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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

A high resolution liquid xenon imaging telescope for 0.3-10 MeV gamma-ray astrophysics: Construction and initial balloon flights

An instrument is described which will provide a direct image of gamma-ray line or continuum sources in the energy range 300 keV to 10 MeV. The use of this instrument to study the celestial distribution of the (exp 26)Al isotope by observing the 1.809 MeV deexcitation gamma-ray line is illustrated. The source location accuracy is 2' or better. The imaging telescope is a liquid xenon time projection chamber coupled with a coded aperture mask (LXe-CAT). This instrument will confirm and extend the COMPTEL observations from the Compton Gamma-Ray Observatory (CGRO) with an improved capability for identifying the actual Galactic source or sources of (exp 26)Al, which are currently not known with certainty. sources currently under consideration include red giants on the asymptotic giant branch (AGB), novae, Type 1b or Type 2 supernovae, Wolf-Rayet stars and cosmic-rays interacting in molecular clouds. The instrument could also identify a local source of the celestial 1.809 MeV gamma-ray line, such as a recent nearby supernova.

Aprile, Elena↗
NASA NTRS1988

Circumstellar material in meteorites - Noble gases, carbon and nitrogen

In addition to preserving a record of isotopically distinct reservoirs in the early solar system, some primitive meteorites contain discrete grains of presolar origin. Such grains are distinguished by the isotopically anomalous noble-gas components they contain. One such component consists of monoisotopic Ne-22, produced by decay of radioactive Na-22 with a 2.6 yr half-life. Two xenon components have also been identified: one synthesized apparently in a supernova, the other probably in a red giant star. Most of the grains that carry these noble-gas components are carbonaceous and contain isotopically anomalous C, N, or both. They include diamond and silicon carbide. Two unidentified carriers of isotopically anomalous nitrogen, unaccompanied by noble gases, occur in the brecciated stony iron meteorite, Bencubbin.

Anders, Edward↗
NASA NTRS1976

Barites - Anomalous xenon from spallation and neutron-induced reactions

Sedimentary barites from South Africa and Western Australia (about 3 billion years old) contain spallogenic Xe isotopes produced by reactions of Ba with nuclear-active particles in cosmic rays. 'Surface residence time' of these samples was calculated from the observed concentrations of spallogenic Xe-126. Comparison of spallogenic ratios of Xe-131/Xe-126 in the two samples provides evidence for the reaction Ba-130(n, gamma) yields Xe-131, which is characterized by a large number of resonances for neutron absorption in the epithermal region. This observation lends additional support to the conclusions already reached regarding the origin of anomalous Xe-131 in lunar samples.

Srinivasan, B.↗
NASA NTRS1979

Xenon from intermediate zones of supernovae

The paper examines the photodisintegration and neutron capture in massive stars which show that the bulk of the p-isotopes of Xe is formed during the gamma-process of Woosley and Howard (1978) by stripping of the Xe + Be seeds. The environments in which the chondrites can be formed were determined by the neutron-capture calculations; they show that the Xe-124-rich gas must be associated at the sources with anomalously large overabundances of Nd-142, Sm-144, and possibly Ba-130, and with anomalously small overabundances of the p-isotopes of Se, Kr, Sr, and Mo.

Heymann, D.↗
NASA NTRS1989

Origin of heavy xenon in meteoritic diamonds

The neutrino burst from the collapsed core in Type II supernovae liberates free neutrons by nu, nu-prime(n) reactions which drive isotopic abundances several mass steps heavier. The neutron fluence in the He shell, abetted by another burst 10 s later from alpha, n reactions, is about right for rendering Xe-136, the most abundant Xe isotope. The Xe isotopic composition is a good match to Xe-H, the unshielded neutron-rich Xe component abundant in carbonaceous meteorites. The He shell is implicated because it is the only C-rich shell in massive stars that can be expected to condense solid carbon thermally, a requirement for locating the Xe-H in meteoritic diamonds, which are so common as to require an abundant Galactic source of unoxidized carbon.

