Dione, a moon of Saturn, may have an ocean beneath its rocky crust, according to new findings from the Cassini spacecraft. This new data includes a new image showing a giant mountain crushing the ground beneath it.
Long thought to be a dead ice world, Dione is radiating a faint stream of particles which have been detected by the magnetomoter aboard Cassini. New photographs also seem to show slush hidden just beneath the surface, as well as fractures in the crust that appear similar to those on other satellites that spout water today.
"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. There may turn out to be many more active worlds with water out there than we previously thought," Bonnie Buratti from Jet Propulsion Laboratory said. Buratti leads the Cassini science team that studies icy satellites.
One of the images that led astronomers to believe that Dione may still be geologically active is an image taken of Janiculum Dorsa - a mountain that stretches out for 500 miles across the satellite. This single mountain covers nearly one-quarter of the nearly 2,200-mile circumference of Dione. Despite its long length, the mountain only peaks between 3,200 and 6,400 feet in elevation. It pushes down on the crust beneath it by nearly 1,600 feet, suggesting a slushy layer beneath the crust.
"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 was formed," Noah Hammond of Brown University, who was lead author of the paper announcing the results, said.
Dione's crust can shift independently of its core - that significantly increases the heating created by tidal forces created as it revolves around Saturn every 65 hours, 41 minutes, creating ten times as much heating as would a solid body in a similar orbit.
If the subsurface ocean is confirmed, this could indicate that Dione might have been geologically active in its recent past, or even today. This also greatly raises the possibility that life - however primitive - may one day be found on this icy moon.
Oceans beneath the surfaces of large moons is not uncommon - Titan and Enceladus (which also orbit Saturn) are thought to possess such water bodies, as well as Jupiter's moon Europa. The reason some worlds like Enceladus are more active than Dione is still unanswered, although it may have to do with differing amounts of heating from tidal forces and radioactive decay.
Cassini has been orbiting Saturn since 2004, studying the planet, its rings and numerous moons.
Research on the possible alien ocean was profiled in the journal Icarus.