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An astrobiological perspective on Meridiani Planum |
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| Authors: | Andrew H Knoll Michael Carr David J Des Marais Woodward W Fischer Scott M McLennan Christian Schröder Nicholas J Tosca |
| Institution: | a Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA b United States Geological Survey 345 Middlefield Rd., MS 975, Menlo Park, CA 94025, USA c Ma Lockheed Martin Corporation, MS8000, PO Box 179, 12257 State Highway 121, Littleton, CO 80127, USA d NASA Ames Research Center, M/S 239-4, Moffett Field, CA 94035-1000, USA e Department of Geological Sciences, Arizona State University, Tempe, AZ 85287-1404, USA f Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA g Department of Geosciences, State University of New York, Stony Brook, NY 11794, USA h Malin Space Science Systems, PO Box 910148, San Diego, CA 92191, USA i Institut für Anorganische und Analytische Chemie, Johannes Gutenberg-Universität, Staudinger Weg 9, D-55128 Mainz, Germany j Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA k Department of Physics, University of Alabama, Birmingham, AL 35294, USA |
| Abstract: | Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations have repeatedly adapted to low pH and both episodic and chronic water limitation, suggesting that, to a first approximation, the Meridiani plain may have been habitable during at least part of the interval when deposition and early diagenesis took place. On the other hand, the environmental conditions inferred for Meridiani deposition would have posed a challenge for prebiotic chemical reactions thought to have played a role in the origin of life on Earth. Orbital observations suggest that the combination of sulfate minerals and hematite found in Meridiani rocks may be unusual on the martian surface; however, there is reason to believe that acidity, aridity, and oxidizing conditions were broadly distributed on ancient Mars. When these conditions were established and how much environmental heterogeneity existed on early Mars remain to be determined. Because sulfates and iron oxides can preserve detailed geochemical records of environmental history as well as chemical, textural and microfossil signatures of biological activity, Meridiani Planum is an attractive candidate for Mars sample return. |
| Keywords: | Mars Meridiani Planum Astrobiology Environmental history Microbiology |
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