Helium-3 (³He)
A light, non-radioactive isotope of helium with two protons and one neutron. It is incredibly rare on Earth, but the lunar surface has been soaking it up like a sponge for billions of years.
Earth Supply
~15 Tonnes
Moon Supply
~1.1 Million Tonnes
Est. Value
$3 Billion / Tonne
Primary Use
Nuclear Fusion
The Solar Wind Sponge
The Sun constantly emits Helium-3 via solar winds. On Earth, our magnetic field and thick atmosphere deflect this wind, preventing the isotope from reaching the ground. The Moon, however, has no magnetic field and no atmosphere.
For 4.5 billion years, the solar wind has bombarded the lunar surface, embedding Helium-3 directly into the top layer of the regolith (dust). To extract it, automated rovers would simply scrape the top few centimeters of soil and heat it to around 600°C, causing the gas to release.
The Holy Grail of Energy
Why do we want it? Current experimental fusion reactors on Earth use Deuterium and Tritium, which produces harmful, high-energy neutrons that degrade the reactor walls and create radioactive waste. A Deuterium + Helium-3 fusion reaction produces zero radioactive neutrons. It is 100% clean, highly efficient energy. Just 25 tonnes of Helium-3 could power the entire United States for a year.