There could be an ocean hidden under the icy crust of Mimas, the small moon as well as the innermost of those that orbit Saturn: this is indicated by the oscillations detected during its rotation by the Cassini mission of NASA, the European Space Agency (ESA) and the Agency Italian space (Asi).
Mimas could therefore be the first example of a new class of small worlds that perfectly mask their internal ocean, as shown by the study published in the journal Icarus by researchers from the Southwest Research Institute (USA).
"Since Mimas's surface is heavily cratered, we thought it was just a block of ice," says geophysicist Alyssa Rhoden. "Worlds with an internal ocean, such as Enceladus and Europa, tend to fracture and show other signs of geological activity. Instead, it turned out that Mimas's surface was deceiving us and this new awareness of ours greatly expands the definition of a potentially habitable world. in our solar system and beyond. "
In their simulations, the researchers took into account different parameters of the moon (the orbital eccentricity and the oscillations of the rotation axis) to evaluate whether tidal warming (i.e. the process by which tidal forces related to the gravitational interaction between the moon and Saturn dissipate the satellite's orbital and rotational energy in the form of heat) could be compatible with the existence of an internal ocean. The tidal warming should be large enough to keep the ocean from freezing, and small enough to keep a thick frozen shell. The simulation results confirmed that Mimas's tidal warming could produce enough energy to justify an ocean of liquid water under a layer of ice 23 to 32 kilometers thick.
