The plumes of gas and ice shooting from the south pole of the Saturnian moon Enceladus contain sodium salts, which is the best evidence so far that the satellite harbors a liquid water ocean.
NASA’s Cassini probe observed the salts in Saturn’s outermost ring, which is believed to be composed of material ejected from Enceladus. That news, published Wednesday in Nature, is sure to excite life-hunters hoping to find extraterrestrial microbes within our solar system.
“Those salty grains provide our current best smoking (or steaming) gun pointing to present-day liquid water near the surface of Enceladus,” space scientist John Spencer of the Southwest Research Institute, who was not involved with the research, wrote in an essay accompanying the findings.
Since 2005, when Cassini spotted plumes jetting out from Enceladus, the moon has become one of the hottest topics in solar-system science. In 2008, water vapor was discovered in the plumes, and Enceladus joined Mars and Jupiter’s moon Europa as the likeliest places to find liquid water — and therefore life as we know it — outside Earth. Though the planet is covered with ice and too far from the sun to derive much warmth, the gravitational field in the Saturnian system is believed to warm the moon by a frictional process called tidal heating, possibly allowing it to maintain a deep liquid water reservoir.
But the presence of the hypothesized subsurface ocean isn’t as simple to confirm as it sounds.
