BOULDER, Colo., June 22 (UPI) -- Scientists say a U.S.-European spacecraft has collected the strongest evidence yet that a large, subterranean saltwater ocean exists on Saturn's moon Enceladus.
Samples of icy spray shooting from the moon's surface, collected during the Cassini spacecraft flybys by the probe's Cosmic Dust Analyzer, suggest a saltwater ocean under Enceladus' frozen surface, a release from the University of Colorado at Boulder reported Wednesday.
Cassini-Huygens' mission to Saturn is a collaboration of NASA, the European Space Agency and the Italian Space Agency.
The plumes of spray coming from so-called tiger stripe surface fractures at the moon's south pole were found to contain large, salt-rich grains, researchers say.
"There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than the salt water under Enceladus' icy surface," Frank Postberg of the University of Germany said.
The salt-rich particles have an "ocean-like" composition that indicates most, if not all, of the expelled ice comes from the evaporation of liquid saltwater rather than from the icy surface of the moon, researchers said.
Scientists say they believe that perhaps 50 miles beneath the surface crust of Enceladus there is a layer of water between the rocky core and the icy mantle, kept in a liquid state by gravitational tidal forces created by Saturn and several neighboring moons.
"Enceladus is a tiny, icy moon located in a region of the outer Solar System where no liquid water was expected to exist because of its large distance from the sun," ESA scientist Nicolas Altobelli said.
"This finding is therefore a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life may be sustainable on icy bodies orbiting gas giant planets."