Hargitai, H.

    The elements that build up a landscape on Earth consists of natural (biogenic and abiogenic - lithologic, atmospheric, hydrologic) and artificial (antropogenic) factors. Landscape is a complex system of these different elements, which interact with one another. For example the same lithology makes different landscapes under different climatic conditions. If the same conditions are present, the same landscape type will appear. The mosaic of ecotopes (topical) units, which are the system of homogenous caharacteristic areas of various geotopes makes up different level geochores (chorical unit). Geochores build up a hierarchic system and cover the whole surface.On Earth, landscapes can be qualified according to their characteristics: relief forms (morphology), and its potential economic value. Aesthetic and subjective parameters can also be considered especially when speaking of a residental area. We now propose the determination of "planetary landscape sets" which can potentially occur on the solid surface of a planetary body during its lifetime. This naturally includes landscapes of the present state of planetary bodies and also paleolandscapes from the past of planets, including Earth. Landscapes occur in the boundary of the planets solid and not solid sphere that is on the solid-vacuum, the solid - gas and on the solid - liquid boundary. Thinking this way a landscape can occurs on the ocean floor as well. We found that for the determination of a planetary landscape system, we can use the experiences from the making of the terminology and nomenclature system of Earth undersea topography. [1] The nomenclature system and the terminology used by astrogeologists could be revised. Common names of features should be defined (nova, tessera, volcano, tholus, lobate ejecta crater etc) with a type example for each. A well defined hierarchy for landscape types should be defined. The Moon is the best example, since it uses many names that originates from the 17th century, mixed

  18. The Anthropocene: A Planetary Perspective

    NASA Astrophysics Data System (ADS)

    Anbar, A. D.; Hartnett, H. E.; York, A.; Selin, C.

    2016-12-01

    The Anthropocene is a new planetary epoch defined by the emergence of human activity as one of the most important driving forces on Earth, rivaling and also stressing the other systems that govern the planet's habitability. Public discussions and debates about the challenges of this epoch tend to be polarized. One extreme denies that humans have a planetary-scale impact, while the other wishes that this impact could disappear. The tension between these perspectives is often paralyzing. Effective adaptation and mitigation requires a new perspective that reframes the conversation. We propose a planetary perspective according to which this epoch is the result of a recent major innovation in the 4 ­billion ­year history of life on Earth: the emergence of an energy-intensive planetary civilization. The rate of human energy use is already within an order of magnitude of that of the rest of the biosphere, and rising rapidly, and so this innovation is second only to the evolution of photosynthesis in terms of energy capture and utilization by living systems. Such energy use has and will continue to affect Earth at planetary scale. This reality cannot be denied nor wished away. From this pragmatic perspective, the Anthropocene is not an unnatural event that can be reversed, as though humanity is separate from the Earth systems with which we are co-evolving. Rather, it is an evolutionary transition to be managed. This is the challenge of turning a carelessly altered planet into a carefully designed and managed world, maintaining a "safe operating space" for human civilization (Steffen et al., 2011). To do so, we need an integrated approach to Earth systems science that considers humans as a natural and integral component of Earth's systems. Insights drawn from the humanities and the social sciences must be integrated with the natural sciences in order to thrive in this new epoch. This type of integrated perspective is relatively uncontroversial on personal, local, and even

  19. Crossing the Boundaries in Planetary Atmospheres - From Earth to Exoplanets

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Genio, Anthony Del

    2013-01-01

    The past decade has been an especially exciting time to study atmospheres, with a renaissance in fundamental studies of Earths general circulation and hydrological cycle, stimulated by questions about past climates and the urgency of projecting the future impacts of humankinds activities. Long-term spacecraft and Earth-based observation of solar system planets have now reinvigorated the study of comparative planetary climatology. The explosion in discoveries of planets outside our solar system has made atmospheric science integral to understanding the diversity of our solar system and the potential habitability of planets outside it. Thus, the AGU Chapman Conference Crossing the Boundaries in Planetary Atmospheres From Earth to Exoplanets, held in Annapolis, MD from June 24-27, 2013 gathered Earth, solar system, and exoplanet scientists to share experiences, insights, and challenges from their individual disciplines, and discuss areas in which thinking broadly might enhance our fundamental understanding of how atmospheres work.

  20. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates

    NASA Astrophysics Data System (ADS)

    Atchley, Adam L.; Navarre-Sitchler, Alexis K.; Maxwell, Reed M.

    2014-09-01

    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb2 +) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb2 + concentrations within the plume. Dissimilarities between ensemble Pb2 + concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb2 + concentrations are the same for all three

  1. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates.

    PubMed

    Atchley, Adam L; Navarre-Sitchler, Alexis K; Maxwell, Reed M

    2014-09-01

    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb(2+)) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb(2+) concentrations within the plume. Dissimilarities between ensemble Pb(2+) concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb(2+) concentrations are the same for all

  2. Diurnal variability of the planetary albedo: An appraisal with satellite measurements and general circulation models

    SciTech Connect

    Potter, G.L.; Cess, R.D.; Minnis, P.; Harrison, E.F.; Ramanathan, V.

    1988-03-01

    This study addresses two aspects of the planetary albedo's diurnal cycle, the first of which refers to directional models of the planetary albedo. It is found that even for clear regions there appear to be deficiencies in our knowledge of how to model this quantity. Over land surfaces, for example, Nimbus-7 data for the directional planetary albedo compare best with model calculations for which a Lambertian surface is assumed, despite ample evidence that the albedo of land surfaces is dependent upon solar zenith angle. Similarly, over ocean surfaces both GOES and Nimbus-7 data produce a weaker dependence of the planetary albedo upon solar zenith angle than would be suggested by model calculations.

  3. Archaea in biogeochemical cycles.

    PubMed

    Offre, Pierre; Spang, Anja; Schleper, Christa

    2013-01-01

    Archaea constitute a considerable fraction of the microbial biomass on Earth. Like Bacteria they have evolved a variety of energy metabolisms using organic and/or inorganic electron donors and acceptors, and many of them are able to fix carbon from inorganic sources. Archaea thus play crucial roles in the Earth's global geochemical cycles and influence greenhouse gas emissions. Methanogenesis and anaerobic methane oxidation are important steps in the carbon cycle; both are performed exclusively by anaerobic archaea. Oxidation of ammonia to nitrite is performed by Thaumarchaeota. They represent the only archaeal group that resides in large numbers in the global aerobic terrestrial and marine environments on Earth. Sulfur-dependent archaea are confined mostly to hot environments, but metal leaching by acidophiles and reduction of sulfate by anaerobic, nonthermophilic methane oxidizers have a potential impact on the environment. The metabolisms of a large number of archaea, in particular those dominating the subsurface, remain to be explored.

  4. Geochemical Evidence of Microbially-Mediated Subglacial Mineral Weathering

    NASA Astrophysics Data System (ADS)

    Montross, S. N.; Skidmore, M. L.

    2006-12-01

    Interactions between dilute meltwater and fine-grained, freshly comminuted debris at the bed of temperate glaciers liberate significant solute. The proportions of solute produced in the subglacial environment via biotic and abiotic processes remains unknown, however, this work suggests the biotic contribution is substantial. Laboratory analyses of microbiological and geochemical properties of sediment and meltwater from the Haut Glacier d'Arolla (HGA) indicates that a metabolically active microbial community exists in water-saturated sediments at the ice-bedrock interface. Basal sediment slurries and meltwater were incubated in the laboratory for 100 days under near in situ subglacial conditions. Relative proportions of solute produced via abiotic v. biotic mineral weathering were analyzed by comparing the evolved aqueous chemistry of biologically active "live" sediment slurries with sterilized controls. Aqueous chemical analyses indicate an increase in solute produced from mineral weathering coupled with nitrate depletion in the biologically active slurries compared with the killed controls. These results infer that microbial activity at HGA is likely an important contributor to chemical weathering associated solute fluxes from the glaciated catchment. Due to the magnitude of past glaciations throughout geologic time (e.g., Neoproterozoic and Late-Pleistocene), and evidence that subglacial microbial activity impacts mineral weathering, greater consideration needs to be given to cold temperature biogeochemical weathering and its impact on global geochemical cycles.

  5. Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations.

    PubMed

    Sengupta, Aditi; Wang, Yadi; Meira Neto, Antonio A; Matos, Katarena A; Dontsova, Katerina; Root, Rob; Neilson, Julie W; Maier, Raina M; Chorover, Jon; Troch, Peter A

    2016-09-11

    Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

  6. Geochemical response to hydrologic change along land-sea interfaces

    NASA Astrophysics Data System (ADS)

    Michael, H. A.; Yu, X.; LeMonte, J. J.; Sparks, D. L.; Kim, K. H.; Heiss, J.; Ullman, W. J.; Guimond, J. A.; Seyfferth, A.

    2016-12-01

    Coastal groundwater-surface water interfaces are hotspots of geochemical activity, where reactants contributed by different sources come in contact. Reactions that occur along these land-sea boundaries have important effects on fluxes and cycling of carbon, nutrients, and contaminants. Hydrologic perturbations can alter interactions by promoting mixing, changing redox state, and altering subsurface residence times during which reactions may occur. We present examples from field and modeling investigations along the Delaware coastline that illustrate the impacts of hydrologic fluctuations on geochemical conditions and fluxes in different coastal environments. Along the highly populated Wilmington coastline, soils are contaminated with heavy metals from legacy industrial practices. We show with continuous redox monitoring and sampling over tidal to seasonal timescales that arsenic is mobilized and immobilized in response to hydrologic change. Along a beach, modeling and long-term monitoring show the influence of tidal to seasonal changes in the mixing zone between discharging fresh groundwater and seawater in the intertidal beach aquifer and associated impacts on biogeochemical reactivity and denitrification. In a saltmarsh, hydrologic changes alter carbon dynamics, with implications for the discharge of dissolved organic carbon to the ocean and export of carbon dioxide and methane to the atmosphere. Understanding the impacts of hydrologic changes on both long and short timescales is essential for improving our ability to predict the global biogeochemical impacts of a changing climate.

  7. Geochemical effects of decoupled fractional crystallization and crustal assimilation

    NASA Astrophysics Data System (ADS)

    Cribb, J. W.; Barton, M.

    1996-05-01

    Most models of crustal assimilation assume that the amount of assimilant added to the magma is proportional to each infinitesimally small amount of solid removed during crystallization (AFC). In some magmatic systems, however, assimilation and crystallization are not strictly related and the mass assimilated is decoupled from, and therefore varies independently of, the mass crystallized (FCA). The geochemical consequences of FCA are examined and compared to those of AFC. The behavior of incompatible elements is identical during AFC and FCA, and ratios of these elements do not allow discrimination between the two processes. Major-oxide least-squares mass-balance models do not discriminate between AFC and FCA at F ≥ 0.7 ( F = fraction of melt remaining). However, FCA yields magmas richer in compatible elements and with higher Sr-isotopic ratios than AFC at a given value of F. Repeated cycles of FCA and AFC combined with magma mixing (FAM) may result in unusual geochemical trends, such as the evolution of a calc-alkaline basaltic parent to a tholeiitic daughter magma, or the evolution of low- and medium-K calc-alkaline basalts to high-K andesites, dacites, trachyandesites or trachydacites. Lavas erupted by the volcano Micro Profitis Ilias on Santorini, Hellenic arc, Greece, provide an example of magmas which evolved by combined fractionation, assimilation by FCA and mixing.

  8. Gigayear Instabilities in Planetary Systems

    NASA Astrophysics Data System (ADS)

    Fabrycky, Daniel

    One of the biggest modern discoveries about the Solar System is that it is chaotic (Laskar 1989, 1994). On million-year timescales, nearby trajectories exponentially diverge; on billion-year timescales, planets can develop large eccentricities and even collide. This is possible because our planets interact with enough energy and with the right (secular) timescales. This has the potential to put the planet Mercury on an unstable orbit in the future, before the Sun exhausts its fuel. Currently, as a standard step in the analysis, exoplanet observing teams check whether the planetary systems they are discovering are stable. This usually involves a few-Megayear numerical integration, and the system usually passes that test. However, the signatures of continuing instability have not been looked for in the exoplanet population, nor has its implications for planetary formation and evolution been fully recognized. We will study several specific evolutionary scenarios in which instability may manifest only on gigayear timescales, i.e. midway through the lives of the host stars. This is relevant to the solicitation in that it characterizes the dynamics of exoplanetary systems. In the first project, we will compare N-body, numerically-calculated secular, and Fourier-expansion secular theories to determine what essential ingredients go into the conclusion that a general planetary system is chaotic. We will apply these tools to specific realizations of Kepler-discovered close-in planetary systems consisting of three or more Neptunes or super-Earths, which is the most populous known exoplanet population. We will thus find the common ailments afflicting middle-age planetary systems. In the second project, we will consider how planets might get stranded in their Kuiper and Oort clouds during early system evolution, only to destabilize the inner system later on. Various investigators have wondered whether the Solar System is accompanied by a massive planetary companion, including a

  9. Teaching, Learning, and Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.

    2002-01-01

    This is the final report of a program that examined the fundamentals of education associated with space activities, promoted educational policy development in appropriate forums, and developed pathfinder products and services to demonstrate the utility of advanced communication technologies for space-based education. Our focus was on space astrophysics and planetary exploration, with a special emphasis on the themes of the Origins Program, with which the Principal Investigator (PI) had been involved from the outset. Teaching, Learning, and Planetary Exploration was also the core funding of the Space Telescope Science Institute's (ST ScI) Special Studies Office (SSO), and as such had provided basic support for such important NASA studies as the fix for Hubble Space Telescope (HST) spherical aberration, scientific conception of the HST Advanced Camera, specification of the Next-Generation Space Telescope (NGST), and the strategic plan for the second decade of the HST science program.

  10. Evolution of Planetary Ringmoon Systems

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1995-01-01

    The last few decades have seen an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of these systems as our intuition (and our computers) catch up with the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is an emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system.

  11. The chemistry of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.

    1976-01-01

    Present knowledge concerning the chemistry of planetary atmospheres is reviewed along with the theories which attempt to explain observational data. The known gross atmospheric compositions of the terrestrial and giant planets are listed, differences between the atmospheres of earth and Venus are discussed, and the atmospheres of the giant planets are described. The origin and evolution of the atmospheres of earth, Venus, Mars, Jupiter, Saturn, and Uranus are outlined, and chemical processes in the atmospheres are examined, particularly cloud formation. The question of organic synthesis and evolution in the reducing atmospheres of the giant planets is considered. It is noted that laboratory work on the individual chemical processes and reactions involved in the evolution of organic compounds in planetary atmospheres, comets, and interstellar space points to the inevitability of organic-compound synthesis in all these situations and to the pervasiveness of organic chemistry throughout the universe.

  12. Integration of Planetary Protection Activities

    NASA Technical Reports Server (NTRS)

    Race, Margaret S.

    2000-01-01

    Research and activities under this grant have focused on a systematic examination and analysis of critical questions likely to impact planetary protection (PP) controls and implementation for Mars sample return missions (MSR). Four areas in the non-scientific and social realms were selected for special attention because of their importance to future mission planning and concern about critical timing or possible economic impacts on MSR mission implementation. These include: (1) questions of legal uncertainty and the decision making process, (2) public perception of risks associated with sample return, (3) risk communication and Education/Public Outreach , and (4) planetary protection implications of alternative mission architectures, for both robotic and human sample return missions. In its entirety, NAG 2-986 has encompassed three categories of activity: (1) research and analysis (Race), (2) subcontracted research (MacGregor/Decision Research), and (3) consulting services.

