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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The causes for geographical variations in OS187/OS186 at the Cretaceous-Tertiary boundary

Researchers at Yale has approached the problem of the osmium isotopic composition of marine deposits formed in contact with both oxidized and reduced bottom waters. The measured (187) Os/(186) Os ratios of modern bulk sediment can be explained using mixing equations involving continental detrital, volcaniclastic, cosmogenic and hydrogeneous components. These studies show that sediments deposited under reducing marine conditions contain a hydrogenous component which is enriched in Re and has a radiogenic (187) Os/(186) Os ratio. The presence of such a hydrogenous component in the marine fish clay at Stevns Klint can account for the elevation of its (187) Os/(186) Os ration above the expected meteoritic value. Mass balance considerations require the Re/Os ratio of the phase precipitated from the terminal Cretaceous sea at Stevns Klint to have been about one tenth the value observed in contemporary deposits in the Black Sea, assuming Re has not been lost (or Os gained) subsequent to precipitation. In continental sections, the elevation of the (187) Os/(186) Os ratio in boundary layers may be due to precipitation from continental waters of crustally-derived radiogenic osmium either contemporaneous with the meteoritic (or mantle) osmium deposition or later during diagenesis.

Turekian, K. K.↗
NASA NTRS1992

An Alpha-p-x Analytical Instrument for Lunar Resource Investigations

An instrument using alpha backscattering, alpha-proton nuclear reactions, and x-ray production by alpha particles and other auxiliary sources can be used on lunar landers to provide detailed analytical information concerning the lunar surface material. This information is important scientifically and can be the basis for utilizing efficiently lunar resources to build lunar colonies in the future. This alpha particle instrument uses radioactive isotopes, silicon detectors for the alpha and proton modes, and mercuric iodide detectors operating at room temperature for the x-ray mode. The alpha and proton modes of the instrument can provide an analysis for all elements (except hydrogen) present in amounts greater than about 1 percent by atom. These modes have excellent sensitivity and accuracy for the lighter elements, in particular, directly determining the amount of oxygen in the lunar soil. This is an element of paramount significance for the lunar resource mission. The x-ray mode makes possible a determination of Ti, Fe, and other important metals with even greater accuracy. In general, the x-ray mode provides increased sensitivity for heavier elements, in many cases achieving a sensitivity of several hundred ppm.

Economou, T. E.↗
NASA NTRS1987

13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites

13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

Non-NASA Center↗
NASA NTRS1999

High-Resolution Spectroscopy of Mars: Recent Results and Implications for Atmospheric Evolution

It is believed that Earth, Venus, and Mars were formed by the same rocky and icy planetesimals, which resembled meteorites and comets in their composition, respectively. These planets are thus expected to have initially had the same chemical and isotope composition. Scaling the mass of the terrestrial ocean by the planetary mass ratio, the expected initial H2O abundance on Mars is a layer of about 1 km thick. Scaling the abundance of CO2 on Venus, the expected initial CO2 abundance on Mars is 15 bars. Evidently, significant parts of the initial H2O and CO2 abundances have been lost. Intense meteorite impact erosion and hydrodynamic escape of hydrogen (which could drag to escape more heavy species) were dominant loss processes in the first 0.8 Byr. Later, atmospheric sputtering by O+ ions resulted in the dissociation of CO2 and massive losses of O, C, and H. Formation of carbonates also reduced CO2 to its present abundance which currently exists in the atmosphere, on the polar caps, and is absorbed by regolith. Water loss is currently due to thermal escape of H and nonthermal escape of O, both formed by photodissociation of H2O. All loss processes resulted in fractionation of the H, O, and C isotopes. Therefore, the current isotope ratios in H2O and CO2 are clues to the history of volatiles on Mars. There are three tools to study H2O and CO2 isotopes in the martian atmosphere: (i) mass spectrometry from landing probes, (ii) analyses of Mars' gases trapped in the SNC meteorites which were ejected from Mars, and (iii) high-resolution spectroscopy of the H2O andCO2 bands. Method (i) is the best but is the most expensive. Mass spectrometers to be used should be designed for high-precision isotope measurements. Method (ii) makes it possible to reach an uncertainty +/- 0.1%. However, the obtained results are affected by some uncontrolled interactions: isotope fractionations of (1) trapped gases and (2) those released in pyrolysis, (3) contribution of the impactor, isotope exchanges (4) in the terrestrial environment and (5) with the host rock during pyrolysis. Therefore, the spectroscopic data are of great interest, though their formal accuracy is lower. High-resolution spectroscopy is also a tool to study the current atmosphere of Mars by mapping of some photochemically important species and searching for some minor constituents and their variations. Additional information is contained in the original extended abstract.

