Researchers have just revealed that Mimas, one of Saturn's smallest moons, has an ocean of liquid water flowing under its entire surface. What is really making waves though, is how young the body of water is: just 5 to 15 million years old.
Mimas' subsurface ocean was revealed after an analysis of data that came from NASA's Cassini spacecraft. Cassini was launched in October 1997 to study Saturn, including its rings and its impressive collection of 146 moons. It stayed in the Saturn system for 13 years, returning a series of striking images and valuable scientific data. In 2017, it ended its mission in spectacular style by plunging into Saturn's atmosphere and turning itself into a screaming fireball.
Using some of Cassini's data, astronomers Nick Cooper of Queen Mary University of London, Valéry Lainey of the Observatoire de Paris-PSL, and their colleagues, not only discovered the secret global ocean lying beneath Mimas's crater-filled surface, but they also came to the conclusion that it is only 5-15 million years old. This makes it a relative newcomer to our solar system in cosmic terms.
They reached their conclusion based on an orbital anomaly uncovered in the Cassini data and say that the ocean's young age was inferred because it has yet to impact the icy surface of the moon.
"Mimas is a small moon, only about 400 kilometers [249 miles] in diameter, and its heavily cratered surface gave no hint of the hidden ocean beneath," said Cooper. "This discovery adds Mimas to an exclusive club of moons with internal oceans, including Enceladus and Europa, but with a unique difference: its ocean is remarkably young, estimated to be only 5 to 15 million years old."
The relative youth of the Mimas ocean makes the moon an excellent candidate for further studies to uncover information about life's genesis in our solar system, says the team.
"The existence of a recently formed liquid water ocean makes Mimas a prime candidate for study for researchers investigating the origin of life," added Cooper.
While there are no immediate plans to return to the Saturn system, NASA says it will use the lessons learned from the Cassini mission to help fuel the strategy of its Europa Clipper mission, due to be launched later this year. That mission will see a spacecraft making 49 swoops around Jupiter's moon Europa to look at the possible habitability of its own under-ice ocean.
The discovery of Mimas's ocean has been detailed in a paper published in the journal Nature.
You can learn more about Mimas in the following video.
Source: Queen Mary University of London