  13. Curie-Montgolfiere Planetary Explorers

    NASA Astrophysics Data System (ADS)

    Taylor, Chris Y.; Hansen, Jeremiah

    2007-01-01

    Hot-air balloons, also known as Montgolfiere balloons, powered by heat from radioisotope decay are a potentially useful tool for exploring planetary atmospheres and augmenting the capabilities of other exploration technologies. This paper describes the physical equations and identifies the key engineering parameters that drive radioisotope-powered balloon performance. These parameters include envelope strength-to-weight, envelope thermal conductivity, heater power-to-weight, heater temperature, and balloon shape. The design space for these parameters are shown for varying atmospheric compositions to illustrate the performance needed to build functioning ``Curie-Montgolfiere'' balloons for various planetary atmospheres. Methods to ease the process of Curie-Montgolfiere conceptual design and sizing of are also introduced.

  14. NASA and the planetary imperative

    NASA Astrophysics Data System (ADS)

    van Allen, J. A.

    1982-10-01

    Previous, existing, and planned NASA planetary programs are reviewed, along with near-earth and solar system studies which still offer areas of significant exploration. The moon received initial concentrated attention and space technology efforts due to the presence of scientific knowledge which served to define specific questions. A Mariner mission to Mars was completed in 1962 and led to the Viking missions of the 1970s, which were generally dedicated to the search for life on Mars. The Pioneer 10 and 11 spacecraft are currently sending data from the outer planets' region as part of a Grand Tour as are Voyagers 1 and 2. It is noted that only the Galileo mission, which will drop a probe into the Jupiter atmosphere, is currently scheduled as a planetary start by NASA. Conversely, the launch of the Space Telescope onboard the Shuttle will give access to stellar and galactic data, while missions closer to home, such as the Venus Orbiting Imaging Radar were cancelled.

  15. Planetary nebulae and stellar evolution

    NASA Technical Reports Server (NTRS)

    Maran, S. P.

    1983-01-01

    Newly defined characteristics of planetary nebulae (PN) derived from analysis of a photometric survey of 57 PN are reported. The data were combined with measurements of 27 other PN made since 1918 and were found to indicate core masses ranging from 0.55-1.0 solar mass. N/O elemental abundance ratios observed were correlated with the planetary nuclei masses, and were in direct proportion. IUE data on PN that overlapped a large part of the survey indicated that the PN in the galactic disk are more massive than PN in the halo. It is suggested that PN evolve into white dwarfs, a hypothesis supported by astrometric solutions for three nearby visual binaries featuring white dwarfs with well-determined masses. It is noted, however, that PN with masses exceeding one solar mass have been sighted in the Magellanic Clouds.

  16. Neutral matter in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Dinerstein, Harriet L.

    1991-01-01

    A review of current studies of neutral envelopes is presented with particular attention given to the use of the envelopes as test cases for understanding the ionization and thermal structure of photodissociation regions. The study of near-IR H2 emission is discussed with detailed spectra given for a few planetary nebulae, and airborne observations of far-IR atomic lines are discussed. These two methods can discern photodissociation regions with warm gas and UV flux is fairly prominent. The use of resonance-absorption-line spectroscopy is also reviewed with respect to the analysis of the Na D lines, and thereby allows the measurement of integrated columns of material through the shell. The methods provide evidence for the notion that planetary nebulae consist of more than just ionized material; large amounts of neutral and molecular material are being confirmed, which has important implications for the mass-loss episode of the nebulae.

  17. A vision for planetary exploration

    NASA Technical Reports Server (NTRS)

    Connolly, John F.; Callaway, Robert K.; Diogu, Mark K.; Grush, Gene R.; Lancaster, E. M.; Morgan, William C.; Petri, David A.; Roberts, Barney B.; Pieniazek, Lester A.; Polette, Thomas M.

    1992-01-01

    A vision for planetary exploration is proposed which combines historical perspective and current NASA studies with the realities of changing political climates, economic environments, and technological directions. The concepts of Strategic Implementation Architectures (SIA), Open System Infrastructure Standards (OSIS), and Minimum Service Level Infrastructure (MSLI) are presented in order to propose a structure for the SEI which allows the realization of incremental mission objectives, establishes an investment strategy that efficiently uses public resources, and encourages partnerships with the government. The SIA is a hypothetical master plan which will allow the implementation of the complete spectrum of envisioned system capabilities for planetary exploration. OSIS consists of standards for interconnection, interoperability, and administration. MSLI can be defined as the minimum level of services provided by the system that are not justified by profit or parochial motives.

  18. Recent progress in planetary balloons

    NASA Astrophysics Data System (ADS)

    Kerzhanovich, Viktor V.; Cutts, James A.

    2001-08-01

    In the last 15 years several balloon mission cencepts have been proposed for Mars and Venus, one of them - Russian-French Mars Aerostat - was extensively developed in 1988-1995 but was terminated before completion. It became clear that a number of critical technologies still needed to be developed prior to committing a costly space mission. In recent years significant progress has been made in two critical fields: aerial deployment and inflation of thin-film balloons for specific planetary applications, and in the development of envelope design for stratospheric applications. This paper describes requirements, proposed concepts, critical elements and trade-offs in planetary balloon missions as well as current results of some of JPL balloon programs.

  19. The PSA: Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Barthelemy, M.; Metselaar, H.; Martinez, S.; Heather, D.; Vazquez, J. L.; Wirth, K.; Manaud, N.; Ortiz, I.; Arviset, C.; Fernandez, M.

    2009-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. Besides data from the GIOTTO spacecraft and several ground-based cometary observations, the PSA contains data from the Mars Express, Venus Express, Rosetta, and Huygens missions. Preparation for the release of data from the SMART-1 spacecraft is ongoing. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: The Classical Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. By nature, this interface requires careful use and heavy interaction with the end-user to input and control the relevant search parameters. The Map-based Interface is currently operational only for Mars Express HRCS and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Classical interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Classical interface. The Dataset Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All data are prepared by the corresponding instrument teams, mostly located in Europe. PSA staff supports the instrument teams in the full archiving process

  20. The PSA: Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Barthelemy, Maud; Metselaar, Harold; Martinez, Santa; Heather, David; Vazquez, Jose Luis; Manaud, Nicolas; Ortiz, Iñaki; Arviset, Christophe; Osuna, Pedro

    2010-05-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. Besides data from the GIOTTO spacecraft and several ground-based cometary observations, the PSA contains data from the Mars Express, Venus Express, Rosetta, and Huygens missions. Preparation for the release of data from the SMART-1 spacecraft is ongoing. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Classical Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. By nature, this interface requires careful use and heavy interaction with the end-user to input and control the relevant search parameters. - The Map-based Interface is currently operational only for Mars Express HRCS and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Classical interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Classical interface. - The Dataset Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All data are prepared by the corresponding instrument teams, mostly located in Europe. PSA staff supports the instrument teams in the full archiving process

  1. The planetary nebula NGC 6826

    NASA Technical Reports Server (NTRS)

    Feibelman, W. A.

    1981-01-01

    Monochromatic photographs have established the NGC 6826 nebula as the third member of a group of very rare triple-shell planetaries (Feibelman, 1971, 1974). Kaler (1974) also characterized NGC 6826 as a giant halo planetary. Numerous errors and confusing statements regarding its size, structure and stratification are discussed, and the correct dimensions of the nebula are reported: the inner ring is 12.7 arcsec x 8.7 arcsec (Feibelman, 1971); the outer ring is 27 arcsec x 24 arcsec according to Curtis (1918), 25.7 arcsec x 24.4 arcsec according to Feibelman (1971), and 36 arcsec x 36 arcsec according to Coleman et al. (1975). The halo measurements range in diameter from 110 arcsec (Duncan, 1937) to 130 arcsec (Kaler, 1974) to 142 arcsec (Millikan, 1974). Values for the distance of NGC 6826 range from 0.75-1.16 kpc (Cahn and Kaler, 1971) to 2.265 kpc (Cudworth, 1974).

  2. The PSA: Planetary Science Archive

    NASA Astrophysics Data System (ADS)

    Barthelemy, M.; Martinez, S.; Heather, D.; Vazquez, J. L.; Arviset, C.; Osuna, P.; PSA development Team

    2012-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. Besides data from the GIOTTO spacecraft and several ground-based cometary observations, the PSA contains data from the Mars Express, Venus Express, Rosetta, SMART-1 and Huygens missions. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Advanced Search Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. By nature, this interface requires careful use and heavy interaction with the end-user to input and control the relevant search parameters. - The Map-based Interface is currently operational only for Mars Express HRCS and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Advanced interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Advanced interface. - The FTP Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All data are prepared by the corresponding instrument teams, mostly located in Europe. PSA supports the instrument teams in the full archiving process, from the definition of the data products, meta-data and product labels

  3. The chemistry of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.

    1976-01-01

    Present knowledge concerning the chemistry of planetary atmospheres is reviewed along with the theories which attempt to explain observational data. The known gross atmospheric compositions of the terrestrial and giant planets are listed, differences between the atmospheres of earth and Venus are discussed, and the atmospheres of the giant planets are described. The origin and evolution of the atmospheres of earth, Venus, Mars, Jupiter, Saturn, and Uranus are outlined, and chemical processes in the atmospheres are examined, particularly cloud formation. The question of organic synthesis and evolution in the reducing atmospheres of the giant planets is considered. It is noted that laboratory work on the individual chemical processes and reactions involved in the evolution of organic compounds in planetary atmospheres, comets, and interstellar space points to the inevitability of organic-compound synthesis in all these situations and to the pervasiveness of organic chemistry throughout the universe.

  4. Northeast Regional Planetary Data Center

    NASA Technical Reports Server (NTRS)

    Schultz, Peter H.; Saunders, Stephen (Technical Monitor)

    2005-01-01

    In 1980, the Northeast Planetary Data Center (NEPDC) was established with Tim Mutch as its Director. The Center was originally located in the Sciences Library due to space limitations but moved to the Lincoln Field Building in 1983 where it could serve the Planetary Group and outside visitors more effectively. In 1984 Dr. Peter Schultz moved to Brown University and became its Director after serving in a similar capacity at the Lunar and Planetary Institute since 1976. Debbie Glavin has served as the Data Center Coordinator since 1982. Initially the NEPDC was build around Tim Mutch's research collection of Lunar Orbiter and Mariner 9 images with only partial sets of Apollo and Viking materials. Its collection was broadened and deepened as the Director (PHS) searched for materials to fill in gaps. Two important acquisitions included the transfer of a Viking collection from a previous PI in Tucson and the donation of surplused lunar materials (Apollo) from the USGS/Menlo Park prior to its building being torn down. Later additions included the pipeline of distributed materials such as the Viking photomosaic series and certain Magellan products. Not all materials sent to Brown, however, found their way to the Data Center, e.g., Voyager prints and negatives. In addition to the NEPDC, the planetary research collection is separately maintained in conjunction with past and ongoing mission activities. These materials (e.g., Viking, Magellan, Galileo, MGS mission products) are housed elsewhere and maintained independently from the NEPDC. They are unavailable to other researchers, educators, and general public. Consequently, the NEPDC represents the only generally accessible reference collection for use by researchers, students, faculty, educators, and general public in the Northeast corridor.

  5. Planetary Data Workshop, Part 2

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Technical aspects of the Planetary Data System (PDS) are addressed. Methods and tools for maintaining and accessing large, complex sets of data are discussed. The specific software and applications needed for processing imaging and non-imaging science data are reviewed. The need for specific software that provides users with information on the location and geometry of scientific observations is discussed. Computer networks and user interface to the PDS are covered along with Computer hardware available to this data system.

  6. Mars 2020 Planetary Protection Status

    NASA Astrophysics Data System (ADS)

    Stricker, Moogega; Bernard, Douglas; Benardini, James Nick; Jones, Melissa

    2016-07-01

    The Mars 2020 (M2020) flight system consists of a cruise stage; an entry, descent and landing system (EDL); and a Radioisotope Thermoelectric Generator (RTG) powered roving science vehicle that will land on the surface of Mars. The M2020 Mission is designed to investigate key question related to the habitability of Mars and will conduct assessments that set the stage for potential future human exploration of Mars. Per its Program Level Requirements, the project will also acquire and cache samples of rock, regolith, and/or procedural "blank" samples for possible return to Earth by a subsequent mission. NASA has assigned the M2020 Mission as a Category V Restricted Earth Return due to the possible future return of collected samples. As indicated in NPR8020.12D, Section 5.3.3.2, the outbound leg of a Category V mission that could potentially return samples to Earth, Mars 2020 would be expected to meet the requirements of a Category IVb mission. The entire flight system is subject to microbial reduction requirements, with additional specific emphasis on the sample acquisition and caching. A bioburden accounting tool is being used to track the microbial population on the surfaces to ensure that the biological cleanliness requirements are met. Initial bioburden estimates based on MSL heritage allows M2020 to gauge more precisely how the bioburden is allocated throughout each hardware element. Mars 2020 has completed a Planetary Protection Plan with Planetary Implementation Plans at a mature draft form. Planetary protection sampling activities have commenced with the start of flight system fabrication and assembly. The status of the Planetary Protection activities will be reported.

  7. INPOP17a planetary ephemerides

    NASA Astrophysics Data System (ADS)

    Viswanathan, V.; Fienga, A.; Gastineau, M.; Laskar, J.

    2017-08-01

    Based on the use of Cassini radio tracking data and the introduction of LLR data obtained at 1064 nm, a new planetary ephemerides INPOP17a was built including improvements for the planet orbits as well as for Moon ephemerides. Besides new asteroid masses, new parameters related to the inner structure of the Moon were obtained and presented here. Comparisons with values found in the literature are also discussed. LLR Residuals reach the centimeter level for the new INPOP17a ephemerides.

  8. Planetary science - 1983-1986

    NASA Technical Reports Server (NTRS)

    Clifford, Stephen M.

    1987-01-01

    Results obtained in the U.S. planetary science programs during 1983-1986 are discussed in a brief review. Topics examined include Halley observations and probes, the flyby of comet Giacobini-Zinner by ISEE-3 (ICE), the Voyager 2 encounter with Uranus, analysis of Voyager 1 and 2 data from the Jupiter and Saturn systems, Pioneer Venus Orbiter observations, theoretical models of lunar evolution, and antarctic meteorites of lunar and perhaps Martian origin.

  9. Stream Lifetimes Against Planetary Encounters

    NASA Technical Reports Server (NTRS)

    Valsecchi, G. B.; Lega, E.; Froeschle, Cl.

    2011-01-01

    We study, both analytically and numerically, the perturbation induced by an encounter with a planet on a meteoroid stream. Our analytical tool is the extension of pik s theory of close encounters, that we apply to streams described by geocentric variables. The resulting formulae are used to compute the rate at which a stream is dispersed by planetary encounters into the sporadic background. We have verified the accuracy of the analytical model using a numerical test.

  10. Reports of planetary astronomy, 1986

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A compilation of abstracts of reports from Principal Investigators funded through NASA's Planetary Astronomy Program, Office of Space Science and Applications, is presented. The purpose is to provide a document which succinctly summarizes work conducted in this program for 1986. Each report contains a brief statement on the strategy of investigation and lists significant accomplishments within the area of the author's funded grant or contract, plans for future work, and publications.

