On-Orbit Performance of the FY-4 GIIRS Stirling Cryocooler Over 2 Years

The Fengyun series 4 (FY-4) Geostationary Interferometric Infrared Sounder (GIIRS) is the first interferometric infrared sounder operating in geostationary orbit internationally, for vertical air soundings of temperature and humidity. This paper describes the long-life Stirling cryocooler operating at 60 K in GIIRS. The cryocooler’s performance at room temperature, mounting status on the GIIRS, performance with and without phase control and on-orbit performance for 2 years are described. Until May 31, 2019, the cooler had more than 20,000 h of continuous running time with no indication of a change in performance. The undegraded performance provided by the cryocooler has enabled the GIIRS to fulfill its mission.