Abstract
ASTER is an advanced multi-spectral imager for EOS spacecraft Terra which was launched with other four instruments on December 18, 1999. The development of ASTER instruments was carried out with Japan Resources Observation System Organization (JAROS) under the control of Ministry of Economy, Trade and Industry (METI). The ASTER instrument covers a wide spectral region, from visible to thermal infrared with 14 spectral bands which are consist of visible and near-infrared (VNIR) subsystem, short-wave infrared (SWIR) subsystem and thermal infrared (TIR) subsystem. Two cryocoolers has been adopted the coolers of the detectors of the SWIR and the TIR subsystems. The performances of these coolers has been very stable and will be maintained until 5 years design life period of this December.