Two space firms have signed an agreement to start mining “commercial quantities” of helium-3 isotopes on the Moon and bring them back to Earth where there is an extreme supply shortage.

In a joint statement, Japanese firm ispace and Magna Petra said their mining activities would utilise “non-destructive” and “sustainable” techniques to harvest the resources from regolith (the layer of unconsolidated solid material covering the bedrock of a planet) on the lunar surface.

Helium-3 is a stable isotope of helium and is predominantly used for nuclear fusion reactions with deuterium (heavy hydrogen) to produce large amounts of energy. Because helium-3 is not radioactive, the fusion process doesn't produce nuclear waste or greenhouse gas emissions.

For many years, the supply of helium-3 from national nuclear weapons programs outstripped demand, but after the terrorist attacks of September 11 2001 the US government began deploying neutron detectors at the US border to help secure the nation...