Krasnopolsky, V. A.↗
NASA NTRS1994

Mars atmospheric escape and isotopic fractionation: Synthesis of data and models

The present Mars atmosphere is relatively thin and cold. It is not at all like that which is presumed to have been responsible for the formation of valley networks and the heavy erosion of craters during the earliest epochs of martian history. An important goal of Mars exploration is to try to understand the properties of the early atmosphere, the initial inventory of volatiles at the planet's surface, the processes by which the atmosphere and climate have evolved over time, and the current location of volatiles presumed to have been in the atmosphere in the earlier times. The current status of understanding of the escape of volatiles to space over geologic time and the resulting fractionation of isotopes of stable atoms remaining in the atmosphere are described, and a scenario for volatile abundance and evolution that is consistent with the available information on the escape and fractionation of each species is constructed. In particular, the evolution of hydrogen, carbon, oxygen, and nitrogen, as contained in atmospheric (and non-atmospheric) water, carbon dioxide, and molecular nitrogen, is examined.

Jakosky, Bruce M.↗
NASA NTRS1994

Scientific objectives of the primitive body sample return missions: An approach from the light-induced effect on water vapor

Water is undoubtedly one of the most crucial components of the solar nebula for determining planetary composition: planets were formed from the accretion of the dust particles in the nebula, and the redox state of Fe in the particles can be determined by the reaction of Fe with water vapor diffused into the interior of the particle in the early stage of solar system formation. It has been discussed from various observations that the cores of Mercury, Venus, and the Earth might be metallic Fe, although the core of the Earth may be somewhat oxidized by the high pressure and temperature reaction of liquid Fe with perovskite at the boundary of the mantle and the core, whereas the core of Mars may be highly oxidized, as suggested by its low density. Isotopic anomalies of various elements have frequently been observed in the solar system (in planetary atmospheres and in meteorites) and some of them can be attributed to the injection of exotic particles formed in other stars into the solar nebula. Hydrogen and D anomalies in planetary atmospheres were frequently believed to correlate with the differential escape of H and D from the exospheres of Venus and Mars, although no one knows the primordial D/H ratios before thermal escape. This paper explains the decrease of the observed D/H ratios with distance from the sun by considering the light-induced drift effect to displace H2(16)O alone to the outside in the solar nebula.

Shimizu, Mikio↗
NASA NTRS1994

Optical model analyses of heavy ion fragmentation in hydrogen targets

Quantum-mechanical optical-model methods for calculating cross sections for the fragmentation of high-energy heavy ions by hydrogen targets are presented. The cross sections are calculated with a knockout-ablation collision formalism which has no arbitrary fitting parameters. Predictions of elemental production cross sections from the fragmentation of 1.2A Ge(V(La-139) nuclei and of isotope production cross sections from the fragmentation of 400A MeV(S-32) nuclei are in good agreement with recently reported experimental measurements.

Townsend, Lawrence W.↗
NASA NTRS1986

Elemental, isotopic and molecular abundances in comets

The chemical composition of comet nuclei and the factors affecting it are discussed, summarizing the results of recent theoretical, experimental, and observational investigations. Consideration is given to the evidence supporting the view that the nucleus is radially differentiation (except for a thin outer layer), surface differentiation by heat processing and outgassing, and mantle buildup on an undifferentiated core. The nature of the refractory and volatile components is examined, and the elemental and isotopic compositions are given in tables and characterized. The uncertain (except for H2O) molecular composition of the volatile fraction is considered, and it is suggested that some oxides or aldehydes (such as CO, CO2, and H2CO), but no large amounts of fully hydrogenated compounds (such as CH4 and NH3) are included.

Delsemme, A. H.↗
NASA NTRS1995

Characteristics and formation of amino acids and hydroxy acids of the Murchison meteorite

Eight characteristics of the unique suite of amino acids and hydroxy acids found in the Murchison meteorite can be recognized on the basis of detailed molecular and isotopic analyses. The marked structural correspondence between the alpha-amino acids and alpha-hydroxy acids and the high deuterium/hydrogen ratio argue persuasively for their formation by aqueous phase Strecker reactions in the meteorite parent body from presolar, i.e., interstellar, aldehydes, ketones, ammonia, and hydrogen cyanide. The characteristics of the meteoritic suite of amino acids and hydroxy acids are briefly enumerated and discussed with regard to their consonance with this interstellar-parent body formation hypothesis. The hypothesis has interesting implications for the organic composition of both the primitive parent body and the presolar nebula.

