Chinese Scientists Propose Magnetic Launcher on the Moon
Aug. 19—Several news agencies have reported on a new proposal from Chinese scientists to build a magnetic launcher on the Moon to deliver resources mined on the lunar surface to Earth.
“Scientists from the Shanghai Institute of Satellite Engineering suggest that the magnetic levitation installation will work on the same principle as the hammer throw in athletics, but the rotation at increasing speed will be carried out before a cargo capsule is sent to Earth,” reported Sputnik.
According to “Interesting Engineering”, “Leveraging the Moon’s high vacuum and low gravity, it could eject payloads twice daily at about 10% of current transport costs…. The proposed launch system would use a 50-meter (165 ft) rotating arm and a high-temperature superconducting motor to launch capsules filled with lunar resources.”
The primary resource that would be extracted and exported would most likely be helium-3, a rare, non-radioactive, non-toxic, and non-flammable isotope of helium; it is a resource that is constantly replenished, since it is deposited on the Moon by the solar wind. Its primary use would be in nuclear fusion reactions in combination with deuterium, providing clean and almost limitless energy.
Hong Kong daily South China Morning Post reports that the launch station would “cost around 130 billion yuan ($18.2 billion) to build.” But the benefits would be great: “The paper’s co-author Chu Yingzhi told last year’s meeting of the China Association for Science and Technology that mining three to five tonnes of helium-3 a year could bring in revenues of 100 billion yuan.”
“After 10 minutes, the rotating arm would reach the Moon’s escape velocity of 2.4km per second—about one-sixth of Earth’s escape velocity—to put it on the correct trajectory to return to Earth,” the article explains. “The system would be powered by solar and nuclear energy, with more than 70% of the energy recovered after each launch thanks to a design that would allow kinetic energy to be converted back to electricity during the deceleration phase after the launch.”
Another propellant-free launch mechanism considered over the years has been linear induction motors, using magnetism to accelerate an object. The U.S. and China have been working on these kinds of linear magnetic launchers for some time. Electromagnetic catapults are currently installed on the Gerald R. Ford-class aircraft carriers and the Chinese aircraft carrier Fujian.
The new launcher proposal appears to use magnetic bearings to reduce friction as an arm spins and spins before releasing the object, like twirling a rope with a stone at the end over your head before releasing it.
The principles of linear electromagnetic acceleration are demonstrated in this video and discussed in this article.