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The case for life on Mars

  • Dirk Schulze-Makuch (a1), Alberto G. Fairén (a2) and Alfonso F. Davila (a2)

There have been several attempts to answer the question of whether there is, or has ever been, life on Mars. The boldest attempt was the only ever life detection experiment conducted on another planet: the Viking mission. The mission was a great success, but it failed to provide a clear answer to the question of life on Mars. More than 30 years after the Viking mission our understanding of the history and evolution of Mars has increased vastly to reveal a wetter Martian past and the occurrence of diverse environments that could have supported microbial life similar to that on Earth for extended periods of time. The discovery of Terran extremophilic microorganisms, adapted to environments previously though to be prohibitive for life, has greatly expanded the limits of habitability in our Solar System, and has opened new avenues for the search of life on Mars. Remnants of a possible early biosphere may be found in the Martian meteorite ALH84001. This claim is based on a collection of facts and observations consistent with biogenic origins, but individual links in the collective chain of evidence remain controversial. Recent evidence for contemporary liquid water on Mars and the detection of methane in the Martian atmosphere further enhance the case for life on Mars. We argue that, given the cumulative evidence provided, life has and is likely to exist on Mars, and we have already found evidence of it. However, to obtain a compelling certainty a new mission is needed, one which is devoted to the detection of life on Mars.

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Abramov, O. & Kring, D.A. (2005). Impact-induced hydrothermal activity on early Mars. J. Geophys. Res. 110, E12S09, doi:10.1029/2005JE002453.
Acuña, M.J. et al. (1999). Global distribution of crustal magnetization discovered by the mars global surveyor MAG/ER experiment. Science 284, 790793.
Amils, R. et al. (2007). Extreme environments as Mars terrestrial analogues: the Rio Tinto case. Plan. Spac. Sci. 55, 370381.
Anders, E. (1996). Evaluating the evidence for past life on Mars. Science 274, 21192121.
Anderson, R., Dohm, J., Golembek, M., Haldemann, A., Franklin, B., Tanaka, K., Lias, J. & Peer, B. (2000). Primary Centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars. J. Geophys. Res. 106, 20 56320 586.
Andrews-Hanna, J.C., Phillips, R.J. & Zuber, M.T. (2007). Meridiani Planum and the global hydrology of Mars. Science 446, 71327135.
Ansan, V. & Mangold, N. (2006). New observations of Warrego Valles, Mars: evidence for precipitation and surface runoff. Planet Space Sci. 54, 219242.
Arrhenius, S. (1903). Die Verbreitung des Lebens im Weltenraum. Umschau 7, 481485.
Arvidson, R.E., Poulet, F., Bibring, J.P., Wolff, M., Gendrin, A., Morris, R.V., Freeman, J.J., Langevin, Y., Mangold, N. & Bellucci, G. (2005). Spectral reflectance and morphologic correlations in eastern Terra Meridiani, Mars. Science 307, 15911594.
Baker, B.J., Tyson, G.W., Webb, R.I., Flanagan, J., Hugenholtz, P., Allen, E.E. & Banfield, J.F. (2006). Lineages of acidophilic Archaea revealed by community genomic analysis. Science 314, 19331935.
Baker, V.R., Strom, R.G., Gulick, V.C., Kargel, J.S., Komatsu, G. & Kale, V.S. (1991). Ancient oceans, ice sheets and the hydrological cycle on Mars. Nature 352, 589594.
Baker, V.R. (2001). Water and the martian landscape. Nature 412, 228236.
Bakermans, C., Tsapin, A.I., Souza-Egipsy, V., Gilichinsky, D.A. & Nealson, K.H. (2003) Reproduction and metabolism at −10°C of bacteria isolated from Siberian permafrost. Environ. Microbiol. 5, 321326.
Ballou, E.V., Wood, P.C., Wydeven, T., Lehwalt, M.E. & Mack, R.E. (1978). Chemical interpretation of Viking lander 1 life detection experiment. Nature 271, 644645.
Banin, A. & Rishpon, J. (1979). Smectite clays in Mars soil: evidence for their presence and role in Viking biology experimental results. J. Mol. Evol. 14, 133152.
Barber, D.J. & Scott, E.R.D. (2002). Origin of supposedly biogenic magnetite in the martian meteorite Alan Hills 84001. Proc. Natl. Acad. Sci. U.S.A. 99, 65566561.
Barriga, F.A.S., de Carvalho, D. & Ribeiro, A. (1997). Introduction to the Iberian Pyritic Belt. In: Geology and VMS of the Iberian Pyrite Belt, eds Barriga, F.A.S. & de Carvalho, D., pp. 120. Society of Economic Geologists.
Bazylinski, D.A. & Frankel, B.R. (2003). Biologically controlled mineralization in prokaryotes. Rev Mineral Geochem. 54, 217247.
Becker, L., Popp, B., Rust, T. & Bada, J.L. (1999). The origin of organic matter in the Martian meteorite ALH84001. EPSL 167, 7179.
Bell, M.S. (2007). Experimental shock decomposition of siderite and the origin of magnetite in Martian meteorite ALH 84001. Meteorit. Planet. Sci. 42, 935949.
Benner, S.A., Devine, K.G., Matveeva, L.N. & Powell, D.H. (2000). The missing organic molecules on Mars. Proc. Natl. Acad. Sci. U.S.A. 97, 24252430.
Bibring, J.P. et al. (2005). Mars surface diversity as revealed by the OMEGA/Mars Express observations. Science 307, 5715–1576.
Bibring, J.P. et al. (2007). Coupled ferric oxides and sulfates on the Martian surface. Science 317, 12061210.
Biemann, K. (1979). The implications and limitations of the findings of the Viking Organic Analysis Experiment. J. Mol. Evol. 14, 6570.
