Establishing life on another planet is a multifaceted process with many problems. Housing is one major challenge, but a new study suggests researchers have found a way to build living quarters on Mars using materials already present on the planet, along with a couple of other clever ingredients.
The study, published on Sept. 10 in the journal Chem Circularity, reports that researchers found a way to turn the sand on Mars into what is functionally low-grade concrete using little more than gelatin, yeast, and the natural Martian environment. Combine the three ingredients, and the dry, cold, low-pressure environment of Mars freeze-dries the mixture, turning it into a porous, foam-like material strong enough to build houses on the red planet.
“My inspiration came from freeze-dried fruits that become harder,” senior author Jishen Qiu of The Hong Kong University of Science and Technology said in a statement. “So, I asked myself if we can take advantage of that and make some materials.”
According to Qiu, the concrete produced by this method measures 10 to 12 megapascals (a metric unit of pressure), putting it on par with low-grade concrete here on Earth. This concrete is strong enough to build a one- or two-story house on Earth, and since Earth has three times the gravity of Mars, it’s more than strong enough to build structures on Mars too.
The gelatin is run-of-the-mill porcine gelatin, which means it’s made from pigs, and it’s quite literally the same stuff that Jell-O uses to make its jiggly dessert. For the yeast, Qiu created a specially engineered version covered in the same proteins mussels use to attach themselves to rocks. These two ingredients, along with pounded-up Martian rocks and water, create the material.
Mars’ frigid cold, low-pressure environment effectively freeze-dries the material, causing water to sublimate, which means it turns directly from a solid to a vapor, leaving the Martian concrete behind. Because this process is so fast, items must be 3D-printed in real time to work properly.
The team tested it by 3D printing two small beehive-shaped structures about the size of a wine cork in a simulated Martian environment, but the team believes the process can scale up. Once the structures have reached the end of their usefulness, people on Mars can break them down, mix them in a bioreactor, and brew a new building with the same materials, as long as there’s still yeast alive to reproduce.
An elegant solution to a long-standing problem
Houses on Mars made with this method would resemble beehives, but be made of what is essentially concrete. Nin Liu
Delivering humans to Mars is already a tall order. Elon Musk tried to get it done by 2025 and missed the mark by at least a decade. However, getting people there is only half the battle. Once there, they need a place to live that can withstand the Martian environment, which includes temperature swings of nearly 100 degrees Celsius and virtually no radiation protection from the sun due to the thin Mars atmosphere.
There are many ideas about the subject, ranging from inflatable domiciles to the idea of letting self-propagating fungi grow whole buildings. Some enterprising scientists from the Indian Space Research Organisation even made space bricks from Martian soil, guar gum, urea, nickel chloride and a bacterium called Sporosarcina pasteurii, which converts urea and calcium into calcite. This lets the soil harden into something resembling concrete.
NASA held a habitat challenge from 2015 to 2019 that tasked companies and researchers to 3D-print homes using unique methods and materials. The winners took home over $2 million in prizes. In short, no stone has been left unturned, and people are using all sorts of exotic materials to try to find the best solution for habitats on Mars, including Qiu.
“I always ask myself: Is there any physical law or fundamental mechanism that prevents us from doing this?” Qiu said. “I can’t see any at this point in time. We are confident in scaling it up. It would surprise me if materials for future Martian engineering will not be as diverse as those used in Earth engineering, and biology will certainly contribute.”
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