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The Upper Atmosphere Research Satellite In-Flight DynamicsUpper Atmosphere Research Satellite flight data from the first 737 days after launch (September 1991) was used to investigate spacecraft disturbances and responses. The investigation included two in-flight dynamics experiments (approximately three orbits each). Orbital and configuration influences on spacecraft dynamic response were also examined. Orbital influences were due to temperature variation from crossing the Earth's terminator and variation of the solar incident energy as the 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 response was dependent upon the orientation of the solar array and the solar incident energy. Orbital influences were also caused by on-board and environmental disturbances and spacecraft configuration changes resulting in dynamic responses which were repeated each orbit. Configuration influences were due to solar array rotation changing spacecraft modal properties. The investigation quantified 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 sufficient 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-specific pattern.
Document ID
19970019258
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Woodard, Stanley E. (NASA Langley Research Center Hampton, VA United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1997
Subject Category
Structural Mechanics
Report/Patent Number
NAS 1.15:110325
NASA-TM-110325
Accession Number
97N21022
Funding Number(s)
PROJECT: RTOP 632-20-21-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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