Cassini Pluming

The Cassini spacecraft exploring Saturn and its domain whizzed through the plumes of Enceladus on November 2. The plumes erupt from the south polar region of the tiny moon, which is only about 310 miles in diameter.

Enceladus, so small and so far from the Sun, would seem a highly unlikely place to find life. The plumes, however, contain water vapor, sodium, and organic chemicals-- similar in composition to the geyser eruptions of Old Faithful in Yellowstone National Park. Water vapor suggests a ready source of liquid water. The plumes themselves demand an energy source to propel them. Put liquid water and enerrgy together with organic chemicals and enough time, and you get organic compounds. Organic compounds are the building blocks of life.

Several moons orbiting Jupiter and Saturn are now seen as having some potential to support life. Saturn's Titan, indeed, may rival Mars as a likely place to find life in the Solar System beyond Earth. Jupiter and Saturn themselves, in their deep, complex, active atmospheres, likely have layers miles thick and stable over substantial periods of time that could support some kind of life. Carl Sagan suggested such a possibility years ago, when there was no real case to be made for life beyond Mars. That case seems to be strengthening steadily.