Methane on Mars: What Does It Mean?

NASA's Astrobiology Magazine has posted the final installment in a four-part series that examines the potential connections between methane and life on Mars. Methane on Earth is mostly produced by living organisms, but it isn't clear whether the same can be said for methane on Mars. Scientists have determined that Martian methane must be younger than 600 years old and must be produced at a rate of 126 metric tons per year to maintain present levels of methane in the atmosphere. Extraterrestrial methane sources have been estimated to be miniscule. While a biogenic methane source is intriguing, methane could alternatively be seeping out from abiogenic sources within or below the rocky crust much like methane-rich vents found on the seafloor at mid-ocean ridges (see Element FYI post on the Lost City vent field). If the source is biogenic, scientists seem to favor the idea that anaerobic microbes living at or beneath the rocky surface could be the source--hardly the little green men in science fiction films.