Dec 21 2000
From The Space Library
NASA's JPL announced that the Cassini spacecraft]], after successfully undergoing a series of tests, was resuming the use of its electrically powered reaction wheels to control its orientation. Although mission scientists were uncertain of the cause of the spacecraft's switch to a different maneuvering system, they suggested that a small piece of material, perhaps from the motor's magnets, might have lodged in an area where it caused friction. Because the scientists were unable actually to detect any such material, they speculated further that either centrifugal force had subsequently forced the material out, or the motor had ground it up. Scientists also suggested that reduced lubrication in the bearings, during prolonged operation at reduced speeds, might have caused the problem, and that, perhaps, the increased motor speeds used during the tests had restored the lubrication.
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