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B. A. Roberts, T. S. Englar, J. W. Kruk, T. B. Ake, W. P. Blair, H. W. Moos (Johns Hopkins University), FUSE Operations Team
The failure of two of the reaction wheels on the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite in late 2001 required the development of an innovative new attitude control scheme in which the onboard magnetic torquer bars (MTBs) are used for fine attitude control about one axis. This new strategy has proven to be effective, but imposes additional constraints on spacecraft operations which must be modeled to schedule observations. At each fixed pointing and during slews, the gravity gradient disturbance torque must be predicted and compared to the magnetic control torque authority available from the MTBs to determine if stable control can be maintained. In the original spacecraft design, the MTBs were only required to manage reaction wheel momentum, and consequently are not powerful enough to completely counteract gravity gradient disturbances at some attitudes. The relationship between torquer bar demand due to wheel momentum management as well pointing control must also be factored in. We describe how the gravity gradient disturbances and the local magnetic field determine the boundary conditions within which FUSE Mission Planning must operate.
This work is supported by NASA Contract NAS5-32985 to the Johns Hopkins University.
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The author(s) of this abstract have provided an email address for comments about the abstract: broberts@pha.jhu.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.