Chernobyl reactor mold tested as a shield on the ISS

Gianluca Riccio

Spazio

The fungi found on the Chernobyl nuclear reactor continue to amaze: they are also able to absorb space radiation on the ISS. They may come in handy on the Martian colonies.

A fungus capable of absorbing radiation discovered on the rubble of the Chernobyl reactor has been shown to do its job well even in space. The mushroom can absorb harmful radiation on the International Space Station and could potentially be used to protect future colonies of Mars.

Exposure to cosmic rays poses a serious health risk to astronauts leaving Earth's protective atmosphere. Shields can currently be made of stainless steel and other materials, but they must be shipped from Earth, which is difficult and expensive.

Xavier gomez e Graham Shunk came up with the idea to grow radioactive shields on Mars from living organisms while still high school students in North Carolina in 2018.

The two found research showing that the mushroom called Cladosporium sphaerospermum which was originally insulated from mold on the ruined Chernobyl nuclear reactor could absorb high levels of radiation.

I have talked about the special characteristics possessed by these mushrooms in this post February 2020.

They wondered if the vegetable found in the perhaps most radioactive area in the world could function as a space radiation shield.

After winning a space innovation contest, in December 2018 they were able to send a petri dish containing the mushroom on the ISS for 30 days to test their idea.

Mushrooms on the Chernobyl reactor absorb space radiation on the ISS
ISS, International Space Station

Green shield

Even though it was very thin (a layer of just 2 millimeters), the fungus sent into space blocked about 2% of the incoming radiation. “This means that a layer of fungi 21 cm thick would be sufficient to effectively protect people on Mars,” say Gómez and Shunk, now at the North Carolina School.

The results are "really good," but there are some technical challenges that need to be addressed before the mushroom can be used as a radiation shield, he says Nilsaveresch from Stanford University in California, which is now collaborating with students.

The mushroom of the Chernobyl reactor, the challenges

The fungus can't be grown outdoors on Mars because it's too cold, but it may be possible to embed it inside the walls of insulated buildings,averesch says. 

People on Mars would also need to find a way to water the mushroom, potentially using water extracted from ice at the poles, he says.

Another option would be to extract the melanin pigment that the fungus uses to convert radiation into chemical energy and incorporate it into spacesuit fabric or other materials.

Melanin mon amour

The “synthetic” approach seems very promising. Researchers at Johns Hopkins University in Baltimore, Maryland also have recently sent to the ISS a plastic material mixed with melanin extracted from another “radiation-loving” mushroom found near the Chernobyl reactor. And the cryptococcus neoformans, and promises to block even more space radiation.

Averesch believes that mushroom-inspired radioactive screens have excellent potential. 

“What makes the mushroom great is that you only need a few grams to get started, it self-replicates and it self-heals. Even in the event of damage, the screen will be able to regrow in a few days."

References: https://doi.org/10.1101/2020.07.16.205534

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