Mimas, one of Saturn's moons, is now known to hide an underground ocean beneath its icy exterior – a revelation that could change our understanding of its formation and potential for life.
Mimas – Not Just an Inactive Ice Moon
Originally identified by William Herschel in 1789, Mimas was primarily considered as a dormant ice moon with a rocky core. Distinguishable by its massive crater, this moon, with an approximate diameter of 400 km, has presented an intriguing discovery recently.
The Discovery of the Hidden Ocean
The unveiling of the underground ocean was initiated by the analysis of Mimas' orbit. Interestingly, Mimas always presents the same face to Saturn due to its synchronous rotation with the planet. It also experiences an additional rotational motion during its orbits, known as precession.
The researchers discovered that the precession was unusually greater than anticipated. This led to the speculation that there could be an underground ocean beneath its icy surface. This hypothesis was further confirmed using data from the Cassini mission.
Underground Ocean and Ice Crust
The underground ocean is protected by a layer of ice. The ice crust is estimated to be around 20-30 km thick.
The Impact of Nearby Moons
Mimas' unique formation process can be attributed to the ocean's existence. The moon may have been entirely frozen for hundreds of millions of years. The orbits of neighboring moons, namely Enceladus and Dione, might have affected Mimas' orbit to become more elliptical. Such a change would have surged tidal forces and warmed Mimas' interior, consequently melting the inside.
New Opportunities for Space Exploration
These findings are particularly significant for space exploration. Planets like Uranus and Neptune, with many frozen moons, have sparked renewed interest. The hypothesis is that these icy worlds may potentially support life under specific conditions.