Particle radiation environment in the heliosphere: Status, limitations, and recommendations

Space weather is a multidisciplinary research area connecting scientists from across heliophysics domains seeking a coherent understanding of our space environment that can also serve modern life and society's needs. COSPAR's ISWAT (International Space Weather Action Teams) “clusters” focus attention on different areas of space weather study while ensuring the coupled system is broadly addressed via regular communications and interactions. The ISWAT H3 cluster “Radiation environment in heliosphere” (https://www.iswat-cospar.org/h3) has been working to provide a scientific platform to understand, characterize, and predict the energetic particle radiation in the heliosphere with the practical goal of mitigating radiation risks associated with areospace activities, the satellite industry, and human space explorations. In particular, present approaches help us understand the physical phenomena at large, optimizing the output of multiviewpoint observations and pushing current models to their limits. In this article, we review the scientific aspects of the radiation environment in the heliosphere, covering four different radiation types: solar energetic particles, ground-level enhancement (a type of solar energetic particle event with energies high enough to trigger signals in ground-level detectors), galactic cosmic rays, and anomalous cosmic rays. We focus on related advances in the research community in the past 10–20 years and what we still lack in terms of understanding and predictive capabilities. Finally, we also consider some recommendations related to the improvement of both observational and modeling capabilities in the field of the space radiation environment.