London: There are many secrets that the enormous planet Saturn and its moons hold within themselves. NASA's Cassini mission, currently on its last leg of the probe, aims to discover all that and more.
Earlier, Cassini made huge revelations on Saturn's moons Titan and Enceladus, which gave evidence of hidden oceans beneath their icy crusts.
Now, in a latest study based on the data from Cassini, a subsurface ocean has been found that lies deep within Saturn's moon Dione as well, somewhere between its crust and core.
The ocean is several tens of kilometres deep and surrounds a large rocky core.
The researchers believe that Dione's ocean has probably survived for the whole history of the moon, and thus offers a long-lived habitable zone for microbial life.
"The contact between the ocean and the rocky core is crucial," said Attilio Rivoldini, co-author of the study.
"Rock-water interactions provide key nutrients and a source of energy, both being essential ingredients for life," Rivoldini noted.
Seen from within, Dione is very similar to its smaller but more famous neighbour Enceladus, whose south polar region spurts huge jets of water vapour into space.
Dione seems to be quiet now, but its broken surface bears witness of a more tumultuous past.
The study findings were published online in the journal Geophysical Research Letters.
(With IANS inputs)