  11. Planetary Systems Around Neutron Stars

    NASA Astrophysics Data System (ADS)

    Wolszczan, Alexander

    1997-01-01

    This project was initiated in 1993, about one year after the announcement of two planets around PSR B1257+12. Its goal was to investigate planetary systems around neutron stars using high precision timing of radio pulsars as a tool. A microsecond precision of the pulse timing analysis, which is equivalent to a millimeter-per-second radial velocity resolution, makes it possible to detect asteroid-mass bodies in orbit around pulsars and to study the dynamics of pulsar planetary systems. The project originally consisted of two longterm efforts: (i) routine observations and timing analysis of the millisecond pulsar PSR B1257+12 which was found to be orbited by at least two earth-mass bodies (Wolszczan and Frail, Nature, 355, 145) and (ii) a sensitive all-sky search for millisecond pulsars to detect further examples of neutron stars with planetary systems. In the third year of the project, it was expanded to include long-term timing observations of slow pulsars in search for planetary systems around these younger neutron stars. The instrumentation used to conduct these investigations included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM-1), the 100-m Effelsberg telescope with the local pulse timing hardware, and the 32-m paraboloid of the Torun Centre for Astronomy in Torun, Poland (TCFA) with the PSPM-2, the second pulsar machine built at Penn State. The PI's collaborators included pulsar groups led by D. Backer (Berkeley), R. Foster (NRL), S. Kulkarni (Caltech), J. Taylor (Princeton) and R. Wielebinski (Bonn). One postdoc (Stuart Anderson), one graduate student (Brian Cadwell) and several undergraduates have been engaged in various aspects of research related to this project.

  12. A study of planetary meteorology

    NASA Technical Reports Server (NTRS)

    Ohring, G.

    1971-01-01

    The concept is described of deducing the temperature profile of a planetary atmosphere from orbiter measurements of the planet's IR limb radiance profile. Expressions are derived for the weighting functions associated with the limb radiance profile for two infrared tranmission models. Analysis of the weighting functions for the Martian atmosphere indicates that a limb radiance profile in the 15 micron CO2 band can be used to determine the Martian atmospheric temperature profile from 20 to 60 km.

  13. Ray tracing planetary radio emissions

    NASA Technical Reports Server (NTRS)

    Green, James L.

    1988-01-01

    Planetary ray tracing calculations of free escaping electromagnetic waves are presented, with special attention given to calculations of the earth's auroral kilometric and continuum radiations and of the Jovian decametric and kilometric radiation. The technique is used to study the composition and propagation effects causing multiion resonances and shadow zones. Although results obtained for Jovian broadband kilometric radiation have been used to estimate the location of the source region, no unique solutions are obtained.

  14. Planetary analogs in Antarctica: Mars

    NASA Astrophysics Data System (ADS)

    Malin, M. C.

    1985-04-01

    A study of chemical and physical weathering rates in Antarctic ice-free areas, sponsored by the National Science Foundation's Antarctic Research Program, permitted observations to be made that also have application other planetary surfaces. Four observations relevent to Mars are addressed: the effects of freezing on sand dune morphology (Mars polar dune field), chemical/physical weathering to create pits (Mars pitted rocks, Viking Lander 1 and 2 sites), armored surfaces (Mars lander sites), and mass movements (movement of Martian debris).

  15. Discovery Planetary Mission Operations Concepts

    NASA Technical Reports Server (NTRS)

    Coffin, R.

    1994-01-01

    The NASA Discovery Program of small planetary missions will provide opportunities to continue scientific exploration of the solar system in today's cost-constrained environment. Using a multidisciplinary team, JPL has developed plans to provide mission operations within the financial parameters established by the Discovery Program. This paper describes experiences and methods that show promise of allowing the Discovery Missions to operate within the program cost constraints while maintaining low mission risk, high data quality, and reponsive operations.

  16. Planetary Systems Around Neutron Stars

    NASA Technical Reports Server (NTRS)

    Wolszczan, Alexander

    1997-01-01

    This project was initiated in 1993, about one year after the announcement of two planets around PSR B1257+12. Its goal was to investigate planetary systems around neutron stars using high precision timing of radio pulsars as a tool. A microsecond precision of the pulse timing analysis, which is equivalent to a millimeter-per-second radial velocity resolution, makes it possible to detect asteroid-mass bodies in orbit around pulsars and to study the dynamics of pulsar planetary systems. The project originally consisted of two longterm efforts: (i) routine observations and timing analysis of the millisecond pulsar PSR B1257+12 which was found to be orbited by at least two earth-mass bodies (Wolszczan and Frail, Nature, 355, 145) and (ii) a sensitive all-sky search for millisecond pulsars to detect further examples of neutron stars with planetary systems. In the third year of the project, it was expanded to include long-term timing observations of slow pulsars in search for planetary systems around these younger neutron stars. The instrumentation used to conduct these investigations included the 305-m Arecibo antenna with the Penn State Pulsar Machine (PSPM-1), the 100-m Effelsberg telescope with the local pulse timing hardware, and the 32-m paraboloid of the Torun Centre for Astronomy in Torun, Poland (TCFA) with the PSPM-2, the second pulsar machine built at Penn State. The PI's collaborators included pulsar groups led by D. Backer (Berkeley), R. Foster (NRL), S. Kulkarni (Caltech), J. Taylor (Princeton) and R. Wielebinski (Bonn). One postdoc (Stuart Anderson), one graduate student (Brian Cadwell) and several undergraduates have been engaged in various aspects of research related to this project.

  17. Reports of planetary astronomy, 1985

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This is a compilation of abstracts of reports from Principal Investigators funded through NASA's Planetary Astronomy Program, Office of Space Science and Applications. The purpose is to provide a document which succinctly summarizes work conducted in this program for 1985. Each report contains a brief statement on the strategy of investigation and lists significant accomplishments within the area of the author's funded grant or contract, plans for future work, and publications.

  18. Small Spacecraft for Planetary Science

    NASA Astrophysics Data System (ADS)

    Baker, John; Castillo-Rogez, Julie; Bousquet, Pierre-W.; Vane, Gregg; Komarek, Tomas; Klesh, Andrew

    2016-07-01

    As planetary science continues to explore new and remote regions of the Solar system with comprehensive and more sophisticated payloads, small spacecraft offer the possibility for focused and more affordable science investigations. These small spacecraft or micro spacecraft (< 100 kg) can be used in a variety of architectures consisting of orbiters, landers, rovers, atmospheric probes, and penetrators. A few such vehicles have been flown in the past as technology demonstrations. However, technologies such as new miniaturized science-grade sensors and electronics, advanced manufacturing for lightweight structures, and innovative propulsion are making it possible to fly much more capable micro spacecraft for planetary exploration. While micro spacecraft, such as CubeSats, offer significant cost reductions with added capability from advancing technologies, the technical challenges for deep space missions are very different than for missions conducted in low Earth orbit. Micro spacecraft must be able to sustain a broad range of planetary environments (i.e., radiations, temperatures, limited power generation) and offer long-range telecommunication performance on a par with science needs. Other capabilities needed for planetary missions, such as fine attitude control and determination, capable computer and data handling, and navigation are being met by technologies currently under development to be flown on CubeSats within the next five years. This paper will discuss how micro spacecraft offer an attractive alternative to accomplish specific science and technology goals and what relevant technologies are needed for these these types of spacecraft. Acknowledgements: Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA. Government sponsorship acknowledged.

  19. Planetary Exploration in the Classroom

    NASA Astrophysics Data System (ADS)

    Slivan, S. M.; Binzel, R. P.

    1997-07-01

    We have developed educational materials to seed a series of undergraduate level exercises on "Planetary Exploration in the Classroom." The goals of the series are to teach modern methods of planetary exploration and discovery to students having both science and non-science backgrounds. Using personal computers in a "hands-on" approach with images recorded by planetary spacecraft, students working through the exercises learn that modern scientific images are digital objects that can be examined and manipulated in quantitative detail. The initial exercises we've developed utilize NIH Image in conjunction with images from the Voyager spacecraft CDs. Current exercises are titled "Using 'NIH IMAGE' to View Voyager Images", "Resolving Surface Features on Io", "Discovery of Volcanoes on Io", and "Topography of Canyons on Ariel." We expect these exercises will be released during Fall 1997 and will be available via 'anonymous ftp'; detailed information about obtaining the exercises will be on the Web at "http://web.mit.edu/12s23/www/pec.html." This curriculum development was sponsored by NSF Grant DUE-9455329.

  20. Geochemical evolution of magmatism in Archean granite-greenstone terrains

    NASA Astrophysics Data System (ADS)

    Samsonov, A. V.; Larionova, Yu. O.

    2006-05-01

    Evolution of Archean magmatism is one of the key problems concerning the early formation stages of the Earth crust and biosphere, because that evolution exactly controlled variable concentrations of chemical elements in the World Ocean, which are important for metabolism. Geochemical evolution of magmatism between 3.5 and 2.7 Ga is considered based on database characterizing volcanic and intrusive rock complexes of granite-greenstone terrains (GGT) studied most comprehensively in the Karelian (2.9-2.7 Ga) and Kaapvaal (3.5-2.9 Ga) cratons and in the Pilbara block (3.5-2.9 Ga). Trends of magmatic geochemical evolution in the mentioned GGTs were similar in general. At the early stage of their development, tholeiitic magmas were considerably enriched in chalcophile and siderophile elements Fe2O3, MgO, Cr, Ni, Co, V, Cu, and Zn. At the next stage, calc-alkaline volcanics of greenstone belts and syntectonic TTG granitoids were enriched in lithophile elements Rb, Cs, Ba, Th, U, Pb, Nb, La, Sr, Be and others. Elevated concentrations of both the “crustal” and “mantle-derived” elements represented a distinctive feature of predominantly intrusive rocks of granitoid composition, which were characteristic of the terminal stage of continental crust formation in the GGTs, because older silicic rocks and lithospheric mantle were jointly involved into processes of magma generation. On the other hand, the GGTs different in age reveal specific trends in geochemical evolution of rock associations close in composition and geological position. First, the geochemical cycle of GGT evolution was of a longer duration in the Paleoarchean than in the Meso-and Neoarchean. Second, the Paleoarche an tholeiitic associations had higher concentrations of LREE and HFSE (Zr, Ti, Th, Nb, Ta, Hf) than their Meso-and Neoarchean counterparts. Third, the Y and Yb concentrations in Paleoarchean calc-alkaline rock associations are systematically higher than in Neoarchean rocks of the same type

  1. Planetary gear train for automatic transmission

    SciTech Connect

    Hiraiwa, K.

    1987-04-28

    A planetary gear train is described for an automatic transmission, the planetary gear train having gear ratios including a first forward gear ratio and a reverse, the planetary gear train comprising: an input shaft; a basic planetary gearing including a first rotary element which is to be held stationary when the first gear ratio is established and also when the reverse is established, and a second rotary element which is to serve as an output member of the basic planetary gearing; an output planetary gear set including a ring gear, a sun gear and a pinion carrier; change speed means for establishing any desired one of the gear ratios; a clutch means for establishing a connection between the other one of the ring gear and the sun gear of the output planetary gear set and the first rotary element of the basic planetary gearing during operation with the first gear ratio and also during operation with the reverse, and a brake means for anchoring the other one of the ring gear and the sun gear of the output planetary gear set during operation with the reverse; and an output shaft connected to the pinion carrier of the output planetary gear set.

  2. PASCAL - Planetary Atmospheres Spectral Catalog

    NASA Astrophysics Data System (ADS)

    Rothman, Laurence; Gordon, Iouli

    2010-05-01

    Spectroscopic observation of planetary atmospheres, stellar atmospheres, comets, and the interstellar medium is the most powerful tool for extracting detailed information concerning the properties of these objects. The HITRAN molecular spectroscopic database1 has traditionally served researchers involved with terrestrial atmospheric problems, such as remote-sensing of constituents in the atmosphere, pollution monitoring at the surface, identification of sources seen through the atmosphere, and numerous environmental issues. A new thrust of the HITRAN program is to extend this longstanding database to have capabilities for studying the above-mentioned planetary and astronomical systems. The new extension is called PASCAL (Planetary Atmospheres Spectral Catalog). The methodology and structure are basically identical to the construction of the HITRAN and HITEMP databases. We will acquire and assemble spectroscopic parameters for gases and spectral bands of molecules that are germane to the studies of planetary atmospheres. These parameters include the types of data that have already been considered for transmission and radiance algorithms, such as line position, intensity, broadening coefficients, lower-state energies, and temperature dependence values. Additional parameters beyond what is currently considered for the terrestrial atmosphere will be archived. Examples are collision-broadened halfwidths due to various foreign partners, collision-induced absorption, and temperature dependence factors. New molecules (and their isotopic variants), not currently included in the HITRAN database, will be incorporated. That includes hydrocarbons found on Titan but not archived in HITRAN (such as C3H4, C4H2, C3H8). Other examples include sulfur-bearing molecules such as SO and CS. A further consideration will be spectral bands that arise as opportunities to study exosolar planets. The task involves acquiring the best high-resolution data, both experimental and theoretical

  3. 11 -year planetary index of solar activity

    NASA Astrophysics Data System (ADS)

    Okhlopkov, Victor

    In papers [1,2] introduced me parameter - the average difference between the heliocentric longitudes of planets ( ADL ) , which was used for comparison with solar activity. The best connection of solar activity ( Wolf numbers used ) was obtained for the three planets - Venus, Earth and Jupiter. In [1,2] has been allocated envelope curve of the minimum values ADL which has a main periodicity for 22 years and describes well the alternating series of solar activity , which also has a major periodicity of 22. It was shown that the minimum values of the envelope curve extremes ADL planets Venus, Earth and Jupiter are well matched with the 11- year solar activity cycle In these extremes observed linear configuration of the planets Venus, Earth and Jupiter both in their location on one side of the Sun ( conjunctions ) and at the location on the opposite side of the Sun ( three configurations ) This work is a continuation of the above-mentioned , and here for minimum ADL ( planets are in conjunction ) , as well as on the minimum deviation of the planets from a line drawn through them and Sun at the location of the planets on opposite sides of the Sun , compiled index (denoted for brevity as JEV ) that uniquely describes the 11- year solar cycle A comparison of the index JEV with solar activity during the time interval from 1000 to 2013 conducted. For the period from 1000 to 1699 used the Schove series of solar activity and the number of Wolf (1700 - 2013 ) During the time interval from 1000 to 2013 and the main periodicity of the solar activity and the index ADL is 11.07 years. 1. Okhlopkov V.P. Cycles of Solar Activity and the Configurations of Planets // Moscow University Physics Bulletin, 2012 , Vol. 67 , No. 4 , pp. 377-383 http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.3103/S0027134912040108. 2 Okhlopkov VP, Relationship of Solar Activity Cycles to Planetary Configurations // Bulletin of the Russian Academy of Sciences. Physics, 2013 , Vol. 77 , No. 5

  4. Lunar and Planetary Science XXXVI, Part 14

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Contents include the following: Destruction of Presolar Silicates by Aqueous Alteration Observed in Murchison CM2 Chondrite. Generation of Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. TEM and NanoSIMS Study of Hydrated/Anhydrous Phase Mixed IDPs: Cometary or Asteroidal Origin? Inflight Calibration of Asteroid Multiband Imaging Camera Onboard Hayabusa: Preliminary Results. Corundum and Corundum-Hibonite Grains Discovered by Cathodoluminescence in the Matrix of Acfer 094 Meteorite. Spatial Extent of a Deep Moonquake Nest A Preliminary Report of Reexamination. Modal Abundances of Carbon in Ureilites: Implications for the Petrogenesis of Ureilites. Trapped Noble Gas Components and Exposure History of the Enstatite Chondrite ALH84206. Deep-seated Crustal Material in Dhofar Lunar Meteorites: Evidence from Pyroxene Chemistry. Numerical Investigations of Kuiper Belt Binaries. Dust Devils on Mars: Effects of Surface Roughness on Particle Threshold. Hecates Tholus, Mars: Nighttime Aeolian Activity Suggested by Thermal Images and Mesoscale Atmospheric Model Simulations. Are the Apollo 14 High-Al Basalts Really Impact Melts? Garnet in the Lunar Mantle: Further Evidence from Volcanic Glass Beads. The Earth/Mars Dichotomy in Mg/Si and Al/Si Ratios: Is It Real? Dissecting the Polar Asymmetry in the Non-Condensable Gas Enhancement on Mars: A Numerical Modeling Study. Cassini VIMS Preliminary Exploration of Titan s Surface Hemispheric Albedo Dichotomy. An Improved Instrument for Investigating Planetary Regolith Microstructure. Isotopic Composition of Oxygen in Lunar Zircons Preliminary Design of Visualization Tool for Hayabusa Operation. Size and Shape Distributions of Chondrules and Metal Grains Revealed by X-Ray Computed Tomography Data. Properties of Permanently Shadowed Regolith. Landslides in Interior Layered Deposits, Valles Marineris, Mars: Effects of Water and Ground Shaking on Slope Stability. Mars: Recent and Episodic Volcanic, Hydrothermal, and Glacial

