Saturn’s ‘Death Star’ moon could harbor a secret ocean

Scientists say Saturn’s “Death Star” moon, Mimas, has a strange wobble that could indicate it has an elongated core — or that it’s hiding a subsurface ocean. (JPL/NASA)

Excerpt from
latimes.com 

When it comes to Saturn’s moons, water-squirting Enceladus and the hydrocarbon lakes of Titan typically steal the spotlight. But now, scientists think that lesser-known Mimas may be harboring a strange secret of its own. Scientists who studied the ‘Death Star’ moon with NASA’S Cassini spacecraft have discovered a weird wobble in its motions that could mean one of two things: Either Mimas has an oddly elongated core, or it’s hiding an ocean inside its icy body.

The findings, described in the journal Science, shed new light on a mysterious but often-overlooked moon that could hold clues to its early formation.

Mimas is an icy moon that’s 246 miles wide and whose most distinctive feature is the 88-mile-wide Herschel crater – a giant Cyclops-like indentation that makes the moon resemble the planet-obliterating superweapon from “Star Wars” that’s known as the Death Star.

But the scientists noticed something strange – the moon seemed to be wobbling, or “librating,” about twice as much as they expected. After going through several different explanations, they settled on two main possibilities. Either this round moon has a football-shaped core that’s causing the wobble, or there’s a liquid water ocean underneath the icy surface.

If Mimas holds an ocean, it joins an elite group of moons (including Enceladus as well as Jupiter’s moon Europa) that potentially hold liquid water – which is key for the search for other worlds besides Earth with life-hosting potential.