Biemann, K. (2007). On the ability of the Viking gas chromatograph–mass spectrometer to detect organic matter. Proc. Natl. Acad. Sci. 104(25), 131010313.
Biemann, K., Oro, J., Toulmin, P., Orgel, L.E., Nier, A.O., Anderson, D.M., Flory, D., Diaz, A.V., Rushneck, D.R. & Simmonds, P.G. (1977). The search for organic substances and inorganic volatitle compounds in the surface of Mars. J. Geophys. Res. 82, 46414658.
Blakemore, R.P. (1982). Magnetotactic bacteria. Annu. Rev. Microbiol. 36, 217238.
Boston, P.J., Ivanov, M.V. & McKay, C.P. (1992). On the possibility of chemosynthetic ecosystems in subsurface habitats on Mars. Icarus 95, 300308.
Bradley, J.P., Harvey, R.P. & McSween, H.Y. Jr., (1997). No ‘nanofossils’ in Martian meteorite. Nature 390, p. 454.
Bräuer, S.L., Cadillo-Quiroz, H., Yashiro, E., Yavitt, J.B. & Zinder, S.H. (2006). Isolation of a novel acidiphilic methanogen from an acidic peat bog. Nature 442, 192194.
Burns, R.G. & Fisher, D.S. (1990). Iron–sulfur mineralogy of Mars: magmatic evolution and chemical weathering products. J. Geophys. Res. 95, 1441514421.
Burns, R.G. & Fisher, D.S. (1993). Rates of oxidative weathering on the surface of Mars. J. Geophys. Res. 98, 33653372.
Cano, R.J. & Borucki, M. (1995). Revival and identification of bacterial spores in 25 to 40 million year old Dominican amber. Science 268, 10601064.
Cisar, J.O., Xu, D.Q., Thompson, J., Swaim, W., Hu, L. & Kopecko, D.J. (2000). An alternative interpretation of nanobacteria-induced biomineralization. Proc. Natl. Acad. Sci. U.S.A. 97, 11 51111 515.
Clark, B. (2001). Planetary interchange of bioactive material: probability factors and implications. Orig. Life Evol. Biosph. 31, 185197.
Clemett, S.J., Dulay, M.T., Seb Gillette, J., Chillier, X.D.F., Mahajan, T.B. & Zare, R.N. (1998). Evidence for extraterrestrial origin of polycyclic aromatic hydrocarbons in the Martian meteorite ALH84001. Faraday Discuss. 109, 417436.
Clifford, S.M. & Parker, T.J. (2001). The evolution of the martian hydrosphere: implications for the fate of a primordial ocean and the current state of the northern plains. Icarus 154, 4079.
Cohen, M.D., Flagan, R.C. & Seinfel, J.H. (1987). Studies of concentrated electrolyte solutions using the electrodynamic balance, 1, water activities for single-electrolyte solutions. J. Phys. Chem. 91, 45634574.
Colaprete, A. & Toon, O.B. (2003). Carbon dioxide clouds in an early dense Martian atmosphere. J. Geophys. Res. Planets 108, E4, 5025, doi:10.1029/2002JE001967.
Daly, M.J. et al. (2007). Protein oxidation implicated as the primary determinant of bacterial radioresistance. PLoS Biology 5, doi:10.1371/journal.pbio.0050092.
Davies, P.C.W. (1996). The transfer of viable microorganisms between planets. In Ciba Foundation Symposium 202 (Evolution of hydrothermal ecosystems on Earth (and Mars?)). Wiley, Chichester.
Davila, A.F., Gomez-Silva, B., de los Rios, A., Ascaso, C., Olivares, H., McKay, C. & Wierzchos, J. (2008). Halite deliquescence facilitates endolithic microbial survival in the hyper–arid core of the Atacama Desert. JGR-Biogeosciences, doi:10.1029/2007JG000561.
de Angelis, M., Morel-Fourcade, M.C., Barnola, J.M., Susini, J. & Duval, P. (2005). Brine micro-droplets and solid inclusions in accreted ice from Lake Vostok (East Antarctica). Geophys. Res. Lett. 32, doi:10.1029/2005GL022460.
Dohm, J.M., Ferris, J.C., Baker, V.R., Anderson, R.C., Hare, T.M., Strom, R.G., Barlow, N.G., Tanaka, K.L., Klemaszewski, J.E. & Scott, D.H. (2001). Ancient drainage basin of the Tharsis region, Mars: potential source for outflow channel systems and putative oceans or paleolakes. J. Geophys. Res. 106(32), 943958.
Dohm, J.M., Ferris, J.C., Barlow, N.G., Baker, V.R., Mahaney, W.C., Anderson, R.C. & Hare, T.M. (2004). The Northwestern Slope Valleys (NSVs) region, Mars: a prime candidate site for the future exploration of Mars, Planet. Space Sci. 52, 189198.
Ebert, M., Inerle-Hof, M. & Weinbruch, S. (2002). Environmental scanning electron microscopy as a new technique to determine the hygroscopic behavior of individual aerosol particles. Atm. Environ. 36, 59095916.
Elwood Madden, M.E., Ulrich, S.M., Onstott, T.C. & Phelps, T.J. (2007). Salinity-induced hydrate dissociation: A mechanism for recent CH4 release on Mars. Geophys. Res. Lett. 34, L11202, doi:10.1029/2006GL029156.
Eschenbach, D.A., Davick, P.R., Williams, B.L., Klebanoff, S.J., Young–Smith, K., Critchlow, C.M. & Holmes, K.K. (1989). Prevalence of hydrogen peroxide-producing Lactobacillus species in normal women and women with bacterial vaginosis. J. Clin. Microbiol. 27, 251256.
