Deep space missions and the issue of overcoming the problem of space radiation

As a member of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), Iran has a long-term space exploration program. Space radiation is one of the challenges facing humans when they go outside Earth s protective atmosphere and magnetic field. Space is an environment that the cardinal principles of radiation protection; i.e. time, distance and shielding cannot be effectively applied. On the other hand, well-known limitations of physical shielding prompt us to explore biological methods for inducing radioresistance during space missions. Screening of the candidates of longterm space missions by ground-based in vitro adaptive response studies might be helpful. It has recently been shown that the detrimental effects of exposure to protons and HZE particles can be prevented by some dietary supplements. Interestingly, in contrast with radioprotectors, these dietary supplements can prevent radiation induced detrimental effects even when applied several days after exposure to radiation. It seems that finding appropriate radiation mitigators with a post-exposure time window in excess of 24 hours will be a critical goal in planning future manned space missions. In this paper, the advantages of biological shielding over current well defined physical shielding will be discussed.