Takao Nakagawa

The infrared space telescope SPICA, Space Infrared Telescope for Cosmology and Astrophysics, which features a 3m-class and 6K cryogenically cooled space telescope, is a next-generation astronomical project of Japan Aerospace Ex-ploration Agency (JAXA). The telescope and scientific instruments are cooled by a combination of an active (mechanical) cooling system and a passive (insulation and radiation) cooling system in the payload module. In this paper, the structural overview is described especially for the passive cooling system in the payload module and the summary of some experi-mental studies is presented.

Space Infrared Telescope for Cosmology and Astrophysics (SPICA) is an infrared IR astronomical satellite to be launched in 2022. It is equipped with sensitive IR sensors, cooled down to 4.5K. It also consists of a high-power X-band transmitting antenna used for downlink to the earth. Since energy leakage should be stringently suppressed from the antenna to the IR sensors, it is necessary to evaluate electromagnetic shielding effectiveness (SE) of structural materials of the satellite, including carbon fiber reinforced plastics (CFRP), multi-layer insulator (MLI), and aluminium plates connected with rivets. The CFRP and MLI were found to yield SE equivalent to aluminium. The SE of the connected aluminium plates increased with decreasing spacings of the rivets. Chromate conversion coating, providing higher surface conductivity than anodized aluminium surface, also enhanced the SE.