Scientists find evidence of water on Saturn moon

LOS ANGELES -- A few interplanetary close-ups, and an icy, tiny, shiny moon of Saturn has gone from solar system wallflower to one of the most promising places to look for liquid water -- and maybe life -- beyond Earth.

The orbiting Cassini spacecraft has found a frigid, massive Yellowstone on the moon Enceladus, with miles-high geysers spewing ice particles and water vapor. The surprising images released Thursday do not show any liquid water, but scientists believe it's hidden in underground reservoirs close to the surface.

The discovery has prompted some scientists like Cynthia Phillips of the SETI Institute to call for further study of Enceladus as a potential place in the solar system that could support extraterrestrial life.

"Liquid water is one of the most essential elements that you need for life" said Phillips, who had no role in the discovery. "All of life as we know it depends on liquid water."

Torrence Johnson, a Cassini scientist from the Jet Propulsion Laboratory in Pasadena, said the Enceladus findings mark the first time scientists have seen evidence of water in liquid form so close to the surface on another body beyond Earth.

The findings were published in Friday's issue of the journal Science.

Scientists believe Mars and Jupiter's icy moons might have -- or once might have had -- conditions hospitable to life. But the evidence of water is indirect: Studying Martian rocks has led them to believe water once flowed on that planet, and magnetic readings of Jupiter's moon Europa strongly suggest its icy surface is hiding an ocean of water.

Enceladus could have both liquid water and a stable heat source, two of the several ingredients that scientists generally agree are needed for life.

The geysers are believed to spring from underground reservoirs of liquid water that are under high pressure. Cassini imaging scientist Carolyn Porco of the Space Science Institute said the venting has probably been going on for at least several thousand years, perhaps indicating a lasting heat source underground.

If Enceladus does harbor life, it probably consists of microbes or other primitive organisms capable of living in extreme conditions, scientists say.

David Morrison, a senior scientist at NASA's Astrobiology Institute, cautioned against rushing to judgment about whether the tiny moon could support life. "It's certainly interesting, but I don't see how much more you can say beyond that," Morrison said.

Enceladus measures 314 miles across and is the shiniest object in the solar system. Enceladus was long thought to be cold and still, in part because it receives so little sunlight. But scientists later found that it is geologically active.