Living on the harsh environments of the Moon and Mars will require new architectural ideas.
A project out of NASA's Ames Research Center is investigating an innovative way of making future space habitats: Grow them.
The myco-architecture initiative is prototyping technologies made specifically from fungi and their unseen underground threads known as mycelia.
"Right now, traditional habitat designs for Mars are like a turtle — carrying our homes with us on our backs – a reliable plan, but with huge energy costs," said Dr. Lynn Rothschild, the principal investigator on the myco-architecture project .
To lighten the cargo load, the myco-architecture team is suggesting a more flexible and greener approach that leaves a lot of the building materials at home.
"Instead, we can harness mycelia to grow these habitats ourselves when we get there," said Rothschild.
A fungus absorbs its nutrients through the root-like mycelia. The more nutrients available, the more branches the mycelia forms to take advantage of the food source.
A simplified way of thinking about a "grown" habitat on another planet: You bring a basic inflatable structure, fill it with fungi, and then, almost like an infomercial, "just add water," says Rothschild.
By using water to fuel the fungi, the mycelia grows into a robust structural material, one that can resemble particle board or Styrofoam, depending on the organism chosen.
The fungi-inspired architecture is a three-layered concept. A protective outer ice layer sends water to a layer of bacterium known as cyanobacteria.
With the Sun's energy, the cyanobacteria converts water and carbon dioxide into oxygen for astronauts and nutrients for the final layer of mycelia. The fungus food enables the mycelia to grow into a contained environment, mold, or structure.
And the fungi can support more than just a sturdy home, according to Rothschild.
"Imagine any structure you want," said the principal investigator.
Mycelia has already been used to create chairs, stools, and 2x4s.
In an edited interview with Tech Briefs below, Rothschild explains how we've only just begun exploring the potential of mycelia on the Moon and Mars.
Tech Briefs: What is mycelia?
Dr. Lynn Rothschild: If you look at a mushroom, what you’re seeing is the feeding body of a fungus. Underground are these tail-like structures called mycelia, and that’s really the body of the fungus. They can go quite a distance. They’re important in terrestrial ecology. They help hold the soil and cycle nutrients.
Tech Briefs: Is mycelia a strong material?
Dr. Lynn Rothschild: Oh, yeah. Fungal mycelia makes very strong mesh networks. They’re flame retardant. They are reasonably water-proof and will grow into any shape that you give them a mold to grow into.
When you end up with a flat sheet and you bake it, it’s pretty darn near indistinguishable from particle board, except you don’t smell the glue. You can have it more like a hard structure like particle board, or you can have it more like Styrofoam.
In fact, there are a couple companies now that are growing mycelia and then turning it into artificial leather.
Tech Briefs: What made you think to use mycelia as a building material?
Dr. Lynn Rothschild: I wish I could say that I was the first to think of using mycelia to build things, but I’m not. We took advantage of the fact that at the time there was at least one company that did that kind of work: Ecovative . They were making molds and growing the mycelia into shapes, feeding them with things like lawn scraps. They were making packing-material for wine bottles at the time. People started to realize that this could be very cool, for example, as a building material.
Tech Briefs: What are the advantages of having a structure "grown" vs. built?
Dr. Lynn Rothschild: The beauty of something that’s grown is it can adapt to the local environment. Say there’s a flat area but it’s not as big as you wanted it to be, or there are some craters and you need to make a nice, smooth surface; mycelia could provide much more flexibility onsite for a mission than another approach would. [Using fungal mycelia] takes away all the heavy equipment required to build structures with regolith, with sintering. Instead, you can sort of grow things in place.
Tech Briefs: What has been the conventional and traditional idea of a space habitat?
Dr. Lynn Rothschild: Anytime a human has lived off planet, they’ve just lived in their spacecraft.
I did a calculation awhile ago. If you look at the volume of the lunar module from Apollo 11, it’s about the volume of a cell block in Alcatraz if it were only 5 feet high. That’s nothing. If you’re the first person on the Moon, you can deal with anything for 36 hours. But if you’re talking about leaving someone in the quarters like that to live for a year and a half, it becomes untenable. That’s why we really need a better way.
Tech Briefs: How complex can these structures be?
Dr. Lynn Rothschild: Oh, you can build any complexity you want because these things will grow to fill a mold. Mycelia will eat darn near anything: from rice to quinoa to cereal to oatmeal to coffee grounds. They even grew on Mars regolith simulant when we added nutrients.
Imagine any structure you want. What we propose, because of planetary protection and because of the environment there, is that you have a double-plastic bag that would inflate into a dome.
Picture an igloo-type habitat, and then the fungal mycelia would grow to fill that structure. Then, you have some rigidity so you don’t have to worry about leaks.
Tech Briefs: How do you envision a habitat made from this fungi? For a Mars habitat, what’s being brought from Earth? What’s being used from the planet itself?
Dr. Lynn Rothschild: I picture it sort of like a tent, except instead of a single sheet of nylon, it’s an enclosed double bag. You can fold it flat. It’s seeded with fungal mycelia.
You get it to Mars or the Moon and, like an inflatable tent on Earth, you basically have this structure self-erect, or you could have some kind of organism in there like a cyanobacteria that photosynthesizes and spits out oxygen so it inflates it.
The idea is that you would get it somehow, either with struts or with inflation, into the size structure that you want and then you activate the fungal mycelia. If you’ve packed dried nutrients in it or soaked the paper in nutrients, basically all you should have to do is add water.
Tech Briefs: Where does the water come from?
Dr. Lynn Rothschild: The question is: Do you source the water locally, or do you bring it with you? These are sort of the mass trade-offs that you’d have to make. Would it be more expensive and more massive to send out rovers to collect the water and eject it? Or do you say, "the heck with it," and just bring a couple of jugs of water. Mycelia don’t need a whole lot [to grow]. These things are fairly dry. They, like all life on Earth, just need some water to get going.
Tech Briefs: What are you working on now to prove the viability of these fungi-inspired shelters?
Dr. Lynn Rothschild: First, we’re focusing on the actual logistics of this, which is what the NIAC program wants for Phase 2: How do we make this happen?
I’m a biologist, so I’m more excited in my own work about what can we do in terms of the fungi themselves. There are a couple ways we can go. Do we have them eat nutrient-covered regolith?
Or maybe you use paper structures which are very low mass, and it’s all folded and ready. I had an architectural student from the International Space University playing with making some scaffolding out of paper that would fold flat and pop up. So, this approach is very low mass, but it gives you a start for the fungi to grow on something.
And, which type of fungi should you use? Some are stronger. Some of them are not as strong.
Tech Briefs: Beyond a shelter, what else can fungi be used for on the Moon or Mars?
Dr. Lynn Rothschild: One of the things that we’ve talked about with the fungi and have a patent disclosure on from NASA is using that as a scaffold for a water filtration system, to pull out metals or purify water.
Another route that we’ve talked about is including biosensors into the material. Imagine if you have a colored protein that is activated when the oxygen level goes down — an oxygen sensor. As the pressure goes down, the walls turns a different color, or a patch of the wall does, which would be unbelievably cool.
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