Implications of the New Radiation Exposure Limits on Space Station Freedom Crews

Spaceflight unavoidably increases the exposure of astronauts to natural ionizing radiation. Any increase in radiation exposure increases the risk of contracting cancer or inducing genetic mutations. Since risk avoidance is equivalent to dose avoidance and since complete dose avoidance in space is not possible, levels of acceptable risk must be established. Research over the last decade indicates that the cancer risk per dose-equivalent has increased and that the relative carcinogenic effectiveness of certain types of space radiations may be much higher than previously thought. Therefore, new dose-equivalent limits have been recommended to NASA by the National Council on Radiation Protection and Measurements (NCRP). Because of this, the measurement and management of radiation exposures and the assessment of the health risks involved will play a significant role in manned operations.