Harvard researchers find moon water reserves cap sustainable population at 10,000
New analysis in Frontiers in Space Technologies suggests lunar water supplies are insufficient to support million-person cities for more than a century without major breakthroughs.
By Marco Whitaker ·
A new study published in Frontiers in Space Technologies indicates that the moon’s available water reserves can sustain a settlement of approximately 10,000 residents for centuries, but likely cannot support a population of one million for more than 100 years. Martin Elvis, a senior astrophysicist at Harvard University’s Smithsonian Astrophysical Observatory, and Jonathan McDowell, an honorary professor at the Durham University Space Research Centre, conducted the analysis to evaluate the feasibility of large-scale lunar habitation.
The research addresses claims made by prominent figures in the space industry. Elon Musk stated in February that SpaceX is prioritizing the construction of a self-growing city on the moon, a goal he estimates could be achieved in under 10 years. Jeff Bezos has previously projected that millions of people will live in space by 2045. Elvis and McDowell tested these visions against current estimates of lunar resources, specifically focusing on power and water requirements.
Power generation poses a manageable challenge for the researchers. Solar and nuclear sources appear sufficient to meet the energy needs of a million-person settlement. Water, however, presents a tighter constraint. Most lunar water is believed to exist in permanently shadowed polar regions. The authors assumed a total of roughly one billion tonnes of water, a figure aligned with current scientific estimates. Under these conditions, a population of one million would deplete the supply in about a century, assuming a 98% recycling rate similar to that of the International Space Station.
Elvis argued that the total volume of water is smaller than it appears. He compared the estimated one billion tonnes to a lake the size of Central Park that only reaches the base of the Statue of Liberty. He noted that this volume is likely 20 or 30 times larger than the amount of water actually recoverable. His best estimate is that only 1% of the original figure is available for use, which would reduce the sustainability window for a million people from 100 years to one year.
Gordon Osinski, a professor of planetary geology at Western University in London, Ontario, cautioned that satellite measurements contain uncertainties. He suggested the water may resemble Arctic permafrost, consisting of sub-millimetre ice crystals mixed into soil that are difficult to extract. Osinski emphasized the need for on-ground confirmation of these resources.
McDowell viewed the findings as a practical guide rather than a negative verdict. He stated that the truth is never negative and that attempting to build something that will not work is the true problem. The study suggests that lunar settlements may need to remain small towns unless new methods for water extraction or transportation are developed.
