[ { "id": "authors:6d6dk-78554", "collection": "authors", "collection_id": "6d6dk-78554", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180925-073151228", "type": "article", "title": "Methane on Mars and Habitability: Challenges and Responses", "author": [ { "family_name": "Yung", "given_name": "Yuk L.", "orcid": "0000-0002-4263-2562", "clpid": "Yung-Y-L" }, { "family_name": "Chen", "given_name": "Pin", "clpid": "Chen-Pin" }, { "family_name": "Nealson", "given_name": "Kenneth", "orcid": "0000-0001-5189-3732", "clpid": "Nealson-K-H" }, { "family_name": "Atreya", "given_name": "Sushil", "orcid": "0000-0002-1972-1815", "clpid": "Atreya-S-K" }, { "family_name": "Beckett", "given_name": "Patrick", "clpid": "Beckett-P" }, { "family_name": "Blank", "given_name": "Jennifer G.", "clpid": "Blank-J-G" }, { "family_name": "Ehlmann", "given_name": "Bethany", "orcid": "0000-0002-2745-3240", "clpid": "Ehlmann-B-L" }, { "family_name": "Eiler", "given_name": "John", "clpid": "Eiler-J-M" }, { "family_name": "Etiope", "given_name": "Giuseppe", "clpid": "Etiope-G" }, { "family_name": "Ferry", "given_name": "James G.", "clpid": "Ferry-J-G" }, { "family_name": "Forget", "given_name": "Fran\u00e7ois", "clpid": "Forget-F" }, { "family_name": "Gao", "given_name": "Peter", "orcid": "0000-0002-8518-9601", "clpid": "Gao-Peter" }, { "family_name": "Hu", "given_name": "Renyu", "orcid": "0000-0003-2215-8485", "clpid": "Hu-Renyu" }, { "family_name": "Kleinb\u00f6hl", "given_name": "Armin", "clpid": "Kleinb\u00f6hl-A" }, { "family_name": "Klusman", "given_name": "Ronald", "clpid": "Klusman-" }, { "family_name": "Lef\u00e8vre", "given_name": "Franck", "clpid": "Lef\u00e8vre-F" }, { "family_name": "Miller", "given_name": "Charles", "orcid": "0000-0002-9380-4838", "clpid": "Miller-C-E" }, { "family_name": "Mischna", "given_name": "Michael", "orcid": "0000-0002-8022-5319", "clpid": "Mischna-M-A" }, { "family_name": "Mumma", "given_name": "Michael", "clpid": "Mumma-M-J" }, { "family_name": "Newman", "given_name": "Sally", "orcid": "0000-0003-0710-995X", "clpid": "Newman-S" }, { "family_name": "Oehler", "given_name": "Dorothy", "clpid": "Oehler-D-Z" }, { "family_name": "Okumura", "given_name": "Mitchio", "orcid": "0000-0001-6874-1137", "clpid": "Okumura-M" }, { "family_name": "Oremland", "given_name": "Ronald", "clpid": "Oremland-R-S" }, { "family_name": "Orphan", "given_name": "Victoria", "orcid": "0000-0002-5374-6178", "clpid": "Orphan-V-J" }, { "family_name": "Popa", "given_name": "Radu", "clpid": "Popa-R" }, { "family_name": "Russell", "given_name": "Michael", "clpid": "Russell-M-J" }, { "family_name": "Shen", "given_name": "Linhan", "orcid": "0000-0003-3871-655X", "clpid": "Shen-Linhan" }, { "family_name": "Sherwood Lollar", "given_name": "Barbara", "clpid": "Sherwood-Lollar-B" }, { "family_name": "Staehle", "given_name": "Robert", "clpid": "Staehle-R-L" }, { "family_name": "Stamenkovi\u0107", "given_name": "Vlada", "orcid": "0000-0003-2416-3683", "clpid": "Stamenkovi\u0107-V" }, { "family_name": "Stolper", "given_name": "Daniel", "orcid": "0000-0003-3299-3177", "clpid": "Stolper-D-A" }, { "family_name": "Templeton", "given_name": "Alexis", "clpid": "Templeton-A" }, { "family_name": "Vandaele", "given_name": "Ann C.", "clpid": "Vandaele-A-C" }, { "family_name": "Viscardy", "given_name": "S\u00e9bastien", "clpid": "Viscardy-S" }, { "family_name": "Webster", "given_name": "Christopher R.", "clpid": "Webster-C-R" }, { "family_name": "Wennberg", "given_name": "Paul O.", "orcid": "0000-0002-6126-3854", "clpid": "Wennberg-P-O" }, { "family_name": "Wong", "given_name": "Michael L.", "clpid": "Wong-Michael-L" }, { "family_name": "Worden", "given_name": "John", "orcid": "0000-0003-0257-9549", "clpid": "Worden-J-R" } ], "abstract": "Recent