Molecular Structure and Dynamics of Titan’s Minerals and their Interfaces with Liquid Hydrocarbons

Abstract:

Titan’s shores, lake beds, and river beds are predicted to be coated with molecular minerals – crystalline solids composed of small organic molecules. On Earth, mineral-water interfaces are important in terrestrial geochemistry and are hypothesized to play a key role in prebiotic chemistry. In complete analogy, molecular mineral-liquid hydrocarbon solution interfaces are expected to play a critical role in Titan’s geochemistry, as well as prebiotic chemistry on Titan’s surface. To fully understand the role of these interfaces in chemical processes, a molecular-level picture is needed. In this work, we use molecular simulations to characterize the structure and dynamics of several molecular minerals hypothesized to exist on the surface of Titan. We find that, because of Titan’s low surface temperature, the quantum mechanical nature of nuclei can substantially enhance dynamic processes within the solid. We discuss how these enhanced dynamics can facilitate transport of material through the solid, as well as their influence on chemistry at interfaces formed by these minerals and liquid methane and ethane solutions. We conclude with a discussion of potential astrobiological implications of our work.