Hidden beneath the heavily cratered surface of Mimas, one in all Saturn’s smallest moons, lies a secret: a worldwide ocean of liquid water. This astonishing discovery, led by Dr. Valéry Lainey of the Observatoire de Paris-PSL and published within the journal Nature, reveals a “young” ocean formed just 5 to fifteen million years ago, making Mimas a first-rate goal for studying the origins of life in our Solar System.
“Mimas is a small moon, only about 400 kilometers in diameter, and its heavily cratered surface gave no hint of the hidden ocean beneath,” says Dr Nick Cooper, a co-author of the study and Honorary Research Fellow within the Astronomy Unit of the School of Physical and Chemical Sciences at Queen Mary University of London. “This discovery adds Mimas to an exclusive club of moons with internal oceans, including Enceladus and Europa, but with a novel difference: its ocean is remarkably young, estimated to be only 5 to fifteen million years old.”
This young age, determined through detailed evaluation of Mimas’s tidal interactions with Saturn, suggests the ocean formed recently, based on the invention of an unexpected irregularity in its orbit. In consequence, Mimas provides a novel window into the early stages of ocean formation and the potential for all times to emerge.
“The existence of a recently formed liquid water ocean makes Mimas a first-rate candidate for study, for researchers investigating the origin of life,” explains Dr Cooper. The invention was made possible by analysing data from NASA’s Cassini spacecraft, which meticulously studied Saturn and its moons for over a decade. By closely examining the subtle changes in Mimas’s orbit, the researchers were in a position to infer the presence of a hidden ocean and estimate its size and depth.
Dr Cooper continues: “This has been an important team effort, with colleagues from five different institutions and three different countries coming together under the leadership of Dr Valéry Lainey to unlock one other fascinating and unexpected feature of the Saturn system, using data from the Cassini mission.”
The invention of Mimas’s young ocean has significant implications for our understanding of the potential for all times beyond Earth. It suggests that even small, seemingly inactive moons can harbor hidden oceans able to supporting life-essential conditions. This opens up exciting latest avenues for future exploration, potentially leading us closer to answering the age-old query: are we alone within the universe?
