Saturn Moon May Have Ocean of Water

[March 21, 2008]  PASADENA, Calif. (AP) -- Scientists say they have found the best evidence yet that an ocean of liquid water may be hidden below the surface of Saturn's giant moon Titan. If the results are confirmed, it would be a starting point for further study into whether the ocean could be capable of supporting life.

The latest evidence of an underground ocean is indirect and is based on analyzing radar images and Titan's spin rates from observations by the international Cassini spacecraft from 2004 to 2007.

Scientists found several dunes, channels, lakes and other geological features on Titan's surface drifted from a fixed point, likely as a result of an increase of the moon's rotation.

Using modeling techniques, scientists determined that winds in Titan's atmosphere exert a torque on the lunar surface and concluded there must be a liquid ocean below. Such a large shift would not be seen if the interior was a solid core, they said.

"Only because the crust is thin and decoupled from the deep interior by this ocean is the wind able to move the crust around as much as we see," lead author Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory said in an e-mail to The Associated Press.

The findings were described in Thursday's issue of the journal Science.

If an internal ocean exists on Titan, it would likely be buried below 62 miles of ice and made of water and traces of ammonia, Lorenz said.

In an accompanying editorial, Christophe Sotin of the Jet Propulsion Laboratory in Pasadena and Gabriel Tobie of the University of Nantes in France wrote that further observations are needed to test for the existence of an underground ocean.

"If the interpretation that Titan has an internal ocean is supported by other measurements, then Titan is a place where organics are produced and where liquid water is present," they wrote.

The presence of an underground ocean could help explain how Titan replenishes methane in its smoggy atmosphere.

Titan is one of the few objects in the outer solar system with a significant atmosphere, and scientists have long puzzled over the source of its methane. They have theorized that methane is locked in the ice covering and released through processes involving an ocean below.

The Cassini probe, a project of NASA and international partners, previously found evidence of hydrocarbon seas on Titan's surface.

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On the Net:

Cassini mission: http://saturn.jpl.nasa.gov/home/index.cfm

Science: http://www.sciencemag.org/

[Associated Press; By RAY LILLEY]

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