A new type of cheaper housing has been proposed for future Mars colonists. All the astronauts need to do is pay in blood.
Researchers from the University of Manchester made the proposal — we promise this isn't the plot of a 90s straight-to-VHS sci-fi horror movie — as a means to greatly reduce the cost and increase the speed of construction for future off-world colonies.
In a paper published in Materials Today Bio, they detail how extra-terrestrial dust can be mixed with the blood, urine, and other bodily fluids of astronauts to build walls that would protect them from radiation and meteor strikes. And the process could also "potentially solve a life-threatening emergency akin to the Apollo 13 disaster," Dr. Aled Roberts, lead author on the study, tells us in an interview via email.
The blood binding of extra-terrestrial dust
In their study, the University of Manchester researchers demonstrated how human serum albumin (HSA), a common protein from blood plasma, and urine, could be used as a binding agent for extra-terrestrial dust, turning it into a material stronger than ordinary concrete.
The researchers state that the blood plasma protein required for the material could be safely extracted from astronauts multiple times a week using an existing procedure similar to blood donation. HSA is the most abundant protein in blood plasma and it replenishes at a rate of 12 – 25 g per day. The question is, would astronauts be able to maintain the mental and physical strength needed for space missions if they have blood plasma extracted several times per week?
"I think the physical and mental health effects will be the main concern if this technique was applied," Roberts tells us. "Micro-gravity is already very taxing on the body, causing problems such as muscle and bone degeneration, and any procedure that further damages astronaut health will likely be completely unacceptable. It’s not clear if the gravity on Mars (about 38% the strength of Earth’s) will cause the same health effects as microgravity (i.e. in space), this will need to be determined experimentally."
Crew diets would also "need to be supplemented with additional protein, calories, and water to make up for the deficit arising from HSA extraction," Roberts says. As future missions to Mars are likely to have overcapacity in food supplies for redundancy, the researchers don't expect the supplemented diet to be a problem. HSA extraction could also be halted in the case of an unforeseen problem reducing a space colonies' food supply.
Emergency blood extraction
With China having recently set its sights on sending humans to Mars in the 2030s and SpaceX's Mars-bound Starship nearing its maiden voyage, scientists are racing to find new construction solutions for future space colonies. Sending all of the required materials from Earth would be prohibitively expensive — the cost of transporting a payload with the weight of a brick to Mars is currently close to $2 million — meaning innovative processes are required to enable the construction of housing using on-site resources such as Martian regolith (loose inorganic heterogeneous deposits).
An added benefit of the University of Manchester researchers' proposal is that it could be used in emergency situations — if a human is present, you always have access to the valuable resources in their bodily fluids.
"Understanding the potential uses and limitations of such materials could be critical in an emergency situation that requires flexibility and ingenuity to solve," Roberts says. "The significant time delay between Earth and Mars, both in terms of logistical resupply (~26 months) and communication (up to 44 minutes), means that the ability for astronauts to devise solutions to novel threats and implement emergency repairs with the resources at hand will be critical to mission safety." In other words, as Roberts puts it, knowledge gained from the new study could "potentially solve a life-threatening emergency akin to the Apollo 13 disaster."
AstroCrete is stronger than traditional concrete
In laboratory tests run by the University of Manchester team, the blood plasma protein-infused material, dubbed AstroCrete, showed compressive strengths as high as 25 MPa (Megapascals). This falls within the range of traditional concrete at 20-32 MPa. However, by adding urea — a biological waste product excreted through urine, sweat, and tears — the researchers found that they could increase the strength of AstroCrete by over 300 percent. The resulting material showed a compressive strength of close to 40 MPa, making it much stronger than traditional concrete.
The scientists calculated that, with a crew of six astronauts, more than a half tonne of AstroCrete could be produced over the course of a two-year mission on Mars. In theory, each crew member could provide the resources to expand a habitat enough to house an additional crew member, meaning that housing could be doubled with every crewed mission to Mars.
While the findings are impressive, Roberts and his team's proposal is one of many ideas that will be considered in the coming years as NASA and other space agencies collaborate with the scientific community on innovative solutions for utilizing and extracting resources in outer space. Whether AstroCrete makes it to Mars or not, "the findings could [also] have applications on Earth," Roberts says. In fact, he has recently established a startup called DeakinBio that utilizes a similar process. Instead of blood, the company uses plant-based biopolymers as a binding agent to make a green alternative to cement, concrete, and ceramic materials — so you can rest easy that human blood isn't about to be harvested for construction on Earth.
Interestingly, Mars and blood are both red for the same reason: They both contain an abundance of iron oxide. So while the new proposal might not literally have astronauts signing housing leases in blood, there's a strange poetry to the fact that future construction on the red planet may be bound by the blood of its human explorers. In a future space colony, the blood that courses through their veins could help to protect them against their deadly surroundings.