The SWIR(Short Wave-length Infrared Radiometer) is one of the optical sensors in ASTER(Advanced Space-borne
Thermal Emission and Reflection Radiometer). ASTER is installed in the EOS(Earth Observing System) TERRA
spacecraft of NASA. TERRA was launched on December18, 1999, and is employed still on the orbit for 14 years in
January, 2014, The detector of SWIR is cooled at temperature 77K by cryocooler with the optimum sensitivity. SWIR
had continued to take the numerous image data for more than five years of the mission period on orbit, and the
cryocooler is still operating normally. However, a gradual rise in temperature of the detector has been seen after launch.
Silicone compound have been used in order to achieve heat transfer between the detector and the cryocooler. On
investigation, we have found that thermal conductivity of the silicone compound has been gradually reduced. We
evaluated the low temperature properties (such as thermal conductivity, strength etc.) of the silicone compound. In
addition, we analyzed the temperature conditions and the thermal stress values of cryostat in the orbit. As a result, the
silicone compound solidified at low temperature shows a behavior similar to adhesive. Depending on the thermal stress
generated at a low temperature, there is a possibility that destruction such as peeling occurs.