Key Takeaways
- Helium-3 from the Sun is found on the Moon.
- Interlune is developing a method to simulate solar wind.
- The company aims to test lunar mining technologies.
- Helium-3 has potential uses in energy and medical fields.
Helium-3 and the Moon
The Sun generates helium-3 as part of its nuclear fusion processes. Some of this isotope escapes into space as part of the solar wind, a stream of charged particles that travels throughout the Solar System. Over billions of years, this solar wind has impacted celestial bodies, including the Moon, which lacks a protective atmosphere or magnetic field.
As a result, helium-3 has been continuously deposited on the Moon’s surface, or regolith. While the concentration of helium-3 is relatively low—about 10 to 20 parts per billion in certain titanium-rich soils—it is still significantly higher than on Earth, which is largely shielded from the solar wind.
Mining Potential
The presence of helium-3 has intrigued scientists and engineers for years, particularly for its potential in energy production through fusion reactions. In the short term, helium-3 can be used for cooling materials to ultra-low temperatures, medical research, and neutron detection. This makes it one of the few materials on the Moon that could be mined profitably and returned to Earth.
Several companies, including Seattle’s Interlune, are exploring the feasibility of mining helium-3. However, before any large-scale extraction can occur, practical experiments need to be conducted to assess the viability of such operations.
Challenges in Experimentation
Obtaining lunar regolith for testing poses a challenge. The Johnson Space Center, which holds a limited supply of lunar material collected during the Apollo missions, is unlikely to provide enough for commercial experiments. Additionally, most lunar simulants available do not accurately replicate the chemical composition of actual lunar soil.
Rob Meyerson, CEO of Interlune, highlighted the scarcity of lunar materials for study, stating, “We have had very little operating time on the Moon. We have very little material to study. We have very little data.”
Innovative Simulations
To overcome these challenges, Interlune’s scientific team, led by planetary scientist Elizabeth Frank, devised a novel approach. They used a vacuum chamber to accelerate ionized helium into lunar regolith, effectively simulating the solar wind. In just four hours, they implanted the equivalent of 15,000 years of solar wind exposure into the lunar material.
After this process, the team heated the regolith to observe how the minerals decomposed, a method known as pyrolysis. The helium released during this heating matched the temperatures at which helium-3 is known to be released from lunar rocks returned by Apollo astronauts, indicating that the simulant closely mimicked actual lunar conditions.
Interlune plans to utilize this new simulant to test the hardware it is developing for helium-3 extraction and will also offer it to other companies interested in lunar mining. As they prepare for a prototype mission later this decade, the goal is to conduct tests on Earth that replicate lunar conditions.
Meyerson emphasized the importance of accurate simulations, stating, “Similitude is a discipline. You simulate the gravity, and in the past we’ve flown in a parabolic airplane to simulate one-sixth gravity, and you want to test in a vacuum because regolith flows differently in a vacuum than it does in an atmosphere. And now we can match the simulant as well.”
