A phrase to make your ears perk up: Yet another of Saturn's moons may have "astrobiological potential," NASA scientists have announced. The agency's Cassini spacecraft recently captured evidence that there once was—and may still be—a subterranean ocean on the ringed planet's icy satellite Dione.
The 700-mile-diameter moon is home to a 500-mile mountain called Janiculum Dorsa (see photo below). Images from NASA's Cassini spacecraft show the surface of the moon puckering nearly 0.3 miles under the mountain, a clue that Dione had a subsurface ocean when the mountain formed.
"The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed," says Noah Hammond, a Brown University researcher and author of a paper about the findings published in the journal Icarus.
Other Saturnian moons that may host underground oceans are Enceladus and Titan. (Jupiter's moon Europa likely has both subterranean and surface water.) These planetary satellites are all prime targets for life-hunting missions in our solar system.
"A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn's geyser moon Enceladus or perhaps a weaker copycat Enceladus," says Bonnie Buratti of NASA's Jet Propulsion Laboratory, who leads the Cassini team that studies icy moons. "There may turn out to be many more active worlds with water out there than we previously thought."