Harvard study: Moon water reserves limit sustainable settlements to 10,000 people
Researchers argue that current lunar ice estimates support only small towns, not the million-person cities promised by major tech executives.
By Gabriela Ivanov ·
A new analysis published in the journal Frontiers in Space Technologies calculates that the Moon's available water can sustain a population of only 10,000 residents for centuries. 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 study to test claims made by prominent space industry leaders.
The research responds to recent public statements about lunar colonization. In February, SpaceX CEO Elon Musk stated on social media that his company had shifted its focus to building a self-growing city on the Moon, a project he estimated could be achieved in under 10 years. Blue Origin CEO Jeff Bezos has separately claimed that millions of people will live in space by 2045.
Elvis and McDowell examined two critical resources for survival: power and water. Their calculations show that solar and nuclear energy sources are sufficient to power a settlement of one million people. The constraint is water. Current estimates suggest roughly one billion tonnes of water exist in permanently shadowed regions at the lunar poles. Under the assumption that 98 percent of this water is recycled, a population of one million would exhaust the supply in approximately 100 years.
Elvis noted that the total volume of water is modest relative to the size of a large city. He compared the reserve to an aquarium the size of Central Park filled until the Statue of Liberty is just underwater. "It's a small lake," Elvis said, "and a small lake is not going to supply a big city for very long." In contrast, a settlement of 10,000 people could remain sustainable for centuries under the same conditions.
The researchers' assumptions may be optimistic. Elvis suggested that the one billion tonne estimate is likely 20 or 30 times too high. He estimated that only one-third to one-half of the water is recoverable, meaning the usable amount might be just one percent of the total. In that scenario, the lifespan of a million-person city would drop from 100 years to one year.
Gordon Osinski, a professor of planetary geology at Western University, noted that satellite measurements carry uncertainties. He believes the water exists but requires ground confirmation. Osinski described the potential form of the water as resembling Arctic permafrost, with sub-millimetre ice crystals mixed into soil that are difficult to extract.
McDowell stated that the findings should not discourage exploration. "The truth is never negative," he said. "What's negative is to actually go and try and do something that isn't going to work."
