Transporting a single brick to Mars is extremely expensive, making the future construction of a Martian colony seem impossible. Scientists have now developed a way to potentially overcome this problem by creating a concrete-like material made of extraterrestrial dust along with the blood, sweat, and tears of astronauts.
A protein from human blood — combined with a compound from urine, sweat, or tears — could glue together simulated Moon or Mars soil to produce a material stronger than ordinary concrete, perfectly suited for construction work in extraterrestrial environments.
The cost of transporting a single brick to Mars has been estimated at about $2 million, meaning future Martian colonists cannot bring their building materials with them but will have to utilize resources they can obtain on-site for construction and shelter. This is known as in-situ resource utilization (ISRU) and typically focuses on the use of loose rock and Martian soil (regolith) and sparse water deposits. However, there is one overlooked resource that will, by definition, also be available on any crewed mission to the Red Planet: the crew themselves.
The scientists demonstrated that a common protein from blood plasma — human serum albumin — could act as a binder for simulated Moon or Mars dust to produce a concrete-like material. The resulting material, called AstroCrete, had compressive strengths as high as 25 MPa (megapascals) — about the same as the 20 - 32 MPa seen in ordinary concrete.
The scientists found that incorporating urea — a biological waste product that the body produces and excretes through urine, sweat, and tears — could further increase the compressive strength by over 300%, with the best performing material having a compressive strength of almost 40 MPa, which is substantially stronger than ordinary concrete.
The scientists calculate that over 500 kg of high-strength AstroCrete could be produced over the course of a two-year mission on the surface of Mars by a crew of six astronauts. If used as a mortar for sandbags or heat-fused regolith bricks, each crewmember could produce enough AstroCrete to expand the habitat to support an additional crewmember, doubling the housing available with each successive mission.
The scientists investigated the underlying bonding mechanism and found that the blood proteins denature, or “curdle,” to form an extended structure with interactions known as “beta sheets” that tightly hold the material together.