Combined effects of fluxes of atomic oxygen and electrons on chemical reactions with polymeric materials.

Understanding the phenomenology of the interaction of the space environment with organic-composite spacecraft surfaces is both interesting science and important to the longevity of our space assets. The importance of this understanding has been made even more critical by the desire to use new organic composite materials whose lower weight and higher stiffness will make it possible to orbit larger payloads. Inconsistencies between ground simulation and space test data clearly indicate that our understanding of the interaction phenomenology is inadequate. This paper describes the test equipment, designed by Phillips Laboratory, to subject materials to a simulated low-earth-orbit (LEG) environment, consisting of simultaneous fluxes of hyperthermal neutral oxygen atoms (AO), energetic electrons, vacuum-ultraviolet light, and hypervelocity-particle impacts characteristic of space debris and micrometeoroids. Preliminary results of studies of the combined effects of fluxes of AO and electrons on polysulfone resins and composites are presented. The chemical species generated by chemical reactions were monitored using a mass spectrometer, and the results indicate that the primary effect of electrons on AO reactions is through electric fields induced by charging the material surface.