measurements of methane (CH_4) by the Mars Science Laboratory (MSL) now confront us with robust data that demand interpretation. Thus far, the MSL data have revealed a baseline level of CH_4 (\u223c0.4 parts per billion by volume [ppbv]), with seasonal variations, as well as greatly enhanced spikes of CH_4 with peak abundances of \u223c7\u2009ppbv. What do these CH_4 revelations with drastically different abundances and temporal signatures represent in terms of interior geochemical processes, or is martian CH_4 a biosignature? Discerning how CH_4 generation occurs on Mars may shed light on the potential habitability of Mars. There is no evidence of life on the surface of Mars today, but microbes might reside beneath the surface. In this case, the carbon flux represented by CH_4 would serve as a link between a putative subterranean biosphere on Mars and what we can measure above the surface. Alternatively, CH_4 records modern geochemical activity. Here we ask the fundamental question: how active is Mars, geochemically and/or biologically? In this article, we examine geological, geochemical, and biogeochemical processes related to our overarching question. The martian atmosphere and surface are an overwhelmingly oxidizing environment, and life requires pairing of electron donors and electron acceptors, that is, redox gradients, as an essential source of energy. Therefore, a fundamental and critical question regarding the possibility of life on Mars is, \"Where can we find redox gradients as energy sources for life on Mars?\" Hence, regardless of the pathway that generates CH_4 on Mars, the presence of CH_4, a reduced species in an oxidant-rich environment, suggests the possibility of redox gradients supporting life and habitability on Mars. Recent missions such as ExoMars Trace Gas Orbiter may provide mapping of the global distribution of CH_4. To discriminate between abiotic and biotic sources of CH_4 on Mars, future studies should use a series of diagnostic geochemical analyses, preferably performed below the ground or at the ground/atmosphere interface, including measurements of CH_4 isotopes, methane/ethane ratios, H_2 gas concentration, and species such as acetic acid. Advances in the fields of Mars exploration and instrumentation will be driven, augmented, and supported by an improved understanding of atmospheric chemistry and dynamics, deep subsurface biogeochemistry, astrobiology, planetary geology, and geophysics. Future Mars exploration programs will have to expand the integration of complementary areas of expertise to generate synergistic and innovative ideas to realize breakthroughs in advancing our understanding of the potential of life and habitable conditions having existed on Mars. In this spirit, we conducted a set of interdisciplinary workshops. From this series has emerged a vision of technological, theoretical, and methodological innovations to explore the martian subsurface and to enhance spatial tracking of key volatiles, such as CH_4.", "doi": "10.1089/ast.2018.1917", "pmcid": "PMC6205098", "issn": "1557-8070", "publisher": "Mary Ann Liebert", "publication": "Astrobiology", "publication_date": "2018-10", "series_number": "10", "volume": "18", "issue": "10", "pages": "1221-1242" }, { "id": "authors:3gcg3-khn91", "collection": "authors", "collection_id": "3gcg3-khn91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180426-110252898", "type": "monograph", "title": "Methane on Mars and Habitability: Challenges and Responses", "author": [ { "family_name": "Yung", "given_name": "Yuk