Mimas, Saturn’s Moon Resembling Death Star, Found to Have Hidden Ocean, Surprising Researchers
In a surprising discovery, researchers have found that Mimas, a moon of Saturn that bears a striking resemblance to the Death Star from Star Wars, has a hidden ocean buried beneath its battered crust. This revelation places Mimas in an exclusive club of moons known to harbor subterranean oceans, joining the likes of Saturn’s Titan and Enceladus, as well as Jupiter’s Europa and Ganymede.
The discovery of this hidden ocean on Mimas has left astronomers astounded. Valéry Lainey, an astronomer at the Observatoire de Paris in France, expressed his surprise, stating, “It’s quite a surprise. If you look at the surface of Mimas, there’s nothing that betrays a subsurface ocean. It’s the most unlikely candidate by far.”
The peculiarities in Mimas’s orbit had led astronomers to consider two possibilities: either it contained an elongated core covered in ice or an internal ocean that allowed its outer shell to shift independently of the core. By meticulously analyzing thousands of images from NASA’s Cassini mission to Saturn, Lainey and his colleagues were able to reconstruct the precise spin and orbital motion of Mimas. Their calculations revealed that Mimas must possess a hidden subsurface ocean to move in the way it does.
Lainey explained, “There is no way to explain both the spin of Mimas and the orbit with a rigid interior. You definitely need to have a global ocean on which the icy shelf can slip.” According to their calculations, this ocean is estimated to be 45 miles deep and lies beneath Mimas’s 15-mile-thick icy shell. The temperatures near the sea floor are believed to reach tens of degrees Celsius. Remarkably, this ocean would account for more than half of Mimas’s volume.
In astronomical terms, Mimas’s ocean appears to be relatively young, forming within the past 25 million years. This occurred when powerful tidal forces exerted by Saturn deformed Mimas’s core, heating it similar to a massaged squash ball. The heated core then melted the overlying ice, creating an ocean within the moon. Despite this, the moon’s surface remains heavily battered, with one giant impact resulting in the Herschel crater, named after the astronomer William Herschel, who first identified Mimas in 1789.
The discovery of global oceans in moons around Saturn and Jupiter has sparked significant interest among space agencies eager to explore their potential for harboring life. Enceladus, for example, has more than 100 geysers that release vapor through surface fractures. If life ever evolved on this tiny moon, the plumes could propel extraterrestrial microbes into space, where they could be detected by visiting missions.
Lainey believes that since Mimas contains water in contact with warm rock, the existence of life cannot be ruled out. However, due to the ocean’s relatively young age, estimated to be tens of millions of years old, it remains uncertain whether life had enough time to emerge. Lainey said, “Whether it’s too young, nobody knows. I would say: why not?”
David Rothery, a professor of planetary geosciences at the Open University, expressed a more cautious view. He stated that even if Mimas did harbor a subsurface ocean, there are easier places to search for life beyond Earth. Rothery explained, “There’s no indication of a connection between the internal ocean, where life could survive, and the surface or space where traces of life could be detected and sampled, such as we have done in the plumes of Enceladus and hope to do on the surface or in plumes at Europa. If there were life inside Mimas, it would be hidden by more than 20km of unbroken ice. If the ocean has existed for only 25 million years, that may not have been enough time for life to get started and established. Europa and Enceladus are much more promising candidates.”
The discovery of a hidden ocean on Mimas has opened up new possibilities for understanding the potential for life beyond Earth. While Mimas may not be the most promising candidate for harboring life, its unique characteristics and surprising secrets continue to captivate astronomers and space enthusiasts alike. As our exploration of the cosmos continues, who knows what other wonders and mysteries await us in the vast expanse of space.
