In-Flight Measurements of Radiation Environment Observed by Hotbird 13F and Hotbird 13G (Electric Orbit Raising Satellites)

Measurements of particle fluxes obtained with the latest version of Influence sur les Composants Avancés des Radiations de l’Espace (ICARE), called ICARE_NG2, onboard Hotbird 13F and Hotbird 13G satellites, are presented. Compared to previous versions of ICARE, a wider range of particle energies is measured. Indeed, low-energy protons are now available, down to ~5 MeV. The missions consist of electric orbit raising (EOR) phases (launched at the end of 2023), followed by an operational orbit in geostationary orbit (GEO). The EOR periods are analyzed through a series of comparisons. Very good agreements are observed with other instruments, while significant discrepancies are found with engineering models, such as AE/P8, AE/P9, and global radiation Earth environment (GREEN). The average fluxes recorded during the EOR phases are presented and compared with the engineering models. None of the models used can accurately reproduce the observed fluxes. Such results will help to optimize specifications for future space missions.