Thermal design and verification of the Geostationary High-speed Imager (GHI) on FY-4B satellite

As a main element of China second generation of geostationary meteorological satellite Fengyun 4B (FY-4B), which was launched on Jun. 03, 2021, the Geostationary High-speed Imager (GHI) is the first round the clock high-frequency imaging instrument working on the international geo-stationary orbit. It can continuously observant and imagine for 2000km×2000km regions with spatial resolution up to 250m in 1 minute interval. The challenge of GHI thermal design was that the sun intrusion of the optic system would induce destabilization of the internal temperature field. It conflicted with the target of the GHI thermal system, which should ensure small temperature difference between two sides of scanner shrouds (less than 3K), the low temperature gradient of optical mounting platform (less than 2K), and high precision temperature control (±0.1K) of blackbody. This paper described the control strategy and requirements of the GHI thermal system, which successfully performs all phases of the mission. The on-orbit data showed that the instrument maintained a stable internal thermal environment when optical system exposed to external heat flux disturbances in mid-night.