Fairén, A.G., Dohm, J.M., Baker, V.R., de Pablo, M.A., Ruiz, J., Ferris, J. & Anderson, R. (2003). Episodic flood inundations of the northern plains of Mars. Icarus 165, 5367.
Fairén, A.G., Fernández-Remolar, D., Dohm, J.M., Baker, V.R. & Amils, R. (2004). Inhibition of carbonate synthesis in acidic oceans on early Mars. Nature 431, 423426.
Fajardo-Cavazos, P., Link, L., Melosh, J. & Nicholson, W.L. (2005). Bacillus subtilis spores on artificial meteorites survive hypervelocity atmospheric entry: implications for lithopanspermia. Astrobiology 5, 726736.
Fernandez-Remolar, D.C., Morris, R.V., Gruener, J.E., Amils, R. & Knoll, A.H. (2005). The Río Tinto Basin, Spain: mineralogy, sedimentary geobiology, and implications for interpretation of outcrop rocks at Meridiani Planum, Mars. EPSL 240, 149167.
Fernandez-Remolar, D., Gómez, F., Prieto-Ballesteros, O., Schelble, R.T., Rodríguez, N. & Amils, R. (2008). Some ecological mechanisms to generate habitability in planetary subsurface areas by chemolithotrophic communities: the Rio Tinto subsurface ecosystem as a model system. Astrobiology 8, 157174.
Finegold, L. (1996). Molecular and biophysical aspects of adaptation of life to temperatures below the freezing point. Adv. Space Res. 18, 8795.
Fisk, M.R., Popa, R., Mason, O.U., Storrie-Lombardi, M.C. & Vicenzi, E.P. (2006). Iron-magnesium silicate bioweathering on Earth (and Mars?). Astrobiology 6, 4868.
Folk, R.L. (1993). SEM imaging of bacteria and nannobacteria in carbonate sediments and rocks. J. Sedim. Petrol. 63, 990999.
Folk, R.L. & Taylor, L.A. (2002). Nanobacterial alteration of pyroxenes in Martian meteorite ALH84001. Meteorit. Planet. Sci. 37, 10571070.
Formisano, V., Atreya, S., Encrenaz, T., Ignatiev, N. & Giuranna, M. (2004). Detection of methane in the atmosphere of Mars. Science 306, 17581761.
Formisano, V. (2005). The search for life on mars with PFS: methane, formaldehyde and water. In Abstracts from the 1st Mars Express Science Conference, p. 113. European Space Research and Technology Centre (ESTEC), Noordwijk, The Netherlands.
Frankel, B.R. & Bazylinski, D.A. (2003). Biologically induced mineralization by bacteria. In: Reviews in Mineralogy and Geochemistry, eds Dove, P.M., De Yoreo, J.J. & Weiner, S., pp. 217247. Mineralogical Society of America/Geochemistry Society.
French, H.M. (1976). In: The Periglacial Environment (Addison-Wesley Longman Limited). Edinburgh Gate, Harlow.
Friedmann, E.I.Wierzchos, J., Ascaso, C. & Winklhofer, M. (2001). Chains of magnetite crystals in the meteorite ALH84001: evidence of biological origin. Proc. Natl. Acad. Sci. U.S.A. 98, 21762181.
Furnes, H., Banerjee, N.R., Muehlenbachs, K., Staudigel, H. & de Wit, M. (2004). Early life recorded in Archean pillow lavas. Science 304, 578581.
Gendrin, A. et al. (2005). Sulfates in Martian layered terrains: the OMEGA/Mars Express view. Science 307, 15871591.
Gilichinsky, D.A. et al. (2007). Microbial populations in Antarctic permafrost: biodiversity, state, age, and implication for astrobiology. Astrobiology 7, 275311.
Gibson, E.K., McKay, D.S., Thomas-Keprta, K.L., Wentworth, S.J., Westall, F., Steele, A., Romanek, C.S., Bell, M.S. & Toporski, J. (2001). Life on Mars: evaluation of the evidence within Martian meteorites ALH84001, Nakhla, and Shergotty. Precambrian Res 106, 1534.
Gladman, B., Dones, L., Levison, H.F. & Burns, J.A. (2005). Impact seeding and reseeding in the inner Solar System. Astrobiology 5, 483496.
Golden, D.C., Ming, D.W., Morris, R.V., Brearley, A.J., Lauer, H.V., Treiman, A.H., Zolensxy, M.E., Schwandt, C.S., Lofgren, G.E. & McKay, G.A. (2004). Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001. Am. Mineral. 89, 681695.
Golubic, S., Friedmann, E.I. & Schneider, J. (1981). The lithobiontic ecological niche, with special reference to microorganisms. J. Sediment. Petrol. 51, 475478.
Grasby, S.E., Allen, C.C., Longazo, T.G., Lisle, J.T., Griffin, D.W. & Beauchamp, B. (2003). Supraglacial sulfur springs and associated biological activity in the Canadian High Arctic–signs of life beneath the ice. Astrobiology 3, 583596.
Griffith, L.L. & Shock, E.L. (1997). Hydrothermal hydration of Martian crust: illustration via geochemical model calculations. J. Geophys. Res. 102, 91359143.
Gulick, V.C. (2001). Origin of the valley networks on Mars: a hydrological perspective. Geomorphology 37, 241268.
Hanson, R.S. & Hanson, T.E. (1996). Methanotrophic bacteria. Microbiol Rev. 60, 439471.
Haskin, L.A. et al. (2005). Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater. Nature 436, 6669.
Head, J.W., Kreslavsky, M., Hiesinger, H., Ivanov, M.A., Pratt, S., Seibert, N., Smith, D.E. & Zuber, M.T. (1998). Oceans in the past history of Mars: test for their presence using Mars Orbiter Laser Altimeter (MOLA) data. Geophys. Res. Lett. 25, 44014404.
