The probe may have found evidence of liquid water that erupts like geysers from Yellowstone park in the western United States, NASA said Thursday.

"The rare occurrence of liquid water so near the surface raises many new questions about the mysterious moon," NASA said.

"We realize that this is a radical conclusion -- that we may have evidence for liquid water within a body so small and so cold," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colorado.

"However, if we are right, we have significantly broadened the diversity of solar system environments where we might possibly have conditions suitable for living organisms," Porco said.

The discovery should make Enceladus a research priority along with Saturn's largest moon, Titan, where the European Space Agency's Huygens probe landed in January 2005, scientists said.

"We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's moon Triton," said John Spencer, a Cassini scientist from the Southwest Research Institute in Boulder.

"Cassini changed all that, making Enceladus the latest member of this very exclusive club, and one of the most exciting places in the solar system," Spencer said.

High-resolution images of Enceladus from Cassini "show icy jets and towering plumes ejecting large quantities of particles at high speed," NASA said.

Scientists "ruled out the idea the particles are produced or blown off the moon's surface by vapor created when warm water ice converts to a gas.

"Instead, scientists have found evidence for a much more exciting possibility. The jets might be erupting from near-surface pockets of liquid water above 0 degrees Celsius (32 degrees Fahrenheit), like cold versions of the Old Faithful geyser in Yellowstone."

"There's no question, along with the moon Titan, Enceladus should be a very high priority for us," said Jonathan Lunine, a Cassini interdisciplinary scientist from the University of Arizona.

"Saturn has given us two exciting worlds to explore," he said.

Cassini was launched in October 1997, carrying Huygens with it.

Huygens separated from Cassini in December 2004 to land on Titan. Cassini is on a four-year mission to survey the ringed giant and its satellites.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

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