L.", "orcid": "0000-0002-4263-2562", "clpid": "Yung-Y-L" }, { "family_name": "Chen", "given_name": "Pin", "clpid": "Chen-Pin" }, { "family_name": "Nealson", "given_name": "Kenneth", "orcid": "0000-0001-5189-3732", "clpid": "Nealson-K-H" }, { "family_name": "Atreya", "given_name": "Sushil", "orcid": "0000-0002-1972-1815", "clpid": "Atreya-S-K" }, { "family_name": "Beckett", "given_name": "Patrick", "clpid": "Beckett-P" }, { "family_name": "Blank", "given_name": "Jennifer", "clpid": "Blank-J-G" }, { "family_name": "Ehlmann", "given_name": "Bethany", "orcid": "0000-0002-2745-3240", "clpid": "Ehlmann-B-L" }, { "family_name": "Eiler", "given_name": "John", "clpid": "Eiler-J-M" }, { "family_name": "Etiope", "given_name": "Giuseppe", "clpid": "Etiope-G" }, { "family_name": "Ferry", "given_name": "James G.", "clpid": "Ferry-J-G" }, { "family_name": "Forget", "given_name": "Francois", "clpid": "Forget-F" }, { "family_name": "Gao", "given_name": "Peter", "orcid": "0000-0002-8518-9601", "clpid": "Gao-Peter" }, { "family_name": "Hu", "given_name": "Renyu", "orcid": "0000-0003-2215-8485", "clpid": "Hu-Renyu" }, { "family_name": "Kleinb\u00f6hl", "given_name": "Armin", "clpid": "Kleinb\u00f6hl-A" }, { "family_name": "Klusman", "given_name": "Ronald", "clpid": "Klusman-R" }, { "family_name": "Lef\u00e8vre", "given_name": "Franck", "clpid": "Lef\u00e8vre-F" }, { "family_name": "Miller", "given_name": "Charles", "orcid": "0000-0002-9380-4838", "clpid": "Miller-C-E" }, { "family_name": "Mischna", "given_name": "Michael", "orcid": "0000-0002-8022-5319", "clpid": "Mischna-M-A" }, { "family_name": "Mumma", "given_name": "Michael", "clpid": "Mumma-M-J" }, { "family_name": "Newman", "given_name": "Sally", "orcid": "0000-0003-0710-995X", "clpid": "Newman-S" }, { "family_name": "Oehler", "given_name": "Dorothy", "clpid": "Oehler-D-Z" }, { "family_name": "Okumura", "given_name": "Mitchio", "orcid": "0000-0001-6874-1137", "clpid": "Okumura-M" }, { "family_name": "Oremland", "given_name": "Ronald", "clpid": "Oremland-R-S" }, { "family_name": "Orphan", "given_name": "Victoria", "orcid": "0000-0002-5374-6178", "clpid": "Orphan-V-J" }, { "family_name": "Popa", "given_name": "Radu", "clpid": "Popa-R" }, { "family_name": "Russell", "given_name": "Michael", "clpid": "Russell-M-J" }, { "family_name": "Shen", "given_name": "Linhan", "orcid": "0000-0003-3871-655X", "clpid": "Shen-Linhan" }, { "family_name": "Sherwood Lollar", "given_name": "Barbara", "clpid": "Sherwood-Lollar-B" }, { "family_name": "Stamenkovi\u0107", "given_name": "Vlada", "orcid": "0000-0003-2416-3683", "clpid": "Stamenkovi\u0107-V" }, { "family_name": "Staehle", "given_name": "Robert", "clpid": "Staehle-R-L" }, { "family_name": "Stolper", "given_name": "Daniel", "orcid": "0000-0003-3299-3177", "clpid": "Stolper-D-A" }, { "family_name": "Templeton", "given_name": "Alexis", "clpid": "Templeton-A" }, { "family_name": "Vandaele", "given_name": "Ann C.", "clpid": "Vandaele-A-C" }, { "family_name": "Viscardy", "given_name": "S\u00e9bastien", "clpid": "Viscardy-S" }, { "family_name": "Webster", "given_name": "Chris", "clpid": "Webster-C-R" }, { "family_name": "Wennberg", "given_name": "Paul O.", "orcid": "0000-0002-6126-3854", "clpid": "Wennberg-P-O" }, { "family_name": "Wong", "given_name": "Michael", "clpid": "Wong-Michael-L" }, { "family_name": "Worden", "given_name": "John", "orcid": "0000-0003-0257-9549", "clpid": "Worden-J-R" } ], "abstract": "Recent measurements of methane (CH_4) by the Mars Science Laboratory (MSL) now confront us with robust data that demand interpretation. Thus far, the MSL data have revealed a baseline level of CH_4 (\u223c0.4 parts per billion by volume [ppbv]), with seasonal variations, as well as greatly enhanced spikes of CH_4 with peak abundances of \u223c7\u2009ppbv. What