If humanity ever manages to build the first permanent buildings on Mars, they will probably need it stones made from Martian regolith– but the construction material may also require blood and other bodily fluids from the astronauts themselves.
The explorers charged with setting up a permanent base on Mars will also have to pack strategically. Space will be at a premium aboard the rocket that takes them to Earth’s neighbor, and the mission’s costs and fuel requirements will rise as the amount of cargo increases. Because of this, the first crews will have to rely on the resources around them, which usually consists of a lot of rocks and dirt. However, a thousands-year-old strategy can help them make the most of other readily available additives.
Ancient Roman concrete is known for its excellent resilience, strength and even self-healing properties. But masons often used other key ingredients when making bricks: blood and urine. Knowing this, a research team from Iran’s Kharazmi University recently mixed and tested multiple potential building materials using different combinations of sediment found on Mars, as well as other easily available components.
[Related: Inside the project to bring ‘self-healing’ Roman concrete to American shorelines.]
“The ancient Romans used organic additives, including animal blood, primarily to improve the durability and workability of their mortar,” they wrote in a subsequent study published in the journal: Acta Astronautica. “Although it’s a bit strange, blood can be used to make strong concrete or bricks for construction work on Mars.”
Depending on the region of the planet, Martian soil contains the right chemical composition for multiple types of concrete. After compiling geological data collected by previous Mars landers and orbiters, the team identified eleven potential concrete options for future astronauts. These include blends of geopolymer and magnesium silica. They then created simulated building material samples using a 3D printer, performed a stress test and recorded the results.
According to the team, sulfur-based concrete will likely be the most reliable starting material for buildings on Mars. But researchers also suggest that another, more bizarre competitor could be AstroCrete, a modern form of Roman concrete that contains additional human-produced ingredients.
“The production process is simple. Aggregates (Martian regoliths) bind together through contact with human serum albumin (HAS), a protein found in blood plasma,” they write.
The team theorizes that a single astronaut could produce enough HAS to make the amount of AstroCrete needed to build a single-person home in about 72 weeks. To increase AstroCrete’s compressive strength and plasticity while reducing its brittleness, the study authors offer another possible additive: urea extracted from sweat, tears and urine. An additional major advantage of AstroCrete is that it does not require water to mix, which is especially useful given the almost completely dry conditions on the planet.
Researchers emphasized that mission engineers and astronauts must consider much more than just sulfur-containing concrete or AstroCrete when planning a base on Mars. Numerous other challenges, such as the planet’s exposure to ultraviolet radiation, its deadly climate, low gravity and lack of water, could all prevent humans from living there permanently. Success, the authors explain, therefore “depends on the development of low-cost and practical solutions,” among which “on-site construction using locally available resources is emerging as the most promising approach.” Resources that may include the blood, sweat and tears of the first visitors to Mars.