Saturn's largest moon, Titan, has a buried ocean that is saltier than many seas on Earth.
Titan, with its thick atmosphere and bodies of surface liquid, is of great interest to scientists looking for life beyond Earth. A team led by Giuseppe Mitri, of the National Institute of Astrophysics in Rome, looked at gravity and elevation measurements taken by NASA's Cassini spacecraft over more than a decade.
The scientists calculated that Titan's icy outer shell is less than 100 kilometres thick and is in the process of freezing and growing thicker. They also calculated that the underlying water is about as dense as the Dead Sea, probably because of high concentrations of sulphur, potassium, sodium and other salts, the authors say.