Perhaps the most familiar use of helium is as a safe, non-flammable gas to fill party and parade balloons. However, helium is a critical component in many fields, including scientific research, medical technology, high-tech manufacturing, space exploration, and national defense.

Helium-3 (3He, see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons.
The existence of helium-3 was first proposed in 1934 by the Australian nuclear physicist Mark Oliphant while he was working at the University of Cambridge Cavendish Laboratory. Oliphant had performed experiments in which fast deuterons collided with deuteron targets (incidentally, the first demonstration of nuclear fusion).

Helium-3 occurs as a primordial nuclide, escaping from Earth's crust into its atmosphere and into outer space over millions of years. It is also thought to be a natural nucleogenic and cosmogenic nuclide, one produced when lithium is bombarded by natural neutrons, which can be released by spontaneous fission and by nuclear reactions with cosmic rays. Some found in the terrestrial atmosphere is a remnant of atmospheric and underwater nuclear weapons testing.

Nuclear fusion using helium-3 has long been viewed as a desirable future energy source.
The fusion of two of its atoms would be aneutronic, not release the dangerous radiation of traditional fusion or require much higher temperatures.
The process may unavoidably create other reactions that themselves would cause the surrounding material to become radioactive.

The Helium-3 Shortage: Supply, Demand, and
Options for Congress
Dec, 22nd, 2010.

Helium-3 is thought to be more abundant on the Moon than on Earth, having been deposited in the upper layer of regolith by the solar wind over billions of years, though still lower in abundance than in the Solar System's gas giants.

Arguments have also been made for mining Helium-3 from Jupiter, where it is much more abundant – it would need to be given the distances involved. Extracting the molecule from Jupiter would also be a less power-hungry process.
...but Jupiter is not a good place to obtain it.
Jupiter has a lot of gravity and a powerful magnetosphere to contend with.
Escape velocity at Jupiter’s surface is 60 km/sec. No existing rocket can do it.

It may be possible with controlled fusion — and you only need helium-3 if you have controlled fusion, — but in that case atmosphere of Uranus is a much better bet. Escape velocity of only 22 km/sec, and the radiation belts you have to pass on the way out (also on the way in) are not nearly as murderous.

So let's mine it on the Moon

Who owns the moon owns the future

"Helium-3 on the moon is worth $4 billion per ton. It's the most valuable thing in space," Gerald Kulcinski, professor emeritus of nuclear engineering at the University of Wisconsin and former director of the Fusion Technology Institute, says.


https://www.wbur.org/onpoint/2023/09/25/moon-planets-space-travel-united-states-race

Harrison Schmitt, wearing the Apollo A7LB pressure suit and backpack, is shown sampling regolith in the Valley of Taurus-Littrow on December 14, 1972.

Of the 12 men who have walked on the moon, the last to set foot there, Harrison (Jack) Schmitt, is the only one with scientific training (he has a Ph.D. in geology). He has seen and done things most scientists only dream of. Schmitt's work on the Moon in 1972 ranks as one of the most exciting and productive episodes in history of exploration.

Schmitt became a consultant to the Fusion Technology Institute at the University of Wisconsin-Madison in 1986, advising on
the economic geology of lunar resources, eventually teaching in the course “Resources from Space” from 1996-2004. He
remains an Associate Fellow of Engineering at the University of Wisconsin.
During NASA’s Constellation Program, Harrison Schmitt became chairman of the NASA Advisory Council in November
2005 and served until October 2008. From 2017 to 2022 he has served as a member of the National Space Council’s User
Advisory Board.

Dr. Schmitt is a prolific writer, having been published in many diverse venues, including Science Magazine, Icraus, The Wall
Street Journal, and the National Geographic Magazine. In 2006, Springer published his book, “Return to the Moon,” outlining
a private sector approach to accessing lunar helium-3 for fusion power, medical diagnosis, and other applications. He also
electronically publishes an annotated and illustrated version of the voice transcript from the Apollo 17 mission.
Active in the private aerospace business sector, Schmitt was a Director of the Orbital ATK Corporation and its predecessor
company, Orbital Sciences Corporation (1983-2018). In 1990, he joined the Board of Directors of the Draper Laboratory, and,
as a retired Director, he continues as an Emeritus Member of the Corporation that oversees the Laboratory.
Dr. Schmitt continues to synthesize scientific data related to his exploration of Taurus-Littrow, including participation in
NASA’s “Apollo Next Generation Sample Analysis” (ANGSA) Program, as well as consulting with NASA and private
entities on issues involved with NASA’s Artemis Program to return to the Moon.

His book, "Return to the Moon" is a legal brief, in which Schmitt makes the case for returning to the Moon to mine the isotope helium-3. He claims that because fossil fuels are limited in supply and because their extraction and use harm the environment, our rapidly industrializing world requires new sources of energy. The ultimate solution, he suggests, is the generation of power by nuclear fusion—not of deuterium and tritium, as is usually proposed, but of deuterium and helium-3.


https://www.americanscientist.org/article/mining-the-moon

Part of the book "Return to the Moon" by Harrison Schmitt

https://download.e-bookshelf.de/download/0000/0010/42/L-G-0000001042-0002369223.pdf