Head, J., Mustard, J., Kreslavsky, M., Milliken, R. & Marchant, D. (2003). Recent ice ages on Mars. Nature 426, 797802.
Head, J.W. et al. (2005). Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars. Nature 434, 346351.
Heldmann, J.L. & Mellon, M.T. (2004). Observations of Martian gullies and constraints on potential formation mechanisms. Icarus 168, 285304.
Heldmann, J.L., Toon, O.B., Pollard, W.H., Mellon, M.T., Pitlick, J., McKay, C.P. & Andersen, D.T. (2005). Formation of Martian gullies by the action of liquid water flowing under current martian environmental conditions. J. Geophys. Res. 110, doi:10.1029/2004JE002261.
Holm, N.G. (1992). Marine hydrothermal systems and the origin of life. In SCOR Working Group 91. Kluwer, Dordrecht.
Hood, L.L. & Zakharian, A. (2001). Mapping and modeling of magnetic anomalies in northern polar regions of Mars. J. Geophys. Res. 106, 14 60114 620.
Horneck, G. (1981). Survival of microorganisms in space: a review. Adv. Space Res. 1, 3948.
Horneck, G. (1993). Responses of Bacillus subtilis spores to the space environment: results from experiments in space. Orig. Life Evol. Biosph. 23, 3752.
Horneck, G. (2006). Bacterial spores survive simulated meteorite impact. In Biological Processes Associated with Impact Events. pp. 4153. Springer, Berlin.
Horneck, G., Bücker, H. & Reitz, G. (1994). Long-term survival of bacterial spores in space. Adv. Space Res. 14, 4145.
Horowitz, N.H., Hobby, G.L. & Hubbard, J.S. (1976). The Viking carbon assimilation experiments: interim report. Science 194, 13211322.
Horowitz, N.H., Hobby, G.L. & Hubbard, J.S. (1977) Viking on Mars: the Viking carbon assimilation experiments. J. Geophys. Res. 82, 46594662.
Houtkooper, J.M. & Schulze-Makuch, D. (2007a). A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted. Int. J. Astrobiology 6, 147152.
Houtkooper, J.M. & Schulze-Makuch, D. (2007b). The hydrogen peroxide–water hypothesis for life on Mars and the problem of detection. In Instruments, Methods, and Missions for Astrobiology X, 6640N, eds Hoover, R.B., Levin, G.V., Rozanov, A.Y. & Davies, P.C.W. (Proc. SPIE, Vol. 6694).
Howard, A.D. (2007). Simulating the development of martian highland landscapes through the interaction of impact cratering, fluvial erosion, and variable hydrologic forcing. Geomorphology 91, 332363.
Hubbard, J.S. (1976). The pyrolytic release experiment: measurement of carbon assimilation. Origins Life Evol. Bios. 7, 281292.
Hurowitz, J.A. & McLennan, S.M. (2007). A ~3.5 Ga record of water-limited, acidic weathering conditions on Mars. EPSL 260, 432443.
Hynek, B.M. (2004). Implications for hydrologic processes on Mars from extensive bedrock outcrops throughout Terra Meridiani. Nature 431, 156159.
Imai, E., Honda, H., Hatori, K., Brack, A. & Matsuno, K. (1999). Elongation of oligopeptides in a simulated submarine hydrothermal system. Science 283, 831833.
Jaeger, W.L., Keszthelyi, L.P., McEwen, A.S., Dundas, C.M. & Russell, P.S. (2007). Athabasca Valles, Mars: a lava-draped channel system. Science 317, 17091711.
Jakosky, B.M. & Phillips, R.J. (2001). Mars' volatile and climate history. Nature 412, 237244.
Jull, A.J.T., Courtney, C., Jeffrey, D.A. & Beck, J.W. (1998). Isotopic evidence for a terrestrial source of organic compounds found in martian meteorites Allan Hills 84001 and Elephant Moraine 79001. Science 279, 366369.
Junge, K., Eicken, H. & Deming, J.W. (2004). Bacterial activity at −2 to −20°C in Arctic wintertime sea ice. App. Environ. Microbiol. 70, 550557.
Kajander, E.O. & Ciftcioglu, N. (1998). Nanobacteris: an alternative mechanism for pathogenic intra- and extracellular calcification and stone formation. Proc. Natl. Acad. Sci. U.S.A. 95, 82748279.
Kajander, E.O., Kuronen, I., Akerman, K., Pelttari, A. & Ciftcioglu, N. (1998). Nanobacteria from blood, the smallest culturable autonomously replicating agent on Earth. Proc. SPIE 3111, 420428.
Kargel, J.S. (2004). Mars: A Warmer Wetter Planet, p. 557. Praxis-Springer, New York.
Kasting, J.F. (1997). Warming early Earth and Mars. Science 276, 12131215.
Kelley, D.S., Karson, J.A., Blackman, D.K., Früh-Green, G., Gee, J., Butterfield, D.A., Lilley, M.D., Olson, E.J., Schrenk, M.O. & Roe, K.R. (2001). An off-axis hydrothermal field discovered near the Mid-Atlantic Ridge at 30°N. Nature 412, 145149.
Kelley, D.S. et al. (2005). A serpentinite-hosted submarine ecosystem: the Lost City hydrothermal field. Science 307, 14281434.
Kerr, R.A. (2004). Heavy breathing on Mars? Science 306, 29.
Kirschvink, J.L., Maine, A.T. & Vali, H. (1997). Paleomagnetic evidence of a low-temperature origin of carbonate in the Martian meteorite ALH84001. Science 275, 16291633.
Klein, H.P. (1978). The Viking biological experiments on Mars. Icarus 34, 666674.
