Researchers at Washington State University (WSU) have developed a material that could be used to 3D print the equipment needed in future missions to explore the red planet.
By mixing titanium with simulated Martian regolith, the scientists have been able to create a feedstock that can be Directed Energy Deposition (DED) 3D printed into structures with greater resistance qualities. Using future iterations of their material, the team say it may be possible to produce tooling or rocket parts on Mars’ surface, rather than flying them there on an expensive-to-launch NASA shuttle.
Economical manufacturing in space
Since the advent of space exploration, the WSU team says “every aspect of space-based operations” has remained very expensive. In fact, citing data from an Ames Research Center report dating back to 2018, the researchers point out that sending each one-kilo of payload into orbit using NASA’s space shuttle costs about $54,000.
Consequently, utilizing in-situ resources to sustain human exploration is vital to ensuring the economic viability of future missions. According to one of the study’s co-authors Amit Bandyopadhyay, doing so is not only a necessity as “we really cannot carry everything from here,” but it drives down the chances of any logistical hiccups, as “if we forgot something, we cannot come back to get it.”
As the scientists highlight in their paper, 3D printing continues to be tipped as a means of manufacturing and repairing equipment off-world, but they say certain technologies are less suited to this than others. With DED, for instance, it’s still challenging to print pure regolith structures due to the material’s ceramic content, which has a high melting point, low laser absorption, and is vulnerable to fracture.
These characteristics mean DED-printed regolith parts suffer from severe cracks or pores that cause them to feature poor interfacial strength for coatings. Prior research has also shown that the abrasiveness of Martian dust could impact the viability of future builds. To get around these issues, the team has previously toyed with the idea of stabilizing structures by mixing simulated Martian dust with different forms of titanium, and they now believe they’ve found the ideal material for the job.
Creating a titanium-regolith composite
In an effort to identify the optimal mixture of crushed Martian rock and titanium, the WSU team added Tekna Ti64 powder to different concentrations of regolith simulant, before sieving the resulting granules into various particle sizes.
Initial testing showed that mixtures loaded with titanium were capable of creating coatings on existing parts of around 2mm, which were significantly thicker than the 200 μm overlays possible with pure regolith. The researchers also found that due to a “thermal mismatch” between the ceramic content of regolith and Ti64 powder, the higher the content of the former, the more cracks are likely to appear.
When it came to strength, the scientists discovered that the addition of simulated Martian dust to titanium allowed it to be 3D printed into structures with twice the microhardness. This, the team believes, is a consequence of the rapid solidification and formation of fine grain microstructures observed in their material upon deposition, as well as cyclic heat accumulation and regolith’s ceramic content.
Moving forwards, Bandyopadhyay says he and his colleagues intend to continue their National Science Foundation (NSF)-backed research into the development of regolith composites. Through experimenting with different metals and 3D printing processes, the scientists ultimately aim to come up with materials suited to the production of lightweight load-bearing parts for in-space applications.
“It [the WSU composite] gives you a better, higher strength and hardness material, so that it can perform significantly better in some applications,” concluded Bandyopadhyay. “This establishes that it is possible, and maybe we should think in this direction because it’s not just making plastic parts which are weak, but metal-ceramic composite parts which are strong and can be used for any kind of structural parts.”
Establishing regolith’s 3D printability
With humankind not having been to the Moon since 1972, the potential of 3D printing regolith on another celestial body remains hypothetical, but there is a fair amount of research being conducted into its feasibility. As part of a project unveiled last year, Redwire’s Regolith Print platform has been installed on the International Space Station, where it’s being used to test 3D printing’s lunar construction capabilities.
At the Technical University of Braunschweig and Laser Zentrum Hannover, meanwhile, scientists have 3D printed lunar regolith under zero gravity for the first time. Through their experimental project, codenamed ‘MOONRISE,’ the team has already managed to mount a custom laser to a lunar rover, and melt moondust into spherical shapes.
Elsewhere, Texan construction firm ICON has been subcontracted to build a 3D printed NASA simulated Martian habitat. Developed for long-term mission simulations at NASA’s Johnson Space Center, the 1,700 sq. ft structure’s unveiling closely followed that of a 3D printed lunar launch and landing pad the firm built using materials found only on the Moon, the year before in 2020.
The researchers’ findings are detailed in their paper titled “Martian regolith—Ti6Al4V composites via additive manufacturing,” which was co-authored by Ali Afrouzian, Kellen D. Traxel and Amit Bandyopadhyay.
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Featured image shows the planet Mars. Image via WSU.