Biological effects due to single accelerated heavy particles and the problems of nervous system exposure in space

The use of accelerated nitrogen and oxygen nuclei with 270 MeV nucleon-1 at the Berkeley Bevatron allowed a beginning to be made of systematic studies of the effects of heavy particles in multicellular organisms. Initial studies will be briefly reviewed. Individual nitrogen particles produced definite light flashes, streaks and interrupted streaks when they crossed light-sensitive parts of the human retina. The possible hazard from primary heavy galactic cosmic ray particles on long-term space flights are discussed, with special attention to the nervous system.