Materials degradation in space is due to the synergistic effects of atomic oxygen and ultraviolet light exposure. Post-flight degradation evaluation is done using spectroscopic ellipsometry, atomic force microscopy, reflectometry, mass loss, electron microscopy, and photothermal deflection spectroscopy. With the exception of ellipsometry, none of these diagnostics are reasonable to fly on space missions for real-time, in-situ sensing. A space-qualified ellipsometer to be used for real-time, in-situ evaluation of materials degradation in space will be developed. It will be lightweight, compact, totally automatic, and highly reliable.This will make an excellent instrument for numerous materials degradation and contamination problems (e.g., corrosion) in terrestrial as well as space applications.atomic oxygen degradation, compact automatic reliable space ellipsometer
