Among the reasons why the United States, Japan, the EU, Russia and China want to build a base on the surface of the moon is to mine helium-3 which is seen as a sustainable energy source of the future. It is estimated that there is enough helium-3 on the moon's surface to power the earth for 1000 years. So one of the issues that needs to be resolved after it is mined is how will it be sent back to earth?
The Shanghai Institute of Satellite Engineering published a paper proposing using a Thor-like system to deliver cargo back to earth. There is a rotating arm that will accelerate the cargo to a velocity so that it is free from the pull of the moon's gravity. This system is said to be more affordable than using rockets because it only requires electricity generated using solar. After the cargo is thrown to earth, up to 70% of the energy can be recovered through the regenerative braking system.
According to the researchers, the system can be built by 2030 and begin testing on the lunar surface by 2045. The current issue is the high cost and China still does not have a rocket that can carry the heavy components of this system to the lunar surface.
The idea of using kinetic propulsion to launch objects into space is not a new idea. SpinLaunch announced in 2021 wants to launch satellites of up to 200kg into orbit using the same concept that got NASA's attention.