Effect of Simulated GEO Environment on the Properties of Solar Panel Coverglasses

The harsh space environment at geosynchronous orbit (GEO) induces differential charging of spacecraft surfaces due to simultaneous fluxes of electrons with a wide distribution of energies onto, into, and through spacecraft surface materials. Thus, satellite surfaces can charge thousands of volts with respect to each other, whereas entire satellites can charge tens of thousands of volts negative relative to their surrounding space plasma. The ensuing electric fields can cause local discharges (arcs) from one part of the spacecraft to another, endangering the normal operation of the satellite. Furthermore, solar cell coverglass contamination induced by the high rate of arcing is sufficient to produce the ~1.5%/year power loss in excess of radiation damage that has been observed on global positioning system (GPS) satellites. This work focuses on evaluation of a GEO space weather effect on material properties caused by irradiating different types of commonly used space solar cell coverglasses (CMX, fused silica, and Corning 0214) with >90-keV electron radiation.