Current status and scientific progress of the Zhangheng-1 satellite mission

The Zhangheng-1 electromagnetic satellite is the space-based observation platform of China's stereoscopic earthquake observation system. Its scientific objective is to obtain the global geomagnetic field, electromagnetic field (waves), ionospheric plasma parameters, and high-energy particles for monitoring the dynamic variation of the ionosphere and the seismo-ionospheric disturbances over China and its surrounding areas to compensate for the deficiency of the ground-based observation system. The project explores new ways of earthquake monitoring and prediction by using space science. The first test probe of the Zhangheng-1 electromagnetic satellite series was successfully launched in February 2018, and has been stably operating in orbit for more than four years. The second is an operational probe that will be launched in early 2023. The in-flight commissioning test and cross-calibration work show that the Zhangheng-1 electromagnetic satellite can provide good data quality to support geophysics and space physics studies, and has obtained valuable scientific results in recent years. The global geomagnetic reference model built by Zhenghang-1 data is the first global geomagnetic field model built using only Chinese satellite data, allowing Chinese scientists to take an important role in the computation of the global geomagnetic reference model (IGRF) for the first time in over a century. The ionospheric electron density 3D model based on Zhangheng-1 satellite data can present the ionospheric structure characteristics. In natural hazards monitoring, Zhangheng-1 has shown good response ability to disturbances related to earthquakes, volcano eruptions, and geomagnetic storms. In terms of the lithosphere-atmosphere-ionosphere coupling mechanism study, the full-wave calculation method can provide the electromagnetic field changes between the lithosphere-ionosphere waveguide and the ionospheric wave propagation feature. The results from the full-wave model prove the capability of the Zhangheng-1 satellite's electromagnetic payloads to detect low-frequency electromagnetic emissions induced from the earthquake epicenter. The simulation and observation studies suggest that the Zhangheng-1 satellite can reflect seismic activities, very low frequency (VLF) transmitter, magnetic anomalies in the lithosphere, and lightning activities in the atmosphere. These recent scientific results show that the Zhangheng-1 electromagnetic satellite is consistent with other similar types of electromagnetic satellites worldwide, indicating its great potential in scientific application.