The superconducting submillimeter-wave limb-emission sounder (SMILES) was operated aboard the Japanese experiment module (JEM) of the International Space Station (ISS). SMILES uses two superconductor-insulator-superconductor (SIS) mixers for submillimeter-wave atmospheric observation, and they are cooled to 4 K levels by a cryogenic system with a two-stage Stirling cycle cooler, a Joule-Thomson (JT) cycle cooler and a cryostat composed of three stages (4 K, 20 K and 100 K). SMILES was launched on September 11, 2009 (UT) from the Tanegashima Space Center (TNSC). The cryogenic system reached 4.1 K in approximately 70 hours after it began to be cooled, and the observation was performed. The cryogenic system has electric drive power of less than 70 W, and continued cooling for 6,010 hours at 4 K levels.
