By 2028, NASA plans to make history by landing the “first woman and first person of color” on the moon, marking humanity’s return to the lunar surface for the first time since 1972. This mission, part of the ambitious Artemis III program, aims to establish a sustainable presence on the moon, potentially leading to long-term facilities and habitats. However, the high cost of launching heavy payloads necessitates innovative solutions for constructing lunar structures.
Given the impracticality of transporting all necessary materials from Earth, the concept of using local resources, known as in-situ resource utilization (ISRU), comes into play. This approach leverages advancements in additive manufacturing (AM), commonly referred to as 3D printing, to transform lunar regolith into building materials. Despite its promise, technical challenges have rendered most 3D printing techniques unfeasible on the lunar surface.
Light-Based Sintering: A New Approach
In a recent study published on the arXiv preprint server, a research team led by the University of Arkansas proposed an alternative method using light-based sintering to manufacture lunar bricks. This method, unlike traditional 3D printing, does not require the transportation of additional materials such as solvents or polymers, which are costly and problematic in the lunar environment.
The team, led by Assistant Professor Wan Shou and comprising members from the University of Houston and Tampere University, suggests that light-based sintering, which uses concentrated sunlight to melt lunar regolith into feedstock, could be a viable solution. This technique has been tested on Earth using lunar regolith simulant, showing promise for manufacturing glass and mirrors.
“There are many AM methods that require a solvent to prepare paste or composites for extrusion or printing; these approaches are not feasible, as transporting solvents can be very expensive,” explained Prof. Sou.
Challenges and Solutions in Lunar Construction
Historically, the idea of a permanent lunar base has been constrained by the need for heavy machinery and construction materials, which would require numerous costly launches. Although the commercial space sector’s development of reusable rockets has reduced payload costs, launching everything needed for a lunar facility remains prohibitive.
The extreme conditions of the moon present additional challenges. In the South Pole-Aitken Basin, where future bases are planned, temperatures vary dramatically, complicating construction efforts. Most AM methods necessitate additional supplies, which are impractical to transport.
Sintering technology, which involves bombarding regolith with energy sources like lasers or microwaves to create a ceramic material, offers a potential solution. However, its energy-intensive nature would likely require a nuclear power source, such as a kilopower reactor.
“Because of this, our team envisions a system where only lunar material is needed for the structures themselves, thus eliminating the bottleneck of binder resupply missions from Earth,” said Cole McCallum, the study’s first author.
From Concept to Reality: Next Steps
While the potential of light-based sintering is significant, the technology still faces hurdles when used for constructing entire structures. The research team has shifted focus to manufacturing building components, specifically interlocking and reconfigurable bricks, which offer flexibility and precision.
This approach builds on existing research into sintering technology, such as NASA’s collaboration with the space architectural firm SINTERHAB. Their work with microwave-sintering technology aims to equip the ATHLETE vehicle for lunar construction. The appeal of reconfigurable bricks lies in their adaptability and the reduced volume constraints for lunar missions.
“The reconfigurability of our brick assemblies is exciting because of the flexibility we can achieve with the building process,” McCallum noted. “For structures where a bulk of material is needed and where high precision isn’t demanded, as in the case of radiation shielding, we feel our method holds a lot of promise.”
Before this concept can be fully realized, further research is needed to optimize sintering parameters and material properties. The team plans to develop a prototype and conduct laboratory tests to refine and scale the technology for lunar use. Considerations such as the 3D printer’s mobility on the lunar surface and power options remain critical.
“When it comes to full implementation, there’s a lot of engineering that still needs to be done,” concluded Cole. “In the future, we’ll need to consider how the sintering process changes in a vacuum, or what modifications to the build platform will be needed so that parts can be reliably made while tracking the sun.”
The journey to establishing a permanent lunar habitat is fraught with challenges, but the innovative approach of using light-based sintering to create reconfigurable building blocks represents a significant step forward. As research progresses, the dream of a sustainable human presence on the moon edges closer to reality.
