Data from NASA’s Cassini spacecraft reveals that Saturn’s moon Enceladus has a global ocean beneath its surface.
In 2005, Cassini discovered water-rich plumes erupting from the moon’s south pole, leading researchers to believe the moon contained a subsurface ocean. After measuring the moon’s gravitational field, scientists believed the data supported this idea. With more mass at its south pole, researchers speculated that a subsurface ocean larger than Lake Superior resides in Enceladus’s southern hemisphere.
But after analyzing more than seven years worth of data collected by Cassini, a team led by research scientist Peter Thomas at Cornell University concludes that the subsurface ocean on Enceladus is global.
Cornell Chronicle describes the process used by the researchers:
With each Cassini photographic pass, Thomas and others painstakingly pinpointed and measured Enceladus’ topographic features – about 5,800 points – by hand. A slight wobble, about a tenth of a degree, was detected, but even this small motion – called a libration – is far larger than if the surface crust were solidly connected to the satellite’s rocky core. Thus, the scientists determined that the satellite must have a global liquid layer, far more extensive than the previously inferred regional liquid “sea” beneath the South Pole.
Enceladus is one of the most likely worlds in the solar system to harbor alien life. And, with new research suggesting the moon’s liquid water ocean is much larger than previous thought, it makes Enceladus an even more exciting target for astrobiologists. NASA is already exploring concepts for Enceladus life-hunting missions that could launch as soon as 2020.
The Cornell University team’s recent Enceladus research is in a paper titled, Enceladus’ measured physical libration requires a global subsurface ocean, and was published in the journal Icarus.