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Skylab attitude control and angular momentum desaturation with one double-gimbaled control moment gyroIn case two control moment gyros fail, attitude control of Skylab can be maintained with the thruster attitude control system. This results, however, in a severely increased fuel consumption, depleting the fuel in a few days. Therefore, an alternate concept was developed which does not have large fuel consumption under any circumstances. In this concept the attitude reference is commanded to oscillate in the orbital plane with twice the orbital frequency and the remaining control moment gyro controls about orbital north and about the minimum moment-of-inertia axis, while the thruster attitude control system controls rate only about the remaining axis. This rate control in conjunction with the restoring torque due to the gravity gradient will keep bounded the excursion of the minimum moment-of-inertia axis out of the orbital plane. This alternate concept has the additional advantage that it needs no information on the principal moment-of-inertia axes misalignment and is completely insensitive to star tracker failure. Proper phasing of the attitude reference oscillation even allows angular momentum desaturation, which is responsible for the insensitivity of the thruster fuel consumption to unknown disturbances, like vent torques and magnetic torques.
Document ID
19730015124
Document Type
Technical Memorandum (TM)
Authors
Kennel, H. F. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
September 2, 2013
Publication Date
January 12, 1973
Subject Category
SPACE VEHICLES
Report/Patent Number
NASA-TM-X-64746
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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