  5. Lunar and Planetary Science XXXVI, Part 14

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Contents include the following: Destruction of Presolar Silicates by Aqueous Alteration Observed in Murchison CM2 Chondrite. Generation of Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. TEM and NanoSIMS Study of Hydrated/Anhydrous Phase Mixed IDPs: Cometary or Asteroidal Origin? Inflight Calibration of Asteroid Multiband Imaging Camera Onboard Hayabusa: Preliminary Results. Corundum and Corundum-Hibonite Grains Discovered by Cathodoluminescence in the Matrix of Acfer 094 Meteorite. Spatial Extent of a Deep Moonquake Nest A Preliminary Report of Reexamination. Modal Abundances of Carbon in Ureilites: Implications for the Petrogenesis of Ureilites. Trapped Noble Gas Components and Exposure History of the Enstatite Chondrite ALH84206. Deep-seated Crustal Material in Dhofar Lunar Meteorites: Evidence from Pyroxene Chemistry. Numerical Investigations of Kuiper Belt Binaries. Dust Devils on Mars: Effects of Surface Roughness on Particle Threshold. Hecates Tholus, Mars: Nighttime Aeolian Activity Suggested by Thermal Images and Mesoscale Atmospheric Model Simulations. Are the Apollo 14 High-Al Basalts Really Impact Melts? Garnet in the Lunar Mantle: Further Evidence from Volcanic Glass Beads. The Earth/Mars Dichotomy in Mg/Si and Al/Si Ratios: Is It Real? Dissecting the Polar Asymmetry in the Non-Condensable Gas Enhancement on Mars: A Numerical Modeling Study. Cassini VIMS Preliminary Exploration of Titan s Surface Hemispheric Albedo Dichotomy. An Improved Instrument for Investigating Planetary Regolith Microstructure. Isotopic Composition of Oxygen in Lunar Zircons Preliminary Design of Visualization Tool for Hayabusa Operation. Size and Shape Distributions of Chondrules and Metal Grains Revealed by X-Ray Computed Tomography Data. Properties of Permanently Shadowed Regolith. Landslides in Interior Layered Deposits, Valles Marineris, Mars: Effects of Water and Ground Shaking on Slope Stability. Mars: Recent and Episodic Volcanic, Hydrothermal, and Glacial

  6. Icelandic Rift Relocations: Melting Models and Geochemical Observations

    NASA Astrophysics Data System (ADS)

    Walters, R. L.; Jones, S. M.; Maclennan, J.; Park, S.

    2007-12-01

    Rift relocations are distinctive features associated with plume-ridge interaction. The underlying processes controlling these relocations are not well understood. Observations of crustal thickness and basalt composition have been commonly used to investigate plume-ridge interaction, but both of these observations are affected by the rift relocation cycle. We therefore need to understand the rift relocation process better in order to isolate its effects from those caused by other processes, such as variations in plume flux, temperature or distance from the ridge. We present the first quantitative model of variations in melt production rates and composition during a rift relocation cycle including the growth and death of spreading centres. The two dimensional time-dependent model of passive upwelling beneath a spreading ridge is based on simple corner flow. The thermal structure is calculated using a control volume approach. The resulting melting structure is then calculated and used to predict the variation in crustal thickness and composition through time. The model shows an initial phase of small melt fractions as the ridge grows, moving into the steady-state phase showing much larger melt fractions and thicker crust. Finally, as the ridge dies and spreading rate decreases, conductive cooling results in a reduction in the melt fraction. The results of the model are compared to geochemical and geophysical observations of the current rift relocation in southern Iceland and a palaeo-rift relocation in northern Iceland. A comparison is also made with the abandoned Phoenix Ridge, Drake Passage, Antartica. The geochemical observations are consistent with smaller degrees of melting at both the birth and death of rift zones. Combination of these observations and the model results will be used to constrain the rate of transfer of spreading between rift zones.

  7. Europlanet Research Infrastructure: Planetary Sample Analysis Facilities

    NASA Astrophysics Data System (ADS)

    Cloquet, C.; Mason, N. J.; Davies, G. R.; Marty, B.

    2008-09-01

    study of long (e.g. Rb- Sr, Sm-Nd…) and short-lived radioisotope (e.g. Mg- Al, Hf-W..), including also Os isotopes, stable and non traditional stable isotope facilities (e.g. Fe, Pb, Zn…). The facility comprises three multicollector Thermal ionization mass spectrometers (TIMS) and two multi-collector ICP-MS one of which is fitted with 193 nm laser for in situ work. In addition these instruments are fully supported by sample preparation labs (crushing, mineral separation/picking), a clean lab and geochemical support (XRF; ICP; ICP-MS etc). Data that can be obtained on samples containing sub nano gram to nanogram amounts. Organic matter analysis at OU Leco Pegasus IV GCxGC-TOFMS - mass spectrometric complete characterisation of very complex mixtures of organic materials. The Pegasus EPSC Abstracts, Vol. 3, EPSC2008-A-00437, 2008 European Planetary Science Congress, Author(s) 2008 4D GCxGC-TOFMS system, from Leco, provides the analyst with four dimensions of analytical resolution for significantly more complete sample analysis compared to conventional GC-Mass Spectrometry. The main advantages include: 1) The significantly increased sensitivity over the whole mass range (5- 1000 amu); 2)The separation of compounds that coelute on standard gas chromatograph systems; 3) Separation of analytes by volatility and polarity enables traditionally unresolved mixtures to be examined in detail, and vastly increases the number of compounds identified; 4) Greatly increased signal to noise ratio, due to compounds being separated from the column bleed of the first column on the second GC column and an enormous increase in the Spectral Generation Rate. A number of different pyrolysis and injection sample introduction facilities are available and access to off-line data processing and reference libraries. This is the only instrument of this type in a European laboratory with a significant focus on extraterrestrial materials. Thermo MAT 253 GC-IRMS -isotopic measurements of H, C or N on

  8. The Chandra planetary nebula survey (CHANPLANS). II. X-ray emission from compact planetary nebulae

    SciTech Connect

    Freeman, M.; Kastner, J. H.; Montez, R. Jr.; Balick, B.; Frew, D. J.; De Marco, O.; Parker, Q. A.; Jones, D.; Miszalski, B.; Sahai, R.; Blackman, E.; Frank, A.; Chu, Y.-H.; Guerrero, M. A.; Zijlstra, A.; Bujarrabal, V.; Corradi, R. L. M.; Nordhaus, J.; and others

    2014-10-20

    We present results from the most recent set of observations obtained as part of the Chandra X-ray observatory Planetary Nebula Survey (CHANPLANS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood (i.e., within ∼1.5 kpc of the Sun). The survey is designed to place constraints on the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. CHANPLANS began with a combined Cycle 12 and archive Chandra survey of 35 PNe. CHANPLANS continued via a Chandra Cycle 14 Large Program which targeted all (24) remaining known compact (R {sub neb} ≲ 0.4 pc), young PNe that lie within ∼1.5 kpc. Results from these Cycle 14 observations include first-time X-ray detections of hot bubbles within NGC 1501, 3918, 6153, and 6369, and point sources in HbDs 1, NGC 6337, and Sp 1. The addition of the Cycle 14 results brings the overall CHANPLANS diffuse X-ray detection rate to ∼27% and the point source detection rate to ∼36%. It has become clearer that diffuse X-ray emission is associated with young (≲ 5 × 10{sup 3} yr), and likewise compact (R {sub neb} ≲ 0.15 pc), PNe with closed structures and high central electron densities (n{sub e} ≳ 1000 cm{sup –3}), and is rarely associated with PNe that show H{sub 2} emission and/or pronounced butterfly structures. Hb 5 is one such exception of a PN with a butterfly structure that hosts diffuse X-ray emission. Additionally, two of the five new diffuse X-ray detections (NGC 1501 and NGC 6369) host [WR]-type central stars, supporting the hypothesis that PNe with central stars of [WR]-type are likely to display diffuse X-ray emission.

  9. Ordinary planetary systems - Architecture and formation

    NASA Technical Reports Server (NTRS)

    Levy, E. H.

    1993-01-01

    Today we believe ordinary planetary systems to be an unremarkable consequence of star formation. The solar system, so far the only confidently known example in the universe of a planetary system, displays a set of striking structural regularities. These structural regularities provide fossil clues about the conditions and mechanisms that gave rise to the planets. The formation of our planetary system, as well as its general characteristics, resulted from the physical environment in the disk-shaped nebula that accompanied the birth of the sun. Observations of contemporary star formation indicate that the very conditions and mechanisms thought to have produced our own planetary system are widely associated with the birth of stars elsewhere. Consequently, it is reasonable to believe that planetary systems occur commonly, at least in association with single, sunlike stars. Moreover, it is reasonable to believe that many planetary systems have gross characteristics resembling those of our own solar system.

  10. Planetary Geology: Goals, Future Directions, and Recommendations

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Planetary exploration has provided a torrent of discoveries and a recognition that planets are not inert objects. This expanded view has led to the notion of comparative planetology, in which the differences and similarities among planetary objects are assessed. Solar system exploration is undergoing a change from an era of reconnaissance to one of intensive exploration and focused study. Analyses of planetary surfaces are playing a key role in this transition, especially as attention is focused on such exploration goals as returned samples from Mars. To assess how the science of planetary geology can best contribute to the goals of solar system exploration, a workshop was held at Arizona State University in January 1987. The participants discussed previous accomplishments of the planetary geology program, assessed the current studies in planetary geology, and considered the requirements to meet near-term and long-term exploration goals.

  11. The Planetary Data System— Archiving Planetary Data for the use of the Planetary Science Community

    NASA Astrophysics Data System (ADS)

    Morgan, Thomas H.; McLaughlin, Stephanie A.; Grayzeck, Edwin J.; Vilas, Faith; Knopf, William P.; Crichton, Daniel J.

    2014-11-01

    NASA’s Planetary Data System (PDS) archives, curates, and distributes digital data from NASA’s planetary missions. PDS provides the planetary science community convenient online access to data from NASA’s missions so that they can continue to mine these rich data sets for new discoveries. The PDS is a federated system consisting of nodes for specific discipline areas ranging from planetary geology to space physics. Our federation includes an engineering node that provides systems engineering support to the entire PDS.In order to adequately capture complete mission data sets containing not only raw and reduced instrument data, but also calibration and documentation and geometry data required to interpret and use these data sets both singly and together (data from multiple instruments, or from multiple missions), PDS personnel work with NASA missions from the initial AO through the end of mission to define, organize, and document the data. This process includes peer-review of data sets by members of the science community to ensure that the data sets are scientifically useful, effectively organized, and well documented. PDS makes the data in PDS easily searchable so that members of the planetary community can both query the archive to find data relevant to specific scientific investigations and easily retrieve the data for analysis. To ensure long-term preservation of data and to make data sets more easily searchable with the new capabilities in Information Technology now available (and as existing technologies become obsolete), the PDS (together with the COSPAR sponsored IPDA) developed and deployed a new data archiving system known as PDS4, released in 2013. The LADEE, MAVEN, OSIRIS REx, InSight, and Mars2020 missions are using PDS4. ESA has adopted PDS4 for the upcoming BepiColumbo mission. The PDS is actively migrating existing data records into PDS4 and developing tools to aid data providers and users. The PDS is also incorporating challenge

  12. The probabilistic structure of planetary contamination models

    NASA Technical Reports Server (NTRS)

    Harrison, J. M.; North, W. D.

    1973-01-01

    The analytical basis for planetary quarantine standards and procedures is presented. The heirarchy of planetary quarantine decisions is explained and emphasis is placed on the determination of mission specifications to include sterilization. The influence of the Sagan-Coleman probabilistic model of planetary contamination on current standards and procedures is analyzed. A classical problem in probability theory which provides a close conceptual parallel to the type of dependence present in the contamination problem is presented.

  13. Activities at the Lunar and Planetary Institute

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The activities of the Lunar and Planetary Institute for the period July to December 1984 are discussed. Functions of its departments and projects are summarized. These include: planetary image center; library information center; computer center; production services; scientific staff; visitors program; scientific projects; conferences; workshops; seminars; publications and communications; panels, teams, committees and working groups; NASA-AMES vertical gun range (AVGR); and lunar and planetary science council.

  14. Mars Technology Program Planetary Protection Technology Development

    NASA Technical Reports Server (NTRS)

    Lin, Ying

    2006-01-01

    The objectives of the NASA Planetary Protection program are to preserve biological and organic conditions of solar-system bodies for future scientific exploration and to protect the Earth from potential hazardous extraterrestrial contamination. As the exploration of solar system continues, NASA remains committed to the implementation of planetary protection policy and regulations. To fulfill this commitment, the Mars Technology Program (MTP) has invested in a portfolio of tasks for developing necessary technologies to meet planetary protection requirements for the next decade missions.

  15. Planetary Science Training for NASA's Astronauts: Preparing for Future Human Planetary Exploration

    NASA Astrophysics Data System (ADS)

    Bleacher, J. E.; Evans, C. A.; Graff, T. G.; Young, K. E.; Zeigler, R.

    2017-02-01

    Astronauts selected in 2017 and in future years will carry out in situ planetary science research during exploration of the solar system. Training to enable this goal is underway and is flexible to accommodate an evolving planetary science vision.

  16. Twenty-Second Lunar and Planetary Science Conference

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The papers in this collection were written for general presentation, avoiding jargon and unnecessarily complex terms. Some of the topics covered include: planetary evolution, planetary satellites, planetary composition, planetary surfaces, planetary geology, volcanology, meteorite impacts and composition, and cosmic dust. Particular emphasis is placed on Mars and the Moon.

  17. Nasa's Planetary Geologic Mapping Program: Overview

    NASA Astrophysics Data System (ADS)

    Williams, D. A.

    2016-06-01

    NASA's Planetary Science Division supports the geologic mapping of planetary surfaces through a distinct organizational structure and a series of research and analysis (R&A) funding programs. Cartography and geologic mapping issues for NASA's planetary science programs are overseen by the Mapping and Planetary Spatial Infrastructure Team (MAPSIT), which is an assessment group for cartography similar to the Mars Exploration Program Assessment Group (MEPAG) for Mars exploration. MAPSIT's Steering Committee includes specialists in geological mapping, who make up the Geologic Mapping Subcommittee (GEMS). I am the GEMS Chair, and with a group of 3-4 community mappers we advise the U.S. Geological Survey Planetary Geologic Mapping Coordinator (Dr. James Skinner) and develop policy and procedures to aid the planetary geologic mapping community. GEMS meets twice a year, at the Annual Lunar and Planetary Science Conference in March, and at the Annual Planetary Mappers' Meeting in June (attendance is required by all NASA-funded geologic mappers). Funding programs under NASA's current R&A structure to propose geological mapping projects include Mars Data Analysis (Mars), Lunar Data Analysis (Moon), Discovery Data Analysis (Mercury, Vesta, Ceres), Cassini Data Analysis (Saturn moons), Solar System Workings (Venus or Jupiter moons), and the Planetary Data Archiving, Restoration, and Tools (PDART) program. Current NASA policy requires all funded geologic mapping projects to be done digitally using Geographic Information Systems (GIS) software. In this presentation we will discuss details on how geologic mapping is done consistent with current NASA policy and USGS guidelines.