Clayton, Donald D.↗
NASA NTRS1988

Iodine-xenon dating

The most readily and widely studied of the extinct radionuclides in meteorites is I-129, and there is an extensive data base for meteorite chronology based on this isotope, but also significant uncertainty about how to interpret many of the data. If the data are interpreted as a straightforward chronology, a time span is inferred for most meteorite classes that appears too long for the events being dated to have taken place in the nebula.

Swindle, T. D.↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 5

Topics discussed include: Automation Recognition oF Crater-Like Structures in Terrestrial and Plantary Images; Condensation from Cluster-IDP Enriched Vapor Inside the Snow Line: Implications for Mercury, Asteroids, and Enstatite Chondrites; Tomographic Location of Potential Melt-Bearing Phenocrysts in Lunar Glass Spherules; Source and Evolution of Vapor Due to Impacts into Layered Carbonates and Silicates; Noble Gases and I-Xe Ages of the Zag Meteorite; The MArs Hand Lens Imager (MAHLI) for the 209 Mars Science Laboratory; The Sedimentary Rocks of Meridiani Planum, in Context; Three-System Isotopic of Lunar Norite 78238: Rb-Sr Results; Constraints on the Role of Curium-247 as a Source of Fission Xenon in the Early Solar System; New Features in the ADS Abstract Service; Cassini RADAR's First Look at Titan; Volcanism and Volatile Recycling on Venus from Lithospheric Delamination; The Fate of Water in the Martian Magma Ocean and the Formation of an Early Atmosphere; Mars Odyssey Neutron Spectrometer Water-Equivalent Hydrogen: Comparison with Glacial; Landforms on Tharsis; Using Models of Permanent Shadow to Constrain Lunar Polar Water Ice Abundances; Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method; Petrological and Geochemical Consideration on the Tuserkanite Meteorite; and Mineralogy of Asteroids from Observations with the Spitzer Space Telescope.

Source record↗
NASA NTRS2003

MRI of the lung gas-space at very low-field using hyperpolarized noble gases

In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static magnetic field (B(0)), making very low-field (VLF) MRI possible; indeed, it is possible to contemplate portable MRI using light-weight solenoids or permanent magnets. This article reports the first in vivo VLF MR images of the lungs in humans and in rats, obtained at a field of only 15 millitesla (150 Gauss).

NASA Discipline Life Sciences Technologies↗
NASA NTRS1992

Trapped xenon in ordinary chondrites

A trapped component of heavy noble gates representing a distinct solar system (presumably asteroid belt) reservoir is known to be concentrated in carbonaceous carriers of chondritic meteorites. The isotopic signature of trapped Xe in separates of the H4 chondrite Forest Vale (FV) was determined by combusting its carrier phases at 600 C in oxygen, discriminating against in situ produced nucleogenic components which are released above 600 C. The isotopic abundances of FV combustion-Xe (FVC-Xe) are compared to signatures of bulk trapped Xe in chondritic meteorites. We conclude that FVC-Xe represents the predominant trapped component in ordinary chondrites (OC) for which we adopt the term OC-Xe. Its isotopic signature differs from Xe in ureilites, in 'average carbonaceous chondrites', in earth's atmosphere, and in the solar wind. Additional minor Xe components were identified in type 3 chondrites and in the metal phase of chondrites. We discuss relationships among solar system Xe reservoirs and show that OC-Xe signature is consistent with a mixture of HL-Xe with slightly mass fractionated solar-type Xe.

Lavielle, Bernard↗
NASA NTRS1974

Problem of nature of inert gases in lunar surface material

The origin of isotopes of inert gases in lunar surface material was investigated from the standpoint of the isotopic two-component status of inert gases in the solar system. Helium and neon represent the solar wind component, while krypton and xenon are planetary gases. Type A gases are trapped by the material of the regolith in the early stages of the existence of the solar system and were brought to the lunar surface together with dust. The material of the regolith therefore cannot be considered as the product of the erosion of the crystalline rocks of the moon and in this sense are extralunar. The regolith material containing type A gases must be identified with the high temperature minerals of the carbonaceous chondrites.

