Washington State University

When future astronauts get to the moon

, they may find that all the materials they need to fabricate new parts and fix broken ones are are right beneath their feet. That could be a huge boon to future missions, especially those of long duration, where the ability to take advantage of the materials in space could be the difference between success and failure.

So far astronauts have spent no more than three days at a time on the moon. But even in that short span they found that equipment tended to break down as the sandpaper-like lunar soil, or regolith, quickly coated everything. (Apollo 17 astronauts had to fashion a spare fender for their rover using a map and duct tape.) But researchers led by Washington State University mechanical engineering professor Amit Bandyopadhyay have shown that future moon explorers might be able to fabricate new parts simply by pouring that regolith into the hopper of a 3D printer. The astronauts would then load a computer-aided design (CAD) file of the part that needs replacing and press the start button. "The main idea is simple," Bandyopadhyay tells PM, "you just scoop up some material and put it there . . . (and) use it to print, to make something."

Taking 3D printers into space is a compelling idea. Computer simulations at NASA's Johnson Space Center found that 5 percent of parts aboard the International Space Station will, at some point, break down. The trouble is that mission planners have no way of predicting in advance which 5 percent of the thousands of parts will fail. For long-duration lunar missions, a similar predicted failure rate could require astronauts to bring along lots of parts in case of emergency, but those extra parts would take up valuable space and add to the cost of the mission, where every pound brought up from Earth comes at a premium. Taking along a 3D printer and CAD files of the spacecraft components could be a cheap, space-saving solution.

Researchers such as those as a startup called Made in Space have already begun testing 3D printers in microgravity environments. Bandyopadhyay's WSU project, however, is the first to test whether a future mission could also leave the 3D-printer feedstock at home and use material from the moon.

For their experiments, Bandyopadhyay and his colleagues called upon NASA's Kennedy Space Center and got some lunar regolith simulant. The simulant is engineered from terrestrial rock to have as many of the chemical and mechanical properties of actual lunar soil as possible. The WSU team screen sifted the material through mesh to obtain a fine powder, then fed the regolith simulant directly into their lab's Optomec LENS 750.

This printer uses a laser to melt metal powders and deposit the resulting molten material into the layers needed to build up a part. In this case, however, Bandyopadhyay wanted to find out whether the printer would work with ordinary, unprocessed regolith. If so, it would mean prospective lunar missions wouldn't need to carry expensive-to-lift refining equipment. "People do mix binders, people do mix metals, but for us, it's just as is," Bandyopadhyay says. "You pick up the material as is, and [see:] Can you make something out of it?"

The researchers created relatively simple parts in this trial, but they say that might be good enough to do the job of filling in for a replacement part manufactured on Earth, or joining together pieces of a broken part. Even improvised parts could be enough to keep astronauts alive, as Apollo 13 astronauts demonstrated after they duct taped together materials scrounged from their spacecraft to make an adaptor for their CO 2 scrubbers.

The printer the WSU team used likely wouldn't make it to the moon. It's a refrigerator-size behemoth meant for terrestrial industrial applications. But a smaller version could potentially fit aboard a moon-bound spacecraft. Up next for the team: experiments with simulated Martian soil.

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