  18. A Planetary Environmental Simulator/Test Facility

    NASA Astrophysics Data System (ADS)

    Kleiman, Jacob; Horodetsky, Sergey; Issoupov, Vitali

    Under a 2-year program funded by the Canadian Space Agency, ITL Inc. is developing and manufacturing a Planetary Environmental Simulator/Test Facility to be used for testing and life-time evaluation of candidate spacecraft materials and mechanical systems, space suits, and planetary mission crew habitats. The basic facility will include a vacuum chamber and a number of environmental sources to simulate the planetary surface environments, including dust particles, UV radiation, temperature conditions and darkness, as well as simple fixtures and test rigs enabling to conduct mechanical testing of planetary rovers' components.

  19. Planetary sample rapid recovery and handling

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Methods for recovering and cost effectively handling planetary samples following return to the vicinity of Earth were designed for planetary mission planners. Three topics are addressed: (1) a rough cost estimate was produced for each of a series of options for the handling of planetary samples following their return to the vicinity of Earth; (2) the difficulty of quickly retrieving planetary samples from low circular and high elliptical Earth orbit is assessed; and (3) a conceptual design for a biological isolation and thermal control system for the returned sample and spacecraft is developed.

  20. Can we teach machines geochemical exploration?

    NASA Astrophysics Data System (ADS)

    Klump, J. F.; Fouedjio, F.

    2016-12-01

    Geochemical surveys are an important part of exploration for mineral resources and in environmental studies. The samples and chemical analyses are often laborious and difficult to obtain and therefore come at a high cost. As a consequence, these surveys are characterised by datasets with large numbers of variables but relatively few data points when compared to conventional big data problems. With more remote sensing platforms and sensor networks being deployed, large volumes of auxiliary data of the surveyed areas are becoming available. The use of these auxiliary data has the potential to improve the prediction of chemical element concentrations over the whole study area. Established geostatistical methods for the prediction of the spatial distributions of chemical elements in geochemical surveys are well understood but require significant pre-processing of the data. Machine learning algorithms, on the other hand, may require less data pre-processing. However, it is not well understood how these methods perform in a geospatial context. In this presentation we use a case study to compare machine learning algorithms against geostatistical methods to compare their performance in a geospatial context. In particular, we test the hypothesis that using geochemical point data and auxiliary remote sensing data can improve the prediction of the spatial distribution of chemical elements in geochemical surveys.

  1. Geochemical Reaction Mechanism Discovery from Molecular Simulation

    SciTech Connect

    Stack, Andrew G.; Kent, Paul R. C.

    2014-11-10

    Methods to explore reactions using computer simulation are becoming increasingly quantitative, versatile, and robust. In this review, a rationale for how molecular simulation can help build better geochemical kinetics models is first given. We summarize some common methods that geochemists use to simulate reaction mechanisms, specifically classical molecular dynamics and quantum chemical methods and discuss their strengths and weaknesses. Useful tools such as umbrella sampling and metadynamics that enable one to explore reactions are discussed. Several case studies wherein geochemists have used these tools to understand reaction mechanisms are presented, including water exchange and sorption on aqueous species and mineral surfaces, surface charging, crystal growth and dissolution, and electron transfer. The impact that molecular simulation has had on our understanding of geochemical reactivity are highlighted in each case. In the future, it is anticipated that molecular simulation of geochemical reaction mechanisms will become more commonplace as a tool to validate and interpret experimental data, and provide a check on the plausibility of geochemical kinetic models.

  2. Geochemical Reaction Mechanism Discovery from Molecular Simulation

    DOE PAGES

    Stack, Andrew G.; Kent, Paul R. C.

    2014-11-10

    Methods to explore reactions using computer simulation are becoming increasingly quantitative, versatile, and robust. In this review, a rationale for how molecular simulation can help build better geochemical kinetics models is first given. We summarize some common methods that geochemists use to simulate reaction mechanisms, specifically classical molecular dynamics and quantum chemical methods and discuss their strengths and weaknesses. Useful tools such as umbrella sampling and metadynamics that enable one to explore reactions are discussed. Several case studies wherein geochemists have used these tools to understand reaction mechanisms are presented, including water exchange and sorption on aqueous species and mineralmore » surfaces, surface charging, crystal growth and dissolution, and electron transfer. The impact that molecular simulation has had on our understanding of geochemical reactivity are highlighted in each case. In the future, it is anticipated that molecular simulation of geochemical reaction mechanisms will become more commonplace as a tool to validate and interpret experimental data, and provide a check on the plausibility of geochemical kinetic models.« less

  3. The stepwise growth of tectonic plates across Earth's evolving supercontinent cycle

    NASA Astrophysics Data System (ADS)

    Van Kranendonk, M. J.; Kirkland, C. L.

    2012-04-01

    Plate tectonics both creates and recycles crust, but the rate of continental growth over Earth history remains contentious: some believe it formed fast and early, others more gradually and, perhaps, episodically, through the supercontinent cycle. Time constrained analysis of both oxygen and hafnium isotopes in zircon grains and incompatible elements (Zr, Th) from magmatic rocks confirms the importance of Earth's supercontinent cycle not only on the degree of crustal recycling rates that arises from the aggregation and dispersal of supercontinents, but also on mantle temperatures, crustal growth rates, and climatic conditions. These changes are used to infer a conditioned duality of the Earth system between alternating periods of hot and cold mantle that arise in response to the supercontinent cycle. Hot mantle periods that accompany supercontinent aggregation events are characterised by mantle superplume events, increased crustal recycling and warm, reducing climatic conditions. Cool mantle periods during supercontinent rifting result from core insulation by slab graveyards and are characterised by low rates of crust production and cool, more oxidizing conditions. Changes in the intensity of the orogenic cycle through time since its inception at c. 3.2 Ga are ascribed to self-reorganisation of progressively larger tectonic plates (tessellation of a sphere) that accommodate the secular decrease in planetary heat. Bursts of crust extraction during Neoarchean and Mesoproterozoic supercontinent assembly led to overstep periods of large plates on subduction-cooled, melt-depleted mantle, accompanied by global ice ages. Optimal packing (pentagonal dodecahedron) of the plates was attained on dispersal of Nuna at 1.4 Ga, leading to a peak in geochemical and isotopic proxies of orogenic intensity during c. 1.2 Ga assembly of Rodinia (large plates on warmer Earth), with declining intensity thereafter as a function of decreasing heat with same-size plates.

  4. Design of Virtual Environments for the Comprehension of Planetary Phenomena Based on Students' Ideas.

    ERIC Educational Resources Information Center

    Bakas, Christos; Mikropoulos, Tassos A.

    2003-01-01

    Explains the design and development of an educational virtual environment to support the teaching of planetary phenomena, particularly the movements of Earth and the sun, day and night cycle, and change of seasons. Uses an interactive, three-dimensional (3D) virtual environment. Initial results show that the majority of students enthused about…

  5. Design of Virtual Environments for the Comprehension of Planetary Phenomena Based on Students' Ideas.

    ERIC Educational Resources Information Center

    Bakas, Christos; Mikropoulos, Tassos A.

    2003-01-01

    Explains the design and development of an educational virtual environment to support the teaching of planetary phenomena, particularly the movements of Earth and the sun, day and night cycle, and change of seasons. Uses an interactive, three-dimensional (3D) virtual environment. Initial results show that the majority of students enthused about…

  6. Teaching, learning, and planetary exploration

    NASA Astrophysics Data System (ADS)

    Brown, Robert A.

    1992-12-01

    The progress accomplished in the first five months of the three-year grant period of Teaching, Learning, and Planetary Exploration is presented. The objectives of this project are to discover new education products and services based on space science, particularly planetary exploration. An Exploration in Education is the umbrella name for the education projects as they are seen by teachers and the interested public. As described in the proposal, our approach consists of: (1) increasing practical understanding of the potential role and capabilities of the research community to contribute to basic education using new discoveries; (2) developing an intellectual framework for these contributions by supplying criteria and templates for the teacher's stories; (3) attracting astronomers, engineers, and technical staff to the project and helping them form productive education partnerships for the future, (4) exploring relevant technologies and networks for authoring and communicating the teacher's stories; (5) enlisting the participation of potential user's of the teacher's stories in defining the products; (6) actually producing and delivering many educationally useful teacher's stories; and (7) reporting the pilot study results with critical evaluation. Technical progress was made by assembling our electronic publishing stations, designing electronic publications based on space science, and developing distribution approaches for electronic products. Progress was made addressing critical issues by developing policies and procedures for securing intellectual property rights and assembling a focus group of teachers to test our ideas and assure the quality of our products. The following useful materials are being produced: the TOPS report; three electronic 'PictureBooks'; one 'ElectronicArticle'; three 'ElectronicReports'; ten 'PrinterPosters'; and the 'FaxForum' with an initial complement of printed materials. We have coordinated with planetary scientists and astronomers

  7. Deprojection of planetary nebula images

    NASA Astrophysics Data System (ADS)

    Volk, Kevin; Leahy, Denis A.

    1993-11-01

    Several optical or radio images of planetary nebulae have been deprojected using the algorithm described in Leahy & Volk (1993). For each image 16 radial cuts from the center of the nebula were independently deprojected assuming either spherical symmetry or a weighting of the emissivity distribution towards the plane of the sky. The deprojection was carried out using the optical line images of Balick (1987) for the Ring Nebula (NGC 6720, PN G063.1+13.9) and NGC 40 (PN G120.0+09.8) and for the 15 GHz radio image of M3-35 (PN G071.6-02.3) from Aaquist & Kwok (1991). These three nebulae were chosen due to their generally ellipsoidal shapes as seen projected on the sky, but in all three cases the deprojection indicates that the nebuale are neither oblate or prolate ellipsoidal shells. Instead, these nebulae have two main regions of emission roughly oppositely positioned around the central star each of which covers a solid angle of approximately pi steradians, and most of the emission is in more or less cylindrical bands with very little emissivity at the 'poles' of the nebulae. The nebulae are therefore more barrel-shaped than ellipsoid-shaped. While the possibility that planetary nebulae are cylindrical in shape has been studied in the past, these results indicate that the body of the nebula is far more patchy than had been postulated which may resolve some of the difficulties that the hypothesis of cylindrical symmetry has had. Such shapes are more complicated than the simplest form of the interacting winds model of planetary nebula formation predicts, but can be explained if the progenitor red giant wind was rather asymmetrical.

  8. Teaching, learning, and planetary exploration

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.

    1992-01-01

    The progress accomplished in the first five months of the three-year grant period of Teaching, Learning, and Planetary Exploration is presented. The objectives of this project are to discover new education products and services based on space science, particularly planetary exploration. An Exploration in Education is the umbrella name for the education projects as they are seen by teachers and the interested public. As described in the proposal, our approach consists of: (1) increasing practical understanding of the potential role and capabilities of the research community to contribute to basic education using new discoveries; (2) developing an intellectual framework for these contributions by supplying criteria and templates for the teacher's stories; (3) attracting astronomers, engineers, and technical staff to the project and helping them form productive education partnerships for the future, (4) exploring relevant technologies and networks for authoring and communicating the teacher's stories; (5) enlisting the participation of potential user's of the teacher's stories in defining the products; (6) actually producing and delivering many educationally useful teacher's stories; and (7) reporting the pilot study results with critical evaluation. Technical progress was made by assembling our electronic publishing stations, designing electronic publications based on space science, and developing distribution approaches for electronic products. Progress was made addressing critical issues by developing policies and procedures for securing intellectual property rights and assembling a focus group of teachers to test our ideas and assure the quality of our products. The following useful materials are being produced: the TOPS report; three electronic 'PictureBooks'; one 'ElectronicArticle'; three 'ElectronicReports'; ten 'PrinterPosters'; and the 'FaxForum' with an initial complement of printed materials. We have coordinated with planetary scientists and astronomers

  9. Gallery of Planetary Nebula Spectra

    NASA Astrophysics Data System (ADS)

    Kwitter, Karen B.; Henry, Richard B. C.

    In the course of our abundance studies over the past decade we have accumulated more than 120 high-quality, medium resolution spectra of planetary nebulae (PNe) from 3600-9600 Å using the KPNO 2.1m Goldcam CCD spectrograph and the CTIO 1.5m RC spectrograph. Results have been published in, e.g., Kwitter & Henry (1998); Henry, Kwitter & Balick (2004); and Milingo et al. (2006). We have created this website as a place where the spectra are available for graphical display, and where PN atlas information and image links are tabulated. The URL is: http://oit.williams.edu/nebulae

  10. Pioneering Concepts of Planetary Habitability

    NASA Astrophysics Data System (ADS)

    Raulin Cerceau, Florence

    Famous astronomers such as Richard A. Proctor (1837-1888), Jules Janssen (1824-1907), and Camille Flammarion (1842-1925) studied the concept of planetary habitability a century before this concept was updated in the context of the recent discoveries of exoplanets and the development of planetary exploration in the solar system. They independently studied the conditions required for other planets to be inhabited, and these considerations led them to specify the term "habitability." Naturally, the planet Mars was at the heart of the discussion. Our neighboring planet, regarded as a sister planet of Earth, looked like a remarkable abode for life. During the second part of the nineteenth century, the possibility of Martian intelligent life was intensively debated, and hopes were still ardent to identify a kind of vegetation specific to the red planet. In such a context, the question of Mars' habitability seemed to be very valuable, especially when studying hypothetical Martian vegetation. At the dawn of the Space Age, German-born physician and pioneer of space medicine Hubertus Strughold (1898-1987) proposed in the book The Green and Red Planet: A Physiological Study of the Possibility of Life on Mars (1954) to examine the planets of the solar system through a "planetary ecology." This innovative notion, which led to a fresh view of the concept of habitability, was supposed to designate a new field involving biology: "the science of planets as an environment for life" (Strughold 1954). This notion was very close to the concept of habitability earlier designated by our nineteenth-century pioneers. Strughold also coined the term "ecosphere" to name the region surrounding a star where conditions allowed life-bearing planets to exist. We highlight in this chapter the historical aspects of the emergence of the (modern) concept of habitability. We will consider the different formulations proposed by the pioneers, and we will see in what way it can be similar to our

  11. Planetary magnetism. [emphasizing dynamo theories

    NASA Technical Reports Server (NTRS)

    Stevenson, D.

    1974-01-01

    The origin and maintenance of planetary magnetic fields are discussed. The discussion is not limited to dynamo theories, although these are almost universally favored. Thermoelectric currents are found to be a possible alternative for Jupiter. Two energy sources for dynamos are considered: convection and precessionally induced fluid flow. The earth is the most favorable planet for precessionally driven dynamo, although Neptune is a possibility. Jupiter is likely to have a convectionally driven dynamo, as may Saturn, but the relevant properties of Saturn are not yet well known. Conclusions for each planet are given.

  12. Planetary magnetism. [emphasizing dynamo theories

    NASA Technical Reports Server (NTRS)

    Stevenson, D.

    1974-01-01

    The origin and maintenance of planetary magnetic fields are discussed. The discussion is not limited to dynamo theories, although these are almost universally favored. Thermoelectric currents are found to be a possible alternative for Jupiter. Two energy sources for dynamos are considered: convection and precessionally induced fluid flow. The earth is the most favorable planet for precessionally driven dynamo, although Neptune is a possibility. Jupiter is likely to have a convectionally driven dynamo, as may Saturn, but the relevant properties of Saturn are not yet well known. Conclusions for each planet are given.

