March 16, 2008

Saturn’s Moon Tethys May Have Housed Liquid Ocean

One of Saturn's moons may have been home to a body of water, according to scientists who reported their findings at the 39th Lunar and Planetary Science Conference in Houston.

With a density similar to pure ice, researchers think that Tethys underwent tidal heating, followed by cooling which could have been responsible for forming the Ithaca Chasma.

Erinna Chen and Francis Nimmo, from the University of California, Santa Cruz, proposed that it was Tethys' orbital interaction with Dione, another of Saturn's moons caused friction which heated Tethys' core.

They said it was when this interaction was broken that Tethys cooled off, thus freezing the ocean and forming the Ithaca Chasma.

"We have a large rift system that brought water to the surface, so it seems likely that this happened," Ms Chen explained.

She said that the team is unable to determine the depth of the moon's ocean, but speculated that it may have been 100km deep at some point in Tethys' history.

Other icy planets thought to have a subsurface ocean include Jupiter's moons Europa and Callisto, while the idea that Saturn's moon Enceladus may have liquid water beneath its surface has been met with recent criticisms.


Image Caption: One of the most exciting features of Tethys (and of the whole Saturnian system as well) is Ithaca Chasma, a huge trench which extends from near the north pole down almost all the way to the south pole. It's average width is 100 kilometers (60 miles) and is 4-5 kilometers (2-3 miles) deep. This artist's rendering is drawn from the lip of the large chasm looking into it, with Saturn in the background. By David Seal - Courtesy NASA


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39th Lunar and Planetary Science Conference

University of California, Santa Cruz