MISSE 2 PEACE Polymers Erosion Morphology Studies
de Groh KK, et al. (2009). "MISSE 2 PEACE Polymers Erosion Morphology Studies." International Symposium on Materials in the Space Environment
Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, were exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly four years as part of the Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications to more recently developed polymers. Additional polymers, not considered for spacecraft applications, were included to explore erosion yield dependence upon chemical composition. The polymers were typically in thin-film form (25 to 500 μm thick) and depending on the polymer thickness and estimated erosion yield, stacking of numerous thin film sample layers was often necessary. Several thick single layer materials, such as epoxy and pyrolytic graphite, were also included. The PEACE Polymers experiment was flown in MISSE Passive Experiment Container 2 (PEC 2) on the exterior of the ISS Quest Airlock and was exposed to ram atomic oxygen, along with solar and charged particle radiation, for the majority of the mission; hence the polymers typically developed very diffuse textures. The average atomic oxygen fluence was 8.43 x 1021 atoms/cm2. This paper documents the erosion morphology of numerous MISSE 2 PEACE polymer samples. Erosion cone structures were examined for high and low erosion yield samples. Also examined were the erosion characteristics for thin film polymers eroded through several layers. Of particular interest was documentation of the erosion of a thin film polymer outer layer at cone valleys, and the corresponding erosion morphology of the underlying layer. This information is relevant to the durability of materials and components on spacecraft that are protected by thin film polymers. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown collectively in LEO for a long duration and was exposed to an unusually clean LEO spacecraft environment. This paper provides high fluence ram atomic oxygen erosion morphology data applicable to spacecraft durability.