A strange little moon orbiting near Saturn has revealed its biggest secret: a hidden ocean beneath its cratered surface.
At less than 123 miles (198 kilometers) across, Mimas is too small to be perfectly round, and its icy crust is covered in deep scars from objects colliding with it. Herschel's most prominent crater extends over a third of its face, giving it the nickname “Death Star” in honor of the giant Imperial Space Station. star Wars. The moon is so modest that scientists thought it was the least likely place to look for a subsurface ocean. However, an analysis of Mimas' orbital motion revealed an ocean 12 to 18 miles (20 to 30 kilometers) beneath its icy crust.
The discovery is detailed in A Stady Published Wednesday in the magazine nature. Using data from the Cassini space probe, which orbited Saturn from 2004 to 2017, the scientists behind the new study observed subtle changes in Mimas' orbit. Based on its motion and rotation as it orbits Saturn, the data suggest that Mimas harbors a recently formed and still evolving ocean.
The ocean is estimated to be 5 to 15 million years old. In comparison, the inner ocean formed on Saturn's moon Enceladus about 1 billion years ago, while Jupiter's moon Europa hosted an ocean about 4 billion years ago.
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Mimas now joins Enceladus and Europa, as well as Saturn's moon Titan and Jupiter's Ganymede, on the list of icy ocean worlds in the solar system, but there may be more. The moons, which are mainly made of ice, are heated by tides, melting the ice internally while the outer shell freezes to form a crust covering it. This elite list of moons constitute the best candidates for life in the solar system, where liquid water is a prerequisite for life on Earth.
“The presence of a recently formed liquid water ocean makes Mimas a prime study candidate for researchers investigating the origin of life,” said Nick Cooper, co-author of the study and a researcher in the Astronomy Unit in the School of Physical and Chemical Sciences at UCL. Queen Mary University of London said in a statement.
The ocean at Mimas reached its current depth only recently, or less than 2 to 3 million years ago, according to the study's simulations. This time period could mean that life may not have had a chance to form yet, offering a rare early glimpse into habitability conditions in the solar system.
Mars may be a hotspot in the search for extraterrestrial habitability because it resembles our planet most, but the solar system's icy moons are really where it's at when it comes to exploring alien life. Luckily, Juice mission On its way to study Jupiter's icy moons, looking for signs of habitability. Since Cassini plummeted to its death in Saturn's atmosphere, there are plans in the works to send another spacecraft to the ringed planet and its moons, namely Enceladus, but we'll have to wait a little longer for those to get the green light.
Meanwhile, we can think about what kind of life might exist on Saturn's misshapen moon.
more: Saturn's moon Enceladus is burping up a key ingredient for life
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