Jun 29, 2021 - Science

Equality in space through new radiation limits

Illustration of a sign that says “Radiation Limit: =” in outer space.

Illustration: Shoshana Gordon/Axios

NASA's proposal to update its radiation limits for astronauts would make space a more equal place for women.

The big picture: Historically, female astronauts haven't been able to fly as often as their male counterparts, in part because of strict limits on the amount of radiation exposure NASA finds allowable.

  • "A female will fly only 45 to 50 percent of the missions that a male can fly," former astronaut Peggy Whitson said in 2013.
  • "I know that they are scaling the risk to be the same, but the opportunities end up causing gender discrimination based on just the total number of options available for females to fly."

Driving the news: A new report from the National Academies of Sciences, Engineering and Medicine suggests NASA should move ahead with a plan to use one career-long radiation limit for all astronauts.

  • A set limit will allow for more equality in spaceflight opportunities, according to the report.
  • The new radiation limits — which would be set at a career-long 600 millisieverts for any astronaut, male or female — would put NASA in line with many other space agencies around the world, which have set standard limits for all of their astronauts.

Why it matters: Radiation — specifically galactic cosmic rays — is one of the major limiting factors for NASA as it's working to send people to deep space destinations like the Moon or Mars.

  • "We know that the central nervous system is relatively susceptible to this type of radiation, so we're thinking about cognitive effects or any mood changes that could potentially happen from this exposure," Emmanuel Urquieta, an assistant professor at the Center for Space Medicine at Baylor College of Medicine, told me.
  • Inflammation in the cardiovascular system is also a major concern.
  • Deep space radiation is difficult to replicate on Earth, making studying its health effects complicated. Right now, radiation standards are based on limited data in part collected after the U.S. bombing of Japan in World War II and mouse studies.
  • But new studies could help scientists bridge what they know about radiation's effects from mouse studies with studies using human tissue — without putting people in danger.

What to watch: Astronauts traveling to and from Mars would far exceed even the new career-long radiation limit proposed by NASA.

  • The new report suggests the space agency could establish a waiver system to say exactly what kinds of missions are worthy of exceeding that limit, but that shouldn't necessarily be used for any given trip to Mars, experts say.
  • "The point of having a standard is it's something for us to think of as a hard limit," Jeff Kahn, one of the committee members who helped author the new report, told me. "If we can't do what we want now because it's too much radiation exposure, then we need to figure out ways to make it safer for astronauts."
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