The University Network

Mining The Moon For Water To Generate Rocket Fuel

Imagine if the moon could generate all of the fuel for future space exploration. Well, that is part of the plan to mine the moon for water, a new mission for Dr. Philip (Phil) Metzger, planetary scientist with the Florida Space Institute (FSI) at the University of Central Florida, and Julie Brisset, research associate with FSI.

Their new contract with United Launch Alliance (ULA) calls for them to develop a viable method for extracting water from the depths of the moon cheaply and efficiently.

ULA is a joint venture between Lockheed Martin and The Boeing Company that was formed in 2006 for the purpose of providing reliable and cost-efficient space launch services for NASA and other U.S. governmental agencies.

The project will be led by Metzger, who worked at Kennedy Space Center for nearly three decades and co-founded the KSC Swamp Works — a hands-on lab that accelerates innovation to benefit NASA and the Earth — before joining UCF.

The presence of water on the moon both near the moon’s pole and on the surface of the moon is supported by data from various space missions.

 

Why mine the moon for water?

The ability to mine lunar bodies of water would advance ULA’s goal, as water could be broken down into hydrogen and oxygen to generate rocket fuel in space. The ability to refuel in space opens the door to more launch possibilities and lower transportation costs throughout lunar space and beyond.

The mined water could be used for other purposes as well, including life support systems, radiation shielding and drinking water for space explorers.

It could also help ULA fulfill its vision of a self-sustaining space economy in CisLunar, the space between the Earth and the moon.

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“It is vital for humanity to get beyond the limits of this single planet,” said Metzger. “Our civilization has grown so much that we are over-stressing the planet, driving species to extinction, polluting the atmosphere and the ocean, and using up the best resources that developing nations would need to get to a better standard of living. We know how to put industry in space to address these global challenges, and mining water on the Moon is an economically viable first step. I am excited about lunar mining not just because it will make space exploration more affordable and produce better science in the solar system, but because it is on the critical path toward becoming a solar system species and solving the problems on planet Earth.”

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Proposed technique for mining water

Up until now, researchers seeking to mine the moon for water have focused on finding ways to collect the regolith of the moon, which has water locked in frigid ice chunks, and then transport it to processing plants on the moon. The regolith is the layer of unconsolidated rocky material covering the bedrock.

The multi-step approach, however, would require large equipment to remove the ice chunks and haul them to processing plants.

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“When you talk about getting things into space, weight matters,” Metzger said in a statement. “So we are looking at a technique that would require less stuff you have to transport which still gets the job done.”

The proposed technique is to extract the water in situ, which would obviate the need for heavy construction equipment and remove the extra step of hauling the soil. It would involve drilling holes into the depths of the moon, pumping heat through the holes to heat the regolith, and collecting the released water vapor through pipes in the holes.

Metzger came up with the idea of vaporizing the water in-place because of the common technique of using phase change of the ore — melting or vaporizing it — in mining and refining here on Earth, he said.

“In space it is different because the entire Moon is in a hard vacuum, so instead of melting the ice will vaporize directly into steam,” said Metzger. “Years ago I did some computer modeling to see if the energy requirements were reasonable, and I concluded that they are. However, I never had a chance to work on it again. More recently, George Sowers (formerly chief engineer at the United Launch Alliance, or ULA, now with the Colorado School of Mines) came up with this idea on his own and asked me to help investigate it. ULA wants to be the customer of a lunar mining operation, so it is looking for ways that another company could operate less expensively. Vaporizing the water in-place seems to require less equipment than any other method, so it may produce the most affordable in-space water.”

The technique could be used to mine water at different depths, but the optimum depth is a matter of cost-benefit analysis.

“We know from NASA’s LCROSS mission, where they impacted a spacecraft into a dark crater at the Moon’s south pole, that the lunar water is mixed in the soil from the surface down to a depth of 2 or 3 meters or even deeper,” said Metzger. “We can mine as shallow as we like, so it is a tradeoff of using more equipment and energy to mine deeper or moving your equipment more often to stay more shallow. Every time you start to mine a location, you heat the soil in that area. That represents an investment in energy that you don’t want to casually walk away from. So if you can keep getting water more deeply from that same location, then you have an incentive to keep doing so. Ultimately we will not know the answer to this question until after we do the research. We will study how efficient it is to mine at varying depths.”

Viability of Proposed Technique

Metzger and Brisset have to determine if their technique is realistic and cost-effective. Brisset, who has multiple degrees in mechanical and space engineering and in physics, will develop the algorithms to run the computer simulations that they hope will lead to a viable model.

While heating the regolith is possible according to data they possess, they need “to figure out the right geometric configuration of the holes to increase the area that is heated,” Brisset said in a statement.

Otherwise, most of the heat would dissipate, and be wasted.

“If we do it right, we should be able to increase the area and the time it stays warm,” she added. “We will be doing a lot of modeling.”

Metzger believes that he and his team could build the necessary hardware to implement the technique within three years if NASA wanted it within that time frame and made funding available.

“There would still be significant risk that it might not work, though, because we lack enough information about the state of the soil and ice in those dark lunar craters,” he said. “So if we built this system and sent it there, it might have less than 50% chance of producing as much water as we hope.”

For a more certain outcome, Metzger would prefer to get more information on the state of the soil first.

“So a smarter approach is to do some prospecting first,” he said. “Send a rover to drive around, measuring the soil properties and the distribution of the ice. NASA has been developing such a mission, the Resource Prospector Mission, which will go to the Moon around 2022. That mission will not go into the deepest craters where the most water is, because it would be a more challenging mission without solar energy, without direct line-of-sight communications back to Earth, and with the extreme temperatures and access requirements. Nevertheless we should do prospecting in the crater. After we know the state of the soil, it will then take only 2 or 3 years to build the hardware and send it to begin mining, if there is adequate startup funding.”

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Susan Chu is a writer and editor who likes to write about trends in higher education.