A committee has just approved NASA's proposal to change the space radiation exposure limits set by the agency for its astronauts. This change should promote the integration of women in future space missions. On the other hand, this revision is still insufficient for human missions on Mars.
Exposure to space radiation, a constant stream of high-energy particles that circulate through the interstellar medium, represents one of the greatest risks inherent in human exploration of space. space. On Earth, we are protected from these rays by a magnetic field and a thick atmosphere. Also, our bodies have not evolved to be able to support them. This is why once in space, we are vulnerable. These rays are in fact so powerful that they can modify, damage or kill our cells, thus promoting the development of serious health problems.
Currently, space radiation exposure limits vary by age and gender. They shoot from 180 millisieverts for a thirty-year-old woman to about 700 millisieverts for a sixty-year-old man. These limits were set not to exceed a 3% risk of death induced by radiation exposure (REID) at the 95% confidence level. However, they should be updated soon.
A few weeks ago, NASA indeed proposed to set only one lifetime exposure limit for astronauts, regardless of age and gender. This limit would be around 600 millisieverts , based on the average 3% risk of REID for a 35-year-old woman. On June 24, a committee established by the National Academies supported this proposal.
Once adopted, this new limit will provide more opportunities for female astronauts to be able to integrate future missions into space, mainly to the Moon. "Overall, the proposed standard creates a level playing field for spaceflight by providing a somewhat higher permissible radiation exposure for a subset of astronauts (primarily female) while limiting exposures below doses otherwise acceptable for others (mainly older men) “, can we read in the report of the committee.
Note that this limit only applies to NASA astronauts. Other bodies such as Roscosmos, the Canadian Space Agency or the European Space Agency (ESA) have set a lifetime exposure limit of 1,000 millisieverts for their astronauts and cosmonauts, regardless of gender and age. Compared to other agencies, NASA is therefore a little more cautious.
However, these limits remain below the radiation levels that astronauts will face on future manned missions to Mars. If necessary, those who will integrate these missions will therefore need a derogation from the exposure limits, which will raise ethical questions according to the report. There will indeed be risks. These will have to be explained as clearly as possible by the agency and ultimately be accepted by the astronauts.
