Self-replicating Chernobyl fungus may protect astronauts from harmful space radiation, new study reveals
The greatest hazard for humans on deep-space exploration missions is radiation. To protect astronauts venturing out beyond Earth’s protective magnetosphere and sustain a permanent presence on Moon or Mars, advanced passive radiation protection is highly sought after. Due to the complex nature of space radiation, there is likely no one-size-fits-all solution to this problem. But a type of fungus found growing in the destroyed Chernobyl nuclear reactor may have the potential to protect astronauts from radiation, according to researchers. A new study shows that it was able to absorb and reduce harmful radiation in an experiment on the International Space Station (ISS), and hence could potentially be used to protect future Mars colonies.
Astronauts on a mission to Mars could be exposed to at least 60% of the total radiation dose limit recommended for their career during the journey itself to and from the Red Planet, according to data from the ESA-Roscosmos ExoMars Trace Gas Orbiter. On Earth, a strong magnetic field and thick atmosphere protect people from the bombardment of galactic cosmic rays, fragments of atoms from outside our Solar System that travel at close to the speed of light and are highly penetrating for biological material. In space, this has the potential to cause serious damage to humans, including radiation sickness, increased lifetime risk for cancer, central nervous system effects, and degenerative diseases, say experts.
“One of the basic factors in planning and designing a long-duration crewed mission to Mars is consideration of the radiation risk. Radiation doses accumulated by astronauts in interplanetary space would be several hundred times larger than the doses accumulated by humans over the same period on Earth, and several times larger than the doses of astronauts and cosmonauts working on the International Space Station. Our results show that the journey itself would provide very significant exposure for the astronauts to radiation,” said Jordanka Semkova of the Bulgarian Academy of Sciences and lead scientist of the Liulin-MO instrument, in a statement in 2018.
Chernobyl is one of the most radioactive places on Earth. But certain fungi thrive in high-radiation environments on Earth, such as the contamination radius of the Chernobyl Nuclear Power Plant. These organisms perform radiosynthesis, using pigments known as melanin (the skin pigment that helps protect people from ultraviolet radiation) to convert gamma-radiation into chemical energy. The research team hypothesized that these organisms can be employed as a radiation shield to protect other lifeforms. It includes experts from the University of North Carolina at Charlotte, Stanford University, and NASA Ames Research Center, all based in the US.
To look into the possibility of using such types of radiation-absorbing fungus as a shield for humans, a sample of one of the types of fungus found at Chernobyl — Cladosporium sphaerospermum — was sent to the ISS, where it was observed for 30 days. “With concrete efforts to return humans to the Moon by 2024 under the Artemis program and establish a permanent foothold on the next rock from Earth by 2028, humankind reaches for Mars as the next big leap in space exploration. Here, growth of Cladosporium sphaerospermum and its capability to attenuate ionizing radiation, was studied aboard the International Space Station over a time of 30 days, as an analog to habitation on the surface of Mars,” say researchers in the analysis, which was published as pre-print in bioRxiv.
The findings suggest that the fungi could be used as a self-healing, self-replicating shield to protect astronauts in deep space. Once aboard the ISS, scientists analyzed its ability to block radiation. Two petri dishes were set up with two sides. One side of the petri dish was coated with Cladosporium sphaerospermum, while the other had no fungus and served as a control. A detector was affixed to the back of the petri dish to measure incoming radiation. The results reveal that the 2-millimeter-thick sample in the experiment was able to reduce radiation levels by 2%, suggesting that it was able to adapt to microgravity and thrive on radiation. A 21-centimeter-thick (8.3-inch) layer would likely be enough to shield people on Mars, suggests the research team.
Since the fungus can grow on its own, it implies that only a small amount could be sent with humans. “The nature of radiotrophic fungi also makes them inevitably/necessarily radioresistant, and thus effectively a self-regenerating and self-replicating radiation shield. Through engineered living materials (ELM) technology, integration of synthetic biology with advanced additive manufacturing methods, like 3D bioprinting, may ultimately also allow the creation of smart ‘living composite’ materials that are adaptive, self-healing and largely autonomous,” write authors. They add, “Often nature has already developed blindly obvious yet surprisingly effective solutions to engineering and design problems faced as humankind evolves – Cladosporium sphaerospermum and melanin could thus prove to be invaluable in providing adequate protection of explorers on future missions to the Moon, Mars and beyond.”