Making Martian Methane via Surface H Release

In recent years, NASA's Curiosity mission has delivered some interesting photochemical findings, specifically, an unexplained methane abundance in the atmosphere. Because methane is quickly consumed via exposure to UV radiation and other chemical reactions, the discovery of trace methane at concentrations from several ppb (Mumma et al. 2003) to 10ppb (Krasnopolskya et al. 2004) indicates a localized production of methane at the surface. In addition, the variance in measured methane concentration supports seasonal production. It is possible that geologic or surface processes are causing this reportedly high methane abundance in the Martian atmosphere. Ammonia (NH3) or dissolved ammonium (NH4+) from groundwater, hydrogen (H2) release from sublimation, and direct CH4 release or production are possible sources for substantial methane accumulation. Release of either NH3 or H2 would deliver H atoms to the atmosphere, which then helps produce CH4 through atmospheric reactions of H with CO and CO2. This consequently creates an opportunity for methane production if the gas gets released at fissures during warm seasons. We used a photochemical model to simulate the Martian atmosphere in order to determine if any of these hypotheses coincide with Curiosity data gathered by SAM, including the measurements of gases other than CH4.