A still taken from HBO's Chernobyl series.

  • Researchers recently sent mould that grows at the site of the Chernobyl nuclear meltdown to the International Space Station for study.
  • The mould appears to feed on radiation, so early research suggests it might help protect astronauts from the dangerous radioactivity of space.
  • Because it grows, it could come at a low launch cost.
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Astronauts take many risks in space, but exposing themselves to dangerous radiation is one of the biggest. On the International Space Station, astronauts are exposed to up to 160 millisieverts of radiation during a six-month mission, according to NASA, - that's about 1,600 chest x-rays. Mars is even worse; an astronaut making an 18-month round trip to the red planet would be exposed to 1,000 millisieverts of radiation, or 10,000 chest x-rays' worth.

For protection, astronauts generally rely on radiation shields made of plastics or metals like aluminium and stainless steel. But these can be heavy and vulnerable to damage.

So in 2018, some high school students from Durham County, North Carolina proposed an unusual solution to this problem: Make a shield out of mould.

Specifically, they suggested cladosporium sphaerospermum, an organism that appears to feed on nuclear radiation the same way most plants feed on sunlight. The mould has thrived in Chernobyl's exclusion zone, the site of the 1986 nuclear meltdown, which is still one of the most radioactive places on Earth.

The students, led by Graham Shunk, now an incoming second-year student at the North Carolina School of Science and Mathematics, obtained samples of the mould species from a company in Minnesota. With the help of the research company Space Tango, they blasted them into outer space in December 2018.

On the International Space Station, astronauts put the mould samples into Petri dishes, leaving one side of each dish empty. Geiger counters then measured radiation levels beneath the dishes every 110 seconds for 30 days. The results showed that radiation levels decreased at the height of the mould's growth: The counters measured a 2.4% decrease in average radiation levels beneath the mould-covered sides.

Researchers grew Cladosporium sphaerospermum mold on the left sides of petri dishes on the International Space Station.
Space Tango, Inc.

The preliminary findings from that experiment were uploaded to the research archive bioRxiv on July 17, but have not yet been peer-reviewed. Still, they suggest that the mould could act as a shield against radiation in space.

That's because the mould appears to absorb radiation and convert it into chemical energy in a process called radiosynthesis. It's similar to photosynthesis, the process most plants use to convert sunlight into energy.

Shunk and the other researchers suggested that if the mould were about 21 centimetres thick, it could provide humans adequate protection from radiation levels on Mars. The protection would be stronger if the mould surrounded an object entirely, they think, instead of just shielding one side as it did in the study.

The International Space Station orbits Earth.

The mould has a big advantage over other types of radiation shields, the researchers also noted, since it can grow and replenish itself in space. That means a microscopic amount of C. sphaerospermum could be all that's needed at the start of a launch - so it wouldn't add extra weight to a rocket.

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