Proceedings PaperTest And Computation Of The Dynamical Environment At The Interface Of An Optical Package Mounted On A Geostationary Spacecraft
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The stringent pointing requirement for establishing an optical intersatellite link (ISL), leads to consider the dynamic interaction between host satellite and optical payload up to relatively high frequencies (f > 200 Hz ). For the optical pointing system design, this dynamic characterization is needed, and except measurements on Landsat 4 spacecraft, very few data are yet available. Cnes and Aerospatiale were associated in the frame of an Intelsat study to identify the dynamic environment of an optical payload on a geo-satellite. This paper presents a part of this study concerning the vibrations (high frequency, small amplitude) identification on a satellite, which is of major importance for the choice of the fine pointing loop rejection bandwidth. Testing and modelling were carried out together on TDFI spacecraft at Aerospatiale/Cannes facilities. Satellite's main body without appendages was mounted on a decoupling device, and high resolution sensors were fixed at potential ISL payload locations to record the disturbances induced by each vibrating source. To validate these test results, a dynamic modelling was performed. The spacecraft equations were generated in a. parametric form, thanks to the use of the symbolic computation software Gemmes. Effects of units which cannot be tested on ground (thrusters,...) are derived from this model. Comparison of tests results and computation are presented; both approaches appear very complementary. Correlations of both results allows to establish the disturbances distribution at the interface in term of amplitude and frequency.