SOLAR-ARRAY-INDUCED DISTURBANCE OF THE HUBBLE-SPACE-TELESCOPE POINTING SYSTEM

The investigation of the vibrational disturbances of the Hubble Space Telescope that were discovered soon after deployment in orbit is descr ibed in detail. It was found that the disturbances were particularly e vident during orbital day-night crossings, and that the magnitude of t he disturbances was considerably larger than the design jitter require ment. This paper describes the process by which the vibrations were ch aracterized and isolated to a particular mechanism, The analysis of th e flight data and comparisons with computer simulation results showed that the source of the disturbances was the thermally driven deformati on of the solar arrays In conjunction with frictional effects in the a rray mechanisms. The control system was successfully modified to atten uate the disturbances to tolerable levels pending mechanical and therm al redesign of the solar arrays, The new arrays were installed during the first Space Telescope servicing mission, and in combination with t he enhanced control system algorithm reduced the disturbances to satis factory levels.