Effect of 1.5 Years of Space Exposure on Tensile Properties of Teflon

Abstract

Materials on the exterior of spacecraft in low Earth orbit are subject to extremely harsh environmental conditions, including exposure to various forms of radiation, temperature extremes, thermal cycling, and atomic oxygen. These environmental exposures can result in erosion and optical and mechanical property degradation of susceptible materials, threatening spacecraft performance and durability. In an effort to better understand the effect of space exposure on the mechanical property degradation of Teflon insulation, 19 tensile samples were exposed to the space environment for 1.5 years on the exterior of the International Space Station. The samples were flown in ram, wake, zenith, or nadir orientations as part of three Materials International Space Station Experiment 7 mission experiments. This paper provides an overview of the flight mission, an introduction to the experiments, and compares the Teflon property degradation in the various orientations. The reduction in ductility of the samples correlates with the amount of solar radiation. Samples with high solar exposure (zenith orientation) experienced a 76% reduction in elongation relative to controls, whereas samples in the shadowed nadir orientation only experienced a 4% reduction. Additionally, thickness loss measurements show that erosion is significant in the ram orientation, but negligible in other orientations.