Sep 29, 2020 - Science

Radiation-proofing the human body for long-term space travel

Illustration of a person in a hazmat suit giving a thumbs up while waist deep in radioactive liquid. 

Illustration: Aïda Amer/Axios

Researchers are working to find new ways to protect the human body from radiation in space in order to allow people to live far from Earth for years at a time.

Why it matters: Big thinkers like Elon Musk and Jeff Bezos believe that one day people will be living and working in space, on the Moon and even on Mars for years at a time, but humans aren’t made to stand up for long to the extreme radiation environment they’ll face off Earth.

  • S0me scientists are hoping to find ways to alter human genetics to make the body more resistant to radiation.

What's happening: While living in space for years at a time is still a long way off, even shorter-duration missions to relatively nearby targets could still expose astronauts to doses of radiation that may up their odds to develop cancer later in life.

  • A study in the journal Science Advances last week found astronauts on the Moon would receive more than 200 times as much radiation per hour than people on Earth, meaning they will likely need specialized shielding designed to protect them from those rays.
  • This measurement — made by China's Chang’e 4 lander — could help inform NASA's Artemis program, which is expected to send astronauts to the lunar surface for at least a week in 2024.
  • NASA is also planning to send people to Mars sometime in the 2030s and would need to find a way to protect astronauts from radiation in space while in transit and on the Martian surface.

Between the lines: It's not clear exactly how bad the effects of radiation exposure actually are to people living in space.

  • Some studies using mice suggest exposure to galactic cosmic rays over a long period of time could cause adverse cognitive effects.
  • While radiation from solar particles is relatively easy to block with shielding during solar storms, it's more complicated to block cosmic rays with known techniques that would be practical for spaceflight.

And scientists are still trying to parse different models for how radiation could cause cancer in astronauts and how high their risks of developing it could be.

  • One model is more straightforward, according to Francis Cucinotta, a radiation researcher at the University of Nevada, Las Vegas, with radiation causing DNA damage that would lead to cancer.
  • Another model, however, says that radiation could cause other effects to biochemistry, tissue regulation and how cells interact, upping the risks of developing cancer, Cucinotta said.
  • If that second model is correct, it could mean the cancer risks to astronauts is two to three times higher than those in Model A, Cucinotta added.

What's next: Weill Cornell Medicine geneticist Chris Mason — who was involved with NASA research on the biological effects of astronaut Scott Kelly's 340 days in space — has written about a 500-year plan to reengineer human genetics to make long-term space travel and even settlement on other worlds possible.

  • Mason, like Musk and Bezos, argues establishing a permanent human presence in space is necessary as a hedge against a catastrophe that could render Earth uninhabitable.

Details: Modifying the DNA of future astronauts through gene therapies or gene editing to make them more resistant to radiation and other threats from long-term space travel is an ambitious strategy.

  • In 2016, geneticist George Church identified more than 40 genes that could be targeted for long-term spaceflight.
  • Another option may involve combining the DNA of other, radiation-hardened species — like microscopic tardigrades — with humans.
  • A group at Duke University is trying to tease out the secrets behind the tardigrade's resistance and possibly translate it to other organisms.
  • "If that is interesting, and shows promise, then can we put those into rodent models? Can we look into human cell lines — starting to tell the translational story from simple organisms all the way up to people?" Kristin Fabre, of the Translational Research Institute for Space Health, told Axios.

Yes, but: Scientists need to have a much better idea of exactly what targeted genes do before they could safely and effectively modify DNA in astronauts.

The bottom line: If future humans do eventually make space home, chances are they'll need protection that doesn't yet exist.

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