Mars Methane Detection and Variability at Gale Crater Measured by the TLS instrument in SAM on the Curiosity Rover

Over the last several years, Earth-based telescopic and Mars orbit remote sensing instruments have reported significant abundances of methane on Mars ranging to tens of parts-per-billion by volume (ppbv). These observations have reported "plumes" or localized patches of methane with variations on timescales much faster than model predictions, leading to speculation of sources from sub-surface methanogen bacteria, geological water-rock reactions, degassing of infalling comets, or UV degradation of micro-meteorites or interplanetary dust. Using the Tunable Laser Spectrometer (TLS) in the Sample Analysis at Mars (SAM) instrument suite on Curiosity, we report in situ detection of methane at background levels of ~0.7 ppbv and also in an episodic release at ten times this value. We will discuss the mechanisms that are believed contributing to these two regimes, report new measurements made since the publication in Science1, and discuss the evidence and implications for seasonal vs. episodic release. Reference 1. "Mars Methane Detection and Variability at Gale Crater", C. R. Webster et al., Science, 347, 415-417 (2015). The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).