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  • Lunar and Planetary Science and Exploration  (6)
  • *Atmosphere  (1)
  • Carbon Dioxide/analysis/chemistry  (1)
  • 1
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2005-04-09
    Description: We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders of magnitude than previously thought. The balance between slow hydrogen escape and volcanic outgassing could have maintained a hydrogen mixing ratio of more than 30%. The production of prebiotic organic compounds in such an atmosphere would have been more efficient than either exogenous delivery or synthesis in hydrothermal systems. The organic soup in the oceans and ponds on early Earth would have been a more favorable place for the origin of life than previously thought.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tian, Feng -- Toon, Owen B -- Pavlov, Alexander A -- De Sterck, H -- New York, N.Y. -- Science. 2005 May 13;308(5724):1014-7. Epub 2005 Apr 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astrophysical and Planetary Science Department, University of Colorado, Boulder, CO 80309, USA. tian@colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15817816" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acids/chemistry ; *Atmosphere ; Carbon Dioxide/chemistry ; Diffusion ; *Earth (Planet) ; Electricity ; Evolution, Chemical ; Evolution, Planetary ; *Hydrogen/chemistry ; Models, Theoretical ; Oceans and Seas ; Organic Chemicals/*chemistry ; Origin of Life ; Photochemistry ; Seawater ; Temperature ; Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-12-11
    Description: H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ming, D W -- Archer, P D Jr -- Glavin, D P -- Eigenbrode, J L -- Franz, H B -- Sutter, B -- Brunner, A E -- Stern, J C -- Freissinet, C -- McAdam, A C -- Mahaffy, P R -- Cabane, M -- Coll, P -- Campbell, J L -- Atreya, S K -- Niles, P B -- Bell, J F 3rd -- Bish, D L -- Brinckerhoff, W B -- Buch, A -- Conrad, P G -- Des Marais, D J -- Ehlmann, B L -- Fairen, A G -- Farley, K -- Flesch, G J -- Francois, P -- Gellert, R -- Grant, J A -- Grotzinger, J P -- Gupta, S -- Herkenhoff, K E -- Hurowitz, J A -- Leshin, L A -- Lewis, K W -- McLennan, S M -- Miller, K E -- Moersch, J -- Morris, R V -- Navarro-Gonzalez, R -- Pavlov, A A -- Perrett, G M -- Pradler, I -- Squyres, S W -- Summons, R E -- Steele, A -- Stolper, E M -- Sumner, D Y -- Szopa, C -- Teinturier, S -- Trainer, M G -- Treiman, A H -- Vaniman, D T -- Vasavada, A R -- Webster, C R -- Wray, J J -- Yingst, R A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1245267. doi: 10.1126/science.1245267. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324276" target="_blank"〉PubMed〈/a〉
    Keywords: Bays ; Carbon Dioxide/analysis/chemistry ; *Exobiology ; Extraterrestrial Environment/*chemistry ; Geologic Sediments/analysis/chemistry ; Hydrocarbons, Chlorinated/*analysis ; *Mars ; Oxygen/analysis/chemistry ; Sulfides/analysis/chemistry ; Volatile Organic Compounds/*analysis ; Water/analysis/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2011-08-24
    Description: Determining the source of Earth's oceans is a longstanding problem in planetary science. Possible sources of water include water ice or water of hydration of silicate minerals in the original material from which the bulk Earth accreted and water brought in by late-arriving planetesimals during the heavy bombardment period (4.5-3.8 Gyr ago) [Chyba, 1989, 1991]. Comets are an attractive source of water because their origin in the outer solar system is consistent with the long timescale for heavy bombardment. However, the high deuterium/hydrogen (D/H) ratio of the three comets that have been studied, Halley, Hyakutake, and Hale-Bopp, indicates that Earth must have had a source with a low-D/H ratio as well. Here we suggest that solar wind-implanted hydrogen on interplanetary dust particles (IDPs) provided the necessary low-D/H component of Earth's water inventory.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Journal of geophysical research (ISSN 0148-0227); Volume 104; E12; 30725-8
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  • 4
    Publication Date: 2019-07-13
    Description: The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient Martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550 degrees Centigrade and 950 degrees Centigrade from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (plus or minus 0.2) times the ratio in standard mean ocean water. The D/H ratio in this approximately 3-billion-year-old mudstone, which is half that of the present Martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN32645 , Science; 347; 6220; 412-414
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  • 5
    Publication Date: 2019-07-13