do these CH_4 revelations with drastically different abundances and temporal signatures represent in terms of interior geochemical processes, or is martian CH_4 a biosignature? Discerning how CH_4 generation occurs on Mars may shed light on the potential habitability of Mars. There is no evidence of life on the surface of Mars today, but microbes might reside beneath the surface. In this case, the carbon flux represented by CH_4 would serve as a link between a putative subterranean biosphere on Mars and what we can measure above the surface. Alternatively, CH_4 records modern geochemical activity. Here we ask the fundamental question: how active is Mars, geochemically and/or biologically? In this article, we examine geological, geochemical, and biogeochemical processes related to our overarching question. The martian atmosphere and surface are an overwhelmingly oxidizing environment, and life requires pairing of electron donors and electron acceptors, that is, redox gradients, as an essential source of energy. Therefore, a fundamental and critical question regarding the possibility of life on Mars is, \"Where can we find redox gradients as energy sources for life on Mars?\" Hence, regardless of the pathway that generates CH_4 on Mars, the presence of CH_4, a reduced species in an oxidant-rich environment, suggests the possibility of redox gradients supporting life and habitability on Mars. Recent missions such as ExoMars Trace Gas Orbiter may provide mapping of the global distribution of CH_4. To discriminate between abiotic and biotic sources of CH_4 on Mars, future studies should use a series of diagnostic geochemical analyses, preferably performed below the ground or at the ground/atmosphere interface, including measurements of CH_4 isotopes, methane/ethane ratios, H_2 gas concentration, and species such as acetic acid. Advances in the fields of Mars exploration and instrumentation will be driven, augmented, and supported by an improved understanding of atmospheric chemistry and dynamics, deep subsurface biogeochemistry, astrobiology, planetary geology, and geophysics. Future Mars exploration programs will have to expand the integration of complementary areas of expertise to generate synergistic and innovative ideas to realize breakthroughs in advancing our understanding of the potential of life and habitable conditions having existed on Mars. In this spirit, we conducted a set of interdisciplinary workshops. From this series has emerged a vision of technological, theoretical, and methodological innovations to explore the martian subsurface and to enhance spatial tracking of key volatiles, such as CH_4.", "doi": "10.7907/Z990220K", "publisher": "Astrobiology", "publication_date": "2018-01" }, { "id": "authors:sjph8-mzw83", "collection": "authors", "collection_id": "sjph8-mzw83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130930-104342097", "type": "article", "title": "Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars", "author": [ { "family_name": "Meslin", "given_name": "P.-Y.", "orcid": "0000-0002-0703-3951", "clpid": "Meslin-P-Y" }, { "family_name": "Ganault", "given_name": "O.", "orcid": "0000-0002-6979-9012", "clpid": "Gasnault-O" }, { "family_name": "Forni", "given_name": "O.", "orcid": "0000-0001-6772-9689", "clpid": "Forni-O" }, { "family_name": "Schr\u00f6der", "given_name": "S.", "orcid": "0000-0003-1870-3663", "clpid": "Schr\u00f6der-S" }, { "family_name": "Cousin", "given_name": "A.", "orcid": "0000-0001-7823-7794", "clpid": "Cousin-A" }, { "family_name": "Berger", "given_name": "G.", "clpid": "Berger-G" }, { "family_name": "Clegg", "given_name": "S. M.", "orcid": "0000-0002-0338-0948", "clpid": "Clegg-S-M" }, { "family_name": "Lasue", "given_name": "J.", "orcid": "0000-0001-9082-4457", "clpid": "Lasue-J" }, { "family_name": "Maurice", "given_name": "S.", "clpid": "Maurice-S" }, { "family_name": "Sautter", "given_name": "V.", "orcid": "0000-0002-4263-7558", "clpid": "Sautter-V" }, { "family_name": "Le