- Researchers recently sent mold that grows at the site of the International Space Station Chernobyl nuclear meltdown for study.
- Mold appears to feed on radiation, so early research suggests that it may help protect astronauts from the dangerous radioactivity of space.
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Astronauts take many risks in space, but exposing themselves to dangerous radiation is the biggest. On the International Space Station, astronauts are exposed to up to 160 milliseconds of radiation during a six-month mission, which is about 1,600 chest X-rays, and 26 times more than the average US citizen, according to NASA. Mars is worse; An astronaut orbiting an 18-month orbit on the red planet would know the cost of 1,000 milliseconds of radiation, or 10,000 chest X-rays.
For safety, astronauts typically rely on radiation shields made of plastics or metals such as aluminum or stainless steel. But they can be heavy and prone to damage.
So in 2018, some high school students in Durham County, North Carolina proposed an unusual solution to this problem: get a shield out of the mold.
In particular, he suggested Cladosporium sphaerospermum, an organism that appears to feed on nuclear radiation in the same way most plants feed on sunlight. The mold has grown in the exclusion zone of Chernobyl, replacing the 1986 nuclear meltdown, which is still one of Earth’s most radioactive locations.
Students led by Graham Shank, now an incoming second-year student at the North Carolina School of Science and Mathematics, obtained mold species samples from a company in Minnesota. With the help of research company Space Tango, he blasted them into outer space in December 2018.
At the International Space Station, astronauts poured mold samples into a Petri dish, leaving one side of each dish empty. Geiger counters measured radiation levels below the dish every 110 seconds for 30 days. The results showed that radiation levels were reduced at the height of mold growth: the counters measured a 2.4% decrease in mean radiation levels below the mold-covered sides.
Preliminary findings from that experiment were uploaded to the research archive Biorexiv on July 17, but have not yet been reviewed. Nevertheless, they suggest that mold may act as a shield against radiation in space.
This is because mold absorbs radiation and converts it into chemical energy in a process called radiosynthesis. This is similar to photosynthesis, with most plants using sunlight to convert them into energy.
Shank and other researchers suggested that if the mold was about 21 centimeters thick, it could provide adequate protection to humans from radiation levels on Mars. Protection would be stronger if the mold completely engulfed an object, they think, instead shielding only one side as it did in the study.
Mold has a major advantage over other types of radiation shields, researchers also noted, because it can grow and replenish itself in space. This means that c. A microscopic amount of spherosperm may be required at the start of a launch – so it will not add extra weight to a rocket. This can be a game-changer, as NASA estimates that launching something into space costs about $ 10,000 per pound.