Could Yeast Help Build 3D-Printed Habitats on Mars? Scientists Are Testing the Recipe

A yeast-based material turns Mars’s hostile environment into part of the construction process.

Bit by bit, humanity is inching towards finally setting foot on the Red Planet. Researchers have been working through the practical problems of living on Mars. How to get there. Where to find water. How to produce food. Then comes a problem that sounds almost mundane: once people arrive, what will they live in?

Any Martian settlement would initially lack the industrial infrastructure needed to make conventional construction materials. Hauling the raw materials for an entire settlement from Earth would consume precious rocket capacity. So any serious attempt at building there will probably have to use much of what is already there.

A new study proposes an unusual recipe for building habitats: mix Martian regolith with a binder made from gelatin and genetically engineered yeast, then extrude the mix through a 3D printer. Better yet, Mars itself might help finish the job.

The mixture, described in a new study, takes advantage of the planet’s cold temperatures and extremely thin atmosphere. Water in the freshly printed mixture freezes, then the ice turns directly into vapor under low pressure, leaving behind a hardened, porous structure. In laboratory tests, the material reached a compressive strength of about 12 megapascals.

The researchers designed the material to serve as a structural shell rather than a complete habitat. A finished Martian home would still need an airtight inner membrane, insulation, radiation shielding, life-support systems, and other technologies before anyone could safely live inside it.

Made on Mars

The researchers call the material Martian living building material (MLBM). Its binder combines gelatin with genetically engineered Saccharomyces cerevisiae. Proteins displayed on the yeast cells help strengthen the microscopic connections between grains, while water sublimation creates a porous but solid scaffold.

The envisioned procedure goes like this. Researchers would produce the yeast-based binder in a pressurized, insulated bioreactor using locally extracted water. Robots would mix it with Martian regolith and feed the paste through a printer, probably inside a temporary enclosure that keeps the material warm enough to flow. The finished shell would then be exposed to the Martian environment to dry and harden.

Researchers have been circling this problem for years. NASA’s 3D-Printed Habitat Challenge explored ways of building shelters using materials available at destinations such as Mars. Moreover, a 2020 PLOS One study on “Martian biolith” investigated binding simulated Martian regolith with chitosan. NASA has even funded research into growing habitat components from fungal mycelium.

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But Qiu’s group has so far printed only a tiny beacon, 45 millimeters tall and 30 millimeters wide. More importantly, they used natural sand rather than Martian regolith simulant.

“So far, no soil samples have been brought back from Mars (you may scan it, but it’s hard to know the situation underneath); we don’t really know how authentic the ‘simulant’ is,” he told ZME Science in an interview.

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The effects of real Martian salts and minerals on the yeast remain untested. Qiu thinks radiation may be the more urgent biological threat.

Scaling up introduces another unknown: Mars’s gravity.

“We are eager to know how the printing will be affected (or perhaps facilitated by the lower gravity),” Qiu said. “To do that, we need a testing bed with reduced gravitational acceleration (which is really challenging, and that’s why we hope our project gets more attention). Besides that, having a bigger testing environment (low temperature, air pressure, full-size printer-controller, full-size bioreactor) will be important to our next steps too.”

Making the Shell Livable

A printed MLBM dome would not hold an atmosphere on its own.

“For airtightness, there should be a membrane that is closely attached to the internal surface of the MLBM dome, to make it airtight,” Qiu explained. He suggested a high-strength polymeric fabric as one possible liner.

Then there’s dealing with the radiation. Qiu said thicker walls made with dense local regolith could improve protection from gamma rays and neutron radiation. Retaining more water within the material could also help reduce exposure to charged particles such as protons and alpha particles, he explained.

But that creates a trade-off because the curing process normally removes water. The team has considered collecting the sublimated vapor and using it again. Qiu said such recovery would become essential if we were to adapt the method for the Moon and builders could not rely on a continuing local water supply. For Mars, however, he said designing that recovery system lies beyond the current plan.

The bottom line is that MLBM is only one component in a larger habitat system involving pressure-retaining membranes, thermal control, radiation protection, and other technologies.

Ultimately, the researchers envision a three-story building 12 meters tall, with 102 square meters of floor area and 93 cubic meters of MLBM. The researchers estimate its binder alone would require about 1.86 metric tons of material brought from Earth.

The Biggest Obstacle—Earth

Yeast offers one obvious advantage. Unlike cement, it can make more of itself. But reproducing microbes still need food.

Qiu ultimately hopes other engineered microorganisms could capture methane and carbon dioxide and convert them into nutrients and raw materials for protein production. Without such a system, the colony would still depend on Earth.

“Even without doing it, shipping nutrients from Earth would be plausible (10-50 kg would be sufficient for making 1 cubic meter MLBM),” he noted.

The strongest formulation also uses Earth-supplied porcine gelatin. The researchers made a gelatin-free version, but it was weaker. They also recycled the material four times without a substantial loss of strength or yeast viability, although they have not yet quantified long-term nutrient requirements, water replenishment, or losses from repeated recycling.

The study estimates considerably lower material-processing energy than high-temperature regolith sintering, but the figures does not yet include the full burden of growing microbes, running bioreactors, controlling temperatures, pumping material, or recovering water.

Asked what might ultimately prove the biggest deal-breaker, Qiu’s answer had little to do with yeast.

“Unsurprisingly, the shipping capacity of rockets (or the gravitational acceleration of Earth),” he said. “If over 20 Starship-scale rockets are launched to Mars within one launch window, it may be enough for construction to achieve a meaningful scale.”

The irony is hard to miss. Mars may eventually provide the dirt, the cold, and even the near-vacuum needed to make its own building shells. For the foreseeable future, however, much of the machinery and biology needed to turn them into homes would still have to escape Earth’s pull first.

The study was published in the journal Chem Circularity.