Space radiation biology

The space radiation environment induces many known and unknown biological effects upon organisms in space. The principal sources of these charged particles are galactic cosmic rays and the Sun. Even when adhering to permissible exposure limits potential health risks such as carcinogenesis, degenerative tissue disease, damage to the central nervous system and acute radiation symptoms are still of concern. The majority of the predicted health problems will occur over the long term, after a mission has ended. However, very high dosages may lead the acute radiation symptoms, which could endanger the functioning of astronauts during a mission. Active shielding by magnetospheres or biological protection using radioprotectors might supplement these classic protection measures. Biophysical models are used to approximate human health risks to the space radiation spectrum. Extrapolation of such models to humans is still error prone due to high physiological complexity. Further developments of these models are critical for safe long-duration missions.