Astronomy in the News

Mercury Autumn 2008 Table of Contents

Cassini Pinpoints Source of Enceladus Jets

NASA / JPL / Space Science Institute

In a feat of interplanetary sharpshooting, NASA’s Cassini spacecraft has pinpointed precisely where the icy jets erupt from the surface of Saturn’s geologically active moon Enceladus.

New carefully targeted pictures reveal exquisite details in the prominent south polar "tiger stripe" fractures from which the jets emanate. The images show the fractures are about 300 meters (980 feet) deep, with V-shaped inner walls. The outer flanks of some of the fractures show extensive deposits of fine material. Finely fractured terrain littered with blocks of ice tens of meters in size and larger surround the fractures.

"This is the mother lode for us," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute, Boulder, Colorado. "A place that may ultimately reveal just exactly what kind of environment — habitable or not — we have within this tortured little moon."

One highly anticipated result of this flyby was finding the location within the fractures from which the jets blast icy particles, water vapor, and trace organics into space. Scientists are now studying the nature and intensity of this process on Enceladus, and its effects on surrounding terrain. This information may answer the question of whether reservoirs of liquid water exist beneath the surface.

"There appears to have been extensive fallout of icy particles to the ground, along some of the fractures, even in areas that lie between two jet source locations, though any immediate effects of presently active jets are subtle," said Porco.

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