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Abstract

Recently, we have begun to hear more and more about news coming from Mars. With the recent confirmation of evidence of liquid water in Mars' past, evidence indicating liquid water in Mars' present, and as many missions planned for this decade and the next than have successfully reached the planet in the last 40 years, life on Mars is beginning to become a more relevant issue in our study of the planet. Although there have been no indications of multicellular life on Mars, there may be a possibility of microbial life in the subsurface. Since it appears that all of the necessary elements for life on Mars exist, it is instrumental for scientists to analyze terrestrial ecosystems that might be analogous to those on Mars. Life on Earth has shown a great amount of diversity in ability to survive extreme environments utilizing a stunning array of energy sources, electron donors, electron acceptors, salinity, pressures, and temperature ranges. From the study of Mars-like terrestrial ecosystems, some scientists have suggested that the methanogens would be a possible candidate to survive Mars' subsurface conditions. There are various Mars' conditions that could be tested on Earth to confirm or deny the methanogens' ability to survive on the planet. Since the survival of methanogens depends on the presence of liquid water, which would probably be seasonal at best on Mars, their ability to survive desiccation will be key in their potential to inhabit Mars' subsurface. In this research, the methanogens Methanobacterium formicicum, Methanothermobacter wolfeii, and Methanosarcina barkeri were grown on JSC Mars-I soil simulant and exposed to varying times of desiccation. Since the byproduct of the methanogens' growth is methane, methane was measured in the head gas of the samples upon rehydration and incubation. These measurements were used to determine survival. The methanogens studied were capable of survival and subsequently methane production upon rehydration after all of the periods of desiccation tested. M. Formicicum was tested over periods of 10 and 27 days, while M. wolfeii and M. barkeri were tested over periods of 10 days. These results support the hypothesis that methanogens could survive in Mars' subsurface if liquid water were present. The methanogens could be a key ingredient in the terraforming of Mars, and at this point remain an increasingly possible candidate for past, present, or future Martian life.

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