“I think pretty much everyone can agree that finding life anywhere else in the solar system would be the scientific discovery of the millennium.”
In a presentation to the American Geophysical Union on December 15, Professor Francis Nimmo of the University of California at Santa Cruz discussed the habitability and prospects for finding life on the icy moons of Jupiter and Saturn, in particular on Europa and Enceladus. For a quick synopsis of his remarks, see Icy Moons of Saturn and Jupiter May Have Conditions Needed for Life in Science Daily:
“Enceladus is so small and its ice so thin that scientists expect its oceans to freeze periodically, making habitability less likely, Nimmo said. Europa, however, is the perfect size to heat its oceans efficiently. It is larger than Enceladus but smaller than moons such as Ganymede, which has thick ice surrounding its core and blocking communication with the exterior. If liquid water exists on Ganymede, it may be trapped between layers of ice that separate it from both the core and the surface.
“The core and the surface of these moons are both potential sources of the chemical building blocks needed for life. Solar radiation and comet impacts leave a chemical film on the surfaces. To sustain living organisms, these chemicals would have to migrate to the subsurface oceans, and this can occur periodically around ice fissures on moons with relatively thin ice shells like Europa and Enceladus. Organic molecules and minerals may also stream out of their cores, Nimmo said. These nutrients could support communities like those seen around hydrothermal vents on Earth.”
For further details, see the original UC Santa Cruz press release, and a related UCSC press release on the mechanism of Enceladus’ plumes, Frictional Heating Explains Plumes On Saturn’s Moon Enceladus, from May 2007.