Design and performance of the space environment in-situ suite on the FY-4B satellite

The FY-4 series represents China’s second generation of geostationary meteorological satellites. FY-4B was launched in June 2021 as the successor to FY-4A, carrying improved payloads including an enhanced Space Environment Package. This paper describes the design and capabilities of the Space Environment In-Situ Suite (SEISS) onboard FY-4B, which comprises seven sensors to detect charged particles, radiation dose, electric potential, and magnetic fields across a wide spectrum of energies. The suite provides real-time monitoring of space weather conditions from geostationary orbit, benefiting activities such as satellite operations, research, and forecasting. Preliminary on-orbit performance results demonstrate the SEISS is successfully measuring various space weather phenomena. Compared to its predecessor, the FY-4B SEISS features expanded detection capabilities with finer energy resolution and faster sampling. The system represents a significant advancement in China’s space environment monitoring capabilities from geostationary orbit.