Test program of multi-junction GaAs/Ge solar array coupons with combined space environmental exposures

A test program was undertaken to understand the changes and degradation of the space solar array panel components in their integrated form after multiple years (up to 15) of simulated Earth geosynchronous (GEO) space environment. The solar array coupon panel design included its electrostatic discharge (ESD) mitigation design features. A set of multi-junction GaAs/Ge solar array test coupons was subjected to 5-year increments of combined environmental exposure tests. These tests consisted of: simulated ultraviolet (UV) radiation, ESD, electron/proton particle radiation, thermal cycling, simulated ion thruster exposures, and simulated ion thruster interaction with ESD events on the solar array. Before and after each increment of combined environmental exposures, the coupons underwent visual inspection using high power magnification and electrical tests that included characterization by LAPSS, dark I-V, insulation resistance, and electroluminescence. This paper discusses the test objective, test methodologies, and preliminary results after 5 years, 10 years and 15 years of simulated combined environmental exposure tests.