Flouorescence measurements of the thermal control coatings on LDEF experiments S0069 and A0114

Strong fluorescence emissions were observed, during post flight ultraviolet light inspection of experiments S0069 and A0114, from some of the surfaces exposed to the space environment. Subsequent wavelength measurements of the fluorescence emission characteristics, indicated large changes occurred between controls and exposed materials. Black urethane based coatings, especially ones having a silicone atomic oxygen protective overcoat, appear bright yellow under ultraviolet exposure. Measurements showed that the urethane based coatings had their emission spectra shifted into the visible wavelength range. In contrast, zinc oxide pigment type coatings showed a different effect, which was a quenching or reduction of their fluorescence versus exposure time. Silver Teflon bonded to aluminum with acrylic adhesive also showed a slight measurable fluorescence, which was found to originate in the acrylic adhesive.