With the latest and unequivocally best movie version of “Dune” in the theaters, most reviews make note that novelist Frenk Herbert was a fan of psilocybin ‘magic’ mushrooms and may have been inspired by the psychedelic ‘shrooms when he came up with the idea for mélange or ‘spice’ – the key reason for the fight over the planet Arrakis. Interest in real space travel has been stimulated by the progress of private space companies and the desire of SpaceX founder Elon Musk and NASA to travel to Mars and eventually colonize Mars, progress has been severely restricted by the challenge of protecting astronauts from cosmic radiation. While the mushrooms used may not be ‘magic’, researchers recently discovered a fungus that not only thrives in high cosmic radiation in space but feeds on it and could be used to grow radiation shields in space. Magic or science?
“Certain fungi thrive in high-radiation environments on Earth, such as the contamination radius of the Chernobyl Nuclear Power Plant. Analogous to photosynthesis, these organisms appear to perform radiosynthesis, utilizing ionizing radiation to generate chemical energy. It has been postulated that the absorption of radiation is attributable to the pigment melanin. It is further hypothesized that this phenomenon translates to radiation-shielding properties.”
Something good has finally come from the Chernobyl disaster – a study published in the preprint journal bioRxiv announces the discovery that Cladosporium sphaerospermum, found thriving in the contamination zone, also enjoy space radiation. A shipment of them was sent to the International Space Station in 2019 where they spent 30 days next to a control bed with no fungus. When returned to Earth, it was found that the radiation levels underneath the fungus were 2.17% lower than the control bed. Even more exciting, the fungi grew 21% faster than on Earth. In other words, when it comes to cosmic radiation … they like it! Are Cladosporium sphaerospermum the ‘spice’ of real space travel?
“To increase density and thus the LAC, fungal biomass or melanin itself could be integrated with in-situ resources that are abundant at destination, such as regolith. In a case study we estimated that a ~ 2.3 m layer of melanized fungal biomass (8.6% [wmelanin/wCWW] melanin-content) would be needed to lower Martian radiation levels to those on Earth (from 234 mSv/a to 6.2 mSv/a, whereas an equimolar composite of melanin and Martian regolith would only require a layer of ~ 1 m for the same reduction of radiation.”
In simple terms, the thicker the fungus, the better the radiation protection. To grow a suitable radiation shield (LAC is linear attenuation coefficient -- a measure for the fungus’ capacity to shield against ionizing radiation) on the surface of Mars to protect astronauts underneath it would require a layer 2.3 meters (7.5 feet) thick. For comparison, the same protection could be achieved by building structures under 3 meters of regolith (Martian surface dirt and rocks). The benefits to growing a renewable shield on the surface versus living underground are obvious – the problem is that the fungi shield hasn’t been tested yet.
The study researchers, led by Graham K. Shunk of the Physics Department at the North Carolina School of Science and Mathematics, tip their hats to nature for providing what may be an excellent and elegant solution to the problem of space travel radiation.
“Often nature has already developed surprisingly effective solutions to engineering and design problems faced as humankind evolves - biotechnology could thus prove to be an invaluable asset for life support and protection of explorers on future missions to the Moon, Mars and beyond.”
Cladosporium sphaerospermum may not be 'spice' but it could be just as beneficial to space travel ... and it's right here on Earth. However, leaving Earth means leaving one of our best sources of innovation -- nature -- behind. Would we be better off staying here?