Exobiology and Evolutionary Biology

Mars Subsurface Warming at Low Obliquity: Effects on the State and Distribution of Water (2)

PI: Stephen Wood

This research proposal is motivated by our recent study (Wood and Griffiths, 2007) that demonstrated how the collapse of the Martian atmosphere, which is expected to occur during periods of low obliquity, can lead to warming in the subsurface by 50K or more. This warming is caused by the decreased thermal conductivity of porous regolith at low pressures, which can effectively block the geothermal heat flux from reaching the surface. While the Wood and Griffiths (2007) study mapped out the dependence of the magnitude of the warming on the thicknesses and physical properties of subsurface layers, it did not model the effects of the warming on Martian ground ice nor evaluate the potential for generating liquid water, brines, or acids. That is the goal of the research proposed here.
Liquid water is thought to be a key requirement for the existence of life on other planets, and this subsurface warming mechanism has the potential for periodically generating warm wet conditions in the upper regolith of Mars that could be exploited by Martian life-forms throughout its history, including several times with the past 1 Myr.
In the study proposed here, we will use a combination of theoretical, experimental, and terrestrial field studies at a Mars analog site (the Antarctic Dry Valleys) to extend, test, and validate a coupled, non-steady-state, 1-D model of heat and vapor diffusion in the icy Martian regolith. We will then use this model to simulate the evolution of subsurface
temperatures and volatiles on Mars over timescales of 10 million years, depths of up to 20 km, and at all latitudes to explore and quantify the potential effects of obliquity and atmospheric pressure variations.