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Web Date: April 3, 2014

Liquid Water Ocean Lies Beneath Saturn’s Moon Enceladus

Space Science: Gravity data from Cassini spacecraft point to ocean, which helps validate water jet observations
Department: Science & Technology | Collection: Life Sciences
News Channels: Analytical SCENE
Keywords: Enceladus, Cassini, Saturn, ocean, astrobiology
Fractures on the surface of Saturn’s moon Enceladus emit mineral-laden water jets.
Credit: NASA/JPL/Space Science Institute
Saturn’s moon Enceladus.
Fractures on the surface of Saturn’s moon Enceladus emit mineral-laden water jets.
Credit: NASA/JPL/Space Science Institute

Scientists have discovered that the icy-surfaced Enceladus, a small moon of Saturn, appears to have a regional ocean of subsurface liquid water at its south pole (Science 2014, DOI:10.1126/science.1250551).

Extraterrestrial liquid water is crucial for creating an environment hospitable for life forms. Enceladus may be joining a growing list of solar system bodies—Mars, Jupiter’s moon Europa, and Saturn’s moon Titan—that have or have had liquid water.

Luciano Iess at Italy’s Laboratorio di Radio Scienza and colleagues base their conclusion on gravity observations from NASA’s Cassini spacecraft, which indicate there is more mass at the south pole than indicated by what they see at the surface. Water, which is denser than the ice at Enceladus’s surface, would fit the bill.

Space scientists have suspected Enceladus has a liquid subsurface ocean since the mid-2000s when Cassini observed jets of water spouting from fractures in Enceladus’s surface.

The authors of the new work suggest that Enceladus’s subsurface ocean is sitting on top of silicate rock, which would explain why Cassini previously detected sodium and potassium salts in those jets. It would also suggest that the jets could support complex chemistry and that the minerals might provide a possible energy source for organisms.

“This makes the interior of Enceladus a very attractive place to look for life,” Cornell University’s Jonathan I. Lunine said at a press conference announcing the finding.

The search for evidence of past or present water is a major focus of solar system exploration, including that of Mars. Recently, Cassini found evidence that there may be a liquid water layer below surface hydrocarbon ices on Saturn’s moon Titan, as well.

Scientists have also been extremely interested in Jupiter’s moon, Europa, which has a liquid ocean underneath water ice. Europa is currently the target of two planned space missions, from the European Space Agency and NASA. Europa is considered, next to Mars, the most likely body in our solar system that could harbor evidence of life.

As to the similarities between Enceladus and Europa, Lunine said, “I look at this as a cornucopia of habitable environments in the outer solar system. I don’t know which would be more likely to have life—it could be both, it could be neither.”

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