    Description: The anomalous abundances of sulfur isotopes in ancient sediments provide the strongest evidence for an anoxic atmosphere prior to 2.45 Ga, but the mechanism for producing this 'mass-independent' fractionation pattern remains in question. The prevailing hypothesis has been that it is created by differences in the UV photolysis rates of different SO2 isotopologues. We investigate here a recently proposed additional source of fractionation during gas-phase formation of elemental sulfur (S4 and S8). Because two minor S isotopes rarely occur in the same chain, the longer S4 and S8 chains should be strongly, and roughly equally, depleted in all minor isotopes. This gives rise to negative (sup 33) S values and positive (sub 36) S values in elemental sulfur-just the opposite of (and much larger than) what is predicted from SO2 photolysis itself. Back-reactions during chain formation, specifically photolysis of S2 and S3, pass sulfur having the opposite fractionation back to atomic S, and thence to other sulfur species, causing H2S, SO2, sulfate, and short-chain elemental sulfur to have positive (sup 33) S and negative (sup 36) S. Positive (sup 33) S values in elemental sulfur produced in laboratory SO2 photolysis experiments could be caused by the initial fractionation during photolysis, combined with rapid condensation of short-chain sulfur species on the walls of the reaction chamber, along with a scarcity of back-reactions. The simulated fractionations produced by the chain formation mechanism do not directly match fractionations from the rock record. The mismatch might be explained if the isotopic signals leaving the atmosphere were significantly modulated by life, by uncertainties in the rates of reactions of both major and minor isotopic sulfur species, or by the relatively large potential range of atmospheric parameters. Further work is needed to better constrain these uncertainties, but this novel mechanism suggests new avenues to explore in our search for a explanation for the S-MIF record.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN58042 , Earth and Planetary Science Letters (ISSN 0012-821X); 496; 238-247
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  • 6
    Publication Date: 2019-07-13
    Description: Variability in the sulfur isotopic composition in sediments can reflect atmospheric, geologic and biological processes. Evidence for ancient fluvio-lacustrine environments at Gale crater on Mars and a lack of efficient crustal recycling mechanisms on the planet suggests a surface environment that was once warm enough to allow the presence of liquid water, at least for discrete periods of time, and implies a greenhouse effect that may have been influenced by sulfur-bearing volcanic gases. Here we report in situ analyses of the sulfur isotopic compositions of SO2 volatilized from ten sediment samples acquired by NASA's Curiosity rover along a 13 km traverse of Gale crater. We find large variations in sulfur isotopic composition that exceed those measured for Martian meteorites and show both depletion and enrichment in S-34. Measured values of S-34 range from -47 +/- 14% to 28 +/- 7%, similar to the range typical of terrestrial environments. Although limited geochronological constraints on the stratigraphy traversed by Curiosity are available, we propose that the observed sulfur isotopic signatures at Gale crater can be explained by equilibrium fractionation between sulfate and sulfide in an impact-driven hydrothermal system and atmospheric processing of sulfur-bearing gases during transient warm periods.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN53781 , Nature Geoscience (ISSN 1752-0894) (e-ISSN 1752-0908); 10; 9; 658–662
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  • 7
    Publication Date: 2019-07-13
    Description: C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is 〈10 ppm, then the "light," potentially "biological" C-13/C-12 ratio would be effectively erased by cosmic rays over 3.5 billion years of exposure. We found that for the rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN21677 , Journal of Geophysical Research-Planets (ISSN 2169-9097); 119; 6; 1390-1402
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  • 8
    Publication Date: 2019-07-13
    Description: Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars. There have been several different measurements by landers and Earth based systems performed in recent years that have not been in agreement. In particular, measurements of the isotopic composition of martian atmospheric CO2 by the Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) are in stark disagreement. This work attempts to use measurements of mass 45 and mass 46 of martian atmospheric CO2 by the SAM and TEGA instruments to search for agreement as a first step towards reaching a consensus measurement that might be supported by data from both instruments.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-30541 , Lunar and Planetary Science Conference; Mar 17, 2014 - Mar 21, 2014; The Woodlands, TX; United States
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