What is helium-3?
"The Moon''s regolith contains vast resources of helium-3, an ideal fuel for terrestrial fusion power systems. Development of plans for private sector investment in obtaining helium-3 and its by-products requires detailed definition of that isotope''s selenographic distribution."
https://solarsystem.nasa.gov/studies/191/lunar-helium-3-fusion-resource-distribution/
"In 1986, scientists at the Institute of Fusion Technology at the University of Wisconsin estimated that the lunar “soil”, called the regolith, contains one million tons of helium-3 (3He), a material that could be used as fuel to produce energy by nuclear fusion. According to the study, mining it would be a profitable undertaking: the energy produced by the helium-3 would be 250 times greater than that needed to extract this resource from the Moon and transport it to Earth, where the lunar reserves of helium-3 could supply human needs for centuries"
https://www.bbvaopenmind.com/en/science/physics/helium-3-lunar-gold-fever/
"Asia Times tells us that there is a “secret mining war” taking place in space over helium-3, a version of helium which is surprisingly abundant on the Moon. Helium-3 is an isotope of helium with two protons and one neutron. The far more prevalent arrangement is helium-4, two protons and two neutrons"
https://www.resilience.org/stories/2021-11-14/another-extraordinary-delusion-mining-helium-from-the-moon/
"With fossil fuels running out and global energy demand increasing, the need for alternative energy sources is apparent. Nuclear fusion using Helium-3 may be a solution. Helium-3 is a rare isotope on Earth, but it is abundant on the Moon. Throughout the space community lunar Helium-3 is often cited as a major reason to return to the Moon. Despite the potential of lunar Helium-3 mining, little research has been conducted on a full end-to-end mission"
https://ui.adsabs.harvard.edu/abs/2014cosp...40E1515K/abstract
"China is now leading the world into an industrial and scientific revolution, the sheer scale of which will of necessity soon require an entirely new form of energy, never before mastered on Earth: controlled thermonuclear fusion power, using helium-3 (He-3) as its fuel. The He-3 isotope is extremely rare on Earth, but exists in abundance on the Moon, and the Chinese leadership has already begun an ambitious program to acquire it"
http://www.spacesafetymagazine.com/space-on-earth/everyday-life/china-helium-3-program/
"The unique atomic structure of helium-3 promised to make it possible to use it as fuel for nuclear fusion, the process that powers the sun, to generate vast amounts of electrical power without creating the troublesome radioactive byproducts produced in conventional nuclear reactors. Extracting helium-3 from the moon and returning it to Earth would, of course, be difficult, but the potential rewards would be staggering for those who embarked upon this venture. Helium-3 could help free the United States--and the world--from dependence on fossil fuels."
https://www.popularmechanics.com/space/moon-mars/a235/1283056/
"Work is in progress to build equipment that can demonstrate the extraction of helium-3 (3He)--helium with two protons and one neutron--and other volatiles from the moon’s resource-rich soil known as regolith."
https://www.nasa.gov/feature/harnessing-power-from-the-moon
"According to a paper published by Jeff Bonde and Anthony Tortorello, helium-3 is an isotope that has been deposited in lunar soil over billions of years by solar wind. Roughly 1.1 million metric tons of the isotope exists on the Moon down to a depth of several meters. Twenty-five metric tons of helium-3, about a quarter of the cargo capacity of a SpaceX Starship, would suffice to fuel all the power needs of the United States for a year."
https://thehill.com/opinion/technology/540856-solving-the-climate-and-energy-crises-mine-the-moons-helium-3
Helium-3 mining on the lunar surface
https://www.esa.int/Enabling_Support/Preparing_for_the_Future/Space_for_Earth/Energy/Helium-3_mining_on_the_lunar_surface