Earth’s magnetosphere is part of a dynamic, interconnected system which responds to solar, planetary, and interstellar conditions. It encloses two belts of magnetically trapped, energetic charged particles, which constitute a well-known hazard to spacecraft systems and crews, significantly constraining human activities in space. Despite notable improvements made in the latest decades,
the modeling of the trapped environment is still incomplete, with largest uncertainties affecting the high-energy fluxes (> 50 MeV) in the inner regions and in the South Atlantic Anomaly (SAA).
Additionally, space weather events increase the spatial and composition variability of the magnetospheric radiation belts, e.g. during geomagnetic storms. The Italian High-Energy Particle
Detector (HEPD-01), on a low-Earth orbit since February 2018, is providing crucial new insight in the physical dynamics of the radiation belts, thus enabling an extensive testing and validation
of current theoretical and empirical models of the near-Earth environment (e.g. AP9 and AE9).
In this contribution, a review of magnetospheric and space weather observations by HEPD-01 is presented, including the study of some major geomagnetic storms, such as the G3-class ones of August 2018 and May 2021, the re-entrant lepton spectrum between 20 and 100 MeV and the proton fluxes inside the SAA in the 40-250 MeV energy range.