There's an ocean hidden beneath the icy crust of Saturn's moon Mimas

HeyB Jupiter's moons Europa and Ganymede or Saturn's moons Enceladus, Dione, and Titan – Many of our solar system's moons have a subsurface ocean. Saturn's small moon Mimas has long been considered another candidate. But so far there is no conclusive evidence of a large water reservoir hiding beneath its rough icy crust. Researchers led by Valerie Linyi of the Paris Observatory now report this In the magazine “Nature”.

Scientists analyzed observational data from the US space probe Cassin, which also orbited Saturn's moon Mimas as part of its mission from 2004 to 2017. Linney and his colleagues believe Mimas's ocean is still relatively small by astronomical standards.

Until now, the presence of a liquid water ocean on Mimas seemed somewhat unlikely. Because he is in contrast to his older sister Enceladus Mimas showed no signs of any activity either on or below the surface of the crater, indicating the presence of a subglacial water reservoir. Moreover, Mimas is a moon with a modest diameter of 400 km. Due to its size, the satellite should not be able to store the heat inside it, which is caused by the liquid ocean, for a long time. For this reason, many planetary scientists have been sympathetic to the idea that Mimas' interior is likely composed of a rocky core. But Lenny and his team came to a different conclusion based on the analyses.

Mimas is not an isolated case?

The researchers examined the Moon's rotation during its elliptical orbits around Saturn. They focused on the strange oscillating motion that scientists on the Cassini mission had already observed. They designed a model of Mimas' orbit and compared their results with observations from the Cassini spacecraft.

They found that Mimas' orbit can be better explained if we assume the existence of a global liquid ocean beneath Mimas' surface, which moves back and forth as it rotates. This rules out the option of a massive rocky core for researchers.