Floating 350 kilometers above the Earth's surface, astronauts aboard the Soviet space station Mir made a frightening discovery. Their once clear porthole was clouded with a green and black web-like substance. Soon, these growths were found throughout the shuttle, blanketing air conditioners and corroding control panels, putting both the station's integrity and the astronauts' lives at risk.
The invaders were identified as several species of Earth-derived fungi that had, against all odds, survived the journey to space. And once there, they'd adapted to the microgravity and radiation-dense environment. Thankfully, the crew managed to keep these threats at bay, and Mir remained in orbit for the next 13 years. During that time, scientists have learned that fungi have the potential not to hinder space travel, but to help it. In fact, these resilient, often overlooked organisms may be the key to our future on other planets.
Once outside the Earth's protective magnetic field, most living things need serious protection to survive the DNA-damaging cosmic radiation in space. But that's not the case for some fungi. Many species produce a unique form of melanin, a pigment that safely absorbs high levels of radiation and, in some cases, uses this energy to fuel growth. Even if dangerous levels of radiation make it past this homegrown armor to damage DNA, many fungi have robust repair systems that spring into action, cutting out and restoring defective sequences. And radiation isn't the only cosmic element fungi can withstand. Their hardy spores sport thick cell walls that allow them to survive extreme temperatures.
So, how might we utilize fungi in space? Well, a big obstacle to settling on other planets is figuring out how to source the materials needed to build suitable habitats. There are two common solutions. First, we could send these supplies up from Earth. But this is expensive— it costs roughly $10,000 for each kilogram of weight added to a launch. Alternatively, we could use what's already there. Homes could be built from the dust and fragmented rock that coat the surface of other planets, which is called regolith. Yet this would require a shipment of large, heavy, energy-intensive machinery to collect, heat, and compact the loose regolith into something usable. That's where fungi come in. Most fungi have hair-like root structures called mycelia. And as they grow, they easily bind nearby materials, whether it be wood chips, sawdust, or regolith. The result is a dense, interconnected web that makes a surprisingly durable building material that's both thermal and radiation protective.
Scientists working with NASA's Innovative Advanced Concepts program have devised plans for using this technology to grow fungal homes on other planets. First, lightweight, flexible bags seeded with dehydrated spores are launched to their new home. Once they've arrived, accompanying rovers source water for rehydration and regolith for binding. Alternatively, the bags could be preseeded with a lightweight binding material, like dehydrated wood chips. And there's another essential ingredient to these packages, cyanobacteria, which provide the fungi with nutrients and convert sunlight into oxygen. The mycelia grow to fit the shape of their bags, creating the walls, roof, and even the furniture of these fungal abodes.
Once completed, maintaining these buildings would likely be relatively simple, as any cracks could be reseeded and regrown. Scientists could engineer cyanobacteria to alert residents if repair is needed, by glowing when oxygen or pressure levels in the habitat dip.
Of course, there's still a lot of work out there before these lightweight habitat packs are ready for launch. In the meantime, researchers have begun to iron out the details by growing these sustainable, carbon-negative fungal habitats right here on Earth.
And housing is just one of many possible uses for fungi in space. Communities will need to grow their own food, yet soil suitable for plants isn't readily available off Earth. Fungi can release a variety of chemical-degrading enzymes capable of dissolving carbon-rich asteroids into soil. And they can also be engineered to mine and extract metals, like aluminum and iron, which could allow space colonies to source these valuable ores locally. Fungi have come a long way from their space hazard beginnings and will undoubtedly continue to break the mold.
