In a new study in PLOS ONE, researchers led by Rashmi Dikshit demonstrate how bacteria and urea can be mixed with Martian or lunar soil to make bricks. Now, if you’re thinking, “I don’t want to live in a building made of pee and bacteria”, I’m with you. But the first settlers on any world are going to have very limited options for building materials, and in the absence of trees to cut down and the energy needed to quarry stone, pee bricks it is.

As described in the press release: A slurry is first created by mixing Martian soil with guar gum, a bacterium called Sporosarcina pasteurii, urea, and nickel chloride (NiCl2). This slurry can be poured into molds of any desired shape, and over a few days, the bacteria convert the urea into crystals of calcium carbonate. These crystals, along with biopolymers secreted by the microbes, act as the cement holding the soil particles together.”

While urea is a protein found abundantly in mammal urine, in this case, the researchers obtained the urea from those Sporosarcina pasteurii. The bricks made so far aren’t quite as stomach-turning as they could be. I just know, having watched The Martian, that you never know what an astronaut is going to be asked to recycle.

More Information

Indian Institute of Science press release

“Microbial induced calcite precipitation can consolidate martian and lunar regolith simulants,” Rashmi Dikshit et al., 2022 April 14, PLOS ONE