Harvard researchers estimate moon water supports 10,000 residents

A new analysis published in the journal Frontiers in Space Technologies estimates that current lunar water reserves could sustain a settlement of 10,000 people for centuries. The study challenges earlier projections that the moon could host much larger populations in the near future. The findings rely on conservative estimates of available water and high recycling rates.

Martin Elvis, a senior astrophysicist at Harvard University's Smithsonian Astrophysical Observatory, co-authored the paper with Jonathan McDowell, an honorary professor at the Durham University Space Research Centre. They examined two critical resources for lunar habitation: power and water. The researchers determined that solar and nuclear power sources are sufficient to support one million people. Water availability emerged as the primary limiting factor.

Current scientific estimates suggest the moon holds approximately one billion tonnes of water, primarily located in permanently shadowed regions near the poles. Elvis noted that this volume is comparable to an aquarium the size of Central Park filled until the Statue of Liberty is submerged. He described the reserve as a small lake, noting it would not supply a large city for a long period.

The calculation assumes a water recycling rate of 98 per cent, matching the efficiency achieved on the International Space Station. Under these conditions, a population of one million would deplete the available water supply in roughly 100 years. A smaller community of 10,000 residents would remain sustainable for several centuries using the same assumptions.

Elvis believes the one billion tonne estimate may be generous. He suggested the actual amount is likely 20 or 30 times smaller, with only one-third to one-half of existing water being recoverable. His best estimate is that usable water represents about one per cent of the initial figure. This would reduce the sustainability window for a million-person city from 100 years to one year.

Gordon Osinski, a professor of planetary geology at Western University in London, Ont., added that satellite measurements contain uncertainties. He compared the potential water structure to Arctic permafrost, where sub-millimetre ice crystals mix with soil. This form makes extraction difficult. Ground confirmation of the water's physical state remains necessary.

The study appears against the backdrop of ambitious statements by industry leaders. Elon Musk, CEO of SpaceX, wrote in February that his company is building a self-growing city on the moon, a goal he said could be reached in under 10 years. Jeff Bezos, CEO of Blue Origin, has stated that millions of people will live in space by 2045. McDowell argued that the findings should not discourage exploration. He stated, The truth is never negative. What's negative is to actually go and try and do something that isn't going to work.