dusty writes "A recent hypothesis paper entititled 'Martian CH4: Sources, Flux, and Detection' delves into the production of methane on Mars. This hypothesis compares Mars with South Africa, and draws the conclusion that the radiolysis of martian ice and water while reacting with carbon dioxide can produce enough methane to account for recently observed concentrations. Methane is important because it is hard to explain. It has a short half-life and must be replenished frequently. As recently as 2005 the public line from NASA/JPL was that the methane could be produced by volcanism. Mars' dormant Olympus Mons is the largest volcano in the solar system but auspiciously quiet. A recent study from NOAA throws into question the whole idea stating, 'If Mauna Loa is a valid terrestrial analog, our findings suggest that volcanic activity is not a significant source of methane to the Martian atmosphere.'"