Mou\u00e9lic", "given_name": "S.", "clpid": "Le-Mou\u00e9lic-S" }, { "family_name": "Wiens", "given_name": "R. C.", "orcid": "0000-0002-3409-7344", "clpid": "Wiens-R-C" }, { "family_name": "Fabre", "given_name": "C.", "orcid": "0000-0001-8627-4050", "clpid": "Fabre-C" }, { "family_name": "Goetz", "given_name": "W.", "clpid": "Goetz-W" }, { "family_name": "Bish", "given_name": "D.", "clpid": "Bish-D-L" }, { "family_name": "Mangold", "given_name": "N.", "orcid": "0000-0002-0022-0631", "clpid": "Mangold-N" }, { "family_name": "Ehlmann", "given_name": "B.", "orcid": "0000-0002-2745-3240", "clpid": "Ehlmann-B-L" }, { "family_name": "Lanza", "given_name": "N.", "orcid": "0000-0003-4445-7996", "clpid": "Lanza-N-L" }, { "family_name": "Harri", "given_name": "A.-M.", "clpid": "Harri-A-M" }, { "family_name": "Anderson", "given_name": "R.", "clpid": "Anderson-R" }, { "family_name": "Rampe", "given_name": "E. B.", "orcid": "0000-0002-6999-0028", "clpid": "Rampe-E-B" }, { "family_name": "McConnochie", "given_name": "T. H.", "clpid": "McConnochie-T-H" }, { "family_name": "Pinet", "given_name": "P.", "orcid": "0000-0002-1933-5631", "clpid": "Pinet-P" }, { "family_name": "Blaney", "given_name": "D.", "clpid": "Blaney-D" }, { "family_name": "L\u00e9veill\u00e9", "given_name": "R.", "clpid": "L\u00e9veill\u00e9-R" }, { "family_name": "Archer", "given_name": "D.", "clpid": "Archer-D" }, { "family_name": "Barraclough", "given_name": "B.", "clpid": "Barraclough-B-L" }, { "family_name": "Bender", "given_name": "S.", "clpid": "Bender-S" }, { "family_name": "Blake", "given_name": "D.", "clpid": "Blake-D" }, { "family_name": "Blank", "given_name": "J. G.", "clpid": "Blank-J-G" }, { "family_name": "Bridges", "given_name": "N.", "clpid": "Bridges-N" }, { "family_name": "Clark", "given_name": "B. C.", "orcid": "0000-0002-5546-8757", "clpid": "Clark-B-C" }, { "family_name": "DeFlores", "given_name": "L.", "clpid": "DeFlores-L" }, { "family_name": "Delapp", "given_name": "D.", "clpid": "Delapp-D" }, { "family_name": "Dromart", "given_name": "G.", "clpid": "Dromart-G" }, { "family_name": "Dyar", "given_name": "M. D.", "orcid": "0000-0003-4272-793X", "clpid": "Dyar-M-D" }, { "family_name": "Fisk", "given_name": "M.", "clpid": "Fisk-M" }, { "family_name": "Gondet", "given_name": "B.", "clpid": "Gondet-B" }, { "family_name": "Grotzinger", "given_name": "J.", "orcid": "0000-0001-9324-1257", "clpid": "Grotzinger-J-P" }, { "family_name": "Herkenhoff", "given_name": "K.", "orcid": "0000-0002-3153-6663", "clpid": "Herkenhoff-K-E" }, { "family_name": "Johnson", "given_name": "J.", "clpid": "Johnson-J" }, { "family_name": "Lacour", "given_name": "J.-L.", "clpid": "Lacour-J-L" }, { "family_name": "Langevin", "given_name": "Y.", "clpid": "Langevin-Y" }, { "family_name": "Leshin", "given_name": "L.", "clpid": "Leshin-L-A" }, { "family_name": "Lewin", "given_name": "E.", "clpid": "Lewin-E" }, { "family_name": "Madsen", "given_name": "M. B.", "orcid": "0000-0001-8909-5111", "clpid": "Madsen-M-B" }, { "family_name": "Melikechi", "given_name": "N.", "clpid": "Melikechi-N" }, { "family_name": "Mezzacappa", "given_name": "A.", "clpid": "Mezzacappa-A" }, { "family_name": "Mischna", "given_name": "M. A.", "orcid": "0000-0002-8022-5319", "clpid": "Mischna-M-A" }, { "family_name": "Moores", "given_name": "J. E.", "clpid": "Moores-J-E" }, { "family_name": "Newsom", "given_name": "H.", "orcid": "0000-0002-4358-8161", "clpid": "Newsom-H-E" }, { "family_name": "Ollila", "given_name": "A.", "clpid": "Ollila-A" }, { "family_name": "Perez", "given_name": "R.", "clpid": "Perez-R" }, { "family_name": "Renno", "given_name": "N.", "clpid": "Renno-N" }, { "family_name": "Sirven", "given_name": "J.