Key facts
- The Sun produces helium-3, an isotope of helium, which is carried to the Moon via solar wind.
- The Moon's regolith contains higher concentrations of helium-3 than Earth, potentially 10-20 parts per billion.
- Helium-3 has potential future applications in energy, medical research, and neutron detection.
- Seattle-based company Interlune is investigating the feasibility of mining helium-3 from the lunar surface.
The Sun continuously emits solar wind, a stream of charged particles that includes the isotope helium-3. Over billions of years, this solar wind has bombarded the Moon's surface, embedding helium-3 into its soil, known as regolith. Unlike Earth, the Moon lacks a magnetic field and atmosphere, offering no protection from this constant flow. While concentrations are low, estimated at 10 to 20 parts per billion in certain titanium-rich soils, they are significantly higher than on Earth. Scientists and engineers, including geologist Harrison Schmitt, have long been fascinated by the potential of lunar helium-3, envisioning its use in fusion energy reactions. More immediate applications include cooling materials to ultra-low temperatures, medical research, and neutron detection. These potential uses make helium-3 one of the few lunar materials that could plausibly be mined and returned to Earth for profit. Consequently, companies like Seattle-based Interlune are investigating the practicalities of extracting helium-3 from the lunar regolith.