Lunar railway from Darpa and Northrop Grumman could do heavy lifting for commercial Moon operations

For three years, those dreams were sustained by five further crewed landings. Then, in December 1972, humans left the surface and never came back.

More than half a century later, hopes for a lasting human presence on the Moon are being revived. Astronauts could return to the lunar surface in NASA's Artemis III mission in 2026, while Darpa (the US Defence Advanced Research Projects Agency) hopes to develop infrastructure for a "thriving lunar economy" based around mining valuable resources.

New Lunar Terrain Vehicles (LTV) could take astronauts further than ever before, but the logistics of commercial operations, habitation, power and communication will require a lot more heavy lifting.

"Starship may soon be able to deliver anywhere from 10 to 100 tons to the surface of the Moon in one drop," says Michael Nayak, manager of Darpa's 10-year Lunar Architecture (LunA-10) programme.

"How would that large amount of mass be distributed from the point of delivery to the point of need? It would take a hundred LTV-class rovers to distribute that amount of mass. And that's just one Starship landing. What happens when there are dozens of landings? A railway on the Moon could help solve this logistical challenge."

Enter the lunar railway from US aerospace and defence firm Northrop Grumman, one of 14 companies selected to support LunA-10's ambitious aims.

'Next stop, Sea of Tranquillity'

Designed to transport people, supplies and resources across the surface, Northrop Grumman's concept "filled a gap we believe had not been fully addressed," says Nayak.

The study will explore designs and architecture for a "fully operating lunar rail system", which would be built and controlled by robots. Tasks for those machines would include surface grading and foundation preparation, track placement and alignment, joining and finishing, inspection, maintenance, and repair.

According to an article on Northrop Grumman's Now site, the railway could provide access to remote areas, such as "permanently shadowed regions in the South Pole region that may contain valuable deposits of water ice and hydrocarbons". The railway could transport those resources to lunar bases, with more capacity and higher speeds than LTVs.  

The Moon itself could provide resources for the project, with valuable metals and materials available in the soil, but extracting and using them will be far from easy. Unprotected by an atmosphere, machinery faces intense heat from the Sun on one side and cryogenic freezing on the other. Charged dust particles are as abrasive as sandpaper, while larger high-velocity particles, 'moonquakes' and solar winds also threaten to cause damage.

Mining the Moon

Darpa believes the lunar railway could support a future commercial lunar economy, but there are "three big challenges" to success, according to Nayak: separating "technology for technology's sake" from technologies that could enable "rapid economic scaling"; collaboration between companies working with their own intellectual property; and developing the 'anchor tenant' for a system.

"Most commercial services, like power, communications, and position, navigation and timing (PNT), are support services. But in support of what? At the moment, the anchor tenant for the Moon appears to be in-situ resource utilisation (ISRU), mining either oxygen, water, or helium-3 from the Moon," says Nayak.

"Currently, reserves of these resources are scarcely known. We need to expand our knowledge of the resources on and in the subsurface of the Moon, in order to develop more cogent economic cases for funding the foundational lunar economy. This remains a key challenge, but one that increasing private investment in the Moon can help to solve."

The railway will "not come about overnight", he adds, and will be at least a decade in the making. Combined with the other LunA-10 projects, which involve companies such as SpaceX and Blue Origin, he hopes it could spur "widespread commercial activity" on and around the Moon.

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