- The Washington Times - Thursday, March 9, 2006

LOS ANGELES — The orbiting Cassini spacecraft has spotted what appear to be water geysers on one of Saturn’s icy moons, raising the tantalizing possibility that the celestial object harbors life.

The images from the moon Enceladus represent some of the most direct and dramatic evidence yet of liquid water beyond Earth. Previous claims have been mostly circumstantial.

Excited by the discovery, some scientists said Enceladus should be added to the shortlist of places within the solar system most likely to have extraterrestrial life.

Saturn is about 800 million miles from Earth. Enceladus measures 314 miles across and is the shiniest object in the solar system.

Cassini recently snapped high-resolution images showing geyserlike eruptions of ice particles and water vapor at Enceladus’ south pole, scientists said. The pictures do not show any liquid water, but scientists surmise that the ice and vapor are coming from underground reservoirs of liquid water near the surface.

“We have the smoking gun” that proves the existence of water, said Carolyn Porco, a Cassini imaging scientist from the Space Science Institute in Boulder, Colo.

Torrence Johnson, a Cassini scientist from the Jet Propulsion Laboratory in Pasadena, Calif., said this marks the first time that scientists have seen evidence of liquid water so close to the surface on another body.

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

The findings were published in today’s issue of the journal Science.

David Morrison, a senior scientist at NASA’s Astrobiology Institute, cautioned against rushing to judgment about whether the tiny moon could support life. Scientists generally agree that habitats need several ingredients for life to emerge, including water, a stable heat source and the right chemical recipe.

“It’s certainly interesting, but I don’t see how much more you can say beyond that,” Mr. Morrison said.

Scientists think Mars and Jupiter’s icy moons might have — or once had — conditions hospitable to life. But the evidence is indirect. In the case of Mars, scientists have never seen any flowing water. But based on their study of rocks, they think water once existed there. They say magnetic readings of Jupiter’s moon, Europa, strongly suggest that it has an ocean of liquid water, covered by ice.

The water on Enceladus is thought to come from underground reservoirs that are under high pressure. It’s thought the venting probably has been going on for at least several thousand years, perhaps indicating a lasting heat source underground.

Cassini found that the geysers are mostly made up of water and ice particles with significant amounts of carbon dioxide and trace amounts of methane — all of which probably help to replenish the moon’s atmosphere.

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