101
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Mitrofanov IG, Zuber MT, Litvak ML, Boynton WV, Smith DE, Drake D, Hamara D, Kozyrev AS, Sanin AB, Shinohara C, Saunders RS, Tretyakov V. CO2 snow depth and subsurface water-ice abundance in the northern hemisphere of Mars. Science 2003; 300:2081-4. [PMID: 12829779 DOI: 10.1126/science.1084350] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Observations of seasonal variations of neutron flux from the high-energy neutron detector (HEND) on Mars Odyssey combined with direct measurements of the thickness of condensed carbon dioxide by the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor show a latitudinal dependence of northern winter deposition of carbon dioxide. The observations are also consistent with a shallow substrate consisting of a layer with water ice overlain by a layer of drier soil. The lower ice-rich layer contains between 50 and 75 weight % water, indicating that the shallow subsurface at northern polar latitudes on Mars is even more water rich than that in the south.
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Affiliation(s)
- I G Mitrofanov
- Space Research Institute, Russian Academy of Sciences, Moscow, 117997, Russia.
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102
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Affiliation(s)
- Michael E. Lipschutz
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - Stephen F. Wolf
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - John M. Hanchar
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - F. Bartow Culp
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
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103
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Christensen PR. Formation of recent martian gullies through melting of extensive water-rich snow deposits. Nature 2003; 422:45-8. [PMID: 12594459 DOI: 10.1038/nature01436] [Citation(s) in RCA: 260] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2002] [Accepted: 01/14/2003] [Indexed: 11/08/2022]
Abstract
The observation of gullies on Mars indicates the presence of liquid water near the surface in recent times, which is difficult to reconcile with the current cold climate. Gullies have been proposed to form through surface runoff from subsurface aquifers or through melting of near-surface ice under warmer conditions. But these gullies are observed to occur preferentially in cold mid-latitudes, where the presence of liquid water is less likely, and on isolated surfaces where groundwater seepage would not be expected, making both potential explanations unsatisfactory. Here I show that gullies can form by the melting of water-rich snow that has been transported from the poles to mid-latitudes during periods of high obliquity within the past 10(5) to 10(6) years (refs 5, 6). Melting within this snow can generate sufficient water to erode gullies in about 5,000 years. My proposed model for gully formation is consistent with the age and location of the gullies, and it explains the occurrence of liquid water in the cold mid-latitudes as well as on isolated surfaces. Remnants of the snowpacks are still present on mid-latitude, pole-facing slopes, and the recent or current occurrence of liquid water within them provides a potential abode for life.
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Affiliation(s)
- Philip R Christensen
- Department of Geological Sciences, Campus Box 876305, Arizona State University, Tempe, Arizona 85287-6305, USA.
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104
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Hode T, von Dalwigk I, Broman C. A hydrothermal system associated with the Siljan impact structure, Sweden--implications for the search for fossil life on Mars. ASTROBIOLOGY 2003; 3:271-289. [PMID: 14582511 DOI: 10.1089/153110703769016370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The Siljan ring structure (368 +/- 1.1 Ma) is the largest known impact structure in Europe. It isa 65-km-wide, eroded, complex impact structure, displaying several structural units, including a central uplifted region surrounded by a ring-shaped depression. Associated with the impact crater are traces of a post-impact hydrothermal system indicated by precipitated and altered hydrothermal mineral assemblages. Precipitated hydrothermal minerals include quartz veins and breccia fillings associated with granitic rocks at the outer margin of the central uplift, and calcite, fluorite, galena, and sphalerite veins associated with Paleozoic carbonate rocks located outside the central uplift. Two-phase water/gas and oil/gas inclusions in calcite and fluorite display homogenization temperatures between 75 degrees C and 137 degrees C. With an estimated erosional unloading of approximately 1 km, the formation temperatures were probably not more than 10-15 degrees C higher. Fluid inclusion ice-melting temperatures indicate a very low salt content, reducing the probability that the mineralization was precipitated during the Caledonian Orogeny. Our findings suggest that large impacts induce low-temperature hydrothermal systems that may be habitats for thermophilic organisms. Large impact structures on Mars may therefore be suitable targets in the search for fossil thermophilic organisms.
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Affiliation(s)
- Tomas Hode
- Department of Paleozoology, Swedish Museum of Natural History, Stockholm, Sweden.
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105
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Mischna MA. On the orbital forcing of Martian water and CO2cycles: A general circulation model study with simplified volatile schemes. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2003je002051] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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106
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107
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108
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Jakosky BM, Nealson KH, Bakermans C, Ley RE, Mellon MT. Subfreezing activity of microorganisms and the potential habitability of Mars' polar regions. ASTROBIOLOGY 2003; 3:343-350. [PMID: 14577883 DOI: 10.1089/153110703769016433] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The availability of water-ice at the surface in the Mars polar cap and within the top meter of the high-latitude regolith raises the question of whether liquid water can exist there under some circumstances and possibly support the existence of biota. We examine the minimum temperatures at which liquid water can exist at ice grain-dust grain and ice grain-ice grain contacts, the minimum subfreezing temperatures at which terrestrial organisms can grow or multiply, and the maximum temperatures that can occur in martian high-latitude and polar regions, to see if there is overlap. Liquid water can exist at grain contacts above about -20 degrees C. Measurements of growth in organisms isolated from Siberian permafrost indicate growth at -10 degrees C and metabolism at -20 degrees C. Mars polar and high-latitude temperatures rise above -20 degrees C at obliquities greater than ~40 degrees, and under some conditions rise above 0 degrees C. Thus, the environment in the Mars polar regions has overlapped habitable conditions within relatively recent epochs, and Mars appears to be on the edge of being habitable at present. The easy accessibility of the polar surface layer relative to the deep subsurface make these viable locations to search for evidence of life.
