3D Printing Lunar Highways with a Pinch of Sun and Dust

Lunar infrastructure projects, including several aimed at creating roads on the Moon, are already underway. Building on these initiatives, a new research effort led by the Bundesanstalt für Materialforschung und -prüfung (BAM), or the German Federal Institute for Materials Research and Testing, wants to turn moon dust into infrastructure.

In partnership with the Clausthal University of Technology, which has strong roots in mining and metallurgy, the Aalen University of Applied Sciences, and the trans-disciplinary company Liquifer Systems Group, BAM embarked on project PAVER in 2021. PAVER, which stands for “paving the road for large area sintering of regolith,” uses 3D printing and a lunar dust equivalent material called EAC-1A from the European Astronaut Centre (EAC) and officially qualified by the European Space Agency (ESA) to create interlocking “paving stones” to potentially pave roads and landing pads on the Moon.

Through a layer-by-layer sintering approach and a representative laser on Earth, they aim to produce large-scale 3D printed elements that could be used during human and robotic lunar explorations. This method employs laser beams of different strengths and sizes, some of which can reach 100 mm in diameter with a remarkable 12 kilowatts of output power. Their goal is to explore how efficiently the EAC-1A material could be melted at high speed into expansive solid structures suitable for lunar construction.

Scanning electron microscope image of the EAC-1A lunar regolith simulant (left) and a piece of the sintered and cracked material (right). Image courtesy of Aalen University, BAM/TU. Clausthal

Yet, this innovative approach wasn’t without its challenges. As they conducted their tests, the team observed that overlapping laser tracks led to excessive temperature differences in the material. This clash in temperature-induced stresses resulted in crack formations. To counter this, the researchers designed triangle-shaped pieces with a hole in the middle. This design made sure the laser didn’t print over the same spot twice. This modification allowed them to create “paving stones” that they could interlock to form a stable surface for lunar roads and landing pads. Space agencies plan to align this project with establishing long-term lunar bases.

Setup used for the manufacturing of interlocking geometries and samples manufactured as paving elements. Image courtesy of BAM.

Lunar resources

Lunar dust, or regolith, isn’t just small particles scattered across the Moon’s surface. When disturbed by movements, such as those from lunar rovers or astronauts, it can become problematic. Due to the Moon’s low gravity, these dust particles can remain suspended in the thin atmosphere for long periods. This poses a threat since the dust can contaminate and potentially harm essential machinery, equipment, and instruments used in space missions. In fact, the Apollo 12 mission documented evidence of damages caused by dust when they found sandblast damage on the Lunar Surveyor III spacecraft.

Therefore, developing permanent infrastructures like roads and landing pads is crucial to reduce these dust-related problems. However, transporting building materials from Earth to the Moon would be too expensive and a logistical nightmare. As a reference, in 2022, the cost of sending just one kilogram of payload to the International Space Station (ISS) was roughly $10,000. Transporting the massive amount of materials required for extensive lunar infrastructure would undoubtedly multiply these costs, emphasizing the need for innovative on-site construction solutions.

Rather than transporting materials across space, scientists are tapping the Moon’s surface. The abundant lunar dust offers a promising solution to the construction challenges on the Moon. BAM’s study was quite innovative in using laser beams to convert this lunar dust simulant into a durable building material, anticipating a construction methodology that could prosper.

But here again, transporting high-powered lasers to the Moon isn’t viable due to their massive weight. So, instead, the study proposes using sunlight. Researchers employ a lightweight film-based Fresnel lens that focuses sunlight with high intensity, eliminating the need for lasers. This approach aligns with the essence of in-space manufacturing (ISM) and in-situ resource utilization (ISRU) technologies, emphasizing utilizing available resources.

Paving the road for large area sintering of regolith. Visualization courtesy of Liquifer Systems Group

The way forward

Additive manufacturing, with its flexibility and geometric freedom, emerges as the ideal candidate for on-site fabrication on the Moon and other planets. By melting lunar regolith with concentrated sunlight, BAM scientists can pave the way for full in-situ construction. Although the project officially ended in December 2022, their work culminated in a report published in the Nature Journal titled Laser melting manufacturing of large elements of lunar regolith simulant for paving on the Moon. As the coordinating leader of ESA’s PAVER project, the team offers plenty of details about the project in the study.

ESA’s PAVER project further underscores the feasibility of BAM’s approach. Through their investigations, the project evaluated the time, power, and conditions necessary for using light to melt regolith for lunar paving applications.

While converting moon dust into solid roads might seem like something from a science fiction story, it spotlights humanity’s determination and ingenuity in space exploration.

Jens Günster, who led the PAVER project for BAM, said these results show that 3D printing could play a big role in setting up actual bases on the Moon.

“Our results show the great potential that additive manufacturing has,” says Günster, who is also head of the Department of Multimaterial Manufacturing Processes at BAM. “They bring us a significant step closer to building a reliable infrastructure on the moon as planned by the European Space Agency (ESA).”

BAM acknowledges that the ESA funded and supported their work under its Discovery Programme. They also shared aspirations for future experiments in alliance with the ESA and the German Aerospace Centre (DLR), which participated as an associate partner throughout the project.

Sunbeams and stardust

Several space agencies and private firms have shown interest in the construction of lunar infrastructure, which includes roads, habitats, and other essential infrastructures. 3D construction giant ICON is delving into developing a lunar surface additive construction system. Meanwhile, the Australian additive construction equipment and technology manufacturer, Luyten, is collaborating with the University of New South Wales Sydney to accelerate the development of 3D printing technology for lunar structures. Jacobs, on the other hand, is channeling its efforts towards innovative methods to derive building materials from Martian and lunar regolith using autonomous additive construction systems.

Initiatives like this not only spotlight the potential of additive manufacturing but also stress the importance of using available resources efficiently, a lesson we can apply better here on Earth.