Space radiation environment
The space radiation environment, impacting human operations within the Earth-Moon system, has three sources. The first is the high energy charged particles (e.g., electrons and protons) trapped within the Earth’s magnetic field. These are called the Van Allen radiation belts. This radiation is of concern because it impacts satellites above LEO, humans passing through the belts going to the Moon or Lagrangian Points, or humans performing logistics support operations on satellites positioned within the belts (e.g., communication satellites in GEO).
The second source of radiation is that emitted by the sun. Solar radiation includes electromagnetic radiation (e.g., sunlight) as well as energetic charged particles. The highly energetic charged particles emitted during intense sunspots or similar sun activity are the primary radiation of concern to human operations in space.
The third source of radiation is cosmic radiation that comes from the surrounding universe. These are emissions from distant suns, black holes, quasars, neutron stars, pulsars, and super nova events. They are comprised of both photons and charged particles. As with solar emissions, the highly energetic charged particles are the primary radiation of concern to human operations in space.