Could shooting arcs of "lightning" across the surface of the moon allow us to mine metal and water from the lunar surface at the same time?
For years, the concept of "lunar mining" has intrigued scientists, space agencies and entrepreneurs alike. Our rocky satellite houses precious resources like water and metals that could be critical for future crewed missions, providing water, which could be turned into rocket fuel, and other valuable materials. Scientists are also keen to study these resources and the commercial sector has shown interest in lunar mining as well. The U.S. government even green-lit a policy supporting lunar mining in 2020.
One new technique called "ablative arc mining," which is part of a project led by Amelia Greig, an assistant professor of mechanical engineering at the Aerospace Center at the University of Texas in El Paso, would allow for water, metals and other resources to all be pulled from the lunar surface material all at once, improving upon older lunar mining concepts and methods.
The technique would use an arc of electricity, Greig told Space.com, and would be "like putting lightning over the surface of the moon."
This technique was recently chosen as part of the Phase I Fellows program for NASA's Institute for Advanced Concept (NIAC), a program that "nurtures visionary ideas that could transform future NASA missions with the creation of breakthroughs — radically better or entirely new aerospace concepts — while engaging America's innovators and entrepreneurs as partners in the journey," according to the agency.
In the technique, arcs of electric current across two electrodes would sublimate frozen water out of the lunar regolith, or surface material, turning it into water vapor. It would also pull other things like metals out of the lunar material. The electric arc would then break apart the water (or other materials like metals) into ionized particles.
Then, electric fields guide those ionized particles into capture chambers. So the technique would, in one fell swoop, suck resources out of the lunar regolith and collect them for later use.
With the NIAC program, Greig and her team will home in on this concept, test it in a laboratory setting and work on a technological system based on the concept that could mine and collect about 22,000 lbs. (10,000 kilograms) of water per year, among other resources.
Previous lunar mining concepts have used "thermal ablation," which heats water frozen into the lunar regolith, pulling it out as water vapor that can then be captured. However, with an atmosphere as thin as that of the moon, "the water vapor just sort of diffuses in all directions, and you can't really tell it which way to go," Greig told Space.com. Thermal ablation also doesn't allow for multiple types of resources to be extracted all at once, like ablative arc mining does.
But if you ionize this water using the electrical arc, Greig explained, "you can push them [the particles] exactly where you want them to go. You're kind of funneling them through these virtual electric magnetic fields into a small collection area, and you can collect a lot more of the water that you can extract from the moon."
The main challenge in ablative arc mining is that it takes quite a lot of power to create an electrical arc in the moon's barely-there atmosphere.
Another challenge is in creating a robotic system that might be able to work autonomously, Barry W. Finger, chief engineer at aerospace company Paragon, who is not involved in this project or research, told Space.com about the general prospect of lunar mining. This is "because there's going to be a while when we get a significant number of people doing, essentially, labor on the lunar surface," he added.
While Greig and her team work to test this concept in a lab and eventually design a prototype to test for actual use in space, conversations here on Earth continue about not just how we could use resources on places like the moon and Mars, but how we should use those resources.
"At least within the community that I'm a part of," Greig said, "we are looking at mining the moon, not necessarily for commercial interest, but to help with having human lunar settlements in the future."
Greig went on to add that it could "be impossible to have lunar settlements," without being able to collect lunar water and other resources. "And because the moon is such an important gateway step to get to Mars, we would probably then struggle to have human settlements on Mars in the future."
Still, many are concerned that in taking resources from off-Earth destinations like the moon, our species is plundering and polluting even more worlds than our own. This is why the 1967 Outer Space Treaty, which continues to evolve, helps to guide space agencies and companies in how to use space resources.
"You can look around on the Earth where we have not done a great job being stewards of our own planet," Finger said. However, he added, the moon has been bombarded with radiation and impacts for so long and isso inhospitable to life that arguments to say that we shouldn't treat the moon like we have treated Earth don't hold much weight for him. "I don't see that being a problem any time in the near future."
Email Chelsea Gohd at firstname.lastname@example.org or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.