Degradation of SpaceSuit Fabrics in Low Earth Orbit

Six samples of pristine and dust -abraded outer layer spacesuit fabrics were included in the Materials International Space Station Experiment-7, in which they were exposed to the wake-side low Earth orbit environment on the International Space Station (ISS) for 18 months in order to determine whether abrasion by lunar dust increases radiation degradation. The fabric samples were characterized using optical microscopy, optical spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and tensile testing before and after exposure on the ISS. Comparison of pre- and post-flight characterizations showed that the environment darkened and reddened all six fabrics, increasing their integrated solar absorptance by 7 to 38 percent. There was a decrease in the ultimate tensile strength and elongation to failure of lunar dust abraded Apollo spacesuit fibers by a factor of four and an increase in the elastic modulus by a factor of two. Nomenclature AFM atomic force microscope AO atomic oxygen AlFEP vapor-deposited aluminum backed FEP film ASTM American Society for Testing and Materials EDS Energy-Dispersive X -ray Spectroscopy EM electromagnetic FEP fluorinated ethylene propylene FESEM Field Emission Scanning Electron Microscopy HST Hubble Space Telescope ISS International Space Station JSC-1A lunar simulant LEO low Earth orbit MISSE Materials International Space Station Experiment PEC passive Experiment Container PGA pressure garment assembly PTFE polytetrafluoroethylene UV ultraviolet α integrated solar absorptance λ wavelength ρ(λ) wavelength-dependent total reflectivity