Saturn's moon may hide watery caverns - and life?

By Ben Hirschler

LONDON (Reuters) - Saturn's icy moon Enceladus could contain watery underground caverns, forming a potential home for alien life, scientists said on Wednesday.

German researchers have found salt -- a signature chemical for seawater -- in ice grains from vapour jets streaming out of surface cracks, providing the strongest evidence yet of a liquid water reservoir beneath the moon's frozen crust.

A U.S. team said the amount of salt they had detected using a different method suggested an earlier theory that water was boiling explosively into the vacuum of space via geysers was wrong, and evaporation was occurring quite slowly.

Both studies were published in the journal Nature.

One explanation for the slower evaporation may be that water is emerging from pressurised chambers below the so-called tiger stripe fractures in the moon's surface, said John Spencer of the Southwest Research Institute in Boulder, Colorado.

"Our picture of its sub-surface must now be expanded to include the possibility of misty ice caverns floored with pools and channels of salty water, lurking beneath the tiger stripes," he wrote in a commentary on the two scientific papers.

"What else may lurk in those salty pools, if they exist, remains to be seen."

The Cassini spacecraft first discovered huge plumes erupting from fissures near the south pole of Enceladus in 2005, sparking speculation of a vast underground ocean spewing vapour through giant Yellowstone-like geysers.