ORBITAL AND CONFIGURATION INFLUENCES ON SPACECRAFT DYNAMIC-RESPONSE

Results of investigating the orbital and configuration influences on t he Upper Atmosphere Research Satellite's dynamic response are presente d. Orbital influences were due to temperature variation from crossing the Earth's terminator and variation of the solar incident energy as t he orbit precessed. During the terminator crossing, the rapid ambient temperature change caused the spacecraft's two flexible appendages to experience thermal elastic bending (thermal snap). The resulting respo nse was dependent on the orientation of the solar array and the solar incident energy. Orbital influences were also due to onboard disturban ces, environmental disturbances, and spacecraft configuration changes resulting in dynamic responses that were repeated each orbit. Configur ation influences were due to the solar array rotation's changing of th e spacecraft modal properties. The orbital and configuration influence s produced measurable spacecraft attitude variations as well as modal and amplitude trends in those variations.