Experimental Investigation of Spacecraft In-Flight Disturbances and Dynamic Response

Abstract

In September 1991, NASA launched the Upper Atmosphere Research Satellite. In addition to its atmospheric sciences mission, analysis of data from the e rst 370 days after launch was used to investigate in-e ight spacecraft disturbances and responses. The investigation included a three-orbit in-e ight experiment to determine how each onboard instrument and subsystem disturbance contributed to the overall spacecraft dynamic response. The investigation quantie ed the spacecraft dynamic response produced by the solar array and high-gain antenna harmonic drive disturbances. The solar array’ s harmonic drive output resonated two solar array modes. Friction in the solar array gear drive provided sufe cient energy dissipation, which prevented the solar panels from resonating catastrophically; however, the solar array vibration amplitude was excessively large. The resulting vibration had a latitude-specie c pattern. Thermal elastic bending of the spacecraft’ s two e exible appendages as the spacecraft crosses the Earth’ s terminator and solar array modal contribution to the spacecraft response were also examined.