Klein, H.P. (1999) Did Viking discover life on Mars? Orig. Life Evol. Biosph. 29, 625631.
Klein, H.P. et al. (1976). The Viking biological investigation: preliminary results. Science 194, 99105.
Knott, S.F., Ash, R.D. & Turner, G. (1995). 40Ar-39Ar Dating of ALH 84001: evidence for the early bombardment of Mars (abstract). Lunar Planet. Sci. 26, 765766.
Koike, J., Oshima, T., Koike, K.A., Taguchi, H., Tanaka, R., Nishimura, K. & Miyaji, M. (1991). Survival rates of some terrestrial microorganisms under simulated space conditions. Adv. Space Res. 12(4), 271(4)274.
Komatsu, G., Dohm, J.M. & Hare, T.M. (2004). Hydrogeologic processes of large-scale tectonomagmatic complexes in Mongolia-southern Siberia and on Mars. Geology 32, 325328.
Komeili, A., Li, Z., Newmann, D.A. & Jensen, G.J. (2006). Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK. Science 311, 242245.
Kompanichenko, V.N. (1996). Transition of precellular organic microsystems to a biotic state: environment and mechanism. Nanobiology 4, 3945.
Kotelnikova, S. (2002). Microbial production and oxidation of methane in deep subsurface. Earth Sci. Rev. 58, 367395.
Krasnopolsky, V.A. (2007). Long-term spectroscopic observations of Mars using IRTF/CSHELL: mapping of O2 dayglow, CO, and search for CH4. Icarus 190, 93102.
Krasnopolsky, V.A., Maillard, J.P. & Owen, T.C. (2004). Detection of methane in the Martian atmosphere: Evidence for life? Icarus 172, 537547.
Laskar, J., Levrard, B. & Mustard, J.F. (2002). Orbital forcing of the Martian polar layered deposits. Nature 419, 375377.
Leman, L., Orgel, L. & Reza-Ghadiri, M. (2004). Carbonyl sulfide-mediated prebiotic formation of peptides. Science 306, 283286.
Levin, G.V. (1997). The Viking Labeled Release Experiment and life on Mars. In Proc. Instruments, Methods, and Missions for the Investigation of Extraterrestrial Microorganisms, 29 July–1 August 1997, San Diego, CA.
Levin, G.V. (2007). Possible evidence for panspermia: the labeled release experiment. Int. J. Astrobiol. 6, 95108.
Levin, G.V. & Straat, P.A. (1976). Viking labeled release biology experiment: interim results. Science 194, 13221329.
Levin, G.V. & Straat, P.A. (1977). Recent results from the Viking labeled release experiment on Mars. J. Geophys. Res. 82, 46634667.
Levin, G.V. & Straat, P.A. (1981). A search for a nonbiological explanation of the Viking Labeled Release Life Detection Experiment. Icarus 45, 494516.
Levrard, B., Foget, F., Montmessin, F. & Laskar, J. (2004). Recent ice-rich deposits formed at high latitudes on Mars by sublimation of unstable equatorial ice during low obliquity. Nature 431, 10721075.
Lyons, J.R., Manning, C. & Nimmo, F. (2005). Formation of methane on Mars by fluid–rock interaction in the crust. Geophys. Res. Lett. 32, doi:10.1029/2004GL022161.
Mahaney, W.C., Dohm, J.M., Baker, V.R., Newsom, H.E., Malloch, D., Hancock, R.G.V., Campbell, I., Sheppard, D. & Milner, W.M. (2001). Morphogenesis of Antarctic paleosols: Martian analogue. Icarus 154, 113130.
Malin, M.C. & Edgett, K.S. (2000a). Sedimentary rocks of early Mars. Science 290, 19271937.
Malin, M.C. & Edgett, K.S. (2000b). Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 23302335.
Malin, M.C. & Edgett, K.S. (2003). Evidence for persistent flow and aqueous sedimentation on early Mars. Science 302, 19311934.
Malin, M.C., Edgett, K.S., Posiolova, L.V., McColley, S.M. & Noe Dobrea, E.Z. (2006). Present-day impact cratering rate and contemporary gully activity on Mars. Science 314, 15731577.
Mancinelli, R.L. (1989). Peroxides and the survivability of microorganisms on the surface of Mars. Adv. Space Res. 9, 191195.
Mancinelli, R. & Landheim, R. (2002). Mars, permafrost and halophiles [abstract 6]. In International Workshop on Water in the Upper martian Surface, Abstracts (NAI Publication, no. 76). NASA Astrobiology Institute, Potsdam, Germany.
Mancinelli, R.L. & Banin, A. (2003). Where is the nitrogen on Mars? Int. J. Astrobiol. 2, 217225.
Mancinelli, R.L., White, M.R. & Rothschild, L.J. (1998). Biopan survival I: exposure of the osmophiles Synechococcus sp. (Nageli) and Haloarcula sp. to the space environment. Adv. Space Res. 22, 327334.
Mancinelli, R.L., Fahlen, T.F., Landheim, R. & Klovstad, M.R. (2004). Brines and evaporites: analogs for martian life, Adv. Space Res. 33, 12441246.
Max, M.D. & Clifford, S.M. (2000). The state, potential distribution, and biological implications of methane in the martian crust. J. Geophys. Res. 105, 41654171.
McEwen, A.S. et al. (2007). A closer look at water-related geologic activity on Mars. Science 317, 17061709.
McKay, D.S., Gibson, E.K., Thomas-Keprta, K.L., Vali, H., Romanek, C.S., Clemett, S.J., Chillier, X.D.F., Maechling, C.R. & Zare, R.N. (1996). Search for past life on Mars: possible relic biogenic activity in martian meteorite ALH84001. Science 273, 924930.
