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  • 1
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    Measurements of physical properties of model Titan atmospheres (1986)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: One aspect of the study of Titan's atmosphere is the elucidation of the chemical and physical nature of the aerosols. In order to facilitate this, a program to produce laboratory synthesized model materials for Titan's aerosol and to study their chemical and physical properties is now in progress. Various processes, including electric discharge, photolysis by ultraviolet light, and irradiation by energetic particles, will be used to produce the materials. A first set of experiments where a nominal Titan mixture (97%N2, 3% CH4, 0.2% H2) was subjected to pulsed high temperature shocks yielded a reddish brown waxy solid. This material was subjected to pyrolysis/gas chromatography, a technique that has been proposed as a method for analysis of the Titan aerosols. Preliminary results show the material to consist of simple hydrocarbons but little else, at least up to temperatures of 600 C. Since the material was colored, compounds other than those mentioned above must be present.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington Second Symposium on Chemical Evolution and the Origin and Evolution of Life; p 50
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  • 2
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    Processing of refractory meteorite inclusions (CAIs) in parent-body atmospheres (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ca-Al-rich inclusions (CAIs) in refractory meteorites are shown to have been subject to partial melting during a suitably high gas density/small scale height regime arising during gasdynamic deceleration in a temporary atmosphere around an accreting parent body. The presence of dust in such an atmosphere would have increased the pressure gradient with height, lowering the boiloff rate, and permitting dust particles to become trapped in the partially melted material. CAIs may therefore be studied as probes of a primitive atmosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 84; 254-260
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  • 3
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    Carbonaceous chondrites. II - Carbonaceous chondrite phyllosilicates and light element geochemistry as indicators of parent body processes and surface conditions (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Petrographic analyses of CM matrices characterized four phyllosilicates in Murray and Murchison meteorites and Fe- and Mg-serpentines in Nogoya. All phyllosilicates and bulk matrices show enrichment of K relative to Na when compared with bulk meteorites; the loss of Na and some Cl, and the addition of H2O, CO2, and water-soluble organics during alteration indicates a partially open system. Synthesis of soluble organic materials may have occurred in CM matrices before aqueous alteration of the precursive phases. Nogoya was 95% altered and has a bulk C content of 5.2%, higher than any meteorite; also, it has the lowest measured C-13/C-12 ratio of any carbonaceous chondrite except for Karoonda.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Oct. 198
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  • 4
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    Noble-gas-rich separates from the Allende meteorite (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Predominantly carbonaceous HF/HCl-resistant residues from the Allende meteorite are studied. Samples are characterized by SEM/EDXA, X-ray diffraction, INAA, C, S, H, N, and noble gas analyses. Isotopic data for carbon show variations no greater than 5%, while isotopic data from noble gases confirm previously established systematics. Noble gas abundances correlate with those of C and N, and concomitant partial loss of C and normal trapped gas occur during treatments with oxidizing acids. HF/HCl demineralization of bulk meteorite results in similar fractional losses of C and trapped noble gases, which leads to the conclusion that various macromolecular carbonaceous substances serve as the main host phase for normal trapped noble gases and anomalous gases in acid-resistant residues, and as the carrier of the major part of trapped noble gases lost during HF/HCl demineralization. Limits on the possible abundances of dense mineralic host phases in the residues are obtained, and considerations of the nucleogenetic origin for CCF-XE indicate that carbonaceous host phases and various forms of organic matter in carbonaceous meteorites may have a presolar origin.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 45; Oct. 198
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  • 5
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    Survival of interstellar matter in meteorities - Evidence from carbonaceous material (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An interstellar origin has been attributed to certain organic and apparently elemental forms of C which occurs in carbonaceous meteorites. Evidence for such an origin comes from anomalous isotopic composition either of the C itself or of elements, such as N, H, or the noble gasses, which are combined with or trapped within the carbonaceous material. Suggested sources for these anomalous compositions include atmospheres of red giant stars, novae and super-novae, and interstellar molecular clouds.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 6
