Atomic-Oxygen Erosion of Photopolymer Materials: Surface Recession, Oxidation, Coatings and Ground Simulation

Atomic oxygen is a dominant surface-reactive species in low Earth orbit and can erode organic polymers by repeated oxidation and volatile-product formation. For printed photopolymers, roughness, pores, cure gradients and thin protective coatings can convert nominally uniform exposure into highly localized recession. The engineering quantity is therefore not merely mass loss after a test, but erosion yield or recession per fluence linked to surface chemistry, roughness evolution and coating-defect growth. Ground plasma and beam facilities are useful only when atomic-oxygen energy, flux, fluence and collateral ultraviolet or ion exposure are known well enough to interpret equivalence. Protective coatings introduce a second problem: small defects can dominate long-duration attack by allowing undercutting and local erosion of the substrate. ER-382 defines a qualification route that separates intrinsic substrate susceptibility, coating integrity and simulator bias.