-B.", "clpid": "Sirven-J-B" }, { "family_name": "Tokar", "given_name": "R.", "clpid": "Tokar-R" }, { "family_name": "de la Torre", "given_name": "M.", "clpid": "de-la-Torre-M" }, { "family_name": "d'Uston", "given_name": "L.", "clpid": "d'Uston-L" }, { "family_name": "Vaniman", "given_name": "D.", "clpid": "Vaniman-D" }, { "family_name": "Yingst", "given_name": "A.", "clpid": "Yingst-A" }, { "literal": "MSL Science Team" } ], "abstract": "The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter\nscale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic\ntype and a locally derived, coarse-grained felsic type. The mafic soil component is representative\nof widespread martian soils and is similar in composition to the martian dust. It possesses a\nubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the\namorphous phases found in the soil by the CheMin instrument. This hydration likely accounts\nfor an important fraction of the global hydration of the surface seen by previous orbital\nmeasurements. ChemCam analyses did not reveal any significant exchange of water vapor between\nthe regolith and the atmosphere. These observations provide constraints on the nature of the\namorphous phases and their hydration.", "doi": "10.1126/science.1238670", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2013-09-27", "series_number": "6153", "volume": "341", "issue": "6153", "pages": "Art. No. 1238670" }, { "id": "authors:250c7-z3438", "collection": "authors", "collection_id": "250c7-z3438", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120821-094529006", "type": "article", "title": "Solubilities of carbon dioxide and water in rhyolitic melt at 850\u00b0C and 750 bars", "author": [ { "family_name": "Blank", "given_name": "J. G.", "clpid": "Blank-J-G" }, { "family_name": "Stolper", "given_name": "E. M.", "orcid": "0000-0001-8008-8804", "clpid": "Stolper-E-M" }, { "family_name": "Carroll", "given_name": "M. R.", "clpid": "Carroll-M-R" } ], "abstract": "Concentrations of carbon dioxide and water dissolved in glasses quenched from rhyolitic melts equilibrated with H_2O-CO_2 fluids at 850\u00b0C and 750 bar were measured using infrared spectroscopy; concentrations of H_2O and CO_2 in the quenched fluids were measured manometrically. The mole fraction of CO_2 in the quenched fluid ranged from 0.06 to 0.91. Concentrations of CO_2 in the coexisting rhyolitic melt increased from 23(\u00b16) ppm for the sample equilibrated with the most CO_2-poor fluid to 515(\u00b116) ppm for that equilibrated with the most CO_2-rich fluid. The water content of the melt varied from 0.51(\u00b10.06) to 3.34(\u00b10.08) wt%.\n\nOur results show that concentrations of molecular CO_2 and H_2O in the glasses obey Henry's Law; i.e., the mole fractions of molecular CO_2 and molecular H_2O in the quenched melts are proportional to their fugacities in the coexisting vapor. CO_2 contents of vapor-saturated melts are not enhanced by addition of water to CO_2-rich vapor, contrary to previous reports for silicate melts at higher pressures. The Henrian behavior of CO_2 and H_2O at low pressure considerably simplifies modeling of the degassing of silicic magmas.", "doi": "10.1016/0012-821X(93)90004-S", "issn": "0012-821X", "publisher": "Elsevier", "publication": "Earth and Planetary Science Letters", "publication_date": "1993-08", "series_number": "1-2", "volume": "119", "issue": "1-2", "pages": "27-36" } ]