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    Colloidally separated samples from Allende residues - Noble gases, carbon and an ESCA-study (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are presented which strengthen the hypothesis of heterogeneity among the carbon- and nitrogen-bearing phases of the Allende meteorite. These data also highlight the possibility of performing physical separations yielding samples in which some of the noble gas- and carbon-bearing phases are extraordinarily predominant over others. The conclusion, based on mass and isotope balance arguments, that a significant portion of the carbonaceous matter in Allende is likely to be gas-poor or gas-free need not weaken the case for carbonaceous carriers for the major noble gas components. The concept that acid-soluble carbonaceous phases contain a multiplicity of components, each of which may have formed under a multiplicity of different physical-chemical conditions, is reemphasized by the results of the present study.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 48; 267-280
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  • 7
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    Chemical and spectroscopic characterization of a suite of Mars soil analogs (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: The National Aeronautics and Space Administration has begun preparations for the flight of the Mars Observer Mission in the early 1990s. An advanced ground-based study is being conducted on a usefully limited suite of Mars Soil Analog Materials (MarSAM) intended to simulate the aeolian material covering the surface of Mars. A series of variably proportioned iron/calcium smectite clays were prepared from a typical montmorillonite clay using the Banin method. The effect of increasing iron on a diverse set of chemical and spectroscopic properties of the suite of clays is discussed. In order to chemically characterize the MarSAM and compare them with the Martian soil studied by Viking, the clays were analyzed for their major and minor elemental compositions by X-ray fluorescence and ion-coupled plasma techniques. It was concluded that the surface iron has a complex and hitherto uninvestigated impact on the catalytic and spectroscopic properties of clays and on the ability of these material to store energy.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., MEVTV Workshop on Nature and Composition of Surface Units on Mars; p 46-48
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  • 8
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    Organic chemistry on Titan (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Observations of nonequilibrium phenomena on the Saturn satellite Titan indicate the occurrence of organic chemical evolution. Greenhouse and thermal inversion models of Titan's atmosphere provide environmental constraints within which various pathways for organic chemical synthesis are assessed. Experimental results and theoretical modeling studies suggest that the organic chemistry of the satellite may be dominated by two atmospheric processes: energetic-particle bombardment and photochemistry. Reactions initiated in various levels of the atmosphere by cosmic ray, Saturn wind, and solar wind particle bombardment of a CH4 - N2 atmospheric mixture can account for the C2-hydrocarbons, the UV-visible-absorbing stratospheric haze, and the reddish color of the satellite. Photochemical reactions of CH4 can also account for the presence of C2-hydrocarbons. In the lower Titan atmosphere, photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. Hot H-atom reactions initiated by photo-dissociation of NH3 can couple the chemical reactions of NH3 and CH4 and produce organic matter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 161-184
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  • 9
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    Comets: Cosmic connections with carbonaceous meteorites, interstellar molecules and the origin of life (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The ions, radicals, and molecules observed in comets may be derived intact or by partial decomposition from parent compounds of the sort found either in the interstellar medium or in carbonaceous meteorites. The early loss of highly reducing primitive atmosphere and its replacement by a secondary atmosphere dominated by H2O, CO2, and N2, as depicted in current models of the earth's evolution, pose a dilemma for the origin of life: the synthesis of organic compounds necessary for life from components of the secondary atmosphere appears to be difficult, and plausible mechanisms have not been evaluated. Both comets and carbonaceous meteorites are implicated as sources for the earth's atmophilic and organogenic elements. A mass balance argument involving the estimated ratios of hydrogen to carbon in carbonaceous meteorites, comets, and the crust and upper mantle suggests that comets supplied the earth with a large fraction of its volatiles. The probability that comets contributed significantly to the earth's volatile inventory suggests a chemical evolutionary link between comets, prebiotic organic synthesis, and the origin of life.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Goddard Space Flight Center Space Missions to Comets; p 59-111
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  • 10
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    Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 240-241
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