Problems of radiation norms development for manned Mars mission Original Research Article

During a Mars mission with duration of about two years the crew members will be exposed to chronic impact of galactic cosmic rays with a dose rate ∼25 times exceeding the one for ground radiation workers. For flights in a solar maximum epoch acute exposure to solar cosmic rays can appear on the mentioned background of chronic exposure to galactic cosmic rays. The solar cosmic rays dose can achieve hundreds of mSv in case of absence of special shielding measures. A carrier limit and limit for an annual flight for near-Earth orbits are restricted by an effective dose of 1.0 and 0.5 Sv, respectively. But for this category of flights it is possible to restrict the cosmonauts’ irradiation after such a massive annual exposure during a long period of time (some years). Such tactics of dose rate restriction corresponds to the established by the ground Radiation Safety Norms NRB-99 regulation of planned exposure to man during radiation accidents elimination. According to Radiation Safety Norms NRB-99 an annual exposure of 200 mSv is considered to be hazardous and can result in deterioration of crewmembers’ health and performance impairment. The same requirements can perhaps be addressed to a case of crewmembers’ exposure to a dose exceeding 200 mSv per flight with duration of one year. Consequently, it is necessary to develop tactics of dose rate restriction during the flight for minimizing the above-mentioned negative consequences of exposure. The report contains peculiarities of developing a dose limit system for a Mars mission and outlines the ways of the problem’s solution.