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Vast ocean found under surface of Saturn moon

April 3: Scientists have determined the shape and size of an underground ocean long suspected to lie sandwiched between the icy surface and the rocky core of Enceladus, one of Saturn’s dozens of moons.

Data sets sent by Cassini, a spacecraft orbiting the Saturnian system, suggest that the sub-surface ocean lies about 30km to 40km below the moon’s surface of ice, a team of Italian and US scientists said today.

The scientists used gravity studies by Cassini to trace the hidden ocean and have published their findings today in the US journal Science. The US National Aeronautics and Space Administration has said the fresh evidence for the sub-surface ocean validates the inclusion of Enceladus, a 300-km diameter moon, among the most likely places in the solar system to be hosting microbial life.

“Everybody was fairly sure there was liquid water under the surface, we now know the size and geometry of the ocean,” Luciano Iess, a physicist at the Sapienza University of Rome told The Telegraph via telephone.

Astronomers have in the past detected evidence for subsurface oceans on Europa and Ganymede, two of Jupiter’s moons, and on Titan, Saturn’s largest moon. The ocean on Enceladus appears to extend to a depth of about 8 to 10km, Iess said.

“It’s sandwiched between the ice and silicate rock that makes up the moon’s core,” Iess said. “The contact between rock and water raises the possibility of chemical reactions at the interface of water and silicates.”

The scientists believe tidal heating — brought about by the gravitational tugs of Saturn while the moon orbits the planet — has melted ice to create the sub-surface ocean which appears to extend from the south pole region to about 50 degrees south latitude.

The ocean explains jets of water vapour that were observed to be shooting out of the moon’s surface near its south pole in 2005.

The study suggests that the ocean has about as much water as Lake Superior, North America’s largest fresh water lake.

 
 
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