Vast ocean lies beneath surface of Saturn’s moon Enceladus, says new study

16 Sep 2015

Beneath the thick, icy crust of Saturn’s moon Enceladus, NASA researchers have found evidence of a vast ocean covering the moon’s entire sub-surface area.

Similar to Jupiter’s moon Europa in attracting the focus of NASA researchers due to its icy surface, it now appears that previous estimates of Enceladus could have been underestimating how much water was actually beneath its surface.

Until now, previous research by Cassini scientists had suggested the possibility of a lens-shaped sea underlying the moon’s south polar region.

When updated gravitational data came in some time later, however, the findings had suggested the possibility of a global ocean rather than a polar one, and from these latest findings this would appear to be the case.

Using data stretching as far back as 2004, the researchers mapped out the features found on the moon, particularly craters, and by analysing it over time found that Enceladus has a tiny but measurable wobble as it orbits Saturn.

Enceladus diagram

A cross-section of Enceladus. Illustration via NASA/JPL-Caltech

“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,” said Matthew Tiscareno, co-author of the paper, which has now been published in Icarus. “This proves that there must be a global layer of liquid separating the surface from the core.”

Researchers said this new information would imply that the water vapour, icy particles and simple organic molecules Cassini has observed coming from fractures near the moon’s south pole is being fed by this newly-confirmed vast liquid ocean.

There is a remaining mystery, however, with researchers still somewhat baffled as to how this ocean does not freeze, with early suggestions raising the possibility of warming tidal forces from Saturn’s own gravity.

The news comes prior to the Cassini craft’s closest approach to Enceladus scheduled for 28 October where it will pass just 49km above the moon’s surface.

Colm Gorey was a senior journalist with Silicon Republic