  13. Public Participation in Planetary Exploration

    NASA Astrophysics Data System (ADS)

    Friedman, Louis

    2000-07-01

    In the past several years The Planetary Society has created several innovative opportunities for general public participation in the exploration of the solar system and the search for extraterrestrial life. The conduct of such exploration has traditionally been the province of a few thousand, at most, of professionally involved scientists and engineers. Yet the rationale for spending resources required by broad and far-reaching exploration involves a greater societal interest - it frequently being noted that the rationale cannot rely on science alone. This paper reports on the more notable of the opportunities for general public participation, in particular: 1) Visions of Mars: a CD containing the works of science fiction about Mars, designed to be placed on Mars as the first library to be found by eventual human explorers; 2) MAPEX: a Microelectronics And Photonics Experiment, measuring the radiation environment for future human explorers of Mars, and containing a electron beam lithograph of names of all the members of The Planetary Society at a particular time; 3) Naming of spacecraft: Involvement in the naming of spacecraft: Magellan, Sojourner; 4) The Mars Microphone: the first privately funded instrument to be sent to another world; 5) Red Rover Goes to Mars: the first commercial-education partnership on a planetary mission; 6) Student designed nanoexperiments: to fly on a Mars lander; and 7) SETI@home: a tool permitting millions to contribute to research and data processing in the search for extraterrestrial intelligence. A brief description of each of the projects will be given, and the opportunity it provided for public participation described. The evolving complexity of these projects suggest that more opportunities will be found, and that the role of public participation can increase at the same time as making substantive contributions to the flight missions. It will be suggested that these projects presage the day that planetary exploration will be truly

  14. SIRTF - Capabilities for planetary science

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Werner, M. W.; Backman, D. E.

    1992-01-01

    Major research areas of the Space Infrared Telescope Facility (SIRTF) are discussed which include Kuiper-belt comets, IR spectroscopy of comets, and circumstellar planetary debris disks. SIRTF instrumentation will include the infrared array camera (IRAC) and multiband imaging photometer (MIP). The IRAC uses large area, 2D infrared array detectors to provide wide-field (7 arcmin) and diffraction-limited imaging over the spectral region from 2 to 30 microns. The MIP will provide background-limited imaging and photometry over the wavelength range from 30 to 200 microns, wide-field, high resolution imaging from 50 to 120 microns, and broad band photometry and mapping from 200 to 700 microns.

  15. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    USGS Publications Warehouse

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  16. Planetary Boundary Layer from AERI and MPL

    SciTech Connect

    Sawyer, Virginia

    2014-02-13

    The distribution and transport of aerosol emitted to the lower troposphere is governed by the height of the planetary boundary layer (PBL), which limits the dilution of pollutants and influences boundary-layer convection. Because radiative heating and cooling of the surface strongly affect the PBL top height, it follows diurnal and seasonal cycles and may vary by hundreds of meters over a 24-hour period. The cap the PBL imposes on low-level aerosol transport makes aerosol concentration an effective proxy for PBL height: the top of the PBL is marked by a rapid transition from polluted, well-mixed boundary-layer air to the cleaner, more stratified free troposphere. Micropulse lidar (MPL) can provide much higher temporal resolution than radiosonde and better vertical resolution than infrared spectrometer (AERI), but PBL heights from all three instruments at the ARM SGP site are compared to one another for validation. If there is agreement among them, the higher-resolution remote sensing-derived PBL heights can accurately fill in the gaps left by the low frequency of radiosonde launches, and thus improve model parameterizations and our understanding of boundary-layer processes.

  17. Geochemical baseline studies of soil in Finland

    NASA Astrophysics Data System (ADS)

    Pihlaja, Jouni

    2017-04-01

    The soil element concentrations regionally vary a lot in Finland. Mostly this is caused by the different bedrock types, which are reflected in the soil qualities. Geological Survey of Finland (GTK) is carrying out geochemical baseline studies in Finland. In the previous phase, the research is focusing on urban areas and mine environments. The information can, for example, be used to determine the need for soil remediation, to assess environmental impacts or to measure the natural state of soil in industrial areas or mine districts. The field work is done by taking soil samples, typically at depth between 0-10 cm. Sampling sites are chosen to represent the most vulnerable areas when thinking of human impacts by possible toxic soil element contents: playgrounds, day-care centers, schools, parks and residential areas. In the mine districts the samples are taken from the areas locating outside the airborne dust effected areas. Element contents of the soil samples are then analyzed with ICP-AES and ICP-MS, Hg with CV-AAS. The results of the geochemical baseline studies are published in the Finnish national geochemical baseline database (TAPIR). The geochemical baseline map service is free for all users via internet browser. Through this map service it is possible to calculate regional soil baseline values using geochemical data stored in the map service database. Baseline data for 17 elements in total is provided in the map service and it can be viewed on the GTK's web pages (http://gtkdata.gtk.fi/Tapir/indexEN.html).

  18. SUSTAINABILITY. Response to Comment on "Planetary boundaries: Guiding human development on a changing planet".

    PubMed

    Gerten, Dieter; Rockström, Johan; Heinke, Jens; Steffen, Will; Richardson, Katherine; Cornell, Sarah

    2015-06-12

    Jaramillo and Destouni claim that freshwater consumption is beyond the planetary boundary, based on high estimates of water cycle components, different definitions of water consumption, and extrapolation from a single case study. The difference from our analysis, based on mainstream assessments of global water consumption, highlights the need for clearer definitions of water cycle components and improved models and databases. Copyright © 2015, American Association for the Advancement of Science.

  19. A modular gas-cooled cermet reactor system for planetary base power

    SciTech Connect

    Jahshan, S.N.; Borkowski, J.A. )

    1993-01-15

    Fission nuclear power is foreseen as the source for electricity in planetary colonization and exploration. A six module gas-cooled, cermet-fueled reactor is proposed that can meet the design objectives. The highly enriched core is compact and can operate at high temperature for a long life. The helium coolant powers six modular Brayton cycles that compare favorably with the SP-100-based Brayton cycle.

  20. Rethinking the Ancient Sulfur Cycle

    NASA Astrophysics Data System (ADS)

    Fike, David A.; Bradley, Alexander S.; Rose, Catherine V.

    2015-05-01

    The sulfur biogeochemical cycle integrates the metabolic activity of multiple microbial pathways (e.g., sulfate reduction, disproportionation, and sulfide oxidation) along with abiotic reactions and geological processes that cycle sulfur through various reservoirs. The sulfur cycle impacts the global carbon cycle and climate primarily through the remineralization of organic carbon. Over geological timescales, cycling of sulfur is closely tied to the redox state of Earth's exosphere through the burial of oxidized (sulfate) and reduced (sulfide) sulfur species in marine sediments. Biological sulfur cycling is associated with isotopic fractionations that can be used to trace the fluxes through various metabolic pathways. The resulting isotopic data provide insights into sulfur cycling in both modern and ancient environments via isotopic signatures in sedimentary sulfate and sulfide phases. Here, we review the deep-time δ34S record of marine sulfates and sulfides in light of recent advances in understanding how isotopic signatures are generated by microbial activity, how these signatures are encoded in marine sediments, and how they may be altered following deposition. The resulting picture shows a sulfur cycle intimately coupled to ambient carbon cycling, where sulfur isotopic records preserved in sedimentary rocks are critically dependent on sedimentological and geochemical conditions (e.g., iron availability) during deposition.

  1. A Hydrogen Reduction Mechanism Relevant to Early Planetary Bodies

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; McCubbin, F. M.; Shearer, C. K.

    2012-12-01

    Isotope and elemental data have been used to constrain the timing and mechanisms of planetary formation in the inner solar system, but no model completely resolves all of the geochemical data collected from differentiated bodies of the inner solar system. We propose that H2 degassing associated with planetary accretion is a thermodynamically mandated mechanism that can have a drastic effect on the f(O2) and chemistry of growing planetesimals. This mechanism explainsthe oxidation of the very youngest differentiated bodies and the striking difference in oxidation state and 'water' content of Earth and the Moon. As the solar system organized, a progression from dust to planetesimals to proto-planets occurred through a series of repeated collisions. Large impacts between differentiated bodies must initially have imposed a low f(O2) value to their mantle by interaction with the Fe metal cores. If the mantle of growing planetesimals were initially hydrous, or had incorporated hydrous material during impact and accretion, then H2 gas would be the dominant phase in the O-H system at low pressure, and due to its low solubility and high diffusion rate in mafic melts, would be liberated during cooling at or near the body's surface. Loss of H2 to space would cause oxidation of the upper mantle and when the next collision occurred, emulsified metal droplets from the impactor would oxidize in the high f(O2) outer mantle, releasing highly siderophile elements (HSE) to the mantle in near-chondritic abundance ratios. Loss of H2 would occur repeatedly over the multi-impact history of a forming planet as long as hydrous material was added periodically during planetary accretion. Two end-member scenarios are envisioned for this process, one explaining the conditions of the Moon and the second those of Earth. The first occurs where the f(O2) buffering capacity of a body is large relative to the amount of volatile elements, as occurred on the Moon. The Moon has a low f(O2) which is

  2. Control technique for planetary rover

    NASA Technical Reports Server (NTRS)

    Nakatani, Ichiro; Kubota, Takashi; Adachi, Tadashi; Saitou, Hiroaki; Okamoto, Sinya

    1994-01-01

    Beginning next century, several schemes for sending a planetary rover to the moon or Mars are being planned. As part of the development program, autonomous navigation technology is being studied to allow the rover the ability to move autonomously over a long range of unknown planetary surface. In the previous study, we ran the autonomous navigation experiment on an outdoor test terrain by using a rover test-bed that was controlled by a conventional sense-plan-act method. In some cases during the experiment, a problem occurred with the rover moving into untraversable areas. To improve this situation, a new control technique has been developed that gives the rover the ability of reacting to the outputs of the proximity sensors, a reaction behavior if you will. We have developed a new rover test-bed system on which an autonomous navigation experiment was performed using the newly developed control technique. In this outdoor experiment, the new control technique effectively produced the control command for the rover to avoid obstacles and be guided to the goal point safely.

  3. Hydrodynamic Simulations of Planetary Rings

    NASA Astrophysics Data System (ADS)

    Miller, Jacob; Stewart, G. R.; Esposito, L. W.

    2013-10-01

    Simulations of rings have traditionally been done using N-body methods, granting insight into the interactions of individual ring particles on varying scales. However, due to the scale of a typical ring system and the sheer number of particles involved, a global N-body simulation is too computationally expensive, unless particle collisions are replaced by stochastic forces (Bromley & Kenyon, 2013). Rings are extraordinarily flat systems and therefore are well-suited to existing geophysical shallow-water hydrodynamics models with well-established non-linear advection methods. By adopting a general relationship between pressure and surface density such as a polytropic equation of state, we can modify the shallow-water formula to treat a thin, compressible, self-gravitating, shearing fluid. Previous hydrodynamic simulations of planetary rings have been restricted to axisymmetric flows and therefore have not treated the response to nonaxisymmetric perturbations by moons (Schmidt & Tscharnuter 1999, Latter & Ogilvie 2010). We seek to expand on existing hydrodynamic methods and, by comparing our work with complementary N-body simulations and Cassini observations, confirm the veracity of our results at small scales before eventually moving to a global domain size. We will use non-Newtonian, dynamically variable viscosity to model the viscous transport caused by unresolved self-gravity wakes. Self-gravity will be added to model the dynamics of large-scale structures, such as density waves and edge waves. Support from NASA Outer Planets and Planetary Geology and Geophysics programs is gratefully acknowledged.

  4. Theory of Planetary System Formation

    NASA Technical Reports Server (NTRS)

    Cassen, Patrick

    1996-01-01

    Observations and theoretical considerations support the idea that the Solar System formed by the collapse of tenuous interstellar matter to a disk of gas and dust (the primitive solar nebula), from which the Sun and other components separated under the action of dissipative forces and by the coagulation of solid material. Thus, planets are understood to be contemporaneous byproducts of star formation. Because the circumstellar disks of new stars are easier to observe than mature planetary systems, the possibility arises that the nature and variety of planets might be studied from observations of the conditions of their birth. A useful theory of planetary system formation would therefore relate the properties of circumstellar disks both to the initial conditions of star formation and to the consequent properties of planets to those of the disk. Although the broad outlines of such a theory are in place, many aspects are either untested, controversial, or otherwise unresolved; even the degree to which such a comprehensive theory is possible remains unknown.

  5. Interactive investigations into planetary interiors

    NASA Astrophysics Data System (ADS)

    Rose, I.

    2015-12-01

    Many processes in Earth science are difficult to observe or visualize due to the large timescales and lengthscales over which they operate. The dynamics of planetary mantles are particularly challenging as we cannot even look at the rocks involved. As a result, much teaching material on mantle dynamics relies on static images and cartoons, many of which are decades old. Recent improvements in computing power and technology (largely driven by game and web development) have allowed for advances in real-time physics simulations and visualizations, but these have been slow to affect Earth science education.Here I demonstrate a teaching tool for mantle convection and seismology which solves the equations for conservation of mass, momentum, and energy in real time, allowing users make changes to the simulation and immediately see the effects. The user can ask and answer questions about what happens when they add heat in one place, or take it away from another place, or increase the temperature at the base of the mantle. They can also pause the simulation, and while it is paused, create and visualize seismic waves traveling through the mantle. These allow for investigations into and discussions about plate tectonics, earthquakes, hot spot volcanism, and planetary cooling.The simulation is rendered to the screen using OpenGL, and is cross-platform. It can be run as a native application for maximum performance, but it can also be embedded in a web browser for easy deployment and portability.

  6. Planetary Balloon-Based Science Platform Evaluation and Program Implementation

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.; Kremic, Tibor; Hibbitts, Karl; Young, Eliot F.; Landis, Rob

    2016-01-01

    This report describes a study evaluating the potential for a balloon-based optical telescope as a planetary science asset to achieve decadal class science. The study considered potential science achievable and science traceability relative to the most recent planetary science decadal survey, potential platform features, and demonstration flights in the evaluation process. Science Potential and Benefits: This study confirms the cost the-benefit value for planetary science purposes. Forty-four (44) important questions of the decadal survey are at least partially addressable through balloon based capabilities. Planetary science through balloon observations can provide significant science through observations in the 300 nm to 5 m range and at longer wavelengths as well. Additionally, balloon missions have demonstrated the ability to progress from concept to observation to publication much faster than a space mission increasing the speed of science return. Planetary science from a balloon-borne platform is a relatively low-cost approach to new science measurements. This is particularly relevant within a cost-constrained planetary science budget. Repeated flights further reduce the cost of the per unit science data. Such flights offer observing time at a very competitive cost. Another advantage for planetary scientists is that a dedicated asset could provide significant new viewing opportunities not possible from the ground and allow unprecedented access to observations that cannot be realized with the time allocation pressures faced by current observing assets. In addition, flight systems that have a relatively short life cycle and where hardware is generally recovered, are excellent opportunities to train early career scientists, engineers, and project managers. The fact that balloon-borne payloads, unlike space missions, are generally recovered offers an excellent tool to test and mature instruments and other space craft systems. Desired Gondola Features: Potential

  7. Infrastructure for Planetary Sciences: Universal planetary database development project

    NASA Astrophysics Data System (ADS)

    Kasaba, Yasumasa; Capria, M. T.; Crichton, D.; Zender, J.; Beebe, R.

