Saturn's Moon Dione May Possess Subsurface Ocean

Saturn’s moon Dione may possess a subsurface ocean, one which may have at one time been geologically active, new images obtained by NASA’s Cassini spacecraft suggest.

Image Credit: NASA
Image Credit: NASA

The new images are of Dione’s rather strange 500-mile-long mountain — Janiculum Dorsa. After analysis by researchers on the Cassini science team, it’s been concluded that the images suggest that the moon may have once been very similar to its sister moon — Enceladus, the ice-geyser moon.

“There may turn out to be many more active worlds with water out there than we previously thought,” stated Bonnie Buratti, the lead researcher on the Cassini science team at NASA’s Jet Propulsion Laboratory.

In recent years subsurface oceans have been discovered on quite a few of Saturn and Jupiter’s moons — suggesting that such watery-moons may be very common in the larger universe. The moon’s that stand out the most in the public perception are no doubt Saturn’s moons Enceladus and Titan and Jupiter’s moon Europa — all of which may potentially harbor life. “These geologic hotspots have garnered the interest of scientists searching for the building blocks of life beyond Earth. If Dione turned out to have a liquid layer under its crust, that would increase the moon’s chances of supporting life,” as notes.

With regards to the recent discovery: “Cassini, which has been exploring Saturn since 2004, detected a weak particle stream coming from Dione with its magnetometer. Images taken by the spacecraft suggest a slushy liquid layer might exist beneath its icy crust, as well as ancient, inactive fractures that now spew water ice and carbon-containing particles, much like ones seen on Enceladus.”

The Janiculum Dorsa mountain on Dione peaks at about 1.2 miles in height, and appears to have deformed the icy crust beneath it by at least as much as 0.3 miles. This deformation suggests that when the mountain formed that the crust was still warm, the researchers think that this warmth was very-likely accompanied by the presence of a large subsurface ocean.

“As Dione swings around Saturn, it gets squished and stretched, causing it to heat up. When you have a subsurface ocean that lets the icy crust float around on top, Saturn’s gravitational pull becomes amplified and generates 10 times more heat, the researchers said. The heating could also be caused by a local hotspot or a crazy orbit, but these explanations are less likely.”

As of now researchers don’t have a very good idea as to why Dione isn’t as geologically active as its sister moon Enceladus. “The latter may have experienced stronger gravitational forces or more radioactive heating in its core, they suggest. Subsurface oceans appear to be common on icy satellites, and could exist on dwarf planets like Ceres and Pluto.”

That would certainly be an interesting discovery to make. A subsurface ocean on Pluto? On that note, the New Horizons mission is only a short while off from offering us our first close up view of Pluto and its moons. It’ll be very interesting to finally see what that world looks like when the mission makes its flyby in early 2015.

The new research was recently published in the journal Icarus.

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