FLIGHT EVALUATION ON SURVIVABILITY OF FEP IN SUPER-LOW EARTH ORBIT ENVIRONMENT

摘要

The super-low altitude test satellite (SLATS) is the first Japanese satellite orbiting the altitude of 200 km assistedby an ion engine. Because of its low altitude, atomic oxygen flux at ram facing surface of SLATS is more than twoto three orders greater than that of the International Space Station. Material Degradation Monitor (MDM) is the firstmaterial evaluation in super low earth orbit. In the previous experiment based on the ground-based simulation (M.Tagawa and K. Yokota, 61st International Astronautical Congress, Prague, Czech Republic, 2010), erosion offluorinated polymer by N_2 collision in LEO is strongly suspected. Due to its small scale-height, increase in densityof N_2 with lowering the altitude increases much more than that of atomic oxygen. If fluorinated polymer wereeroded by N_2, the life of fluorinated polymer in SLEO would be quite short compared with that expected based onthe atomic oxygen fluence. In order to evaluate the survivability of fluoropolymer in SLEO environment, MDMwill carry FEP samples. It provides not only the lifetime of FEP, but also the evidence of origin of fluoropolymererosion in space environment.