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Washington, 20 Mar 2006

Recent Cassini images of Enceladus at high phase show the fountain-like sources of the fine spray of material that towers above the south polar region of Enceladus. (CICLOPS)

By Kristin Bolluck

NASA's Cassini spacecraft detected a dramatic event on one of Saturn's icy moons – an eruption that ejected water and carbon-based ice crystals thousands of miles out of Enceladus' atmosphere and ultimately into one of Saturn's rings. The eruption's composition and proposed localization in a fissure suggests the presence of water near the moon's surface and an environment potentially suitable for living organisms.

Typically, small satellites do not have geologic activity. But Enceladus, though only 300 miles in diameter, possesses regions with high levels of activity. Observations of the south pole reveal a smooth surface, covered by fresh snow and ice flows from geyser-like activity. Tidal forces also rupture the moon's surface and create deep canyons and surface fissures. Further, a warm region found near the recent eruption indicates the presence of a heat source under the icy surface.