The development and test of a long-life, high reliability solar array drive actuator

To meet the life and reliability requirements of five to ten year space missions, a new solar array drive mechanism for 3-axis stabilized vehicles has been developed and is undergoing life testing. The drive employs a redundant lubrication system to increase its reliability. An overrunning clutch mechanism is used to permit block redundant application of two or more drives to a common array drive shaft. Two prototype actuator and clutch assemblies, in continuous vacuum life test under load at 10 to the minus 8th power torr for more than sixteen months, have each accumulated more than 34,000 output revolutions without anomaly, the equivalent of more than seven years of operation in a 1000 km orbit or nearly ninety-five years at synchronous altitude.