Fungi From Chernobyl Could Be Used As A Radiation-Shield In Space

An abandoned building in the Chernobyl exclusion zone, where radiation levels are up to five orders of magnitude above normal background levels. Special View/Shutterstock

Katy Pallister 27 Jul 2020, 17:11

The site of the infamous Chernobyl nuclear disaster in 1986 is still beaming with radiation. Yet even in these inhospitable conditions some life has managed to survive and thrive by munching their way through the radiation itself.

So-called “black fungi”, or radiotrophic fungi, harnesses the power of melanin (the skin pigment that helps protect us from ultraviolet radiation) to convert gamma-radiation into chemical energy for growth. Previously, this has been touted as a solution to feed astronauts during long space flights, but a new study has reported on the mold’s additional potential as a self-replicating radiation shield that could protect future Mars settlers from the dangers of space. The peculiarities of Chernobyl just keep on growing.

Outside of the Earth’s protective magnetosphere, astronauts are exposed to high levels of cosmic radiation, which in large doses can penetrate tissue and lead to radiation sickness or even death. Protecting explorers from this hazard as they journey further from our planet is paramount.

A few years ago, then high-school students Xavier Gomez and Graham Shunk suggested that a radiation-absorbing fungus from Chernobyl, Cladosporium sphaerospermum, could offer the necessary protection. It would also be a cheaper and easier material to transport than the current alternatives (e.g. stainless steel sheets).

So, in December 2018, the students watched their competition-winning project blast off to the International Space Station (ISS). A small sample of the fungus was studied onboard for 30 days, the results of which have now been published on the pre-print server bioRxiv.

Cladosporium sphaerospermum (pictured on potato dextrose agar after incubation for 14 days at 25°C). Medmyco/Wikimedia Commons (CC BY-SA 4.0)

The 2-millimeter-thick sample in the experiment blocked around 2 percent of the incoming radiation. However, a 21-centimeter-thick (8.3-inch) layer would likely be enough to shield people on Mars, the study authors conclude. But the fungi’s talents don’t stop there.

“What makes the fungus great is that you only need a few grams to start out, it self-replicates and self-heals, so even if there’s a solar flare that damages the radiation shield significantly, it will be able to grow back in a few days,” study co-author Nils Averesch of Stanford University, California, told New Scientist.

Overall, the study shows some promising results, but further technical consideration is needed before it is rolled out, Averesch continued. For starters, the fungus could not be grown outdoors on Mars due to the cold temperatures and its additional need for water would have to be met.

An alternative could be to extract the melanin pigment found in Cladosporium sphaerospermum and incorporate it into a spacesuit. Indeed, a different team from Johns Hopkins University, Baltimore, recently sent a melanin sample grown in another Chernobyl fungus, Cryptococcus neoformans, to the ISS for more radiation-blocking tests.

No matter the fungus, this growing area of study is certainly one to watch.

 [H/T: New Scientist]

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