The researchers said they have, for the first time, detected sodium salts in Saturn's outermost ring. That finding, they said, suggests Enceladus, which primarily replenishes the ring with material from discharging jets, could harbor a reservoir of liquid water -- perhaps an ocean -- beneath its surface.
The Cassini spacecraft's instruments discovered the Enceladus water-ice jets in 2005. Those jets expel tiny ice grains and vapor, some of which escape the moon's gravity and form Saturn's outermost ring. Cassini's cosmic dust analyzer examined the composition of the ice grains and found salt within them.
"We believe that the salty minerals deep inside Enceladus washed out from rock at the bottom of a liquid layer," said Frank Postberg, Cassini scientist for the cosmic dust analyzer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.
Postberg and his colleagues conclude liquid water must be present because it's the only way to dissolve the significant amounts of minerals that would account for the levels of salt detected. The process of sublimation, the mechanism by which vapor is released directly from solid ice in the crust, cannot account for the presence of salt.
The discovery is reported in the June 25 issue of the journal Nature.
Copyright 2009 by United Press International.
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