China Proposes Magnetic Launch System to Send Resources Back to Earth

The Earth rising above the surface of the Moon as seen from the Apollo 8 spacecraft.

In his famous novel The Moon Is a Harsh Mistress, Robert Heinlein describes a future lunar settlement in which future lunar inhabitants (“Mooners”) send payloads of wheat and water ice to Earth using an electromagnetic catapult. In the story, a group of Mooners plot to seize control of the catapult and threaten to “pelt Earth with stones” unless it recognizes the Moon as an independent world. Interestingly, scientists have been exploring this concept for decades as a means of transferring lunar resources to Earth.

With space agencies planning missions to the moon to create permanent infrastructure, there has been renewed interest in the concept. In a recent paper, a team of scientists from China Shanghai Institute of Satellite Engineering (SAST) has detailed how a magnetic launch vehicle on the lunar surface could be a cost-effective means of delivering resources to Earth. The proposal could be part of China's long-term vision for a lunar settlement known as International Lunar Research Station (ILRS) is a joint project with the Russian Space Agency (Roscosmos).

According to a recent article in South China Morning Postthe catapult would use magnetic levitation (maglev) technology and operate on the same principle as the hammer throw in track and field, “but spinning at increasing speed before throwing the launch vehicle toward Earth.” On the lunar surface, the near-vacuum environment and low gravity—approximately 16.5 percent of Earth’s (0.165 g)—would facilitate the ejection of the payload. According to the SAST team, the proposed system could perform two launches per day at one-tenth the cost of existing transportation methods.

ILRS visualization from CNSA's Partnership Guide (June 2021).

As noted, the concept of a magnetic catapult on the Moon is a time-tested idea. Previous versions of the concept include slingatronproposed in 1998 by renowned physicist Derek A. Tiedman, which envisioned using a circular magnetic accelerator rather than a rotating arm. A similar launch system proposed by a Chinese research team would consist of a 50-metre rotating boom and a high-temperature superconducting motor. It would be powered by solar panels and a nuclear reactor, and would be designed to convert kinetic energy into electricity during the deceleration phase. This would allow it to recover more than 70% of the energy consumed after each launch.

After a 10-minute boost, the robotic arm will reach an escape velocity of 2.4 km/s (1.5 m/s) on the Moon and place the payload on a trajectory toward Earth. The team also emphasizes that the primary payload will be helium-3 collected from lunar soil, which can be used to power fusion reactors on Earth. “The technical readiness of the system is relatively high,” they write. “Since it only consumes electricity and does not require fuel, its scale is relatively small and implementation is simple. The main objective is to extract and return helium-3 to solve the energy crisis on Earth. The project will also contribute to the development of space mining technologies, heavy launch vehicles, and artificial intelligence.”

While only 0.5 tons of the element are found on Earth, the lunar regolith contains about 1 million tons. According to the team’s paper, 20 tons would be enough to meet China’s annual energy needs, and 1 million tons would be enough to meet the world’s energy needs for more than a thousand years. They estimate that the system would weigh about 80 tons and would be able to remain operational for at least 20 years.

However, construction of the system will have to wait until China completes development of its Long March 9 (CZ-9) and Long March 10 (CZ-10) super-heavy launch vehicles. These rockets are needed to build the ILRS, which is scheduled to be completed by 2035 with the help of other national space agencies. As such, the proposed launch system could become part of China’s long-term lunar exploration plans in the late 2030s or 2040s. The team’s proposed timeline is consistent with this: They hope to complete development of key components of the system by 2030 and anticipate full-scale deployment by 2045.

Hyper V Technologies Corp.'s Slingatron launch system concept, which would be a 200-300 meter wide rail track into space.

Naturally, as with other proposals to build and explore the moon, there is the question of cost. According to the research group, the cost of building a launch system would be about $18.25 billion. However, at a meeting of the China Association for Science and Technology (CAST) last year, group member Chu Yingzhi said that extracting three to five tons of helium-3 per year could generate revenues of 100 billion yuan. In order to build such a system, many technical and logistical problems would need to be solved.

For starters, the research team’s paper doesn’t address how helium-3 would be mined from the local regolith. As Chu noted, there would also be the need to install the system on the rugged lunar surface, ensure the rotating arm is stable at high speeds, and ensure it can operate in the lunar environment, which is subject to extreme temperature fluctuations, cosmic rays, and elevated solar radiation. But in the long term, a magnetic launch system is an elegant proposal and a relatively cost-effective alternative to launching spacecraft from the surface of Earth.