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Affiliation(s)
- Bruce M Jakosky
- Laboratory for Atmospheric and Space Physics, Department of Geological Sciences, University of Colorado, Boulder, CO 80303, USA.
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109
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Russell PS. Elysium-Utopia flows as mega-lahars: A model of dike intrusion, cryosphere cracking, and water-sediment release. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je001995] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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110
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111
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Trautner R. Detection of subsurface ice and water deposits on Mars with a mutual impedance probe. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je002008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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112
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Wyatt MB. Analysis of surface compositions in the Oxia Palus region on Mars from Mars Global Surveyor Thermal Emission Spectrometer Observations. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je001986] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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113
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Barlow NG. Martian impact crater ejecta morphologies as indicators of the distribution of subsurface volatiles. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je002036] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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114
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Milliken RE. Viscous flow features on the surface of Mars: Observations from high-resolution Mars Orbiter Camera (MOC) images. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002je002005] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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115
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Abstract
During thermal cycling, organisms could live on thermosynthesis, a theoretical mechanism applicable to the origin of life and the early evolution of biological energy conversion. All extraterrestrial ice may be a repository for frozen dead or dormant organisms from earlier stages of evolution. In the presence of a thermal gradient within the ice, organisms might still be harvesting energy from thermosynthesis. Possible habitats for thermosynthesizers can be found throughout the Solar System, particularly in the cold traps on Mercury and the Moon, convecting waters on Mars, the oceans on moons in the outer Solar System, and smaller bodies rotating in the sunlight such as cosmic dust, meteorites, asteroids, and comets. A general strategy for detecting thermosynthetic organisms on Earth is offered, and highlights of current and upcoming robotic exploratory missions relevant to the detection of thermosynthesis are reviewed.
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116
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Gilichinsky D, Rivkina E, Shcherbakova V, Laurinavichuis K, Tiedje J. Supercooled water brines within permafrost-an unknown ecological niche for microorganisms: a model for astrobiology. ASTROBIOLOGY 2003; 3:331-341. [PMID: 14577882 DOI: 10.1089/153110703769016424] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study describes brine lenses (cryopegs) found in Siberian permafrost derived from ancient marine sediment layers of the Arctic Ocean. The cryopegs were formed and isolated from sediment ~100,000-120,000 years ago. They remain liquid at the in situ temperature of -10 degrees C as a result of their high salt content (170-300 g/L). [(14)C] Glucose is taken up by the cryopeg biomass at -15 degrees C, indicating microbial metabolism at low temperatures in this habitat. Furthermore, aerobic, anaerobic heterotrophs, sulfate reducers, acetogens, and methanogens were detected by most probable number analysis. Two psychrophilic microbes were isolated from the cryopegs, a Clostridium and a Psychrobacter. The closest relatives of each were previously isolated from Antarctica. The cryopeg econiche might serve as a model for extraterrestrial life, and hence is of particular interest to astrobiology.
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Affiliation(s)
- D Gilichinsky
- Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
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117
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Mitrofanov I, Anfimov D, Kozyrev A, Litvak M, Sanin A, Tret'yakov V, Krylov A, Shvetsov V, Boynton W, Shinohara C, Hamara D, Saunders RS. Maps of subsurface hydrogen from the high energy neutron detector, Mars Odyssey. Science 2002; 297:78-81. [PMID: 12040089 DOI: 10.1126/science.1073616] [Citation(s) in RCA: 289] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
After 55 days of mapping by the High Energy Neutron Detector onboard Mars Odyssey, we found deficits of high-energy neutrons in the southern highlands and northern lowlands of Mars. These deficits indicate that hydrogen is concentrated in the subsurface. Modeling suggests that water ice-rich layers that are tens of centimeters in thickness provide one possible fit to the data.
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Affiliation(s)
- I Mitrofanov
- Institute for Space Research, Moscow 117997, Russia
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118
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Boynton WV, Feldman WC, Squyres SW, Prettyman TH, Bruckner J, Evans LG, Reedy RC, Starr R, Arnold JR, Drake DM, Englert PAJ, Metzger AE, Mitrofanov I, Trombka JI, D'Uston C, Wanke H, Gasnault O, Hamara DK, Janes DM, Marcialis RL, Maurice S, Mikheeva I, Taylor GJ, Tokar R, Shinohara C. Distribution of hydrogen in the near surface of Mars: evidence for subsurface ice deposits. Science 2002; 297:81-5. [PMID: 12040090 DOI: 10.1126/science.1073722] [Citation(s) in RCA: 753] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42 degrees latitude to about 40 grams per square centimeter at -77 degrees. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 +/- 15% of the layer by weight.
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Affiliation(s)
- W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
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119
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Affiliation(s)
- Jim Bell
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.
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