Permanent structures on the Moon could start with what is already underfoot - lunar dust. A new study from the University of Arkansas has shown that pure regolith (the loose material covering the Moon's surface) can be 3D-printed into blocks that connect like LEGO pieces. Using such material for construction would reduce the cargo NASA would have to deliver from Earth for future lunar settlements.
The work was published in the journal npj Advanced Manufacturing. The first author was Cole McCallum, at the time an undergraduate student at the University of Arkansas. The senior author is Wan Shou, an assistant professor in the Department of Mechanical Engineering.
The researchers used a type of 3D printing - laser powder bed fusion. A thin powder is spread across a flat platform, then a powerful light source, such as a laser, fuses the particles in a process known as sintering. The platform lowers, a new layer of powder is applied, and the next layer is created.
Unlike Earth soil, lunar regolith contains no organics. It consists of loose particles with jagged edges formed over billions of years by impacts from asteroids, micrometeorites and other space debris. The experiments used a commercial lunar soil simulant, Lunar Highlands Regolith Simulant (LHS-1), created to reproduce samples collected during the "Apollo" missions.
Other researchers added binders to lunar regolith for 3D printing. But such additives would have to be brought from Earth. The Arkansas group was the first to show that regolith simulant can be sintered directly, without a binder, into reconfigurable building blocks using a relatively low-power light source.
"It doesn't bind to anything else. The regolith powder binds to itself," McCallum said.
The researchers printed blocks several centimeters wide: some in the shape of crosses, others in the shape of the letter H. These two distinctive shapes can be connected like LEGO to build larger structures. However, objects made of pure regolith are more porous and mechanically weaker than items printed with a binder.
"These structures are self-supporting," McCallum noted. "But I would be cautious about saying that our process can already be used for something that bears other loads."
According to Shou, further research is needed to understand how the process would behave under microgravity and vacuum conditions. In addition, the mechanical characteristics of the bricks should be optimized for practical application. The scientist is optimistic: the proposed approach could become an efficient way to create components and structures for a permanent settlement on the Moon.