Investigations of Spacecraft Surface Charging in the Geosynchronous Orbit

Abstract

Spacecraft surface charging (absolute and differential charging) induced electrostatic discharge (ESD) events are one of the most detrimental effects of the GEO space environment. Considering the fact that emission of secondary electron and back-scattered electron is a dominant surface effect causing significant influence on spacecraft surface charging, the work presented in this thesis investigates spacecraft surface charging in presence of secondary electron yield (SEY) and back-scattered electron Yield (BEY); and ascertains its contribution in surface charging leading to a probable event of ESD. In order to enhance the immunity of the space systems in GEO against ESD due to surface charging in spacecraft structures, an accurate evaluation of the temporal profile of a spacecraft body potential through reliable numerical modeling is imperative. Evaluation of the temporal profile of the body potential involves the computation of various absolute and coupling newlinecapacitances formed in spacecraft structures. The details of capacitances formed in a spacecraft are not available in various computational tools of spacecraft charging such as NASA spacecraft charging analysis program (NASCAP-2K), spacecraft plasma interaction software (SPIS), multiutility spacecraft charging analysis tool (MUSCAT), PTetra, and COLOUMB-2. Therefore, newlinethe variations in the results produced by these tools are difficult to study and analyze. We avoid continuing with assuming a satellite as a spherical body in our computations and derive the lumped equivalent capacitance circuit model of the following realistic spacecraft modules by applying the well-recognized numerical technique of Method of Moments (MoM) for reliable prediction of ESD events: (i) A metallic pyramid (ii) Solar panel coupon forming an artificial triple junction (iii) A cuboid with two coplanar rectangular plates. Integral equations are applied by involving the known potential to the unknown charge density on the composite spacecraft body.