Evaluation and analysis of thermal control materials under ground simulation test for space environment effects

Thermal control materials such as white paint comprising silicone resin mat rix (NASDA-1049/101-S), black paint comprising urethane resin matrix (NASDA -1049/201-U-1), aluminized polyimide adhesive tape (Sheldahl G408810) and s ilver-backed fluorinated ethylene propylene (silvered FEP) adhesive tape (S heldahl G402500) were exposed to electron beam (EB), proton (H+), iron ion (Fe 5(+)), ultraviolet (UV) and atomic oxygen (AO):radiation with ground si mulation test facilities. Combined irradiation of EB --> UV and another com bined irradiation of EB -->. AO, where EB was irradiated at first and then UV or AO was irradiated, were also examined for white paint and black paint . Irradiation energies were 0.5 and 1.9 MeV for EB; 1, 3 and 10 MeV for H+; 15 MeV for Fe (5+); equal to or larger than 3.1 eV for UV, and 5 eV for AO . Fluences of EB, HI and Fe5+ were selected to simulate the environment of geostationary orbit (GEO) for 10 years. UV irradiation was equal to 300 equ ivalent solar days. AO fluence corresponded to the environment of low Earth orbit (LEO) for about 1 year. The solar absorptance. (alpha (S)) and norma l infrared emittance (epsilon (N)) of the examined materials both before an d after irradiation were acquired. The durability of the materials against each irradiation treatment was judged by evaluating the changes in alpha (S ) and epsilon (N). White paint and black paint were strongly affected by AO , EB --> UV, EB --> AO and UV irradiation. White paint was also affected by EB and weakly by H+ and Fe5+. Aluminized polyimide and silvered FEP were d egraded most by AO and EB. EB had a stronger effect than ions (H+, Fe (5+)) in all the samples, the reason for which can be explained by the larger ab sorbed dose with EB compared with ions. The mass loss caused by the irradia tion treatment was also measured for white paint and black paint. Analytica l techniques such as scanning electron microscopy (SEM), electron spectrosc opy for chemical analysis (ESCA) and Fourier transform infrared spectroscop y (FTIR) were applied to identify morphology and composition of the materia ls to obtain a deeper understanding of the mechanism of space environment e ffects on the materials.