A combination of yeast, gelatin, and sand could be used to build structures on Mars, through 3D printing, according to an international study published in the journal Chem Circularity. The team developed a biologically based construction material that, once dried and hardened, exhibited a compressive strength comparable to low-strength concrete.
The proposal aims to address one of the main challenges of a future human occupation of Mars: constructing structures using, as much as possible, resources available on the planet itself and without resorting to large amounts of energy to transform Martian rocks into building materials. The material developed combines sand with gelatin and a genetically modified yeast, coated with highly adhesive proteins, including proteins similar to those used by mussels to adhere to rocks.
Gelatin acts as a binding element and provides a medium for cell growth, while sand confers mass and structure to the material. When the mixture is extruded through a nozzle, under conditions that simulate the Martian environment, cold temperatures and low pressure trigger its freeze-drying. Water passes directly from solid to vapor, leaving small pores in the material.
In tests conducted, the material exhibited a compressive strength between 10 and 12 megapascals, a value comparable to low-strength concrete. The first structures produced, however, are still very small: they measure about 45 millimeters in height and 30 millimeters in width.
A material that can be recycled
One of the features that distinguishes the proposal is the possibility of reusing the biological component. Rather than simply producing and discarding construction materials, the researchers acknowledge that the yeast can be recovered from dismantled structures and re-cultivated in bioreactors, enabling the production of new material.
“As long as there is a yeast that remains alive, we can re-cultivate it,” says Jishen Qiu, a civil engineer at the Hong Kong University of Science and Technology and the study’s lead author.
The approach could also reduce the energy required to produce construction materials. Some proposals for future extraterrestrial structures involve heating or fusing Martian rocks or lunar dust to produce bricks and other elements, processes that would require significant amounts of energy.
In the case of the material developed by the team, the use of biological processes avoids that heating step and opens up the possibility of establishing a production and recycling system of materials on the planet itself.
Still far from a construction on Mars
Despite the results, the technology is in an early stage. The materials have been tested only on Earth, in conditions that simulate some of the characteristics of the Martian environment, and it remains unknown whether the yeast would actually survive on Mars.
Moreover, the system continues to rely on ingredients sourced from Earth, though in smaller quantities than some alternatives. The researchers estimate that a future engineering application at a relevant scale would still require transporting hundreds of tons of cargo to Mars.
The team now intends to increase the size of the structures and assess the material’s viability for larger-scale applications.
“I always ask myself: is there any physical law or fundamental mechanism that prevents us from doing this? At this moment, I can’t see any,” says Qiu. “We are confident that we can scale up.”
