Chemical Physics of Charge Mechanisms in Nonmetallic Spacecraft Materials.

The interactions of spacecraft and space systems with the changing solar illumination and charged-particle environments in the vacuum of space result in the occurrence of a number of electrostatic and electromagnetic phenomena. These phenomena, commonly referred to collectively as spacecraft charging effects, can produce undesirable and sometimes serious problems with the performance and operation of military, commercial and NASA spacecraft. This report explores the behavior of typical polymeric spacecraft surface materials under simulated orbital conditions to provide a better understanding of the electrostatic and electromagnetic charging and discharging processes associated with spacecraft charging phenomena. The results of the materials charging behavior studies provide an empirical measure of some of the complexities of materials behavior under dynamic conditions more typical of those encountered in space than are normally used in ground-based simulations and indicate that many present laboratory simulation and measurement techniques may not provide data truly representative of actual in-orbit spacecraft charging effects. The results of the discharge characterization experiments indicate that electromagnetic transients caused by sample discharges produced signals in external sensors indicative of transient electric field changes of tens of kVm at locations several inches from the sample boundaries. These transient electromagnetic signals can therefore be considered as extremely energetic sources of possible electromagnetic interference on spacecraft.