Baffling discovery inside Chernobyl may hold secret to safe space colonization

The discovery of a black mold thriving inside the Chernobyl nuclear reactor in 1990 reshaped scientific views on radioactivity.

In 1997, Ukrainian researcher Nelli Zhdanova collected samples from within the Earth's most radioactive site and found that these fungi were not only drawn to ionizing radiation but could also break down radioactive material.

Scientists named them radiotrophic fungi because of their ability to convert gamma radiation into energy for growth. Although this revelation marked a major shift in understanding extreme-life organisms, progress remained slow until recent research explored similar phenomena at another, similarly dangerous site: outer space.

Spanish researcher Fernando Cremades sought to understand what organisms that survive on radioactivity could teach humans. He examined how black fungi could aid in restoring areas exposed to ionising radiation, including nuclear plants, waste facilities, accident sites, and even environments in space.

He described developing a prototype that measured gamma radiation and dispersed radiotrophic spores when levels spiked in a blogpost for the European Architecture Platfor.

Zhdanova’s broader surveys also identified 36 additional fungi species, some distantly related, thriving around the nuclear site (Chornobyl in Ukrainian).  Over the following decades, her early work laid the foundation for recognizing a potential new form of life—one that relies on radiation rather than sunlight.

While Cremades expanded on her ideas, NASA scientists pursued their own innovations, contemplating protective fungal walls to shield astronauts, as noted in a BBC article.

Deep-space travel exposes crews to galactic cosmic radiation, an invisible flux of charged protons moving near light speed. These particles originate from stellar explosions outside the solar system and can even penetrate lead, a very dense element widely used for radiation shielding.

While Earth’s atmosphere shields people on the planet from radiation, astronauts in outer space face it, which has been called "the greatest hazard" to their health on such missions.

Building on earlier research, Ekaterina Dadachova of the Albert Einstein College of Medicine had shown in 2007 that melanised fungi increased their growth rate under radiation, with Chernobyl strains growing 10% faster when exposed to radioactive Caesium than identical fungi without exposure. 

In 2018, researchers sent samples of Cladosporium sphaerospermum—the same strain Zhdanova found at Chernobyl—to the International Space Station (ISS). The fungi tolerated the galactic cosmic radiation with surprising ease.

On the ISS, the results were even more striking. "What we showed is that it grows better in space," noted Nils Averesch, a University of Florida biochemist and co-author of the space study. Over 26 days, cosmic-radiation-exposed fungi grew an average of 1.21 times faster than control samples on Earth.

The team also tested melanin’s ability to block radiation. Sensors placed beneath fungal samples aboard the ISS showed reduced radiation levels compared to control setups. Even a thin smear of fungi appeared to function as a shield.

"Considering the comparatively thin layer of biomass, this may indicate a profound ability of C. sphaerospermum to absorb space radiation in the measured spectrum," they wrote. However, the authors cautioned that biological components such as water—an excellent radiation shield—might account for some of the observed protection.

Nevertheless, the findings offer promising solutions for human habitation in space. The US and China both plan to establish lunar bases, and SpaceX aims for its first Mars mission by 2026, followed by human landings several years later. 

Any long-term base will require protection from cosmic radiation, but conventional shielding materials—water, plastic, metal, or glass—are prohibitively heavy to transport. NASA astrobiologist Lynn J Rothschild compared the challenge to a turtle hauling its own shell: "[It's] a reliable plan, but with huge energy costs," she said in a 2020 NASA release. 

Her research explores "myco-architecture," or fungal-based structures grown directly on the Moon or Mars. Such materials would reduce launch weight and, if the work by Dadachova and Averesch holds true, could also provide a self-regenerating radiation barrier for future space explorers.

By Nazrin Sadigova