Cronin, J. R.↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 22

The Lunar and Planetary Science XXXVI, Part 22 is presented. The topics include: 1) Pressure Histories from Thin and Thick Shock-induced Melt Veins in Meteorites; 2) Nano-structured Minerals as Signature of Microbial Activity; 3) The Insoluble Carbonaceous Material of CM Chondrites as Possible Source of Discrete Organics During the Asteroidal Aqueous Phase; 4) Discovery of Abundant Presolar Silicates in Subgroups of Antarctic Micrometeorites; 5) Characteristics of a Seismometer for the LUNAR-A Penetrator; 6) Heating Experiments of the HaH 262 Eucrite and Implication for the Metamorphic History of Highly Metamorphosed Eucrites; 7) Measurements of Ejecta Velocity Distribution by a High-Speed Video Camera; 8) Petrological Comparison of Mongolian Jalanash Ureilite and Twelve Antarctic Ureilites; 9) Metallographic Cooling Rate of IVA Irons Revisited; 10) Inhomogeneous Temperature Distribution in Chondrules in Shock-Wave Heating Model; 11) Subsurface Weathering of Rocks and Soils at Gusev Crater; 12) Extinct Radioactivities in the Early Solar System and the Mean Age of the Galaxy; 13) Correlation of Rock Spectra with Quantitative Morphologic Indices: Evidence for a Single Rock Type at the Mars Pathfinder Landing Site; 14) Silicon Isotopic Ratios of Presolar Grains from Supernovae; 15) Current Status and Readiness on In-Situ Exploration of Asteroid Surface by MINERVA Rover in Hayabusa Mission; 16) Long Formation Period of Single CAI: Combination of O and Mg Isotope Distribution; 17) Supra-Canonical Initial 26Al/27Al Indicate a 105 Year Residence Time for CAIs in the Solar Proto-Planetary Disk; 18) Evolution of Mercury's Obliquity; 19) First Results from the Huygens Surface Science Package; 20) Polyhedral Serpentine Grains in CM Chondrites; 21) Mountainous Units in the Martian Gusev Highland Region: Volcanic, Tectonic, or Impact Related? 22) Petrography of Lunar Meteorite MET 01210, A New Basaltic Regolith Breccia; 23) Earth-Moon Impacts at ~300 Ma and ~500 Ma Ago; 24) Chemical and Isotopic Analyses of Apollo 16 Glasses: An Integrated Approach; 25) Measuring the Surfaces on Mars; 26) Melting in Martian Snowbanks; 27) The Effect of Ni on Fe-FeS Phase Relations: Implications for the Chemistry of the Martian Core; 28) Shorelines in the Western United States as Analogs for Hypothesized Shoreline Features on Mars; 29) Al and Ti Isotopic Ratios of Presolar SiC Grains of Type Z; 30) Physicochemical Conditions of Clinopyroxene Crystallization in the Parental Bodies of Ordinary Chondrites; 31) Metamorphosed CM and CI Carbonaceous Chondrites Could be from the Breakup of the Same Earth-crossing Asteroid; 32) Aqueous Alteration and Hydrogen Generation on Parent Bodies of Unequilibrated Ordinary Chondrites: Thermodynamic Modeling for the Semarkona Composition; and 33) Preliminary Analysis of Relative Abundances of Hydrothermal Alteration Products in the C1-N10, Y6-N19, and Yax-1_863.51 Impact Melt Samples, Chicxulub Structure, Mexico

Source record↗
NASA NTRS1987

Was Venus wet? Deuterium reconsidered

The ratio of deuterium to hydrogen on Venus has been accepted as proof of a wetter, more earth-like part on that planet. However, the present-day water abundance and the nonthermal hydrogen escape flux on Venus imply that hydrogen is in a steady state and that a hydrogen source, most likely cometary infall, is present. An alternative interpretation of the D/H ratio is offered, in which the measured value is consistent with a steady-state evolution over the age of the solar system. No past water excess is required to explain the isotopic data.