McKay, C.P., Friedmann, E.I., Frankel, R.B. & Bazylinski, D.A. (2003). Magnetotactic bacteria on Earth and on Mars. Astrobiology 2, 263270.
McKay, D.S., Gibson, E. Jr., Thomas-Keprta, K. & Vali, H. (1997). Reply. Nature, 390, 455.
Melosh, H.J. (1988). The rocky road to panspermia. Nature 332, 687688.
MEPAG (2007) COSPAR Colloquium on Mars Special Regions. 18–20 September 2007, Rome, Italy.
Mikucki, J.A. & Priscu, J.C. (2004). Microbial life in Blood Falls: an ancient Antarctic ecosystem. In Proc. 2nd Conf. on Early Mars, Abstract #8023.
Mileikowsky, C., Cucinotta, F.A., Wilson, J.W., Gladman, B., Horneck, G., Lindegren, L., Melosh, H.J., Rickman, H., Valtonen, M. & Zheng, J.Q. (2000). Natural transfer of viable microbes in space. Part 1: From Mars to Earth and Earth to Mars. Icarus 145, 391427.
Min, K. & Reiners, P.W. (2007). High-temperature Mars-to-Earth transfer of meteorite ALH84001. EPSL, 260, 7285.
Mittlefehldt, D.W. (1994). ALH84001, a cumulate orthopyroxenite member of the SNC meteorite group. Meteoritics, 29, 214221.
Moreno, M.A. (1988). Microorganism transport from Earth to Mars. Nature 336, 209.
Mountfort, D.O., Kaspar, H.F., Asher, R.A. & Sutherland, D. (2003). Influences of pond geochemistry, temperature, and freeze-thaw on terminal anaerobic processes occurring in sediments of six ponds of the McMurdo ice shelf, near Bratina Island, Antarctica. App. Environment. Microbiol. 69, 583592.
Mumma, M.J., Novak, R.E., DiSanti, M.A. & Bonev, B.P. (2003). A sensitive search for methane on Mars. Am. Astron. Soc. Bull. 35, 937938.
Mumma, M.J., DiSanti, M.A., Novak, R.E., Bonev, B.P., Dello Russo, N., Hewagama, T. & Smith, M. (2005). Detection and mapping of methane and water on Mars: evidence for intense local enhancements in methane. Astrobiology 5, 300301.
Murray, J.B. et al. (2005). Evidence from the Mars Express High Resolution Stereo Camera for a frozen sea close to Mars' equator. Nature 434, 352356.
Mustard, J.F., Poulet, F., Head, J.W., Mangold, N., Bibring, J.-P., Pelkey, S.M., Fassett, C.I., Langevin, Y. & Neukum, G. (2007). Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 1. Ancient impact melt in the Isidis Basin and implications for the transition from the Noachian to Hesperian, J. Geophys. Res. 112, doi:10.1029/2006JE002834.
National Research Council (1999). Proc. Workshop on Size Limits of Very Small Microorganisms. Space Studies Board, National Academies Press.
Navarro-González, R. et al. (2003). Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life. Science 7, 10181021.
Navarro-González, R. et al. (2006). The limitations on organic detection in Mars-like soils by thermal volatilization–gas chromatography–MS and their implications for the Viking results. Proc. Natl. Acad. Sci. U.S.A. 103, 16 08916 094.
Nicholson, W.L., Munakata, N., Horneck, G., Melosh, H.J. & Setlow, P. (2000). Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments. Microbiol. Mol. Biol. Rev. 64, 548572.
Nicholson, W.L., Fajardo-Cavazos, P., Langenhorst, F. & Melosh, H.J. (2006). Bacterial spores survive hypervelocity launch by spallation: implications for lithopanspermia. In Proc. Lunar Planet Sci. Conf. XXXVII, #1808.
Onstott, T.C., McGown, D., Kessler, J., Lollar, B.S., Lehmann, K.K. & Clifford, S.M. (2006). Martian CH4: sources, flux, and detection. Astrobiology 6, 377–295.
Osterloo, M.M., Hamilton, V.E., Bandfield, J.L., Glotch, T.D., Baldridge, A.M., Christensen, P.R., Tornabene, L.L. & Anderson, F.S. (2008). Chloride-bearing materials in the southern highlands of Mars. Science 319, 16511654.
Oyama, V.I. (1972). The gas exchange experiment for life detection: The Viking Mars Lander. Icarus 16: 167184.
Oyama, V.I. & Berdahl, B.J. (1977). The Viking gas exchange experiment results from Chryse and Utopia surface samples. J. Geophys. Res. 82, 46694676.
Oyama, V.I. & Berdahl, B.J. (1979). A model for martian surface chemistry. J. Mol. Evol. 14, 199210.
Oyama, V.I., Berdahl, B.J. & Carle, G.C. (1977). Preliminary findings of the Viking gas exchange experiment and a model for Martian surface chemistry. Nature 265, 110114.
Oze, C. & Sharma, M. (2005). Have olivine, will gas: serpentinization and the abiogenic production of methane on Mars. Geophys. Res. Lett. 32, doi:10.1029/2005GL022691.
Parker, T.J., Gorsline, D.S., Saunders, R.S., Pieri, D.C. & Schneeberger, D.M. (1993). Coastal geomorphology of the martian northern plains. J. Geophys. Res. 98, 11 06111 078.
Pellenbarg, R.E., Max, M.D. & Clifford, S.M. (2003). Methane and carbon dioxide hydrates on Mars: potential origins, distribution, detection, and implications for future in situ resource utilization. J. Geophys. Res. 108, doi:10.1029/2002JE001901.
Petersen, N., von Dobeneck, T. & Vali, H. (1986). Fossil bacterial magnetite in deep-sea sediments from the South Atlantic Ocean. Nature 320: 611661.
