Saturn moon’s geysers draw water from subsurface sea

Study suggests space probes can directly sample an extraterrestrial ocean

SEA SPRAY  Water from a subsurface sea on Enceladus blasts through cracks in the moon’s icy shell, in a picture taken by the Cassini spacecraft. 


The seas of Saturn’s moon Enceladus are blasting into space.

Saltwater-spewing geysers on Enceladus’ icy surface — 101 of them — appear to connect to the moon’s warm subsurface ocean, scientists report July 28 in two new studies in the Astronomical Journal. The results suggest that these geysers offer an unprecedented chance to collect samples of a potentially habitable reservoir of liquid water away from Earth.

Over the last decade, Enceladus has become a tantalizing spot for finding extraterrestrial life because of discoveries of a deep underground ocean (SN: 5/3/14, p. 11) and ice erupting from the moon’s south pole (SN: 8/27/05, p. 141). Researchers have wondered whether the geysers’ spray originates in that ocean or at the icy surface, where friction along cracks could create hot spots that melt the ice.

The new findings, based on over six years of data from NASA’s Cassini spacecraft, reveal that hot spots around each geyser — regions that are slightly warmer than the surrounding ice — are too small to fuel the jets. Instead, the researchers suggest, Saturn’s gravity opens fractures in the ice, causing water from the ocean to get drawn up into the vacuum of space.

BELOW THE ICE Water geysers on Enceladus are fed by an underground saltwater ocean via deep cracks in the surface ice, as seen in an artist’s illustration. Saturn’s gravity pulls open fractures in the frozen shell, which lets water escape and warms the surrounding ice. JPL-Caltech/NASA, SSI

Christopher Crockett is an Associate News Editor. He was formerly the astronomy writer from 2014 to 2017, and he has a Ph.D. in astronomy from the University of California, Los Angeles.

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