Grinspoon, David H.↗
NASA NTRS1984

Relic interstellar grains in Murchison meteorite

It is shown that, in the Murchison meteorite, the D/H ratios of hydrogen are unusually high in several separates and in one case up to 30 times the cosmic value of 2 x 10 to the -5th. Many phases show high C-13/C-12 ratios, up to 2.5 times the terrestrial value of 0.011. These C-13-rich and D-rich components of the two chemical elements are not correlated. They are heterogeneously distributed, suggesting that different components in the meteorite originated from different astrophysical sites and at different times. The D-rich hydrogen in the meteorite is probably due to molecules formed by ion-molecule reactions in interstellar clouds while the tiny amount of C-13-rich carbon is probably due to nucleosynthesis in red giant stars as suggested by Swart et al. (1983). Both of these heavy-isotope enriched components survived homogenization in the accumulation and subsequent history of the meteorites.

Yang, J.↗
NASA NTRS2006

Overview of Mars Science Laboratory (MSL) Environmental Program

This viewgraph presentation is an overview of the Mars Science Laboratory (MSL) program. The engineering objectives of the program are to create a Mobile Science Laboratory capable of one Mars Year surface operational lifetime (670 Martian sols = 687 Earth days). It will be able to land and operation over wide range of latitudes, altitudes and seasons It must have controlled propulsive landing and demonstrate improved landing precision via guided entry The general science objectives are to perform science that will focus on Mars habitability, perform next generation analytical laboratory science investigations, perform remote sensing/contact investigations and carry a suite of environmental monitoring instruments. Specific scientific objectives of the MSL are: (1) Characterization of geological features, contributing to deciphering geological history and the processes that have modified rocks and regolith, including the role of water. (2) Determination of the mineralogy and chemical composition (including an inventory of elements such as C, H, N, O, P, S, etc. known to be building blocks for life) of surface and near-surface materials. (3) Determination of energy sources that could be used to sustain biological processes. (4) Characterization of organic compounds and potential biomarkers in representative regolith, rocks, and ices. (5) Determination the stable isotopic and noble gas composition of the present-day bulk atmosphere. (6) Identification potential bio-signatures (chemical, textural, isotopic) in rocks and regolith. (7) Characterization of the broad spectrum of surface radiation, including galactic cosmic radiation, solar proton events, and secondary neutrons. (8) Characterization of the local environment, including basic meteorology, the state and cycling of water and C02, and the near-surface distribution of hydrogen. Several views of the planned MSL and the rover are shown. The MSL environmental program is to: (1) Ensure the flight hardware design is capable of surviving all the environments throughout its mission life time, including ground, transportation, launch, cruise, entry decent and landing (EDL) and surface operation environments. (2) Verify environmental testing and analysis have adequately validated the flight hardware's ability to withstand all natural, self-induced, and mission-activity-induced environments. The planned tests to ascertain the capability of the MSL to perform as desired are reviewed.

spacecraft↗
NASA NTRS1996

Research activities in nuclear astrophysics and related areas

NASA/GRO grant NAG 5-2081, at the University of Chicago, has provided support for a broad program of theoretical research in nuclear astrophysics and related areas, with regard to gamma-ray and hard X-ray emission from classical nova explosions. This research emphasized the possible detection of 22Na gamma-ray line emission from nearby novae involving ONeMg white dwarfs, the detailed examination of 26Al production in novae, and the possible detection of the predicted early gamma ray emission from novae that arises from the decay of the short lived, positron emitting isotopes of CNO elements. Studies of nova related problems have consumed an increasing fraction of the Principal Investigator's research efforts over the past decade. Current research addresses problems associated with the standard model for the outbursts of the classical novae: the occurrence of thermonuclear runaways (TNR) in the accreted hydrogen rich envelopes on white dwarfs in close binary systems (see, e.g., the reviews by Truran 1982; and Shara 1989). Research in progress and planned for the next three years has three main objectives: (1) to gain an improved understanding of the early evolution of the light curves of, particularly, the fastest novae; (2) to gain an improved understanding of the relative importance of the various possible mechanisms of envelope hydrogen depletion (e.g. winds, common envelope driven mass loss, and nuclear burning) to the long term evolution of novae in outburst; and (3) to seek to provide a somewhat more definitive statement of the role of classical novae in nucleosynthesis. Our proposed 2-D studies of convection during the early phases of the TNR and our systematic attempt to incorporate an improved treatment of radiation hydrodynamics into the hydrodynamic code utilized in our calculations, are particularly relevant to the first of these objectives. Further 2-D studies of the effects of common envelope evolution are intended to provide more realistic constraints on the mass depletion mechanisms. Finally, detailed calculations of the thermonuclear history of the matter ejected in novae will be carried out for representative nova configurations involving both carbon-oxygen (CO) and oxygen-neon-magnesium (ONeMg) white dwarfs.

