A European study suggests that huge geysers on Saturn's moon Enceladus may be fed by a salty sea below its surface.
Researchers detected salt particles in the volcanic vapour-and-ice jets that shoot hundreds of kilometres into space, which is the strongest evidence to date of a liquid ocean under the moon's icy crust.
The study published in the journal Nature boosts the odds of extraterrestrial life in our solar system.
Scientists knew that tiny Enceladus had two of the three essential ingredients for life.
One is an energy source produced by tidal warming, which may be driven by the shifting gravitational tug of its parent planet during the moon's lopsided orbit.