Small-scale mechanical characterization of space-exposed fluorinated ethylene propylene recovered from the Hubble Space Telescope

Multi-layer insulation (MLI) blankets from the Hubble Space Telescope have been recovered during the last servicing mission, after 19.1 years of on-orbit service. Based on testing and analysis of returned insulation material from earlier Hubble servicing missions, the space environment is known to have detrimental effects on the mechanical properties. The most recently retrieved MLI blankets were highly degraded with many cracks, limiting the material available for full-scale mechanical testing. As a result, micro-tensile experiments have been performed to characterize the effect of space exposure on the mechanical response of the outermost layer of the MLI. This outer layer, 127 μm thick fluorinated ethylene propylene with a 100 nm thick vapor deposited aluminum reflective coating, maintained significant tensile ductility but exhibited a degradation of strength that scales with severity of space exposure. This change in properties is attributed to damage from incident solar flux, atomic oxygen damage and thermal cycling.