Characterization testing of Measat GaAs/Ge solar cell assemblies

Abstract

The first commercial communications satellite with gallium arsenide on germanium (GaAs/Ge) solar arrays was launched in January 1996. The spacecraft, named Measat, was built by Hughes Space and Communications Company. The solar cell assemblies consisted of large-area GaAs/Ge cells supplied by Spectrolab Inc. with infrared reflecting (IRR) coverglass supplied by Pilkington Space Technology. A comprehensive characterization program was performed on the GaAs/Ge solar cell assemblies used on the Measat array. This program served two functions: first to establish the database needed to accurately predict on-orbit performance under a variety of conditions; and second, to demonstrate the ability of the solar cell assemblies to withstand all mission environments while still providing the required power at end-of-life. Characterization testing included: measurement of electrical performance parameters as a function of radiation exposure, temperature and angle of incident light; reverse bias stability; optical and thermal properties; mechanical strength tests, panel fabrication, humidity and thermal cycling environmental tests. The results provided a complete database enabling the design of the Measat solar array, and demonstrated that the GaAs/Ge cells meet the spacecraft requirements at end-of-life.