Bold claim: Mars’ toxic soil could actually make bricks stronger, turning a feared hazard into a helpful resource. And this is the part most people miss: perchlorates, long considered a nuisance, might be an asset when combined with bacteria and smart binders. Here’s a clear, beginner-friendly rewrite that keeps every key detail intact, with a bit more explanation and context.
A local resource strategy will be essential for any Moon or Mars mission because hauling everything from Earth is prohibitively expensive. Mars, in particular, contains a notable local component that has long been viewed as a problem: perchlorates. These chemicals are toxic to almost all life and make up about 0.5–1% of Martian soil. For a long time, scientists assumed perchlorates would hinder colonization efforts rather than help. Now, a new study from the Indian Institute of Science and the University of Florida shows that perchlorates can actually aid the brick-making process for a Martian outpost.
In past reports about making bricks from Martian regolith, we noted that most regolith simulants used in experiments did not include perchlorates because they pose a fire risk. Consequently, those experiments often relied on biocementation processes driven by bacteria but omitted a crucial soil component found on Mars.
That gap is precisely what this new PLOS One paper addresses. The researchers deliberately added perchlorates to their previously used Martian simulant mix, mixed it into a slurry, and then formed bricks from the resulting material. They tested these bricks for compressive strength to gauge their viability.
A key element of the mix was the bacteria. The team used a strain of Sporosarcina pasteurii discovered in Bangalore soil. In the lab, this bacterium responded impressively to perchlorates, forming dense multi-cell clusters and, most importantly, creating an extracellular matrix (ECM) with microbridges linking the bacteria to the soil minerals.
But bacteria alone weren’t enough. Various control experiments with different ingredients showed that a slurry containing only bacteria and water fell apart quickly, and a mix with just bacteria, water, and simulant performed even worse. The breakthrough came when the researchers added guar gum, a natural adhesive derived from the guar bean. This additive acted as both an adhesive and a nutrient source for the bacteria, enabling the biofilm to flourish. When combined with bacteria, guar gum boosted compressive strength to more than three times that of samples with either component alone or in other combinations.
Another important factor was nickel chloride, included initially as a catalyst to drive the ureolysis reaction that underpins biocementation. However, nickel chloride is not readily available in Martian soil, so it would require a separate processing step or Earth supply. Interestingly, the strongest brick produced in the study did not include nickel chloride at all.
The top-performing formulation turned out to be a trio of bacteria, guar gum, and perchlorate, delivering compressive strength more than double the strength achieved with bacteria and guar gum alone. So, why would a known toxin like perchlorate end up fortifying bricks?
The exact mechanism is still being explored, but the authors propose that the ECM the bacteria form in the presence of perchlorate could play a role. The microbridges between bacteria and minerals may enhance the material’s resistance to compression. This is a compelling hypothesis that the researchers are actively testing. In this specific context—building with Martian materials—the perchlorate appears to be more of a help than a hindrance.
If you’d like to dive deeper, you can check out these sources:
- IISc: How brick-building bacteria react to toxic chemical in Martian soil
- S. Dubey et al.: Effect of perchlorate on biocementation capable bacteria and Martian bricks (PLOS ONE)
- Universetoday articles on unusual ideas for Martian construction with bacteria and human waste
Bottom line: this study suggests perchlorates could play a constructive role in future Mars construction, at least in the specific context of bio-mediated brick formation. Do you think perchlorates should be treated as a resource or a risk in Martian manufacturing, and why? Would you support further experiments to refine this approach, or prefer alternative soil-processing methods for outpost building?
