Space Atomic Oxygen Erosion Effects on Epoxy and Silicone Adhesives Used in LEO Spacecraft

Abstract

Atomic oxygen (AO) is among the predominant factors in Low Earth Orbit (LEO) space environment. Ground‐based laboratory AO exposure testing was performed to investigate interaction between atomic oxygen and materials that were intended for use in future missions on LEO spacecraft. Two types of adhesive materials, i.e., E‐32 epoxy and GS414 silicone were tested in Atomic Oxygen Test Facility at the Beijing Institute of Spacecraft Environment Engineering (BISEE). The effective atomic oxygen fluence in the conducted tests was approximately 1.4×1021 atoms/cm2 which is close to the fluence of a two‐year exposure in LEO orbit. Significant mass losses of epoxy adhesive materials were detected after the exposure to atomic oxygen, but relatively small mass changes were found in silicone samples. The erosion yields of epoxy samples were from 3.2×10−24 cm3/atom to 3.8×10−24 cm3/atom. Surface bleaching by atomic oxygen was found in epoxy samples. The surface on silicone sample remained glossy after AO exposure. Both materials were analyzed using Scanning Electron Microscopy (SEM) and X‐ray Photoelectron Spectroscopy (XPS) to study the changes of material surfaces. A number of interesting results concerning the surface changes in the exposed materials have been found after a comparison study between unexposed and exposed samples.