WASHINGTON — A National Academies committee has endorsed a NASA proposal to change the radiation exposure limits the agency sets for its astronauts

Report backs NASA proposal to change astronaut radiation exposure limits

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2021-06-26 15:30:11

WASHINGTON — A National Academies committee has endorsed a NASA proposal to change the radiation exposure limits the agency sets for its astronauts but cautioned that the revised limit is still insufficient for human Mars missions.

The June 24 report by a committee established by the National Academies and sponsored by NASA backs the agency’s proposal to set a single lifetime radiation exposure limit for astronauts, rather than different limits based on age and gender.

Currently, lifetime exposure limits range from 180 millisieverts for a 30-year-old woman to 700 millisieverts for a 60-year-old man. Those limits are based on models intended to set a limit of no more than a 3% risk of radiation exposure-induced death (REID) at the 95% confidence level.

NASA proposed changing that to a limit of about 600 millisieverts, regardless of age or gender. That limit is based on the mean 3% risk of REID for a 35-year-old woman, the most conservative case but measured to a different standard than the earlier calculation.