This illustration shows the ways in which methane from the subsurface might find its way to the
surface where its uptake and release could produce a large seasonal variation in the atmosphere
as observed by Curiosity. Potential methane sources include methanogenesis, UV degradation of
organics, or water-rock chemistry; and its losses include atmospheric photochemistry and surface
reactions. Seasons refer to the northern hemisphere. The plotted data is from Curiosity's TLSSAM
instrument, and the curved line through the data is to aid the eye. This material relates to a paper that appeared in the date, issue of Science, published by AAAS. The paper, by C.R. Webster at NASA Jet Propulsion Laboratory in Pasadena, CA, and colleagues was titled, "Background levels of methane in Mars' atmosphere show strong seasonal variations."
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