Levskiy, L. K.↗
NASA NTRS1973

Krypton and xenon in lunar fines

Data from grain-size separates, stepwise-heated fractions, and bulk analyses of 20 samples of fines and breccias from five lunar sites are used to define three-isotope and ordinate intercept correlations in an attempt to resolve the lunar heavy rare gas system in a statistically valid approach. Tables of concentrations and isotope compositions are given.

Basford, J. R.↗
NASA NTRS2004

Chondrites and the Protoplanetary Disk, Part 3

Contents include the following: Ca-, Al-Rich Inclusions and Ameoboid Olivine Aggregates: What We Know and Don t Know About Their Origin. Aluminium-26 and Oxygen Isotopic Distributions of Ca-Al-rich Inclusions from Acfer 214 CH Chondrite. The Trapping Efficiency of Helium in Fullerene and Its Implicatiion to the Planetary Science. Constraints on the Origin of Chondritic Components from Oxygen Isotopic Compositions. Role of Planetary Impacts in Thermal Processing of Chondrite Materials. Formation of the Melilite Mantle of the Type B1 CAIs: Flash Heating or Transport? The Iodine-Xenon System in Outer and Inner Portions of Chondrules from the Unnamed Antarctic LL3 Chondrite. Nucleosynthesis of Short-lived Radioactivities in Massive Stars. The Two-Fluid Analysis of the Kelvin-Helmholtz Instability in the Dust Layer of a Protoplanetary Disk: A Possible Path to the Planetesimal Formation Through the Gravitational Instability. Shock-Wave Heating Model for Chonodrule Formation: Heating Rate and Cooling Rate Constraints. Glycine Amide Hydrolysis with Water and OH Radical: A Comparative DFT Study. Micron-sized Sample Preparation for AFM and SEM. AFM, FE-SEM and Optical Imaging of a Shocked L/LL Chondrite: Implications for Martensite Formation and Wave Propagation. Infrared Spectroscopy of Chondrites and Their Components: A Link Between Meteoritics and Astronomy? Mid-Infrared Spectroscopy of CAI and Their Mineral Components. The Origin of Iron Isotope Fractionation in Chondrules, CAIs and Matrix from Allende (CV3) and Chainpur (LL3) Chondrites. Protoplanetary Disk Evolution: Early Results from Spitzer. Kinetics of Evaporation-Condensation in a Melt-Solid System and Its Role on the Chemical Composition and Evolution of Chondrules. Oxygen Isotope Exchange Recorded Within Anorthite Single Crystal in Vigarano CAI: Evidence for Remelting by High Temperature Process in the Solar Nebula. Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. Organic Globules with Anormalous Nitrogen Isotopic Compositions in the Tagish Lake Meteorite: Products of Primitive Organic Reactions. Yet Another Chondrule Formation Scenario. CAIs are Not Supernova Condensates. Microcrystals and Amorphous Material in Comets and Primitive Meteorites: Keys to Understanding Processes in the Early Solar System. A Nearby Supernova Injected Short-lived Radionuclides into Our Protoplanetary Disk. REE+Y Systematics in CC and UOC Chondrules. Meteoritic Constraints on Temperatures, Pressures, Cooling Rates, Chemical Compositions, and Modes of Condensation in the Solar Nebula. The I-Xe Record of Long Equilibration in Chondrules from the Unnamed Antarctic Meteorite L3/LL3. Early Stellar Evolution.

Source record↗
NASA NTRS1985

A review of noble gas geochemistry in relation to early Earth history

One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

Kurz, M. D.↗
NASA NTRS2007

Huygens GCMS Results from Titan

The Huygens Probe executed a successful entry, descent and impact on the Saturnian moon of Titan on January 14, 2005. The Gas Chromatograph Mass Spectrometer (GCMS) instrument conducted isotopic and compositional measurements throughout the two and one half hour descent from 146 km altitude, and on the surface for 69 minutes until loss of signal from the orbiting Cassini spacecraft. The GCMS incorporated a quadrupole mass filter with a secondary electron multiplier detection system. The gas sampling system provided continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. Data products from the GCMS included altitude profiles of the major atmospheric constituents dinitrogen (N2) and methane (CH4), isotope ratios of 14N/15N, 12C/13C, and D/H, mole fractions of radiogenic argon (40Ar) and primordial argon (36Ar), and upper limits on the mole fractions of neon, krypton and xenon, which were found to be absent. Surface measurements confirmed the presence of ethane (C2H6) and cyanogen (C2N2). Later data products expanded atmospheric profiles to include the surface response of C2N2. C2H6, acetylene (C2H2), and carbon dioxide (CO2). More recent results include the profiles of benzene (C6H6) and molecular hydrogen (H2). The GCMS data are being further analyzed to obtain higher precision results and to identify other trace species ion the atmosphere and evaporating from the surface.

