Realistically, in-situ resource utilization seems like the only way of sustaining human presence outside of low Earth orbit. This is certainly the case for Mars, and it’s likely also the case for the Moon—even though the Moon is not all that far away (in the context of the solar system). It’s stupendously inefficient to send stuff there, especially when that stuff is, with a little bit of effort, available on the Moon already.
A mix of dust, rocks, and significant concentrations of water ice can be found inside permanently shaded lunar craters at the Moon’s south pole. If that water ice can be extracted, it can be turned into breathable oxygen, rocket fuel, or water for thirsty astronauts. The extraction and purification of this dirty lunar ice is not an easy problem, and NASA is interested in creative solutions that can scale. The agency has launched a competition to solve this lunar ice mining challenge, and one of competitors thinks they can do it with a big robot, some powerful vacuums, and a rocket engine used like a drilling system. (It’s what they call, brace yourself, their Resource Ore Concentrator using Kinetic Energy Targeted Mining—ROCKET M.)
This method disrupts lunar soil with a series of rocket plumes that fluidize ice regolith by exposing it to direct convective heating. It utilizes a 100 lbf rocket engine under a pressurized dome to enable deep cratering more than 2 meters below the lunar surface. During this process, ejecta from multiple rocket firings blasts up into the dome and gets funneled through a vacuum-like system that separates ice particles from the remaining dust and transports it into storage containers.
Unlike traditional mechanical excavators, the rocket mining approach would allow us to access frozen volatiles around boulders, breccia, basalt, and other obstacles. And most importantly, it’s scalable and cost effective. Our system doesn’t require heavy machinery or ongoing maintenance. The stored water can be electrolyzed as needed into oxygen and hydrogen utilizing solar energy to continue powering the rocket engine for more than 5 years of water excavation! This system would also allow us to rapidly excavate desiccated regolith layers that can be collected and used to develop additively manufactured structures.
Despite the horrific backronym (it couldn’t be a space mission without one, right?) the solid team behind this rocket mining system makes me think that it’s not quite as crazy as it sounds. Masten has built a variety of operational rocket systems, and is developing some creative and useful ideas with NASA funding like rockets that can build their own landing pads as they land. Honeybee Robotics has developed hardware for a variety of missions, including Mars missions. And Lunar Outpost were some of the folks behind the MOXIE system on the Perseverance Mars rover.
It’s a little bit tricky to get a sense of how well a concept like this might work. The concept video looks pretty awesome, but there’s certainly a lot of work that needs to be done to prove the rocket mining system out, especially once you get past the component level. It’s good to see that some testing has already been done on Earth to characterize how rocket plumes interact with a simulated icy lunar surface, but managing all the extra dust and rocks that will get blasted up along with the ice particles could be the biggest challenge here, especially for a system that has to excavate a lot of this stuff over a long period of time.
Fortunately, this is all part of what NASA will be evaluating through its Break the Ice Challenge. The Challenge is currently in Phase 1, and while I can’t find any information on Phase 2, the fact that there’s a Phase 1 does imply that the winning team (or teams) might have the opportunity to further prove out their concept in additional challenge phases. The Phase 1 winners are scheduled to be announced on August 13.