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Project Progress

We are trying to understand the habitability of Mars as a way of learning about habitability of planets in general. During the past year, we have made progress on two different approaches.

First, we have been examining potential micro-environments on Mars in which liquid water could exist even at sub-zero temperatures. In particular, we are looking at the ability of thin films of liquid water to form at temperatures as high as -20°C in high-latitude ground ice or polar deposits of water ice. These temperatures can occur at moderate and high obliquity values, meaning that liquid water could have been accessible essentially at the surface as recently as a few million to a few tens of millions of years ago on Mars—essentially at the present epoch. Organisms can survive in these environments, so it is conceivable that evidence for Martian life could be found at relatively shallow depths below the surface (e.g., centimeters to meters, rather than hundreds of meters).

Second, we are looking at the geochemical environment in which organisms might live on Mars. We have been examining in detail the ability of organisms to get energy to support metabolism from geochemical reactions in Martian hydrothermal systems. We are using geochemical models of the Gibbs energy available from redox reactions, using Martian meteorite compositions to constrain our rock composition and using a variety of reasonable assumptions about the composition of the water with which it reacts. Our results suggest that abundant energy is available, especially in potential aqueous systems that might involve relatively reduced rocks (such as olivine-rich rocks).

Results on these tasks appear in two manuscripts that are in press in the journal Astrobiology.