Evaluation of active damping performances in orbit

The efforts dedicated to predicting and overcoming the vibrations of structures in space have increased dramatically over the last ten years. Motivating factors behind this increase are optical systems with high stability requirements, large antennas, sensitive microgravity payloads and compatibility of flexible appendages with attitude control. Prediction activities combine analytical model and ground tests to simulate the behaviour of structures. The requirements on structural dynamic transmissions often lead to specific developments in conception such as frequency decoupling with noise sources in the spacecraft, adding passive or active damping in the structural path, or setting up suspension devices. This paper focuses on the active damping involved in a truss structure which will be tested in the MIR station in 1996 within the frame of the CNES experiment CASTOR. This experiment aims at validating the analysis and test procedure for advanced space structure dynamic prediction, and demonstrating in zero gravity conditions the efficiency of passive and active damping technologies. After introducing the context, the paper is organised as follows: objectives of CASTOR design and optimisation of active damping system test results flight hardware and test plan conclusion, further activities