Simulated lunar dirt can be turned into extremely durable structures, potentially paving the way to more sustainable and cost-effective space missions, a new study suggests.
Using a special laser 3D printing method, researchers melted fake lunar soil - a synthetic version of the fine dusty material on the moon surface, called regolith simulant - into layers and fused it with a base surface to manufacture small, heat-resistant objects.
If utilized on the lunar surface, the material may help build sturdy, nontoxic habitats and tools for future astronauts, capabilities that would be vital to the NASA Artemis missions that aim to establish a long-term human presence on the moon by the end of the decade.
But to assess how well this new construction material may work in space, the team tested their fabrication process under a range of different environmental conditions, revealing that the overall quality of the material depends greatly on the surface onto which the soil is printed.
"By combining different feedstocks, like metal and ceramics, in the printing process, we found that the final material is really sensitive to the environment," said Sizhe Xu, lead author of the study and a graduate research associate in industrial systems engineering at The Ohio State University. "Different environments lead to different properties, which directly affect the mechanical strength and the thermal shock resistance of certain components."
The study was recently published in the journal Acta Astronautica.
There are two types of lunar regolith simulants that scientists use to study the surface of the moon. The one this team used, called LHS-1, is designed to replicate soil found in the lunar highlands, a heavily cratered area rife with dark-colored basaltic rock.
In this case, researchers discovered that while trying to print LHS-1 on stainless steel and glass surfaces was challenging, it adhered well to alumina-silicate ceramic, likely because the two compounds form crystals that enhance thermal stability and mechanical strength.
Other environmental factors, such as the amount of oxygen in the atmosphere, the strength of the laser and even the speed of the printing process, were also shown to impact the stability of the structure, said Sarah Wolff, senior author of the study and an assistant professor in mechanical and aerospace engineering at Ohio State.
"There are conditions that happen in space that are really hard to emulate in a simulant," she said. "It may work in the lab, but in a resource-scarce environment, you have to try everything to maximize the flexibility of a machine for different scenarios."
Unsurprisingly, developing special systems for prolonged space travel is one of the most challenging aspects of successful human exploration, as technologies created for In-Situ Resource Utilization, or the harnessing of local natural resources at mission destinations, must be engineered to survive extreme vacuum, dust and thermal environmental conditions.
To accomplish this, scientists are rapidly evolving additive manufacturing systems, which would help reduce the need to transport large quantities of materials and heavy equipment from Earth and enable astronauts to create an array of structures, tools and habitats.
The promise of these technologies would not only save essential mission time but also allow for extended independence as crews travel into deep space.
Still, more data is needed to overcome any potential limitations future travelers might face as they lift off for other worlds. This study, for example, suggests that instead of being powered by electricity as their printing system is on Earth, future designs of the system could likely be scaled up using solar-driven or other hybrid power architectures.
"There are so many applications that we're working toward that with new information, the possibilities are endless," said Xu.
This team's work also extends beyond supporting humanity's push to the stars, as gaining a better sense of how manufacturing might work in space could help researchers discover new ways to address critical material shortages back home, said Wolff.
"If we can successfully manufacture things in space using very few resources, that means we can also achieve better sustainability on Earth," she said. "To that end, improving the machine's flexibility for different scenarios is a goal we're working really hard toward."
Other Ohio State co-authors include Marwan Haddad, Aslan Bafahm Alamdari, Annabel Shim and Alan Luo.
The study was supported by Ohio State's Institute for Materials and Manufacturing Research and the Center for Electron Microscopy and Analysis.
