Moon and Mars biocomposites

Space concrete created with ‘literally blood-curdling’ technique

Image credit: University of Manchester

Scientists from the University of Manchester have developed a material stronger than concrete and suitable for extra-terrestrial construction. The material is made from space dust and the waste body fluids from astronauts.

If humanity is to establish permanent colonies on other astronomical bodies, it must find some way of constructing buildings from local materials; transporting a single brick to Mars has been estimated to cost around $2m. Using local materials is known as in-situ resource utilisation.

Proposals for in-situ resource utilisation tend to focus on sparse water deposits and regolith (loose rock, soil and dirt) available on the Martian or lunar surface. However, there is an important overlooked resource available to any crewed mission: the crew themselves.

In a study ('Blood, sweat, and tears: extraterrestrial regolith biocomposites with in vivo binders') published in Materials Today Bio, scientists demonstrated that a common protein in human blood plasma - human serum albumin - could act as a binder for simulated Martian or lunar dust to produce a concrete-like material.

The material, which the scientists termed 'AstroCrete', has compressive strength as high as 25MPa, comparable with the 20-32MPa strength observed in ordinary concrete. Incorporating urea – a waste product excreted through urine, sweat and tears – could further increase the compressive strength by over 300 per cent in the best cases, to reach strengths of 40MPa.

“Scientists have been trying to develop viable technologies to produce concrete-like materials on the surface of Mars, but we never stopped to think that the answer might be inside us all along,” said Dr Aled Roberts, who worked on the project.

Historically, non-human animal blood has been used as a binder for mortar. He added: “It is exciting that a major challenge of the space age may have found its solution based on inspirations from mediaeval technology.”

The scientists investigated the underlying bonding mechanism and found that blood proteins denature (or “curdle”) to form an extended structure with interactions called beta sheets, which tightly hold the material together through a mechanism analogous to that utilised in spider silk. “The concept is literally blood-curdling,” said Roberts.

Roberts and colleagues calculated that over 500kg of high-strength AstroCrete could be produced by a crew of six astronauts during a two-year mission to Mars. If used as a mortar for sandbags or heat-fused regolith bricks, each crew member could produce enough AstroCrete to expand the habitat to support an additional crew member and doubling the housing available with each successive mission.

Furthermore, the researchers demonstrated that AstroCrete has the potential to be 3D printed, opening up another potential avenue for efficient extra-terrestrial construction.

Earlier this month, engineers from the University of Arizona published a plan for mining the surface of the Moon, using an autonomous swarm of robots and innovative excavation techniques. Research in these previously speculative areas has been growing and last September, Nasa announced an initiative to pay private companies to mine lunar regolith (rock and dirt covering the surface), in the hope of establishing international standards for business in space.

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