Organic Geochemistry on Titan

Abstract: The Cassini-Huygens mission has revealed Saturn’s largest moon Titan to be a remarkably Earth-like world, with a diverse landscape of rivers, lakes and seas, vast dune fields, plains and mountains. Unlike Earth, however, Titan’s visible surface is dominated by solid organic materials at cryogenic temperatures, and altered by the action of liquid methane and ethane. Our group at JPL focuses on understanding the fundamental chemical processes that lead to this varied landscape. Dissolution and solubility of solid organics in the lakes and seas leads to erosion of Titan’s surface, and the precipitation of dissolved materials as the lakes dry can result in organic evaporite deposits.  Our work shows that these deposits likely contain novel crystalline forms only possible at cryogenic temperatures, constituting a new class of cryogenic organic minerals whose properties are mostly unknown.  We use Raman spectroscopy and X-ray diffraction to elucidate the structure and the nature of the interactions between these minerals, and relate their properties to Titan’s geology and evolution.  Titan’s assorted environments and array of organic molecules are intriguing as a venue for prebiotic chemistry, and make Titan an important target for future astrobiology missions.