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Written by spacetravel.org
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Thursday, 28 July 2005 21:48 |
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Data from NASAs Cassini spacecraft has provided compelling evidence in support of astronomers suspicions that Saturns moon Phoebe was captured from the further reaches of the Solar System.
Torrence V. Johnson of the Jet Propulsion Laboratory, California, Jonathan I. Lunine, of the Lunar and Planetary Laboratory, Arizona and Roger N. Clark of the US Geological Survey, Colorado used data from Cassinis flyby of Phoebe on June 11, 2004 to measure the composition of Phoebes surface layers. They discovered that Saturn has more in common with Kuiper-belt objects, the icy cometary bodies found beyond Neptunes orbit, than with Saturns other moons. The Kuiper belt is over three times further from the Sun than Saturn.
Johnson and Lunine used Cassinis movement to calculate Phoebes mass and density. They found that it was lightweight, more likely to have a large ice content, like a comet, than a rocky interior, like the other moons of Saturn. Clark and his colleagues discovered a complex array of surface materials, which ranged from expected minerals to volatile organic compounds found in cometary bodies.
Phoebe orbits Saturn in the opposite direction from most of Saturns other moons.
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