NASA Scientists believe they have found evidence of geysers spewing icy jets of water on Saturn's moons -- a sign the remote world could conceivably harbor primitive life.
The evidence was uncovered by NASA's Cassini spacecraft, which first entered orbit around Saturn on July 1, 2004. Scientists say Cassini's images lead them to believe there are liquid water reservoirs that erupt in Yellowstone-like plumes on the moon Enceladus.
Cassini mission scientists speculated the water could be heated by volcanic activity below the surface of the Saturn moon, which is about 1 billion miles from Earth.
"We realize that this is a radical conclusion, that we may have evidence of liquid water within a body so small and so cold," said Carolyn Porco, a Cassini team leader at the Space Science Institute in Boulder, Colo. "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."
Evidence of a geyser on Enceladus does not indicate life, however, although water is helpful if not essential for life to exist. Nor is Enceladus believed to be the first world beyond Earth to contain liquid water.
"Other moons in the solar system have liquid water oceans covered by kilometers of icy crust," said Andrew Ingersoll of the California Institute of Technology. "What's different here is that pockets of liquid water may be more than tens of meters below the surface."
NASA said Cassini images show icy jets and towering plumes ejecting huge quantities of particles at high speed. After studying the images, the scientists believe they show evidence of water jets erupting from near the icy surface.
If those jets are powered by volcanic activity, Saturn's moon joins an exclusive solar system club. John Spence of Colorado's Southwest Research Institute in Boulder said, "We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth and possibly Neptune's moon Triton."
The potential discovery may raise more questions than it answers: Might the geyser activity have been continuous enough over the moon's history for life to have had a chance to take hold on the moon's interior?
"Our search for liquid water [on other planets] has taken a new turn," said Peter Thomas of Cornell University. "The type of evidence for liquid water on Enceladus is very different from what we've seen at Jupiter's moon Europa," he said. Thomas said the evidence on Europa points to internal oceans there. On Saturn's moon, the evidence indicates that water vapor is coming from a source close to the surface, which would mean that liquid water is still present there.
Galileo was the first to see Saturn through a telescope in the year 1610. Saturn was first visited by NASA's Pioneer 11 in 1979 and later by Voyager 1 and Voyager 2.
With today's announcement the next phase in Cassini's mission, which is a joint NASA-European Space Agency project, becomes even more important. In the spring of 2008, it will fly within 220 miles of Enceladus and perhaps find more signs of liquid water.