A new report issued today from the National Academies of Science is recommending that NASA adopt a new health standard for limiting the exposure of astronauts to radiation during long space missions. The new standard, based on a maximum accumulative dosage of 600, is indicated by the figure to the right, taken from the report [pdf] and annotated to show both the new recommendation as well as the standards used by other space-faring nations.
The key result of this change is expressed in the report in this one sentence:
Compared with the existing standard, this proposed standard will increase the allowable exposure for a 35-year-old female by a factor of ~3 and for a 55-year-old male by a factor of ~1.5.
The new recommendations however remain below the 1,000 dose standard used by Russia, Canada, and Europe, as shown by the figure.
Based on the present technology planned for any year+ Mars mission, all these standards would still be exceeded and will thus require a waiver of the standard in order for NASA or the other space agencies to send their astronauts.
The report also recommends that NASA develop detailed procedures for issuing that waiver:
NASA should develop a protocol for waiver of the proposed space radiation standard that is judicious, transparent, and informed by ethics. To avoid the perception that an exception to the standard is built into the space radiation standard itself, NASA should follow the ethics decision framework in developing a waiver protocol and it should provide supporting analysis and explanation justifying any waiver to the standard.
The new recommendations are being suggested partly because the present health limits, first established in 1989, make it difficult if not impossible for any young woman to participate in a Mars mission. Their health risk is greater than a comparable male partly because of the risk to any future children the woman may have, and partly because past radiation research has suggested that women are more vulnerable to high doses of radiation. The new standard eases these restrictions for female American astronauts, and puts it more in line, though still more stringent, with the standards being used by other nations.
These health standards are meant as a guide to NASA and its astronauts in planning future manned interplanetary missions. While they are not law, and do not restrict the decisions of non-NASA space tourists, do not assume the government will not try to impose these rules on private manned launches also. We live in a time that ignores the clear constitutional limits on the federal government, so I fully expect the federal government will eventually try to make these rules apply to everyone. Though these radiation limits appear somewhat reasonable if limiting, what if a private citizen decides they want to go, even if it means the radiation exposures will be higher than these limits?
In a free society they should have that right. Sadly I doubt we live in such a free society.
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