Aled Roberts was in his lab, coaxing proteins together to develop synthetic spider silk, when he stumbled upon an unforeseen breakthrough. To test his own silk, he created what scientists call a “control.” It was a comparison sample, using a protein from cow’s blood that wasn’t supposed to work much at all. This cow silk wasn’t supposed to be as sticky as anything spiders could produce.
“Surprisingly, we found it to be really good to stay together,” says Roberts, a researcher at the University of Manchester.
Roberts knew immediately that this shocking discovery deserved more research. And now, a year later, his team has developed something extraordinary, if ever so smelly, out of that work. They proved that by mixing regolith (the inorganic spatial dirt found on the Moon and on Mars) and a common protein in human blood, we can produce concrete on other planets that is as strong as most concrete. made on Earth. Mix in some urea – the most common component of urine, other than water – and this concrete becomes even stronger.
Given that Roberts says it could cost over $ 1 million to send a single brick to Mars, his research could offer a cost-effective alternative to building on alien planets. But even bigger benefits could be here on Earth.
The historical precedent of concrete with blood
While the prospect of mixing blood in concrete may seem disgusting, Roberts later found out that it wasn’t a new idea. The addition of pork and beef blood to mortar dates back to ancient China and was relatively common in Europe during the Middle Ages (and potentially hundreds of years after). Albumin protein – the specific type of blood protein that offered so much adhesion in mortar – had also been used as a glue in other settings.
Although blood is no longer used to produce mortar today, “historical precedent shows it was done,” says Roberts. “Modern society, I guess, has gone mad with the production of oil and cement. We can go back and look at how we used to do things, and with our modern understanding, improve them and take them further. “
Why these animal proteins are so sticky is something Roberts has explored but not yet definitively concluded. In the body of animals, these proteins provide a predictable viscosity to their blood. But they also have many binding sites, which allow them to transport hormones and fatty acids throughout the body.
“Initially, we thought [the binding sites were] the mechanism, ”says Roberts. “It may have something to do with it, but in our [further] investigation, we found out that the structure of the protein had completely changed when it was hardened.
To create concrete, these proteins mix with silica (i.e. glass and sand) in a wet form, much like typical cement-based concrete. But as concrete dries and hardens, Roberts observed that proteins unfolded, altering their structure. Through this structural change, they produce hydrogen bonds, the same strong bond that holds water and, yes, spider silk together.
“We don’t know why,” admits Roberts. “It could have something to do with blood clotting. It is the main protein in the blood. So when it coagulates, [this protein] gets involved. “
So far this all makes sense. But how did Roberts come up with the idea of mixing urea in his concrete? Two reasons. First, urea is readily available in space because it is found in urine. Second, urea is a molecule that naturally forms strong hydrogen bonds. Urea therefore further feeds the mechanisms that made blood-based concrete work.
How would that work in space?
While it might seem overwhelming for astronauts to mix their own concrete on Mars – from fluids from their own bodies, nothing less – the process would be practical, Roberts says, and would only rely on a few simple pieces of machinery.
Astronauts would donate plasma a few days a week, just like people donate plasma on Earth. This process does not require red or white blood cells, so it is less difficult to collect than a general blood donation. A centrifuge is all that is needed to extract the specific protein from the blood sample. The production of urea is even easier. Astronaut pee could be collected in a toilet and then centrifuged to obtain this component.
With these bodily materials in hand, just mix them with the dust of space. Bricks could harden out on the planet’s surface, so no energy would need to be expended to heat, melt, or harden the material. Of course, none of this would matter if the astronauts couldn’t produce a significant amount of material from their own efforts. According to Roberts’ calculations, during a 3-year mission, an astronaut could produce enough concrete to accommodate one more person. This means, at least on paper, that this concrete could evolve to produce a larger and more sustainable Martian habitat.
Landing on Earth
Producing cosmic concrete in space is the literal definition of a moonshine. However, the biggest impact of Roberts’ research may be here on Earth. As part of his company Deakin, he is investigating how his protein-infused concrete could be scaled to make concrete, the most ubiquitous and environmentally harmful material on Earth, more environmentally friendly. . Deakin wouldn’t need to stock up on space regolith for this concrete to work; everyday sand could do the job instead. He is currently seeking funding to advance this research.
“Animal and human blood is not sustainable on a large scale, but plants and algae could potentially be a source [of alternative proteins], says Roberts. “Now that we understand the mechanism, we can use other proteins to study it.”