Radiation protection measures of the space agencies on the ISS

Knowledge of the composition of the radiation environment in near-Earth space was patchy at the beginning of manned spaceflight. There was great concern about the level of radiation exposure from the particles of the radiation belts and from galactic cosmic rays. In particular, the lack of knowledge about the radiobiological effects of the heavy ions of the cosmic component allowed only a very uncertain estimate of the radiation risks to astronauts. It was important to prevent potentially high exposures caused by solar flares and thus the occurrence of acute radiation damage in order not to endanger the mission and to minimise the occurrence of radiation-induced late damage in the astronauts' organs. Radiation protection limits have been worked out, new research programmes have been created, new heavy ion accelerators have been built (probably the most powerful in the world is currently being built in Darmstadt, called FAIR), measures to reduce radiation exposure in space missions have been developed. The efforts to develop ethically acceptable radiation protection limits are therefore briefly described using NASA as an example. Operational measures for radiation protection and the determination of radiation exposure by the individual space agencies are briefly outlined and future activities to optimise radiation protection are indicated.