NASA wants to set a new radiation limit for astronauts

Now that the The Biden government has indicated its support for NASA’s Artemis mission to the moon, perhaps we should think about the risks astronauts face when they arrive, and what could happen during a longer trip to Mars.

Of all the things you need to worry about while traveling in space – equipment failures, the strange effects of weightlessness, collisions with space debris and just being far away – one of the most difficult to deal with are the health consequences of solar radiation or cosmic effects. happenings. This radiation consists of atoms that have lost their electrons as they accelerate in interstellar space and approach the speed of light – something that happens, for example, just after a star has exploded. It occurs in three forms: particles trapped in the Earth’s magnetic field; particles fired into space during solar flare; and galactic cosmic rays, which are protons with high energy and heavy ions from outside our solar system.

It is also one of the ‘red risks’ identified by a NASA study published last year on the top-priority health problems facing astronauts. Radiation damages DNA and can lead to mutations that can cause cancers. It can also cause cardiovascular health problems, such as heart damage, narrowing of arteries and blood vessels, and neurological problems that can lead to cognitive impairment, according to a NASA website.

On Earth, humans are exposed to radiation from 3 to 4 milliseconds (mSv) per year, mostly from natural sources such as some types of rocks and the few cosmic rays that come through the atmosphere. At the International Space Station, astronauts receive about 300 mSv per year. Until now, a 55-year-old male NASA astronaut has been limited to an effective dose of 400 mSv during his career, while a 35-year-old female astronaut could only be exposed to 120 mSv.

Now that NASA plans to send humans on much longer missions, the agency is considering the threshold to increase astronauts of any gender or age to 600 mSv. Under the existing standard, some veteran astronauts could be excluded from longer-term space missions because they bulge against lifelong radiation limits. Younger astronauts have less flight time in space and therefore less exposure, but the success of a major mission may require experience across the youth.

NASA’s proposed new limit will still be lower than that for other space agencies; European, Russian and Canadian astronauts can be exposed to up to 1000 mSv before being grounded by their space officials. But NASA officials do not apologize for their more conservative stance. “It’s a different risk attitude than we accept acceptable risks,” said David Francisco, technical fellow for human space standards at NASA’s chief medical officer’s office. ‘We chose 600 because we are more acceptable to our culture. This is something we are constantly working on and going back and forth. We debated going to 1,000, and that’s one of the questions: are we still conservative with 600? ‘

To solve the question, the space agency asked an expert panel from the National Academy of Sciences to determine what is the best number to use. The panel began meeting last month and is expected to complete its work this summer. The experts will look at how NASA has calculated its new exposure limits, and how they align with existing clinical data and animal studies.

To understand the link between radiation and cancer, medical researchers have long followed the survivors of the atomic bomb blasts in Japan during World War II (as well as the health of their children). There have also been studies done on medical workers who are exposed to x-rays, and nuclear workers who receive low doses of radiation during the course of their careers. But NASA does not have much information about the effects of space travel on its astronauts’ health.

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