Development of a Surface Charging Assessment System for the GEO Region by Combining Global Magnetosphere MHD and Spacecraft Charging Models

For the safety and stability of satellite operations, we have been conducting a satellite charging estimation project, Space Environment Customized Risk Estimation for Satellites (SECURES), by linking space environment models and spacecraft charging models. In SECURES-Surface Charging, we use the global magnetosphere MHD model as the environment model and target the geostationary orbit (GEO) region as the first step of the surface charging estimation. To perform the magnetosphere simulation under realistic conditions, we improved the model by introducing the effects of the tilt and precession of the Earth’s dipole axis. By comparing the simulation data of the improved magnetosphere MHD model and observation data for the GEO region, we found that the simulated pressure is in good agreement with the observed electron pressure. However, the simulated density is much higher than the observed electron density, and the simulated temperature is lower than the observed electron temperature. Utilizing these characteristics, we developed a method of estimating the input parameters for spacecraft charging models from the magnetosphere MHD simulation output. As for the satellite surface charging calculation, we developed a method of estimating instantaneously the equilibrium surface potentials based on the precalculation analysis using the spacecraft plasma interaction system (SPIS). Based on these two methods, we developed a surface charging assessment system for a model satellite in the GEO region (https://secures.nict.go.jp), which operates in real time by combining the global magnetosphere MHD model and SPIS.