Mimas, a tiny moon orbiting Saturn, might be hiding an ocean under its frozen surface, according to new research published in the planetary science journal Icarus.
Mimas has a wobbly rotation that suggests it either has an elongated core or an internal ocean. Scientists have been skeptical about an ocean being the cause because Mimas is very small and, unlike other moons with oceans, it doesn’t have any markers on its surface indicating one.
Alyssa Rhoden, a specialist in the geophysics of icy satellites, was setting out to disprove the ocean hypothesis when she and her colleague Matthew Walker realized it might actually hold water. They used tidal heating models to find a plausible explanation for a liquid ocean beneath 14 to 20 miles of ice.
“I was saying Mimas can’t have an ocean, but what I was really saying was, for Mimas to have an ocean would really challenge our intuition about Mimas,” Rhoden told the New York Times. “And when I realized that, I thought, well, that’s not how scientists are supposed to work. We don’t come to a conclusion without actually testing the hypothesis.”
Mimas’ potential secret ocean could expand scientists’ conceptions of icy satellites. “If Mimas has an ocean, it represents a new class of small, ‘stealth’ ocean worlds with surfaces that do not betray the ocean’s existence,” Rhoden said in a press release.
It will take further study to confirm if there really is an ocean lurking beneath the surface, rather than a stretched core. “Mimas is a compelling target for continued investigation,” Rhoden said.