In-orbit performance of INTELSAT V communications antennae deployment systems

The INTELSAT hinged antenna deployment system is described, and use of real time telemetry from spacecraft sensors to evaluate the success of the deployments, and the actions taken to correct performance anomalies are discussed. Two partial failures were successfully diagnosed using the telemetry from nutation accelerometers and Sun and Earth sensors. Both anomalies arose from conditions where initial clearances in the mechanism were too small to accommodate the thermal distortions encountered in orbit. A large increase in the friction torque resulted, which was beyond the capacity of the springs to overcome until temperatures moderated. Thermal distortion effects were accounted for in the hinge design, the clearances were correctly adjusted at final assembly and reverified by an inspection and test program, so INTELSAT 5 overcame deployment problems.