NASA's Cassini spacecraft and Deep Space Network have uncovered evidence that Saturn's moon Enceladus harbors a large underground ocean of liquid water, furthering scientific interest in the moon as a potential home to extraterrestrial microbes.
Researchers theorized the presence of an interior reservoir of water in 2005 when Cassini discovered water vapor and ice spewing from vents near the moon's south pole. The new data provides the first geophysical measurements of the internal structure of Enceladus, consistent with the existence of a hidden ocean inside the moon.
The gravity measurements suggest a large, possibly regional, ocean about 6 miles deep, beneath an ice shell about 19 to 25 miles thick. The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our Solar System to host microbial life. Before Cassini reached Saturn in July 2004, no version of that short list included this icy moon, barely 300 miles in diameter.
There is no certainty the subsurface ocean supplies the water plume spraying out of surface fractures near the south pole of Enceladus, however, scientists reason it is a real possibility. The fractures may lead down to a part of the moon that is tidally heated by the moon's repeated flexing, as it follows an eccentric orbit around Saturn.
"Material from Enceladus’ south polar jets contains salty water and organic molecules, the basic chemical ingredients for life," said Linda Spilker, Cassini's project scientist at JPL. "Their discovery expanded our view of the 'habitable zone' within our Solar System and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment."
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