Water Found On Saturn Moon
The Cassini spacecraft has found evidence of liquid water spewing from geysers on Saturn's icy moon, Enceladus, raising the tantalizing possibility that the celestial object harbors life.
The discovery surprised scientists who are looking for signs of life in space.
"If the finding is true, it means Enceladus will join a very short list of places in this solar system that could, in theory at least, support life," says CBS News space consultant Bill Harwood.
"We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's moon Triton," said Dr. John Spencer, a Cassini scientist at the Southwest Research Institute in Boulder, Colo. "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."
Recent high-resolution images snapped by the orbiting Cassini confirmed the eruption of icy jets and giant water vapor plumes from geysers resembling frozen Old Faithfuls at Enceladus' south pole.
"We have the smoking gun" that proves the existence of water, said Carolyn Porco, a Cassini imaging scientist from the Space Science Institute in Boulder, Colo.
"The simple fact that this exists apparently in liquid form near the surface really puts Enceladus in a class by itself," Harwood said. "Aside from earth, there is nowhere in the solar system where there is liquid water so near a surface. Even Mars doesn't have reservoirs like this, as far as we know."
If Enceladus does harbor life, it probably consists of microbes or other primitive organisms capable of living in extreme conditions, scientists say.
David Morrison, a senior scientist at NASA's Astrobiology Institute, cautioned against rushing to judgment about whether the tiny moon could support life. Scientists generally agree habitats need several ingredients for life to emerge, including water, a stable heat source and the right chemical recipe.
"It's certainly interesting, but I don't see how much more you can say beyond that," Morrison said.
Scientists believe Mars and Jupiter's icy moons might have — or once had — conditions hospitable to life.
Enceladus measures 314 miles across and is the shiniest object in the solar system.
It was long thought to be cold and still. But scientists now believe it is a geologically active moon that possesses an unusually warm south pole.
The water is believed to vent from fissures in the south pole. Porco said the venting has probably been going on for at least several thousand years, potentially providing a lasting heat source.
The Cassini-Huygens mission is a joint NASA-European Space Agency project. The spacecraft was launched in 1997 and went into orbit around Saturn in 2004, exploring its spectacular rings and many moons. Cassini made three flybys of Enceladus last year and is expected to fly within 220 miles of the moon again in 2008.