Comparison between Surface Charging Event from MICHIBIKI (QZS) Satellite and Space Environment Data from Global MHD Simulation

Abstract

Space environment in geospace changes depending on the solar wind and high energy particles originated from the Sun. It is well known that the satellite anomaly sometimes occurred because of the dynamical variations of the space environment. To understand the current and future conditions of space environment, which we call 'Space Weather Forecast', is one of the quite important activities for safety and security operations of the spacecraft. On the other hand, the detailed information of spacecraft anomaly, possibly related to space disturbances, cannot be available in usual. The risk of the individual satellite depends not only on the space environment, but also on the satellite charging condition, which depend on the structure and materials of the satellite body. Therefore, it is not easy for the satellite operator to judge the risk of the satellite based on the space environment information only. To improve this situation, we start developing specialized information for the nowcasting and forecasting space environment for each satellite, and estimate the risk of satellite anomaly by combining information of space environment and that of satellite materials with a charging model. To seek this approach, the risk of satellite charging will be estimated based on the prediction of space environment using the case study of MICHIBIKI satellite, which is on the quasi-zenith orbit. As a first step, relationship among the space environment data and surface charging data obtained from MICHIBIKI satellite, and space environment data obtained from global magnetospheric MHD simulation are examined. Since the MHD simulation calculate temperature and density as single MHD fluid, an empirical relationship between simulation and observation needs to be made for obtaining the estimated temperature and density of electrons and ions. Initial comparison is introduced in this paper.