Perron, J.T., Mitrovica, J.X., Manga, M., Matsuyama, I. & Richards, M.A. (2007). Evidence for an ancient Martian ocean in the topography of deformed shorelines. Nature 447, 840843.
Phillips, R.J. et al. (2001). Ancient geodynamics and global-scale hydrology on Mars. Science 291, 25872591.
Poulet, F., Bibring, J.-P., Mustard, J.F., Gendrin, A., Mangold, N., Langevin, Y., Arvidson, R.E., Gondet, B., Gómez, C. & the Omega Team (2005). Phyllosilicates on Mars and implications for early Martian climate. Nature 438, 623627.
Prieto-Ballesteros, O., Kargel, J.S., Fairén, A.G., Fernández-Remolar, D., Dohm, J.M. & Amils, R. (2006). Interglacial clathrate destabilization in Mars: possible contributing source of its atmospheric methane. Geology 34, 149152.
Priscu, J.C., Fritsen, C.H., Adams, E.E., Giovannoni, S.J., Paerl, H.W., McKay, C.P., Doran, P.T., Gordon, D.A., Lanoil, B.D. & Pinckney, J.L. (1998). Perennial Antarctic lake ice: an oasis for life in a polar desert. Science 280, 20952098.
Quinn, R.C. & Zent, A.P. (1999). Peroxide-modified titanium dioxide: a cemical analog of putative Martian soil oxidants. Orig. Life Evol. Biosph. 29, 5972.
Rathbun, J.A. & Squyres, S.W. (2002). Hydrothermal systems associated with martian impact craters. Icarus 157, 365372.
Rivkina, E.M., Friedmann, E.I., McKay, C.P. & Gilichinsky, D.A. (2000). Metabolic activity of permafrost bacteria below the freezing point. Appl. Environ. Microbiol. 66, 32303233.
Romanek, C.S., Grady, M.M., Wright, I.P., Mittlefehldt, D.W., Socki, R.A., Pillinger, C.T. & Gibson, E.K. Jr. (1994). Record of fluid–rock interactions on Mars from the meteorite ALH 84001. Nature 372, 655657.
Rohde, R.A. & Price, P.B. (2007). A new habitat in glacial ice: metabolism by solid-state diffusion to isolated microbes. Proc. Natl. Acad. Sci. U.S.A. 104, 16 59216 597.
Rosing, M.T. (1999). 13C-depleted carbon microparticles in >3700-Ma sea-floor sedimentary rocks from west Greenland. Science 283, 674676.
Roslev, P., Iversen, N. & Henriksen, K. (1997). Oxidation and assimilation of atmospheric methane by soil methane oxidizers. Appl. Environ. Microbiol. 63, 874880.
Rothschild, L.J. & Mancinelli, R.L. (2001). Life in extreme environments. Nature 409, 10921101.
Ruiz, J., Fairén, A.G., Dohm, J.M. & Tejero, R. (2004). Thermal isostasy and deformation of possible paleoshorelines on Mars. Planet. Space Sci. 52, 12971301.
Russell, N.J. (1990). Cold adaptation of microorganisms. Phil. Trans. R. Soc. London B Biol. Sci. 326, 595611.
Ryan, S., Dlugokencky, E.J., Tans, P.P. & Trudeau, M.E. (2006). Mauna Loa volcano is not a methane source: implications for Mars. Geophys. Res. Lett. 33, doi:10.1029/2006GL026223.
Ryan, C.S. & Kleinberg, I. (1995). Bacteria in human mouths involved in the production and utilization of hydrogen peroxide. Arch. Oral. Biol. 40, 753763.
Saffary, R., Nandakumar, R., Spencer, D., Robb, F.T., Davila, J.M., Swartz, M., Ofman, L., Thomas, R.J. & DiRuggiero, J. (2002). Microbial survival of space vacuum and extreme ultraviolet irradiation: strain isolation and analysis during a rocket flight. FEMS Microbiol. Lett. 215, 163168.
Sassen, R., Milkov, A.V., Ozgul, E., Roberts, H.H., Hunt, J.L., Beeunas, M.A., Chanton, J.P., DeFreitas, D.A. & Sweet, S.T. (2003). Gas venting and subsurface charge in the Green Canyon area, Gulf of Mexico; continental slope evidence of a deep bacterial methane source? Org. Geochem. 34, 14551464.
Scheffel, A., Gruska, M., Faivre, D., Linaroudis, A., Plitzko, J.M. & Schüler, D. (2006). An acidic protein aligns magnetosomes along a filamentous structure in magnetotactic bacteria. Nature 440, 110114.
Schopf, J.W. & Packer, B.M. (1987). Early Archean (3.3 billion to 3.5 billion-year-old) microfossils from Warrawoona Group, Australia. Science 237, 7073.
Schopf, J.W. (1993). Microfossils of the early Archean Apex Chert; new evidence of the antiquity of life. Science 260, 640645.
Schulze-Makuch, D. & Irwin, L.N. (2004). Life in the Universe: Expectations and Constraints, p. 172. Springer, Berlin.
Schulze-Makuch, D., Irwin, L.N., Lipps, J.H., LeMone, D., Dohm, J.M. & Fairén, A.G. (2005). Scenarios for the evolution of life on Mars. J.Geophys. Res. 110, E12S23, doi:10.1029/2005JE002430.
Schulze-Makuch, D., Dohm, J.M., Fan, C., Fairén, A.G., Rodriguez, J.A.P., Baker, V.R. & Fink, W. (2007). Exploration of hydrothermal targets on Mars. Icarus 189, 308324.
Schulze-Makuch, D., Turse, C., Houtkooper, J.M. & McKay, C.P. (2008). Testing the H2O2–H2O hypothesis for life on Mars with the TEGA instrument on the Phoenix Lander. Astrobiology 8, 205214.
