Methane in plumes of Saturn's moon Enceladus: Possible signs of life?

A study concludes that known geochemical processes can't explain the levels of methane measured by the Cassini spacecraft on Saturn's icy moon. While the paper by no means suggests that life exists on Enceladus, the results would be consistent with microbial activity similar to that known to occur at hydrothermal vents in Earth's oceans.