2005 Annual Science Report
Virtual Planetary Laboratory (JPL/CalTech) Reporting | JUL 2004 – JUN 2005
Exploring Conditions for Habitability on Mars
In this task we explored long-term climate, surface and sub-surface characteristics of Mars, including the effects of obliquity changes, and looked for evidence of snow/ice interactions with the atmosphere on Mars today.
We have used a 1 Gyr integration of the Martian orbit and a seasonally resolved energy balance climate model (the NASA Ames General Circulation Model (Haberle et al., 2003) to understand Martian atmospheric pressure evolution over long periods. We found that the Martian atmospheric pressure is remarkably static over time, and decreases both at high and low obliquity. We also explored the distribution of potential wind surface erosion with respect to orbital parameter variations, and quantified the sensitivity of wind erosion to changes in global mean surface pressure.
Water ice is believed to exist in the regolith over much of the Martian surface, and might provide a water/ice boundary that could harbor microorganisms .To determine the sensitivity of this putative water/ice boundary to seasonal and orbital cycle changes we used a latitude-dependent regolith diffusion model that computes subsurface temperatures (to 3-6 km) and tracks the water/ice boundary. Using the calculation of Mars’ orbit over 1 billion years, we show the boundary is largely unaffected by changes in the orbital cycle, except during prolonged events of extreme obliquity. We also used the model to compute molecular diffusion of methane in the regolith, and use recent observations of atmospheric methane abundance to constrain Mars’ potential subsurface ecosystem.
Data on Korelev crater from the Mars Odyssey Thermal Emission Imaging System, and Thermal Emission Spectrometer (TES) were combined with models of annual surface temperature variations to determine the nature and behavior of deposits within the crater. This work may help constrain polar processes, and provide context for the Phoenix polar lander. TES spectra were also used to monitor atmospheric water vapor levels near suspected snowpack sites, but no interaction above the background regolith was found.
PROJECT INVESTIGATORS:John Armstrong
PROJECT MEMBERS:Francis Nimmo
RELATED OBJECTIVES:Objective 1.2
Indirect and direct astronomical observations of extrasolar habitable planets