Optimization of radiation exposures during extravehicular activity using the effect of the West-East asymmetry of the fluxes of trapped protons

To estimate the protective properties of a space suit against cosmic radiation the dose rates were calculated for extravehicular activity in the ISS orbit for a number of representative points of critical organs of the human body. The screening functions of the Orlan-M space suit obtained by the authors earlier are used in the calculations. In addition, the effect of East-West asymmetry of the fluxes of high-energy protons trapped by the geomagnetic field is taken into account. It is shown that during passages through the South Atlantic Anomaly, choosing the optimal orientation of astronauts in relation to the cardinal directions, one can achieve for the most critical body organs a dose rate reduction by a factor of ∼1.5–1.8 (in the maximum of solar activity) and by a factor of ∼2–2.5 (in the solar activity minimum). The obtained results can serve for obtaining more accurate estimation of radiation risk for astronauts working in the Orlan-M space suit in the near-terrestrial orbits and for elaborating practical recommendations to reduce their radiation exposures.