Scientists hope to build houses on Mars using yeast and gelatin

By Stephen Beech

Scientists plan to 3D print houses on Mars — after being inspired by freeze-dried fruit.

They have cooked up a recipe that they say could one day be used to construct buildings on the red planet.

Mars is a hostile environment to build a house as it’s bitterly cold, blasted by radiation and a near vacuum, while traditional building materials would take months to transport from Earth.

Now scientists in Hong Kong have created a recipe that combines Martian rocks with Earthly ingredients: gelatin and yeast.

Once dried and hardened, they say the living building material is as strong as low-grade concrete and can be broken down, recycled and even brewed again for new construction.

Study senior author Jishen Qiu, an associate professor in civil engineering, said: “My inspiration came from freeze-dried fruits that become harder.

“Mars’s extremely low temperature and pressure create conditions similar to freeze-drying.

“So I asked myself if we can take advantage of that and make some materials.”

To conjure the printable material, Qiu needed the right mixture of sand and glue, the latter, which is made from gelatin and a specialized yeast.

His team at The Hong Kong University of Science and Technology engineered yeast coated with highly adhesive proteins, including those that mussels use to cling to rocks.

Qiu explained that the gelatin knits the ingredients together and provides a place for the cells to grow, while the sand gives mass and structure.

The team then tested the material in simulated Martian conditions.

Once the mixture pushes through the nozzle, the extreme cold and low pressure freeze-dry it.

Water freezes and turns directly from ice into vapor, leaving behind microscopic pores.

Qiu says the result resembles a foam, light and porous.

For now, the printed structures are about wine-cork-sized small domes, standing at 45 millimeters (1.7 inches) tall and 30 millimeters (1.18 inches) wide.

But the material itself is strong with a compressive strength of 10 to 12 megapascals — comparable to low-grade concrete, according to the research published in the journal Chem Circularity.

Qiu said: “This is actually strong enough to build a one- or two-story building on Earth whose gravity is three times that of Mars.

“So, you can probably easily build a multistory building on Mars with the material.”

Many proposals for building extraterrestrial cities involve heating and melting Martian rocks or moon dust into bricks and beams.

But that requires substantial energy.

Qiu says the biology-based material not only saves energy on heat by taking an entirely different manufacturing approach, but it could also support a circular economy on Mars.

He explained that settlers could recover the yeast from dismantled structures and regrow it in bioreactors.

Qiu said: “As long as there’s one yeast that’s still alive, you can grow them again.£

So far, the biology-based material has only been tested on Earth.

The Hong Kong team doesn’t know whether the yeasts can survive actual Martian conditions.

The living building material still relies on, albeit less, Earthly ingredients, and its success will depend on advances in rocket technology.

Qiu estimates a meaningful on-site engineering could require hundreds of tons of cargo from Earth.

He added: “I always ask myself: Is there any physical law or fundamental mechanism that prevents us from doing this?

“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.”