Study Finds Lunar Water Limits Long-Term Large-Scale Human Settlement

A new analysis published in Frontiers in Space Technologies suggests that the Moon’s water supply is insufficient to sustain large, permanent human settlements. The study, conducted by senior astrophysicist Martin Elvis of Harvard’s Smithsonian Astrophysical Observatory and astrophysicist Jonathan McDowell of Durham University, examined the power and water requirements for lunar habitation.

The authors concluded that solar and nuclear power could meet the energy needs of up to one million residents, but water availability would be a critical constraint. Assuming the higher end of current estimates—about one billion tonnes of lunar water—the researchers calculated that a population of one million could be supported for roughly 100 years, provided that 98% of water could be recycled, a rate comparable to the International Space Station.

“Our work shows that, yeah, if you want to have an Antarctic base on the moon for the next few hundred years, no problem. If you want to have a small town, that's doable. If you want to cover the face of the moon with cities, like in the best science fiction, then you have to find a way to get the water there, because it's not there right now,” McDowell said.

Elvis emphasized that the estimated water volume, while seemingly large, is comparable to a “small lake” and would not sustain a major city for long. He also warned that the billion-tonne figure may be an overestimate, potentially by a factor of 20 to 30, and that actual recoverable water could be as low as one percent of that amount, reducing the viable habitation period to about one year.

“Very likely a billion is way overestimating. It's probably 20 or 30 times too big,” Elvis said.

Planetary geologist Gordon Osinski of Western University noted uncertainties about the form of lunar water, stressing the need for ground-truth measurements to determine whether it exists as accessible ice or in more challenging permafrost-like deposits.

“I think it is there, but let's go and ground-truth that and confirm it. And then there's the bigger unknowns of what form it's in…,” Osinski said.

The findings contrast with recent statements by space industry leaders who have projected large lunar colonies within the next decade. McDowell cautioned that realistic assessments are essential for planning viable missions.

“The truth is never negative. What's negative is to actually go and try and do something that isn't going to work,” he added.