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  • 1
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    Molecular and Elemental Dust Analyzer (MEDA) for the comet rendezvous asteroid flyby mission (1986)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Comets are some to the most primitive bodies in the solar system and therefore should contain elemental, chemical, and isotopic records of the early history of the solar system. An opportunity to perform in situ analyses of a comet nucleus exists with the Comet Rendezvous Asteroid Flyby (CRAF) mission. An integrated gas chromatograph/X-ray fluorescence instrument (MEDA), being proposed for inclusion onboard the CRAF spacecraft, will measure the molecular and elemental constituents of collected dust grains and ices. The gas chromatograph, employing helium ionization detectors and three columns designed to separate light gases, polar gases, and hydrocarbons will measure the volatile compounds of the biogenic elements thermally released from collected dust grains. The sensitivity of the GC for compounds of interest is at the picogram level. X-ray fluorescence utilized cryogenically cooled Si(Li) solid state detectors of nominal 150 eV resolution at 5.9 keV. Based on laboratory work with carbonaceous meteorites, both the GC and XRF can perform meaningful analyses with a few micrograms of collected comet dust.
    Keywords: SPACE BIOLOGY
    Type: NASA, Washington Second Symposium on Chemical Evolution and the Origin and Evolution of Life; p 54
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Heterogeneous phase reactions of Martian volatiles with putative regolith minerals (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The chemical reactivity of several minerals thought to be present in Martian fines is tested with respect to gases known in the Martian atmosphere. In these experiments, liquid water is excluded from the system, environmental temperatures are maintained below 0 C, and the solar illumination spectrum is stimulated in the visible and UV using a xenon arc lamp. Reactions are detected by mass spectrometric analysis of the gas phase over solid samples. No reactions were detected for Mars nominal gas over sulfates, nitrates, chloride, nontronite clay, or magnetite. Oxidation was not observed for basaltic glass, nontronite, and magnetite. However, experiments incorporating SO2 gas an expected product of volcanism and intrusive volatile release - gave positive results. Displacement of CO2 by SO2 occurred in all four carbonates tested. These reactions are catalyzed by irradiation with the solar simulator. A calcium nitrate hydrate released NO2 in the presence of SO2. These results have implications for the cycling of atmospheric CO2, H2O, and N2 through the regolith.
    Keywords: SPACE BIOLOGY
    Type: Journal of Molecular Evolution; 14; Dec. 197
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Solar-driven chemical energy source for a Martian biota (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Microorganisms deep in the Martian soil could derive energy indirectly from the sun via chemical reactions involving atmospheric photolysis products of the solar ultraviolet flux. The Viking discovery of a chemically uniform regolith which, though poor in organics, is rich in sulfur-containing compounds suggests reaction sequences in which sulfur is recycled through reduced and oxidized states by biologically catalyzed reactions with photochemically-produced atmospheric constituents. One candidate reaction, reduction of soil sulfate minerals by molecular hydrogen, is already exploited on earth by bacteria of the ubiquitous and tenacious Desulfovibrio genus.
    Keywords: SPACE BIOLOGY
    Type: Origins of Life; 9; July 197
    Format: text
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