Charging And Contamination During Geosynchronous Orbit Insertion

Spacecraft operating at geosynchronous altitude are subject to sporadic bursts of energetic electrons that can charge vehicle surfaces to multi-kilovolt potentials. Electric fields emanating from these surfaces attract ions and charged particulates from vehicle outgassing and propellant exhausts, which substantially enhance the collection of contaminants. Solar arrays, second-surface mirrors, thermal control paints, and other dielectric surfaces are especially vulnerable because their charge dissipation requires solar photoemission. This study is particularly concerned with sensor contamination from rocket exhaust during geosynchronous orbit insertion. The Inertial Upper Stage and its payloads have been analyzed with three dimensional finite-element models to obtain electrostatic field configurations and with lumped-constant electric circuits for dynamic charging and arcing response. Results indicate these natural charging events seriously contaminate payloads if they occur during orbit insertion maneuvers. Preventive actions are suggested to alleviate the charging and avoid such contamination.