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Now that the The Biden administration has shown its support for NASA’s Artemis mission to the Moon, perhaps we should think about the risks astronauts will face when they get there and what can happen during a longer trip to Mars.
Of all the things to worry about when traveling in space (malfunction of the computer, the strange effects of weightlessness, collisions with space debris and being far away), one of the most difficult to treat is the health effects of solar or cosmic radiation. Events. This radiation consists of atoms that have lost their electrons as they accelerate into interstellar space, approaching the speed of light, which happens just after a star explodes, for example. It comes in three forms: particles trapped in the Earth’s magnetic field; particles fired into space during solar flares; and galactic cosmic rays, which are high-energy protons 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 issues astronauts face. Radiation damages DNA and can cause mutations that can lead to cancer. 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 3 to 4 millisieverts (mSv) of radiation a year, mainly from natural sources such as some types of rocks and the few cosmic rays that pass through the atmosphere. At the International Space Station, astronauts get about 300 mSv a year. Until now, a 55-year-old male NASA astronaut was limited to an effective dose of 400 mSv throughout his career, while a 35-year-old astronaut could only be exposed to 120 mSv.
Now that NASA plans to send people on much longer missions, the agency is considering raising this threshold to 600 mSv for astronauts of any gender or age. According to the existing standard, some veteran astronauts could have been excluded from long-term space missions because they run into lifetime radiation limits. Younger astronauts have less flight time in space and therefore less exposure, but the success of a large mission may require experience during youth.
The new limit proposed by NASA would still be lower than other space agencies; European, Russian and Canadian astronauts can be exposed to up to 1,000 mSv before their space officials put them on the ground. But NASA officials do not apologize for their more conservative stance. “It’s a different risk stance in what we believe is an acceptable risk,” says David Francisco, a technical member of human spaceflight standards in the office of NASA’s chief medical officer. “We have chosen 600 because we consider it more acceptable for our culture. It’s something we work on constantly and go back and forth. We debated about 1,000, and that’s one of the questions: are we still conservative with 600? “
To solve this question, the space agency has asked a group of experts from the National Academy of Sciences to determine which number is best to use. The group began meeting last month and is expected to finish its work this summer. Experts will examine how NASA has calculated its new exposure limits and how they match existing clinical data and animal studies.
To understand the links between radiation and cancer, medical researchers have long been following the survivors of atomic bomb explosions in Japan during World War II (as well as the health of their children). There have also been studies of medical workers exposed to X-rays and nuclear plant workers who receive low doses of radiation throughout their careers. But NASA doesn’t have much data on the health effects of space radiation on its astronauts.