Study Finds the Moon's Water Isn't Enough for Lasting Cities

The discovery of water ice in permanently shadowed craters at the Moon's poles has fueled plans for lunar bases, villages and even cities, with entrepreneurs such as Jeff Bezos and Elon Musk imagining heavy industry and self-growing settlements there. A new feasibility study in Frontiers in Space Technologies asks a basic question: is any of this sustainable?

Near the lunar poles, dozens of crater floors have not seen direct sunlight in about 4 billion years, staying colder than 110 Kelvin. These permanently shadowed spots — cold traps — keep water ice from evaporating by more than a millimetre in a billion years. Since 2013, orbiting missions have mapped such deposits, estimating as much as 1 billion tons of water ice, brought by asteroid impacts, may lie inside them.

The study's authors say power would not be the limiting factor: crater rims near these shadowed pockets stay in near-permanent sunlight, and kilometre-tall towers covered in solar panels there could generate 3 gigawatts of electricity, potentially even running AI data centers on the Moon.

Water is the harder problem. Even starting with a generous 1 billion tons and no recycling, the study found a lunar city would run dry within a few years. At 98% water-recycling efficiency, the level already achieved on the International Space Station, a city of 1 million people would still exhaust its supply in just over a century. Today's best estimates put the Moon's water at roughly 30 times less than that figure, shortening a small city's supply to about a decade. A village of 1,000 people or a town of 10,000, however, could remain sustainable for centuries.

Possible fixes include raising recycling efficiency five-fold or more, cutting water use through methods such as vertical farming, importing water from nearby asteroids, or simply finding more of it. Current surveys do not look more than a few metres below the surface, while the Moon's loose surface layer extends tens of metres down and may hold additional ice.