Modeling Complex Geochemical Processes in the Outer Planets Region

Affiliation(s) PI Project period Funded by
DEES Marion, Giles M 12/15/2009 - 12/14/2012 National Aeronautics & Space Administration

Project Description

NASA's mission is driven, in part, "to explore the Universe and search for life." In this proposal, we address scientific questions such as: What roles have pressure, temperature, and chemical composition played in controlling potential environments for life on Titan and Enceladus? Why are observations of ammonia on objects in the outer Solar System so sparse? Did ammonia evolve into ammonium salts or N2 gas? How do pressure and temperature control the stability of hydrocarbon mixtures on Titan? Can gas hydrates or gas bubbles in ice explain geyser eruptions on Enceladus and Triton? This proposal builds on the FREZCHEM model that was developed to quantify low-temperature, low- and high-pressure aqueous chemistries. The recent Galileo mission to the Jovian System and the current Cassini-Huygens mission to Saturn and its satellites has stimulated considerable new thinking about the geochemical evolution of Enceladus, Titan and other icy bodies. The FREZCHEM model is ideally structured to explore the subsurface geochemistries of these objects, but lacks some essential components such as ammonia-water and ammonium salts, N2 gas hydrates, an extreme low-temperature range, and organic chemistries needed for some objects. The specific objectives are to (1) add ammonia-water and ammonium salt equilibria to FREZCHEM, (2) add pure N2 gas hydrate and N2 mixtures with CO2 and CH4 to FREZCHEM, (3) incorporate organic chemistries such as methane and ethane into a new low-temperature model (CRYOHCHEM), and (4) apply these new model parameterizations to Enceladus, Titan, Triton, and other outer planet bodies. These updates will make the FREZCHEM and CRYOHCHEM models better suited for exploring alternative explanations for the complex geochemistries of, and the prospects for life in, outer planet bodies such as icy satellites, comets, main belt asteroids, and Kuiper Belt Objects.