CASTOR ACTIVE DAMPING EXPERIMENT, PRELIMINARY FLIGHT RESULTS

The experiment ''CASTOR'' (French acronym for ChAracterization of STru ctures in ORbit) is dedicated to the analysis of the structural dynami c modes of the MIR station, and to the investigation of the dynamic be haviour-in zero g conditions-of a truss mock-up with various damping t echnologies. This project has been developed under CNES management in less than three years. The work in orbit was performed by a French cos monaut within the frame of the CASSIOPEE mission in MIR at the end of August 1996. This paper is dedicated to the active damping systems for CASTOR's truss structure. The consist essentially of three piezoelect ric members, and one reaction mass actuator. Both systems use collocat ed sensors and actuators. Their development and flight tests are part of CNES' general activities whose aim is to improve, demonstrate the e fficiency. and prepare the application of active control techniques fo r future space missions. Typical applications include optical systems with high stability requirements, large antennas, sensitive microgravi ty payloads, spacecrafts with flexible appendages, and large orbital i nfrastructures. In Bous (1995), we presented the motivations behind th e test in zero g conditions, and a full description of the equipment. In this paper, we briefly recapitulate upon the design of the active s ystems, before summing-up the recent development activities. The opera tions in flight are then presented. A few zero-g measurements are show n without much interpretation considering the short time available bet ween flight and conference. The active systems exhibited excellent per formances in flight. Preliminary conclusions are drawn with respect to the CASSIOPEE mission and to further activities.