Record charging events from Applied Technology Satellite 6

Abstract

Applied Technology Satellite 6 regularly charged to large negative potentials in sunlight and eclipse in the earth's midnight to dawn region. This geosynchronous satellite normally reached potentials of -100 to -1000 V in sunlight, and potentials of -100 to -10,000 V in eclipse. The largest potential recorded in eclipse for this satellite was -19 kV, in an environment characterized by an electron temperature of 18 keV. The most negative potential recorded in sunlight was -2 kV, at local dawn, while immersed in an 11-keV electron population. These are the most negative potentials reported from the geosynchronous orbit to date for eclipse and sunlight, respectively. The magnitudes of these potentials indicate the need for methods of potential control on satellites at these altitudes, particularly those with shadowed insulating surfaces.