---

Here’s what you’ll learn when you read this story:

• Decades ago, scientists found a black mold inside the Chernobyl nuclear reactor complex, seemingly feeding off the radiation and thriving in an environment hostile to life.
• Researchers still have many questions about why and how the fungus is doing it, but they think its cells probably evolved to take advantage of the high energy radioactive source.
• It may be possible to use this fungus in a practical way in environments that are highly radioactive, such as space. The mold could consume bio-waste and help make spare parts, pharmaceuticals, or even food for space journeys, scientists surmise.

---

Deep inside the Chernobyl nuclear reactor complex, in one of the most inhospitable places on Earth, thrives a little black fungus with very big implications for space travel.

Cladosporium sphaerospermum was considered a rather unremarkable black mold before scientists found it and dozens of other species of mycobiota inside of the fourth unit of the Chernobyl Nuclear Power Plant in the late 1990s.

Speculation about the fungus ran rampant: How could it survive in such a hostile place? Was it eating radiation? Could it eventually somehow aid in the cleanup of nuclear spills? Could it help humans in other areas with high levels of radiation, like space? To that last question, researchers are willing to say maybe. Some are even studying if the fungus could help make plastic parts or eliminate human waste on journeys to other worlds, like Mars.

Decades later, scientists still have a lot to understand about this odd life form before they can harness its full potential.

First, Cladosporium sphaerospermum and other fungi can’t neutralize radiation, says University of Florida space biology professor Nils Averesch, PhD, who has studied the fungus for years. Actually destroying radioactive isotopes would require changing them into nonradioactive elements, not being munched on by mold.

“But that doesn’t mean it’s not very cool,” says Aaron Berliner, PhD, a space bioprocess engineering researcher with Weill Cornell Medicine.

After scientists found Cladosporium sphaerospermum and other black mold species growing inside the damaged fourth reactor complex—the one that burned down and spewed radioactive material for miles—they realized the fungus appeared to be growing toward the radiation. That meant it wasn’t simply surviving despite radiation, but potentially because of it. And the amount of radiation contained in the fourth reactor cannot be overstated. Without protection from the radiation, a human death sentence would be delivered within minutes, says Berliner.

Wikimedia Commons

A sample of Cladosporium sphaerospermum grown in a lab. In Chernobyl, it has apparently evolved to grow on the radioactivity that still persists after the 1986 catastrophe.

It’s their ability to survive that makes the fungus a type of extremophile.

“Organisms that live in extreme heat are called thermophiles. In very, very cold places, they’re called psychrophiles,” Berliner says. “It has been proposed that this organism is capable of utilizing radiation, which is why it has been called radiotrophic.”

Ekaterina Dadachova, PhD, a radiobiology professor at the University of Saskatchewan, hypothesized in a 2007 paper that the mold may well be feeding off of energy from the radiation like plants use energy from the sun for photosynthesis.

If that’s happening, and how, exactly, it would work, is what researchers like Berliner and Averesch are trying to figure out. Much of the answer likely revolves around the fungi’s black color, or melanin. The melanin likely provides the fungi both with protection from harmful radiation and also a way to make its own food using energy. A plant, for example, uses chlorophyll to turn sunlight, carbon dioxide, and a little water into nutrients. The fungus might be doing something slightly similar but using its melanin to turn much more energetic photons into food, Berliner says.

“Maybe it developed a new cellular machinery or adapted one it currently had under the selective push of this radiation environment,” he says.

**🔮 Check Out Our New Video Series, **Pop Mech Explains: PrecognitionYou’ve probably had that eerie feeling before—knowing what’s about to happen before it actually does. Flashes of deja vu. A text from someone you were just thinking about. A dream predicting the future. Coincidence? Or something deeper? Across four chapters, we investigate the science and speculation behind those “gut feelings.”

Go Down the Rabbit Hole With Us

While that doesn’t mean much for remediating irradiated spaces like Chernobyl, it could mean quite a bit for space travel.

Space, Berliner explains, is full of radiation. Incredible, harmful amounts of solar radiation coming from our sun and galactic cosmic radiation coming from other galaxies. Humans have learned how to largely protect themselves by using radiation shields. But as countries and space companies consider more extreme journeys to places like Mars, or extended stays on, say, the moon, they risk running out of space and money to bring everything they need.

Space travel, unsurprisingly, is incredibly expensive. It costs about $1,000 to send a can of Coke into Earth’s low orbit, Berliner says.

So he and Averesch are exploring the possibility of astronauts growing and even producing their own products in space. To do that, they would need something that consumes its dead biomass and can feed off the energy surrounding it. Enter molds like *Cladosporium sphaerospermum. *Astronauts could potentially use the mold to help make spare parts and even pharmaceuticals in space.

“Or it could break down waste products like human waste or plastics and turn those into edible biomass,” says Averesch.

It could also become a kind of radiation shield for astronauts, adding a layer of protection on long journeys, albeit, he adds, with “major limitations.”

And it could do all that using ambient energy found in space. Though Berliner notes scientists are still in very preliminary stages of proving any of this, and many other researchers are “rightfully skeptical.”

The team has samples of the fungus found in the Chernobyl reactor that they’re using for testing and experiments. But the fungus itself is not all that rare, and can be found in soils, plant material, and even refrigerated foods, says Averesch.

It also wasn’t the only one found in the reactor. Ukrainian researcher Nelli Zhdanova published a paper in 2000 documenting 37 species of 19 genera, including Cladosporium sphaerospermum, which was one of the most common. She also noted the species with a “dominance of melanin” were in the most heavily contaminated regions.

“This speaks to something I find very human, of our desire to survive and thrive in very difficult circumstances,” Berliner says. “And I think that’s what this organism is doing. And we want to know how it’s doing it.”

Peterson Christine has covered science, the environment, wildlife and outdoor recreation from her home in Wyoming for 15 years. Her work has appeared in National Geographic, Outdoor Life, The Atlantic, High Country News and New York Times, among others. She is also a 2025 Alicia Patterson Foundation fellow.