Seven Year Thermal Vacuum Real Life Test of a Medium Speed (DESPIN) Mechanism Manufactured by Dornier System

摘要

A satellite despin mechanism succesfully completed a 7 yr thermal vacuum real life test, extended by 1 yr operation at nominal ambient temperature. During the 7 yr test the thermal conditions were changed at four-weekly intervals to simulate the flight conditions, at a mechanism speed of 60 rpm. Earth eclipses were simulated at six-monthly intervals. Grease/oil lubrication was used. There is a gradual increase in the current demanded by the motor to enable the speed control system to maintain a constant speed. This is not due to an increase in friction torque within the mechanism, but to a progressive reduction in the field strength of the motor rotor permanent magnets due to aging. The thermal distribution within the mechanism remains constant except that during eclipse simulations towards the end of the test motor power dissipation increases slightly.