The Spacecraft Power Supply System

The power supply .system used in the Telstar spacecraft employs a solar cell plant which converts solar radiation to electrical energy when the satellite is illuminated by the sun. During periods of eclipse and/or peak power drain of transmission, reserve power is provided by a 19-cell, nickel-cadmium battery. To conserve power and allow battery recharging, continuous power is supplied only to those circuits in the satellite necessary for ground tracking and command. All others are turned off when not required. l.i Characterization of Loads The electrical systems in the spacecraft are divided into three major parts: (a) the communications repeater, which contains the microwave transmitter, microwave receiver and microwave beacon; (b) the radiation damage and particle distribution experiment; (c) the command receivers, telemetry system, and YHF beacon transmitter. The microwave transmitter contains a traveling-wave tube, the only electron tube in the satellite. The power requirements for the travelingwave tube total 15.8 watts. 943