    The International Planetary Data Alliance (IPDA), formally formed under COSPAR (Formal start: from the COSPAR 2008 at Montreal), is a joint international effort to enable global access and exchange of high quality planetary science data, and to establish archive stan-dards that make it easier to share the data across international boundaries. In 2008-2009, thanks to the many players from several agencies and institutions, we got fruitful results in 6 projects: (1) Inter-operable Planetary Data Access Protocol (PDAP) implementations [led by J. Salgado@ESA], (2) Small bodies interoperability [led by I. Shinohara@JAXA N. Hirata@U. Aizu], (3) PDAP assessment [led by Y. Yamamoto@JAXA], (4) Architecture and standards definition [led by D. Crichton@NASA], (5) Information model and data dictionary [led by S. Hughes@NASA], and (6) Venus Express Interoperability [led by N. Chanover@NMSU]. 'IPDA 2009-2010' is important, especially because the NASA/PDS system reformation is now reviewed as it develops for application at the international level. IPDA is the gate for the establishment of the future infrastructure. We are running 8 projects: (1) IPDA Assessment of PDS4 Data Standards [led by S. Hughes (NASA/JPL)], (2) IPDA Archive Guide [led by M.T. Capria (IASF/INAF) and D. Heather (ESA/PSA)], (3) IPDA Standards Identification [led by E. Rye (NASA/PDS) and G. Krishna (ISRO)], (4) Ancillary Data Standards [led by C. Acton (NASA/JPL)], (5) IPDA Registries Definition [led by D. Crichton (NASA/JPL)], (6) PDAP Specification [led by J. Salgado (ESA/PSA) and Y. Yamamoto (JAXA)], (7) In-teroperability Assessment [R. Beebe (NMSU) and D. Heather (ESA/PSA)], and (8) PDAP Geographic Information System (GIS) extension [N. Hirata (Univ. Aizu) and T. Hare (USGS: thare@usgs.gov)]. This paper presents our achievements and plans summarized in the IPDA 5th Steering Com-mittee meeting at DLR in July 2010. We are now just the gate for the establishment of the Infrastructure.

  8. Planetary plains: subsidence and warping

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    A common feature of all celestial bodies is their tectonic dichotomy best studied, naturally, at Earth [1]. Here there is an opposition of the eastern continental hemisphere and the western oceanic one. The first one is uplifted and cracked, the second one subsided, squeezed and warped. The next excellent example of dichotomy is at Mars where the subsided northern hemisphere is opposed by the highly uplifted southern one. The enigmatic two-face Iapetus now with help of Cassini SC presents a more clear picture: the leading dark hemisphere is opposed by the trailing light one. The light hemisphere is built mainly of water ice, the dark one of some more dense material. Bean-shaped asteroids with one convex and another concave hemispheres are best exemplified by Ida. Examples of dichotomic asteroids, satellites, planets and stars could be extended. Ubiquity of this phenomenon was expressed as the 1st theorem of the planetary wave tectonics [2 & others]: "Celestial bodies are dichotomic". A reason of this phenomenon is in action of inertia-gravity waves occurring in any celestial body because of its movement in non-round but elliptical (parabolic) orbit with periodically changing accelerations. The inertia-gravity standing waves warp rotating bodies (but all bodies rotate !) in 4 ortho- and diagonal interfering directions and in several harmonic wave-lengths. The fundamental wave1 produces ubiquitous tectonic dichotomy (2πR-structure): an opposition of two hemispheres with different planetary radii. To keep angular momenta of two hemispheres equal (otherwise a body will fall apart) the lower subsiding one is constructed of denser material than the higher one. Normally in terrestrial planets lowlands are filled with dense basalts, highlands are built by lighter lithologies. A subsidence means diminishing radius, otherwise, the larger surface must be fit into a smaller space. It is possible only if an original infilling is warped. At Earth cosmic altimetry shows complex

  9. Lunar and Planetary Science XXXVI, Part 13

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Mars Express HRSC Data. Mapping Compositional Diversity on Mars: Spatial Distribution and Geological Implications. A New Simulation Chamber for Studying Planetary Environments. Folded Structure in Terra Sirenum. Mars. Nitrogen-Noble Gas Static Mass Spectrometry of Genesis Collector Materials. Neon Isotope Heterogeneity in the Terrestrial Mantle: Implication for the Acquisition of Volatile Elements in Terrestrial Planets. The Cosmic Clock, the Cycle of Terrestrial Mass Extinctions.

  10. Hierarchies of Models: Toward Understanding Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.; Hajian, Arsen R.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Stars like our sun (initial masses between 0.8 to 8 solar masses) end their lives as swollen red giants surrounded by cool extended atmospheres. The nuclear reactions in their cores create carbon, nitrogen and oxygen, which are transported by convection to the outer envelope of the stellar atmosphere. As the star finally collapses to become a white dwarf, this envelope is expelled from the star to form a planetary nebula (PN) rich in organic molecules. The physics, dynamics, and chemistry of these nebulae are poorly understood and have implications not only for our understanding of the stellar life cycle but also for organic astrochemistry and the creation of prebiotic molecules in interstellar space. We are working toward generating three-dimensional models of planetary nebulae (PNe), which include the size, orientation, shape, expansion rate and mass distribution of the nebula. Such a reconstruction of a PN is a challenging problem for several reasons. First, the data consist of images obtained over time from the Hubble Space Telescope (HST) and spectra obtained from Kitt Peak National Observatory (KPNO) and Cerro Tololo Inter-American Observatory (CTIO). These images are of course taken from a single viewpoint in space, which amounts to a very challenging tomographic reconstruction. Second, the fact that we have two disparate and orthogonal data types requires that we utilize a method that allows these data to be used together to obtain a solution. To address these first two challenges we employ Bayesian model estimation using a parameterized physical model that incorporates much prior information about the known physics of the PN. In our previous works we have found that the forward problem of the comprehensive model is extremely time consuming. To address this challenge, we explore the use of a set of hierarchical models, which allow us to estimate increasingly more detailed sets of model parameters. These hierarchical models of increasing complexity are akin

  11. Observations and Modeling of Tropical Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Laraia, Anne

    2016-01-01

    This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn's atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn's subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find that these subtropical bands require very low ammonia relative humidity below the ammonia cloud layer in order to achieve the high brightness temperatures observed. We suggest that these bright subtropical bands represent dry zones created by a meridionally overturning circulation. Second, I use a dry atmospheric general circulation model to study equatorial superrotation in terrestrial atmospheres. A wide range of atmospheres are simulated by varying three parameters: the pole-equator radiative equilibrium temperature contrast, the convective lapse rate, and the planetary rotation rate. A scaling theory is developed that establishes conditions under which superrotation occurs in terrestrial atmospheres. The scaling arguments show that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global-warming simulations. Third, I use a moist slab-ocean general circulation model to study the impact of a zonally-symmetric continent on the distribution of monsoonal precipitation. I show that adding a hemispheric asymmetry in surface heat capacity is sufficient to cause symmetry breaking in both the spatial and temporal distribution of precipitation. This spatial symmetry breaking can be understood from a large-scale energetic perspective, while the temporal symmetry breaking requires

  12. Lunar and Planetary Science XXXVI, Part 13

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Mars Express HRSC Data. Mapping Compositional Diversity on Mars: Spatial Distribution and Geological Implications. A New Simulation Chamber for Studying Planetary Environments. Folded Structure in Terra Sirenum. Mars. Nitrogen-Noble Gas Static Mass Spectrometry of Genesis Collector Materials. Neon Isotope Heterogeneity in the Terrestrial Mantle: Implication for the Acquisition of Volatile Elements in Terrestrial Planets. The Cosmic Clock, the Cycle of Terrestrial Mass Extinctions.

  13. Exploring the planetary boundary for chemical pollution.

    PubMed

    Diamond, Miriam L; de Wit, Cynthia A; Molander, Sverker; Scheringer, Martin; Backhaus, Thomas; Lohmann, Rainer; Arvidsson, Rickard; Bergman, Åke; Hauschild, Michael; Holoubek, Ivan; Persson, Linn; Suzuki, Noriyuki; Vighi, Marco; Zetzsch, Cornelius

    2015-05-01

    Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if "unacceptable global change" is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient evidence shows stresses on ecosystem and human health at local to global scales, suggesting that conditions are transgressing the safe operating space delimited by a PBCP. As such, current local to global pollution control measures are insufficient. However, while the PBCP is an important conceptual step forward, at this point single or multiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control and response variables, that will aid in quantifying a PBCP(s) and gauging progress towards reducing chemical pollution; develop new technologies and technical and social

  14. Hierarchies of Models: Toward Understanding Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.; Hajian, Arsen R.; Clancy, Daniel (Technical Monitor)

    2003-01-01

    Stars like our sun (initial masses between 0.8 to 8 solar masses) end their lives as swollen red giants surrounded by cool extended atmospheres. The nuclear reactions in their cores create carbon, nitrogen and oxygen, which are transported by convection to the outer envelope of the stellar atmosphere. As the star finally collapses to become a white dwarf, this envelope is expelled from the star to form a planetary nebula (PN) rich in organic molecules. The physics, dynamics, and chemistry of these nebulae are poorly understood and have implications not only for our understanding of the stellar life cycle but also for organic astrochemistry and the creation of prebiotic molecules in interstellar space. We are working toward generating three-dimensional models of planetary nebulae (PNe), which include the size, orientation, shape, expansion rate and mass distribution of the nebula. Such a reconstruction of a PN is a challenging problem for several reasons. First, the data consist of images obtained over time from the Hubble Space Telescope (HST) and spectra obtained from Kitt Peak National Observatory (KPNO) and Cerro Tololo Inter-American Observatory (CTIO). These images are of course taken from a single viewpoint in space, which amounts to a very challenging tomographic reconstruction. Second, the fact that we have two disparate and orthogonal data types requires that we utilize a method that allows these data to be used together to obtain a solution. To address these first two challenges we employ Bayesian model estimation using a parameterized physical model that incorporates much prior information about the known physics of the PN. In our previous works we have found that the forward problem of the comprehensive model is extremely time consuming. To address this challenge, we explore the use of a set of hierarchical models, which allow us to estimate increasingly more detailed sets of model parameters. These hierarchical models of increasing complexity are akin

  15. An outline of planetary geoscience. [philosophy

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A philosophy for planetary geoscience is presented to aid in addressing a number of major scientific questions; answers to these questions should constitute the basic geoscientific knowledge of the solar system. However, any compilation of major questions or basic knowledge in planetary geoscience involves compromises and somewhat arbitrary boundaries that reflect the prevalent level of understanding at the time.

  16. Visualization of Kepler's Laws of Planetary Motion

    ERIC Educational Resources Information Center

    Lu, Meishu; Su, Jun; Wang, Weiguo; Lu, Jianlong

    2017-01-01

    For this article, we use a 3D printer to print a surface similar to universal gravitation for demonstrating and investigating Kepler's laws of planetary motion describing the motion of a small ball on the surface. This novel experimental method allows Kepler's laws of planetary motion to be visualized and will contribute to improving the…

  17. Lunar and Planetary Science XXXV: Education

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Education" includes the following topics: 1) Convection, Magnetism, Orbital Resonances, Impacts, and Volcanism: Energies and Processes in the Solar System: Didactic Activities; 2) Knowledge Management in Aerospace-Education and Training Issues; 3) Creating Easy-to-Understand Planetary Maps; 4) Planetary Environment comparison in the Education of Astrobiology; and 5) Design and Construction of a Mechanism for the Orbital Resonances Simulation.

  18. Astronomy: Hurling comets around a planetary nursery

    NASA Astrophysics Data System (ADS)

    Roberge, Aki

    2014-10-01

    An analysis of hundreds of star-grazing comets in a young planetary system shows that they form two families: a group of old, dried-out comets and a younger group probably related to the break-up of a larger planetary body. See Letter p.462

  19. Impact erosion of terrestrial planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.

    1992-01-01

    I review current ideas about the nature of the planetesimals - composition, size distribution, and the planetary encounter velocity. Previous papers on accretion and erosion of planetary atmospheres as a result of multiple impacts are reviewed. Finally, the effects of blowing off a substantial fraction of the atmosphere from a terrestrial planet due to a single giant body impact are discussed.

  20. Post Viking planetary protection requirements study

    NASA Technical Reports Server (NTRS)

    Wolfson, R. P.

    1977-01-01

    Past planetary quarantine requirements were reviewed in the light of present Viking data to determine the steps necessary to prevent contamination of the Martian surface on future missions. The currently used term planetary protection reflects a broader scope of understanding of the problems involved. Various methods of preventing contamination are discussed in relation to proposed projects, specifically the 1984 Rover Mission.

  1. The Formation of a Planetary Nebula.

    ERIC Educational Resources Information Center

    Harpaz, Amos

    1991-01-01

    Proposes a scenario to describe the formation of a planetary nebula, a cloud of gas surrounding a very hot compact star. Describes the nature of a planetary nebula, the number observed to date in the Milky Way Galaxy, and the results of research on a specific nebula. (MDH)

  2. The Formation of a Planetary Nebula.

    ERIC Educational Resources Information Center

    Harpaz, Amos

    1991-01-01

    Proposes a scenario to describe the formation of a planetary nebula, a cloud of gas surrounding a very hot compact star. Describes the nature of a planetary nebula, the number observed to date in the Milky Way Galaxy, and the results of research on a specific nebula. (MDH)

  3. Lunar and Planetary Science XXXV: Education

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Education" includes the following topics: 1) Convection, Magnetism, Orbital Resonances, Impacts, and Volcanism: Energies and Processes in the Solar System: Didactic Activities; 2) Knowledge Management in Aerospace-Education and Training Issues; 3) Creating Easy-to-Understand Planetary Maps; 4) Planetary Environment comparison in the Education of Astrobiology; and 5) Design and Construction of a Mechanism for the Orbital Resonances Simulation.

  4. Meteoritics and Planetary Science Supplement. Volume 35

    NASA Technical Reports Server (NTRS)

    Sears, Derek W. G. (Editor); Binzel, Richard P. (Editor); Gaffey, Michael J. (Editor); Kraehenbuehl, Urs (Editor); Pieters, Carle M. (Editor); Shaw, Denis (Editor); Wieler, Rainer (Editor); Brownlee, Donald E. (Editor); Goldstein, Joseph I. (Editor); Lyon, Ian C. (Editor)

    2000-01-01

    This special supplement of the Meteoritics and Planetary Science Society Journal contains the abstracts of 324 technical presentations, and the presentations of awards during the Annual meeting of the Meteoritical Society. The abstracts review current research on meteors and planetary sciences.

  5. Introduction to the special issue: Planetary geomorphology

    NASA Astrophysics Data System (ADS)

    Burr, Devon M.; Howard, Alan D.

    2015-07-01

    Planetary geomorphology is the study of extraterrestrial landscapes. In recognition of the promise for productive interaction between terrestrial and planetary geomorphologists, the 45th annual Binghamton Geomorphology Symposium (BGS) focused on Planetary Geomorphology. The aim of the symposium was to bring planetary and terrestrial geomorphologists together for symbiotic and synthetic interactions that would enrich both subdisciplines. In acknowledgment of the crucial role of terrestrial field work in planetary geomorphology and of the BGS tradition, the symposium began with a field trip to the Appalachian Mountains, followed by a dinner talk of recent results from the Mars Surface Laboratory. On Saturday and Sunday, the symposium was organized around major themes in planetary geomorphology, starting with the geomorphic processes that are most common in our Solar System-impact cratering, tectonism, volcanism-to set the stage for other geomorphic processes, including aeolian, fluvial, lacustrine, and glacial/polar. On Saturday evening, the banquet talk provided an historical overview of planetary geomorphology, including its roots in the terrestrial geosciences. The symposium concluded with a full-afternoon tutorial on planetary geomorphologic datasets. This special issue of Geomorphology consists of papers by invited authors from the 2014 BGS, and this introduction provides some context for these papers.

  6. Planetary rock corer and drill concepts

    NASA Technical Reports Server (NTRS)

    Imus, R. E.

