Variation of radiation exposure depending on the solar cycle and during solar flares

The complexity of the radiation fields prevailing in space reflects the diversity of physical conditions during past, present and future manned missions. Not only do fundamental differences between the various sources from which the radiation originates play a major role, but also mechanisms that influence the radiation field to which the space travellers are exposed. In addition to local influences, such as shielding by a spaceship, a space station or the atmosphere on extraterrestrial planets, or by a planetary magnetic field, these are in particular effects that arise from the cycle of activity that the sun goes through over a period of about 11 years, which has been known for centuries. The fact that galactic cosmic rays also exhibit a similar periodicity, which is, however, essentially anti-correlated to the number of sunspots, was recognised after the beginning of the systematic measurement of cosmic rays by neutron monitors, which record the intensity of the secondary hadronic component, especially the neutrons, on the Earth's surface. Likewise, both the probability for the occurrence of solar eruptions and their strength as well as the intensity of the radiation belts surrounding the Earth are influenced by the solar cycle.