NASA: Cassini Mission Finds Global Ocean Beneath Saturn’s Moon, Enceladus

NASA’s Cassini mission has confirmed the presence of what it termed a “global ocean” beneath the icy crust of Saturn’s moon, Enceladus. In a press release issued earlier today, NASA said it has managed to deduce the presence of the ocean after analyzing new data from the Cassini mission.

How researchers came to the conclusion that the ocean exists underneath the crust of Enceladus is interesting in itself. They noticed that Enceladus wobbles a bit as it orbits Saturn. This wobble can only be explained by deducing that the moon’s thick icy crust is in fact resting on a liquid surface — that causes the moon to wobble a tiny bit as it goes around Saturn.

Earlier, data from the Cassini mission had observed a fine spray of water vapor, icy particles, and simple organic molecules being emitted from fractures located near the moon’s south pole. Now, researchers have a clue as to where these materials came from. On first impression, it seems these materials have their source in this newly discovered global ocean underneath the crust of Enceladus. Earlier analysis of data from Enceladus suggested the possibility of an underwater sea near the south pole. However, on further investigation of gravity data received from the moon as Cassini moved around it, it became clear that this sea is global in nature. The new results also provide credence to the presence of a global ocean underneath the surface of Enceladus.

“This was a hard problem that required years of observations, and calculations involving a diverse collection of disciplines, but we are confident we finally got it right,” said Peter Thomas, a Cassini imaging team member at Cornell University, Ithaca, New York.

How the scientists managed to detect the tiny wobble as Enceladus circled Saturn is also interesting. Scientists analyzed over seven years worth of data and images of Enceladus sent in by Cassini which has been orbiting Saturn since 2004. After carefully analyzing the images, they were in a position to measure minor changes in the moon’s rotation. And measure they did. They figured that the moon rocks back and forth as it goes round Saturn.

Matthew Tiscareno, a Cassini participating scientist at the SETI Institute, explained the process.

“If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be. This proves that there must be a global layer of liquid separating the surface from the core.”

What still remains undiscovered is the mechanism that prevents the global ocean below Enceladus’ crust from freezing up completely. In the next few months, Cassini is scheduled to make another close flyby of Enceladus on October 28. It is expected to fly just 30 miles above its surface.

[Image Via NASA/JPL]