Saturn Moon Revealed as Watery World

Dec. 17, 2008 -- Evidence is mounting that Saturn's moon Enceladus has water somewhere beneath its frozen surface, analysis of recent flybys by the Cassini spacecraft shows.

"It's virtually impossible that we don't have liquid water some place in the body," Carolyn Porco, the head of Cassini's imaging team at the Space Science Institute in Boulder, Colo., said during a press conference at the American Geophysical Union conference in San Francisco this week.

One of the biggest surprises of Cassini's ongoing mission at Saturn was the discovery of geyser-like jets shooting streams of organics-laced ice and water vapor out into space. Cassini flew as close as 15.5 miles above one of Enceladus' fractures, warm spots scientists call "tiger stripes," during its last pass over the moon in October.

The jets of ice particles of water vapor spew from vents inside the fractures.

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Scientists have enough information to conclude that the face of Enceladus changes over time, with some vents opening and others closing due to tectonic forces similar to what occurs on the floors of some of Earth's oceans where volcanic material wells up to create new crust.

On Enceladus, however, the spreading is almost entirely in one direction, like a conveyor belt, rather than multi-directional like on Earth.

"We are not certain about the geological mechanisms that control the spreading," said Paul Helfenstein with Cornell University in New York.

"It's very unusual. You wouldn't find something like this on Earth."

The mechanism is similar enough to Earth-like systems, however, to suggest that subsurface heat and convection are involved, he added.