Scott, E.R., Yamaguchi, A. & Krot, A.N. (1997). Petrological evidence for shock melting of carbonates in the Martian meteorite ALH84001. Nature 22, 377379.
Segura, T., Toon, O.B., Colaprete, A. & Zahnle, K. (2002). Environmental effects of large impacts on Mars. Science, 298, 19771980.
Sleep, N.H. & Zahnle, K. (1998). Refugia from asteroid impacts on early Mars and the early Earth. J. Geophys. Res. 103(28), 529544.
Squyres, S.W. et al. (2004). In situ evidence for an ancient aqueous environment at Meridiani Planum, Mars. Science 306, 17091714.
Stevens, T.O. & McKinley, J.P. (1995). Lithoautotrophic microbial ecosystems in deep basalt aquifers. Science 270, 450455.
Stöffler, D., Horneck, G., Ott, S., Hornemann, U., Cockell, C.S., Moeller, R., Meyer, C., de Vera, J.-P., Fritz, J. & Artemieva, N.A. (2007). Experimental evidence for the potential impact ejection of viable microorganisms from Mars and Mars-like planets. Icarus 186, 585588.
Tanenbaum, S.W. (1956). The metabolism of Acetobacter peroxidans. I. Oxidative enzymes. Biochim. Biophys. Acta 21, 335342.
Taylor, A.P., Barry, J.C. & Webb, R.I. (2001). Structural and morphological anomalies in magnetosomes: possible biogenic origin for magnetite in ALH84001. J. Microsc. 201, 84106.
Thomas-Keprta, K.L., Bazylinski, D.A., Kirschvink, J.L., Clemett, S.J., McKay, D.S., Wentworth, S.J., Vali, H., Gibson, E.K. & Romanek, C.S. (2000). Elongated prismatic magnetite crystals in ALH84001 carbonate globules: potential Martian magnetofossils. Geochim. Cosmochim. Acta 64, 40494081.
Thomas-Keprta, K.L., Clemett, S.J., Bazylinski, D.A., Kirschvink, J.L., McKay, D.S., Wentworth, S.J., Vali, H., Gibson, E.K., McKay, M.F. & Romanek, C.S. (2001). Truncated hexa-octahedral magnetite crystals in ALH84001: presumptive biosignatures. Proc. Natl. Acad. Sci. U.S.A. 98, 21642169.
Thomas-Keprta, K.L., Clemett, S.J., Bazylinski, D.A., Kirschvink, J.L., McKay, D.S., Wentworth, S.J., Vali, H., Gibson, E.K. & Romanek, C.S. (2002). Magnetofossils from ancient Mars: a robust biosignature in the martian meteorite ALH84001. Appl. Environ. Microbiol. 68(8), 36633672.
Tokuoka, K. (1993). A review: sugar and salt-tolerant yeasts. J. Appl. Microbiol. 74, 101110.
Tung, H.C., Price, P.B., Bramall, N.E. & Vrdoljak, G. (2006). Microorganisms metabolizing on clay grains in 3 km-deep Greenland basal ice. Astrobiology 6, 6986.
Ueno, Y., Yamada, K., Yoshida, N., Maruyama, S. & Isozaki, Y. (2006), Evidence from fluid inclusions for microbial methanogenesis in the early Archaean era. Nature 440, 516519.
Uwins, P.J.R., Webb, R.I. & Taylor, P. (1998). Novel nano-organisms from Australian sandstones. Amer. Mineral. 83, 15411550.
Vestal, J.R. (1988). Carbon metabolism of the cryptoendolithic microbiota from the Antarctic desert. Appl. Environ. Microbiol. 54, 960965.
von Sonntag, C. (1987). The Chemical Basis of Radiation Biology, p. 515. Taylor & Francis, London.
Vreeland, R.H., Rosenzweig, W.D. & Powers, D.W. (2000). Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal. Nature 407, 897900.
Walker, J.J., Spear, J.R. & Pace, N.R. (2005). Geobiology of a microbial endolithic community in the Yellowstone geothermal environment. Nature 434, 10111014.
Warren-Rhodes, K.A., Rhodes, K.L., Pointing, S.B., Ewing, S.A., Lacap, D.C., Gómez-Silva, B., Amundson, R., Friedmann, E.I. & McKay, C.P. (2006). Hypolithic cyanobacteria, dry limit of photosynthesis, and microbial ecology in the hyperarid Atacama Desert. Microb. Ecol. 52, 389398.
Wierzchos, J., Ascaso, C. & McKay, C.P. (2006). Endolithic cyanobacteria in halite rocks from the hyperarid core of the Atacama Desert. Astrobiology 6, 415422.
Wilson, S.A., Howard, A.D., Moore, J.M. & Grant, J.A. (2007). Geomorphic and stratigraphic analysis of Crater Terby and layered deposits north of Hellas basin, Mars. J. Geophys. Res. 112, E08009, doi:10.1029/2006JE002830.
Winfrey, M.R. & Zeikus, J.G. (1977). Effect of sulfate on carbon and electron flow during microbial methanogenesis in freshwater sediments. Appl. Environ. Microbiol. 33, 275281.
Yen, A.S., Kim, S.S., Hecht, M.H., Frant, M.S. & Murray, B. (2000). Evidence that the reactivity of the Martian soil is due to superoxide ions. Science 289, 19091912.
Zent, A.P. & McKay, C.P. (1994). The chemical reactivity of the Martian soil and implications for future missions. Icarus 108, 146157.
Zolotov, M.Y. & Shock, E.L. (2005). Formation of jarosite-bearing deposits through aqueous oxidation of pyrite at Meridiani Planum, Mars. Geophys. Res. Lett. 32, doi:10.1029/2005GL024253.
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