Just an update on the significance of the Martian methane story from Open the Future:
While both geology and biology can produce methane on Earth, inorganic production of methane is generally associated with volcanic and tectonic activity, none of which has been witnessed on Mars (it's clear that Mars was once geologically active, but there's little or no evidence of current vulcanism). In addition, the three source areas each have very different geologies, further complicating the argument that the methane comes from geological activity. Finally, the 'serpentinization' process on Earth tends to plug up sources of methane. NASA's Lisa Pratt, one of the scientists delivering the press conference today, argues that while this isn't positive proof that the methane comes from biological activity, it does make the geological argument harder to sustain and makes the biological argument 'more plausible.'
We know that organic and heat-producing processes are active elsewhere in the solar system - enormous volcanoes on Io, carbon lakes on Titan, potentially hidden oceans on Europa and vents spewing water ice from Enceladus. Most have been observed at close range by robotic missions.
It would be hard to overestimate the impact that confirmation of life in any form would have for those of us on this floating blue sphere, and departing NASA administrator Mike Griffin recently said, in fact, that he believes unintelligent life will be discovered on another planet during his lifetime.
'I would be very surprised if we didn't find life elsewhere, and frankly I expect to live to see it,' Griffin said. 'I would be surprised to find that life never originated on Mars, and I wouldn't be terribly surprised to find dormant or quiescent life underground,' he added.