Mars is an exciting, and comparatively accessible target for astrobiological studies aimed at detection of current or past extraterrestrial life. Our NAI team will analyze the evolution of the Martian hydrosphere and surface topography to understand the history of water distribution and investigate atmospheric processes that may have contributed to a UV shield. Our objective is to identify the types of sites on Mars that experienced long-term fluid flow as these may be, or have been, conducive to life.  We will develop models for Mars planetary evolution to constrain the timing and scale of hydrosphere development and subsurface water circulation. We will couple these hydrosphere models to geomorphological models based on terrestrial field site analyses and experimental studies to allow detailed interpretation of Mars surface features. This will permit analysis of the history, form, and timing of fluid flow events that shaped the planetary surface and determination of the factors that control them. In parallel, we will explore atmospheric processes that could have contributed to a UV shield and conduct spectroscopic studies to constrain Mars surface mineralogy.

Life on Mars may have developed in redox gradients between reduced basaltic rocks or minerals and oxidized fluids and/or gases.   Element cycling in these systems could underpin (or could have underpinned) a substantial biosphere. We will characterize biomes that develop in Earth environments chosen to resemble potential Martian habitats. We will focus on terrestrial chemoautotrophically-based ecosystems at sites of groundwater discharge in basaltic rocks and habitats in volcanically-hosted metal sulfide-rich deposits as these appear to offer the best combination of energy sources, sustained water flow, and protection from UV radiation. We will characterize these habitats in terms of their population structure, aqueous geochemistry, mineralogy, and isotopic signatures. Parallel laboratory-based studies will explore the ranges of temperature, concentration, and pH consistent with life in these habitats and biochemical analyses will explore the factors that set these limits.  We will analyze the structure, elemental and isotopic composition, microstructure, morphology, and distribution of minerals generated by, or impacted by, life in these rock hosted systems so as to develop and test potential new biosignatures. Parallel inorganic experiments will be conducted in order to resolve non-biological features and to examine changes in mineralogical biosignatures with time.  We will carry out robot-based sampling and in situ analyses of terrestrial sites so as to develop methods for dealing with the challenges of remote geomicrobiological investigations. Our work will provide constraints for selection of optimal sites for future Mars exploration and methods for sample analysis.