Lifetime Test and Heritage On-Orbit of SHI Coolers for Space Use

Since 1987, Sumitomo Heavy Industries, Ltd. (SHI) has developed small Stirling coolers of two types and two Joule–Thomson (JT) coolers with operating temperatures ranging from 80 K to 1 K for space use. Ground lifetime tests of four coolers were conducted to demonstrate their long life and reliability. A single-stage Stirling cooler was tested for 113,640 hr. Two single-stage Stirling coolers were tested for 108,370 and 104,771 hr. Also, a two-stage Stirling cooler was tested for 72,906 hr. An advanced 4¶K cooler with 4 He was tested for over 36,140 hr. Also, a 1¶K-class cooler with 3 He was tested for 6721 hr from last year. All of these coolers, except for the 1¶K-class cooler, have shown good results on orbit. Three single-stage Stirling coolers were carried on the “SUZAKU” Xray astronomical satellite, the “KAGUYA” Japanese lunar polar orbiter, and the “AKATSUKI” Japanese Venus Climate Orbiter. Two units of a two-stage Stirling cooler were carried on the “AKARI” infrared astronomical satellite. Moreover, a 4 K cooler was carried on the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS). A Japanese X-ray astronomy satellite “ASTROH (Hitomi)” including a 4 K cooler, two sets of two-stage Stirling coolers, and two sets of singlestage coolers was launched on February 17, 2016. This report describes the updated results and operating status from an earlier report 1 of ground lifetime testing and achievements on orbit of SHI coolers for space use.