Exploration for Evidence of Habitable Environments and Life on Mars Can Benefit from Research in Analog Environments

Abstract:

Analog studies help to understand the processes that might sustain any habitable environments on Mars and the attributes of organisms that might have inhabited them. These studies must consider key differences between Mars and Earth, for example, the ways that tectonics, impacts, hydrologic cycles, and aeolian processes have interacted to shape climate, the conditions in the near subsurface, and the processes that can preserve any evidence of any past habitable environments and life. Key questions include the following: How can we characterize Martian geochemical cycles of biogenic elements? What is the minimum chemical water activity of Mars-relevant aqueous solutions that might sustain the propagation by life as we know it? Can life persist inside rocks that have been altered isochemically at relatively low water/rock values? What are the minimum combinations of free energy and power needed to sustain life in Mars-relevant environments? Given the pervasive harsh conditions at the Martian surface, where and how can we seek evidence of any extant life? What kinds of nonbiological features that mimic biosignatures might be produced in potentially habitable Martian environments? Which methods can most effectively resolve Earthly contamination from potential Martian biosignatures in situ? What biosignatures might be produced by subsurface life and how can they be distinguished from abiotic features? How might we recognize evidence of any “life as we DON’T know it?” For future landing site selection, how can remotely sensed features be related more effectively to key attributes of habitable environments such as past availability and persistence of water, potential sources of biochemical energy, and favorable environmental conditions? Which Martian processes and environments are most favorable for preservation of evidence of any past environments and biosignatures? How can deposits that might be favorable for preservation be found and characterized from orbit? How can we assess radiation hazards for the preservation of biosignatures in order to guide sample selection during landed missions? The need to understand such issues in a Martian context should influence the design and implementation of analog studies.