A famous scene from the movie The Martian is when the astronaut stranded on Mars is forced to use his own poop as fertilizer to grow potatoes.
Now a research group at the University of Manchester has proposed something even more deliciously ghoulish: Future Mars astronauts could mix their own blood and urine with Martian dust to create building materials that are stronger than concrete.
The scientists tested their formula by making some "simulated moon or Mars regolith" and mixing it with water human serum albumin, a protein found in human blood. The protein acted as a binder and produced a material — which they dubbed "AstroCrete" — that was about as strong as concrete.
When they added in some urea, a component of human urine, it was stronger than 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.
The idea is that astronauts on Mars could periodically extract blood, providing themselves with nice source of AstroCrete binder material. Maybe they'd craft it all the time, slowly building themselves Lovecraftian Martian blood-dwellings as they terraform the red planet. Or maybe they'd save it up for an emergency, when they need to repair something.
The challenge, as that story in Interesting Engineering notes, is that extracting blood can tax one's system, and astronauts on the hostile terrain of Mars are already going to be in very-taxed shape. But given that Mars is a hellishly hard planet to supply, having some backup plan for fashioning building materials out of local stuff is not a bad idea.
The Manchester group's original paper –"Blood, sweat and tears: extraterrestrial regolith biocomposites with in vivo binders" — is here, and is worth reading. Many academic papers have pretty dry style, but they had a lot of fun with this one. Here's how it opens ..
The proverbial phrase "you can't get blood from a stone" is used to describe a task that is practically impossible regardless of how much force or effort is exerted. This phrase is well-suited to humanity's first crewed mission to Mars, which will likely be the most difficult and technologically challenging human endeavour ever undertaken. The high cost and significant time delay associated with delivering payloads to the Martian surface means that exploitation of resources in situ – including inorganic rock and dust (regolith), water deposits and atmospheric gases – will be an important part of any crewed mission to the Red Planet. Yet 25 there is one significant, but chronically overlooked, source of natural resources that will – by definition – also be available on any crewed mission to Mars: the crew themselves.