The Magical Helium on the Moon

From The Magic School Bus (1994-1997) episodes about Ms. Frizzle exploring the Moon with her class to infamous movies like Interstellar (2014), space exploration has clutched our imagination because of an innate curiosity to understand the unknown. But now, instead of exploring space for political reasons—such as how the Cold War influenced the Apollo missions—or for experimentation, the added exploration of space to efficiently mine the Moon prompts the question of how far we should continue with human colonization of space. Despite the technological issues surrounding moon mining, the potential economic benefits of moon mining outweigh these drawbacks.

Currently, the world depends largely on fossil fuels for energy. One of the most efficient alternatives is nuclear energy, as it has a 92.5 percent capacity factor, which means it can operate consistently at full power over a given amount of time. Its shortcomings are the small amount of radioactive waste it produces—around five grams per person—and the less than one percent usable uranium for nuclear energy. Nuclear energy requires a specific isotope called uranium-235, which is limited on Earth. The uranium is hit by a neutron, causing it to split into two smaller nuclei, which then continue to hit other uranium atoms. This creates a domino effect that generates multiple nuclei in a fraction of a second. Each time the reaction happens, there is a release of heat that will later be converted to electricity. 

As a result, a frequently cited reason for returning to the Moon is harvesting helium-3 for Earth’s benefit. It is non-radioactive, would not produce waste products if it is harvested for nuclear energy, and is 70 percent efficient because it can generate immense electrical power for a unit of thermal power. However, it is a rare isotope to find on Earth because the Earth’s magnetic field protects it from being bombarded with solar wind, unlike on the Moon. In fact, it is estimated that the Moon holds at least one million tons of helium-3, and therefore this substance has captured the imagination of scientists and startups alike to bring mined helium-3 to Earth for use in nuclear energy.

One practical method for mining helium-3 is using extractors to scoop up regolith on the Moon’s surface; sieve out the rocks and particles by shaking them; and use an oven and cooling methods to separate the helium-3. This method is a favorite among some researchers and is easily implementable. For instance, the Mark II miner was created in the early 1990s for this method, later being refined to create the Mark III with half the mass and only 350 kW of electrical power required to support it. 

From a technological perspective, these designs to harvest helium-3 likely will not fulfill global economic needs, but technologies can be developed over a reasonable time period to be commercially viable. For instance, to supply 10 percent of the global energy demand in 2040, we’d need to mine 630 tons of regolith per second, annually. However, to meet the energy needs of the U.S. for a year, we’d need 44 tons of helium-3, with the generated electricity valued at $3.7 billion. Whether nuclear energy from helium-3 becomes a reality for the U.S. may depend on technological advancement and public perception of whether it is worth the risk to mine and transport helium-3.

Through the Artemis mission, NASA plans to innovate technologies to create a lunar colony. It certainly would not be a stretch to imagine that we could develop sufficient technology to mine enough helium-3 for viability, especially if helium-3 is used for nuclear energy in said lunar colony. Once we can obtain enough helium-3 to experiment by developing these mining and transportation processes, there will likely be greater efforts to create a fusion reactor with helium-3 as the fuel source, considering its potential demand.

However, the most interesting technological aspect of utilizing helium-3 on Earth is transportation. One proposed method by Princeton Satellite Systems is the use of aerodynamic braking to bring helium-3 to low Earth orbit; retrieve it using another spacecraft; and bring it to any location. In other words, the payload would enter Earth’s atmosphere at high speeds through an entry vehicle and then slow into a low Earth orbit through friction and other aerodynamic forces.

However, there is no way to discuss moon mining without bringing up ethics. Space archaeologist Alice Gorman raises valid concerns about moon ownership, as the Moon is “important for the environments in which we live and for our cultural and scientific worldviews. It really does not belong to anyone.” Although global cooperation will dictate responsible management of lunar resources, moon mining provides us with an opportunity to advance clean energy and foster economic growth through this possibly better source of energy. It likely will not be in the present due to underdeveloped technology and lack of case studies, but as humans inevitably march on to the next frontier, they will be able to efficiently extract and transport helium-3 to Earth.