Water World Discovery? Saturn’s ‘Death Star’ Moon May Hide Massive Ocean

A recent research study has unveiled that Saturn’s moon Mimas, known for its large impact crater that gives it a resemblance to the Death Star from Star Wars, conceals an ocean beneath its icy surface. This revelation places Mimas among a select group of moons, including Saturn’s Titan and Enceladus and Jupiter’s Europa and Ganymede, which possess underground oceans.

Valery Lainey, an astronomer at the Observatoire de Paris in France, expressed surprise at this discovery, noting Mimas’s surface shows no signs of a hidden ocean, making it an unexpected candidate.

The study, which hinges on the peculiarities observed in Mimas’s orbit, suggests two possibilities: the presence of an internal ocean allowing the moon’s outer shell to move separately from its core, or an elongated core encased in ice.

Utilizing images from NASA’s Cassini mission to Saturn, Lainey and his team concluded that Mimas harbors a concealed ocean beneath a 15-mile-thick ice layer, potentially as deep as 45 miles, with sea floor temperatures reaching several degrees Celsius.

This discovery raises questions about the potential for life in the global oceans of moons orbiting Jupiter and Saturn. Enceladus, for instance, has over 100 geysers ejecting vapor, which could, hypothetically, disperse extraterrestrial microbes into space for detection by missions.

Lainey suggests the possibility of life cannot be dismissed since the ocean is in contact with warm rock, but notes the chances might be lower if the ocean is relatively young.

David Rothery, a professor of planetary geosciences at the Open University, commented that while the presence of a subsurface ocean on Mimas is intriguing, other moons like Europa and Enceladus offer more viable environments for searching for extraterrestrial life due to easier access to potential biosignatures. Rothery highlighted the challenges of detecting life on Mimas, hidden beneath over 20km of ice, and the potential limitation posed by the ocean’s age for the development of life.