    1972-01-01

    Several planetary rock corers and drill design concepts have been developed for obtaining subsurface rock samples in future planetary explorations. Tools are designed for unmanned space vehicles. Two devices are rotary impact multiple chisel trepan rock corer and hole drilling tool.

  7. Meteoritics and Planetary Science Supplement. Volume 35

    NASA Technical Reports Server (NTRS)

    Sears, Derek W. G. (Editor); Binzel, Richard P. (Editor); Gaffey, Michael J. (Editor); Kraehenbuehl, Urs (Editor); Pieters, Carle M. (Editor); Shaw, Denis (Editor); Wieler, Rainer (Editor); Brownlee, Donald E. (Editor); Goldstein, Joseph I. (Editor); Lyon, Ian C. (Editor)

    2000-01-01

    This special supplement of the Meteoritics and Planetary Science Society Journal contains the abstracts of 324 technical presentations, and the presentations of awards during the Annual meeting of the Meteoritical Society. The abstracts review current research on meteors and planetary sciences.

  8. Origins of planetary systems: Observations and analysis

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.; Bernstein, Max

    1995-01-01

    This cooperative agreement was established with the scientific goal of understanding the conditions of early solar-type planetary systems. We investigated two facets of young solar systems: The effects on planetary bodies of young solar-type stellar mass loss, and photo-production of various organic materials due to radiation under comet-like conditions.

  9. The survival of geochemical mantle heterogeneities

    NASA Astrophysics Data System (ADS)

    Albarede, F.

    2004-12-01

    The last decade witnessed major changes in our perception of the geochemical dynamics of the mantle. Data bases such as PETDB and GEOROC now provide highly constrained estimates of the geochemical properties of dominant rock types and of their statistics, while the new generation of ICP mass spectrometers triggered a quantum leap in the production of high-precision isotopic and elemental data. Such new advances offer a fresh view of mantle heterogeneities and their survival through convective mixing. A vivid example is provided by the new high-density coverage of the Mid-Atlantic ridge by nearly 500 Pb, Nd, and Hf isotopic data. This new data set demonstrates a rich harmonic structure which illustrates the continuing stretching and refolding of subducted plates by mantle convection. Just as for oceanic chemical variability, the survival of mantle geochemical heterogeneities though mantle circulation can be seen as a competition between stirring and renewal. The modern residence (renewal) times of the incompatible lithophile elements in the mantle calculated using data bases vary within a rather narrow range (4-9 Gy). The mantle is therefore not currently at geochemical steady-state and the effect of its primordial layering on modern mantle geochemistry is still strong. Up to 50 percent of incompatible lithophile elements may never have been extracted into the oceanic crust, which generalizes a conclusion reached previously for 40Ar. A balance between the buoyancy flux and viscous dissipation provides frame-independent estimates of the rates of mixing by mantle convection: primordial geochemical anomalies with initial length scales comparable to mantle depths of plate lengths are only marginally visible at the scale of mantle melting underneath mid-ocean ridges (≈~50~km). They may show up, however, in hot spot basalts and even more in melt inclusions. Up to 50 percent primordial material may be present in the mantle, but scattered throughout as small (<~10~km

  10. A geochemical examination of humidity cell tests

    USGS Publications Warehouse

    Maest, Ann; Nordstrom, D. Kirk

    2017-01-01

    Humidity cell tests (HCTs) are long-term (20 to >300 weeks) leach tests that are considered by some to be the among the most reliable geochemical characterization methods for estimating the leachate quality of mined materials. A number of modifications have been added to the original HCT method, but the interpretation of test results varies widely. We suggest that the HCTs represent an underutilized source of geochemical data, with a year-long test generating approximately 2500 individual chemical data points. The HCT concentration peaks and valleys can be thought of as a “chromatogram” of reactions that may occur in the field, whereby peaks in concentrations are associated with different geochemical processes, including sulfate salt dissolution, sulfide oxidation, and dissolution of rock-forming minerals, some of which can neutralize acid. Some of these reactions occur simultaneously, some do not, and geochemical modeling can be used to help distinguish the dominant processes. Our detailed examination, including speciation and inverse modeling, of HCTs from three projects with different geology and mineralization shows that rapid sulfide oxidation dominates over a limited period of time that starts between 40 and 200 weeks of testing. The applicability of laboratory tests results to predicting field leachate concentrations, loads, or rates of reaction has not been adequately demonstrated, although early flush releases and rapid sulfide oxidation rates in HCTs should have some relevance to field conditions. Knowledge of possible maximum solute concentrations is needed to design effective treatment and mitigation approaches. Early flush and maximum sulfide oxidation results from HCTs should be retained and used in environmental models. Factors that complicate the use of HCTs include: sample representation, time for microbial oxidizers to grow, sample storage before testing, geochemical reactions that add or remove constituents, and the HCT results chosen for use

  11. Mechanistic Studies of Planetary Haze Formation

    NASA Astrophysics Data System (ADS)

    Hicks, Raea Kay

    2015-10-01

    controlling the total mass produced depends on pressure. We also report an overall increase with pressure in the N/C ratio, which supports the importance of a pressure- dependent mechanism for nitrogen incorporation. In order to understand carbon incorporation into early Earth aerosols, we devised an analysis technique that allows retrieval of the elemental analysis from unit-mass resolution (UMR) mass spectra of isotopically-labeled data. A quadrupole aerosol mass spectrometer (Q-AMS) was used to obtain UMR data of 13C-labeled and unlabeled aerosol generated by FUV photochemistry of gas mixtures containing 0.1% of either CH4 or 13CH 4 in N2. In this method, the differences in the positions of ion groups in the resulting spectra are used to estimate the mass fraction of carbon in the aerosol, and estimation of the remaining elements follows. Analysis of the UMR data yields an elemental composition of 63+/-7% C, 8+/-1% H, and 29+/-7% N by mass. Unlabeled aerosols formed under the same conditions are found by the HR-ToF-AMS to have an elemental composition of 63+/-3% C, 8+/-1% H, 20+/-4% N, and 9+/-3% O by mass, in good agreement with the UMR method. This favorable comparison verifies the method, which expands the UMR mass spectrometry toolkit. Chemical mechanisms posited to explain the aerosol-forming chemistry treat CH4 as carbon source in these hazes and treat CO2 as a source of oxygen only. We have generated early Earth aerosol analogs in the laboratory by FUV irradiation of gas mixtures containing isotopically-labeled permutations of 1,000 ppmv unlabeled and 13C-labeled CH 4 and CO2 in N2. Products in the particle phase were analyzed by the Q-AMS and the HR-ToF-AMS. Results indicate that CH 4 can account for 100% of the total carbon contained in the hazes. These results have implications for the geochemical interpretations of inclusions found in Archaean rocks on Earth, and for the astrobiological potential of other planetary atmospheres.

  12. Iron cycling in the Amazon River Basin: the isotopic perspective

    NASA Astrophysics Data System (ADS)

    Poitrasson, Franck; Vieira, Lucieth; Mulholland, Daniel; Seyler, Patrick; Sondag, Francis; Allard, Thierry

    2014-05-01

    interaction between organic matter and iron in rivers, and ultimately the nature of their source in soils. As such, they may become a powerfull tracer of changes occurring on the continents in response to both weathering context and human activities. References: Bergquist, B.A., Boyle, E.A., 2006. Iron isotopes in the Amazon River system: Weathering and transport signatures. Earth and Planetary Science Letters, 248: 54-68. Emmanuel, S., Erel, Y., Matthews, A., Teutsch, N., 2005. A preliminary mixing model for Fe isotopes in soils. Chemical Geology, 222: 23-34. Fantle, M.S., DePaolo, D.J., 2004. Iron isotopic fractionation during continental weathering. Earth and Planetary Science Letters, 228: 547-562. Ingri, J., Malinovsky, D., Rodushkin, I., Baxter, D.C., Widerlund, A., Andersson, P., Gustafsson, O., Forsling, W., Ohlander, B., 2006. Iron isotope fractionation in river colloidal matter. Earth and Planetary Science Letters, 245: 792-798. Poitrasson, F., Viers, J., Martin, F., Braun, J.J., 2008. Limited iron isotope variations in recent lateritic soils from Nsimi, Cameroon: Implications for the global Fe geochemical cycle. Chemical Geology, 253: 54-63. Wiederhold, J.G., Teutsch, N., Kraemer, S.M., Halliday, A.N., Kretzchmar, R., 2007. Iron isotope fractionation in oxic soils by mineral weathering and podzolization. Geochimica et Cosmochimica Acta, 71: 5821-5833.

  13. Expanding the Planetary Analog Test Sites in Hawaii - Planetary Basalt Manipulation

    NASA Astrophysics Data System (ADS)

    Kelso, R.

    2013-12-01

    The Pacific International Space Center for Exploration Systems (PISCES) is one of the very few planetary surface research test sites in the country that is totally funded by the state legislature. In recent expansions, PISCES is broadening its work in planetary test sites to include much more R&D work in the planetary surface systems, and the manipulation of basalt materials. This is to include laser 3D printing of basalt, 'lunar-concrete' construction in state projects for Hawaii, renewable energy, and adding lava tubes/skylights to their mix of high-quality planetary analog test sites. PISCES Executive Director, Rob Kelso, will be providing program updates on the interest of the Hawaii State Legislature in planetary surface systems, new applied research initiatives in planetary basalts and interests in planetary construction.

  14. On the Diversity of Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Models of planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  15. Planetary CubeSats Come of Age

    NASA Technical Reports Server (NTRS)

    Sherwood, Brent; Spangelo, Sara; Frick, Andreas; Castillo-Rogez, Julie; Klesh, Andrew; Wyatt, E. Jay; Reh, Kim; Baker, John

    2015-01-01

    Jet Propulsion Laboratory initiatives in developing and formulating planetary CubeSats are described. Six flight systems already complete or underway now at JPL for missions to interplanetary space, the Moon, a near-Earth asteroid, and Mars are described at the subsystem level. Key differences between interplanetary nanospacecraft and LEO CubeSats are explained, as well as JPL's adaptation of vendor components and development of system solutions to meet planetary-mission needs. Feasible technology-demonstration and science measurement objectives are described for multiple modes of planetary mission implementation. Seven planetary-science demonstration mission concepts, already proposed to NASA by Discovery-2014 PIs partnered with JPL, are described for investigations at Sun-Earth L5, Venus, NEA 1999 FG3, comet Tempel 2, Phobos, main-belt asteroid 24 Themis, and metal asteroid 16 Psyche. The JPL staff and facilities resources available to PIs for analysis, design, and development of planetary nanospacecraft are catalogued.

  16. Deep sulfur cycle

    NASA Astrophysics Data System (ADS)

    Shimizu, N.; Mandeville, C. W.

    2009-12-01

    Geochemical cycle of sulfur in near-surface reservoirs has been a subject of intense studies for decades. It has been shown that sulfur isotopic compositions of sedimentary sulfides and sulfates record interactions of the atmosphere, hydrosphere, biosphere and lithosphere, with δ34S of sedimentary sulfides continuously decreasing from 0‰ toward present-day values of ~-30 to -40‰ over the Phanerozoic (e.g., Canfield, 2004). It has also been shown that microbial reduction of the present-day seawater sulfate (δ34S=+21‰) results in large shifts in isotopic compositions of secondary pyrites in altered oceanic crust (to δ34S=-70‰: Rouxel et al., 2009). How much of these near surface isotopic variations survive during deep geochemical cycle of sulfur interacting with the mantle infinite reservoir with δ34S=0‰? Could extent of their survival be used as a tracer of processes and dynamics involved in deep geochemical cycle? As a first step toward answering these questions, δ34S was determined in-situ using a Cameca IMS 1280 ion microprobe at Woods Hole Oceanographic Institution in materials representing various domains of deep geochemical cycle. They include pyrites in altered MORB as potential subducting materials and pyrites in UHP eclogites as samples that have experienced subduction zone processes, and mantle-derived melts are represented by olivine-hosted melt inclusions in MORB and those in IAB, and undegassed submarine OIB glasses. Salient features of the results include: (1) pyrites in altered MORB (with O. Rouxel; from ODP site 801 and ODP Hole 1301B) range from -70 to +19‰, (2) pyrites in UHP eclogites from the Western Gneiss Region, Norway (with B. Hacker and A. Kylander-Clark) show a limited overall range from -3.4 to + 2.8‰ among five samples, with one of them covering almost the entire range, indicating limited scale lengths of isotopic equilibration during subduction, (3) olivine-hosted melt inclusions in arc basalts from Galunggung (-2

  17. Sulphur geodynamic cycle

    PubMed Central

    Kagoshima, Takanori; Sano, Yuji; Takahata, Naoto; Maruoka, Teruyuki; Fischer, Tobias P.; Hattori, Keiko

    2015-01-01

    Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/3He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/3He ratios of high-temperature volcanic gases show sulphur flux of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S flux ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle. PMID:25660256

  18. Diurnal variability of the planetary albedo - An appraisal with satellite measurements and general circulation models

    NASA Technical Reports Server (NTRS)

    Potter, G. L.; Cess, R. D.; Minnis, P.; Harrison, E. F.; Ramanathan, V.

    1988-01-01

    An atmospheric radiation model is used here to illustrate several features associated with modeling the diurnal cycle of the planetary albedo. It is found that even for clear regions there appear to be deficiencies in our knowledge of how to model this quantity. The diurnal amplitude factor, defined as the ratio of the diurnally averaged planetary albedo to that at noon, between two GCMs and measurements made from a geostationary satellite. While reasonable consistency is found, the comparisons underscore difficulties associated with converting local-time albedo measurements, as made from sun-synchronous satellites, to diurnally averaged albedos.

  19. The hydrogen shell game - Pulsational instabilities in hydrogen shell-burning planetary nebula nuclei

    NASA Technical Reports Server (NTRS)

    Kawaler, Steven D.

    1988-01-01

    Fully nonadiabatic g-mode pulsation calculations have been obtained for evolutionary models of planetary nebula nuclei (PNN) with active hydrogen-burning shells. Expressions have been developed for the phase delays which can develop between the temperature variations and the abundance variations of agents in the CN cycle. G-mode instabilities are noted that are driven by the epsilon mechanism at the position of the nuclear burning shells in standard PNN models. The results indicate that the central stars do not retain sufficient hydrogen to support nuclear burning following ejection of the planetary nebula.

  20. Using Geochemical Indicators to Distinguish High Biogeochemical Activity in Sediments

    NASA Astrophysics Data System (ADS)

    Kenwell, A. M.; Navarre-Sitchler, A.; Prugue, R.; Spear, J. R.; Williams, K. H.; Maxwell, R. M.

    2014-12-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict elevated rates of biogeochemical activity (microbial "hotspots") in subsurface environments by correlating microbial community structure with the spatial distribution of geochemical indicators in subsurface sediments. Statistical hierarchical cluster analyses (HCA) of X-ray fluorescence (XRF), simulated precipitation leachate, bioavailable Fe and Mn, total organic carbon (TOC), microbial community structure, grain size, bulk density and moisture content data were used to identify regions of the subsurface characterized by biogeochemical hotspots and sample characteristics indicative of these hotspots within fluvially-derived aquifer sediments. The methodology has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 33 sediment samples were taken from 8 sediment cores and at the East River 33 soil/sediment samples were collected across and perpendicular to 3 active meanders. The East River watershed exhibits characteristic fluvial progression and serves as a representative example of many headwater catchments with the upper Colorado River basin. Initial clustering revealed that operationally defined hotspots were characterized by high organic carbon, bioavailable iron and dark colors but not necessarily low hydraulic conductivity. Applying the method to identify hotspots in both contaminated and natural floodplain deposits and their associated alluvial aquifers demonstrates the broad applicability of a geochemical indicator based approach.