Another icy ocean has been discovered in the solar system. The water body on Mimas is only 5 to 15 million years old.

Researchers have just discovered that there is an ocean of liquid water flowing beneath the entire surface of Saturn's smallest moon, Mimas. What's really sensational, though, is how young these bodies of water are: only 5 million to 15 million years old.

Mimas' subsurface ocean was revealed after analyzing data from NASA's Cassini spacecraft. Cassini was launched in October 1997 to study Saturn, including its rings and its impressive 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 fashion, crashing into Saturn's atmosphere.

Using some of the Cassini data, astronomers Nick Cooper of Queen Mary University of London, Valéry Lainey of the PSL Observatory in Paris and their colleagues not only discovered a secret global ocean beneath Mimas' crater-filled surface, but also concluded that Mimas is between 5 and 15 million years old. From a cosmological perspective, this makes it a relatively new planet in the solar system.

They based their conclusion on an orbital anomaly found in Cassini data and concluded that the ocean is younger because it has not yet impacted the moon's icy surface.

"The discovery that Mimas is a small moon, only about 400 kilometers (249 miles) across, and its cratered surface gives no hint of a hidden ocean below, joins a club of moons that have internal oceans, including Enceladus and Europa, but with one unique difference: Its ocean is very young, estimated to be only 5 million to 15 million years old," Cooper said.

Mimas' oceans are relatively young, making the moon an excellent candidate for further study to reveal information about the origins of life in the solar system.

While there are currently no plans for human space exploration to return to the Saturn system, NASA says it will use lessons learned from the Cassini mission to help shape the strategy for the Europa Clipper mission, due to launch later this year. During the mission, the spacecraft will make 49 dives around Jupiter's moon Europa to study the habitability of Europa's subglacial ocean.

A paper published in the journal Nature details the discovery of Mimas' ocean.