Source record↗
NASA NTRS2008

Volatile Analysis by Pyrolysis of Regolith (Vapor) on the Moon using Mass Spectrometry

The identification of lunar resources such as water is a fundamental component of the the NASA Vision for Space Exploration. The Lunar Prospector mission detected high concentrations of hydrogen at the lunar poles that may indicate the presence of water or other volatiles in the lunar regolith [1]. One explanation for the presence of enhanced hydrogen in permanently shadowed crater regions is long term trapping of water-ice delivered by comets, asteroids, and other meteoritic material that have bombarded the Moon over the last 4 billion years [2]. It is also possible that the hydrogen signal at the lunar poles is due to hydrogen implanted by the solar wind which is delayed from diffusing out of the regolith by the cold temperatures [3]. Previous measurements of the lunar atmosphere by the LACE experiment on Apollo 17, suggested the presence of cold trapped vola'tiles that were expelled by solar heating [4]. In situ composition and isotopic analyses of the lunar regolith will be required to establish the abundance, origin, and distribution of water-ice and other volatiles at the lunar poles. Volatile Analysis by Pyrolysis of Regolith (VAPoR) on the Moon using mass spectrometry is one technique that should be considered. The VAPoR pyrolysis-mass spectrometer (pyr-MS) instrument concept study was selected for funding in 2007 by the NASA Lunar Sortie Science Opportunities (LSSO) Program. VAPoR is a miniature version of the Sample Analysis at Mars (SAM) instrument suite currently being developed at NASA Goddard for the 2009 Mars Science Laboratory mission (Fig. 1).

Glavin, D. P.↗
NASA NTRS1989

New insights in the photochemistry of grain mantles: The identification of the 4.62 and 6.87 micron bands

The mid-IR spectral region of molecular clouds is known to show the fingerprints of molecules frozen in the icy mantles of the interstellar grains. To study the complex chemical and physical interactions on the ice mantles accreted on grains in molecular clouds numerous UV irradiation and diffusion experiments were performed. The irradiation of binary ices was studied. Using isotopic labelling on NH3/CO and NH3/O2 ices numerous compounds were identified, of which OCN(-), NO2(-), NO3(-), and NH4(+) ions reveal a new type of chemical reactions. It appeared that these compounds were formed by proton transfer reactions induced by the interaction between an acid (HNCO, HNO2, HNO3) and a base (NH3) through a hydrogen bond. This mechanism was confirmed by a study of photolyzed diluted argon mixtures. The main astrophysically relevant data from the overall study are presented. The 4.62 micron band in W33A can be reproduced with NH3/CO containing irradiated ices and was identified with OCN(-). The 6.87 micron band in W33A and other photostellar objects is reproduced with NH3/O2 containing ices and is identified with NH4(+).

Grim, Ruud↗
NASA NTRS1990

Far infrared balloon-based limb emission measurements of HO(sub x) gases in the middle atmosphere

The aim of the measurements is to obtain vertical mixing of profiles of hydrogen and halogen trace gases and to study the related processes of diurnal change, OH/HO2 ratio, and HO sub x total budget involved in stratospheric ozone. The species to be measured in the first planned 1990 flight of this new series include OH, H2O2, HO2, HOCl, HBr, HCl, HF, H2O, HDO, O3, and isotopic O3. Recent analyses have been completed for the retrieval of the OH concentration profile and the first measurement of the HBr column concentration.

Russell, James M., III↗
NASA NTRS1996

ATMOS Stratospheric Deuterated Water and Implications for Troposphere-Stratosphere Transport

The isotopic composition of stratospheric water vapor is used as a tracer for the convective history of air injected into the stratosphere. Stratospheric profiles of HDO, H 2 O,CH 3 D, and CH 4 fro the ATMOS instrument, obtained over four missions from 1985-1994, are used to determine the initial deuterium-to-hydrogen ration of water vapor entering the stratosphere. We find that the initial DeltaD of stratospheric water is - 680 ± 80 (68 percent loss of deuterium), consistent with extrapolations from previous measurements at higher altitudes.

stratospheric↗