Niemann, Hasso B.↗
NASA NTRS1988

Iodine-xenon studies of Allende inclusions - Eggs and the Pink Angel

The I-Xe systems of six Allende inclusions (five Eggs and the Pink Angel) appear to have been altered by nonnebular secondary processes. Evidence for this includes temperature-ordered variations in the initial I isotopic composition within several objects (with older apparent I-Xe ages associated with higher extraction temperatures) and the absence of primitive I-Xe ages. The span of apparent ages seen in Allende objects (10 Myr or more) is probably too long to reflect any nebular process, so at least some alteration probably occurred ont the parent body. The range in initial (Pu-244)/(U-238) ratios for the Eggs (0.003-0.014) includes the current best estimates of the bulk solar system value (0.004-0.007). For Egg 3, the Pu/U ratio varies by a factor of two between extractions, probably the result of fractionation of Pu from U among different phases.

Swindle, T. D.↗
NASA NTRS1976

The atmosphere of Mars near the surface - Isotope ratios and upper limits on noble gases

Several analyses of the Martian atmosphere have been carried out with the mass spectrometer in the molecular-analysis experiment. The ratios of abundant isotopes of carbon and oxygen are within 10 per cent of terrestrial values, whereas nitrogen-15 is considerably enriched on Mars. Argon-38 has been detected, and new limits on abundances of krypton and xenon have been set. The limit on krypton is sufficiently low to suggest that the inventories of volatile substances on Mars and on earth may be distinctly different.

Biemann, K.↗
NASA NTRS2008

Huygens Gas Chromatograph Mass Spectrometer Results from Titan

The Huygens Probe executed a successful entry, descent and impact on the Saturnian moon of Titan on January 14, 2005. Gas Chromatograph Mass Spectrometer (GCMS) instrument conducted isotopic and compositional measurements throughout the two and one half hour descent from 146 km altitude, and on the surface for 69 minutes until loss of signal from the orbiting Cassini spacecraft. The GCMS incorporated a quadrupole mass filter with a secondary electron multiplier detection system. The gas sampling system provided continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. Data products from the GCMS included altitude profiles of the major atmospheric constituents dinitrogen (N2) and methane (CH4), isotope ratios of N-14/N-15, C-12/C-13, and D/H, mole fractions of radiogenic argon (Ar-40)and primordial argon Ar-36), and upper limits on the mole fractions of neon, krypton and xenon, which were found to be below the detection limit of the instrument or absent. Surface measurements confirmed the presence of ethane (C2H6) and cyanogen (C2N2). Later data products include the instrument response to surface outgassing of C2N2, C2H6, acetylene (C2H2),and carbon dioxide (CO2). More recent results include the detection of benzene (C6H6) and height profiles of molecular hydrogen (H2). Numerous other trace species evaporating from the surface were also identified using the GCMS data.

Niemann, Hasso↗
NASA NTRS1980

Xenon, osmium, and lead formed in O-shells and C-shells of massive stars

In this paper it is shown that the explosive products from O-shells of massive stars which contain Xe-124 with large overproduction factors do not contain any of the naturally occurring isotopes of Os and Pb. Further, it is shown that the explosive products from C-shells (explosive carbon burning) do contain Os and Pb along with Xe which is strongly enriched in r-Xe of anomalous isotopic composition. The composition of Os in this matter is probably s-like rather than r-like. Pb in this matter is enriched in Pb-208. The results and arguments of this paper have implications for studies of isotopic compositions of Xe, Os, and Pb in residues of the Allende and other carbonaceous chondrites.

Heymann, D.↗