Water scarcity and recycling will cap lunar settlements: even with near-perfect recycling, a one-million-person city would exhaust lunar water in about a century, while much smaller communities could endure for centuries due to lower absolute water needs.

Finding substantial water reserves on the Moon could dramatically alter projections, enabling more ambitious settlements than current estimates allow.

Ultimately, water availability governs feasibility and longevity of lunar settlements, with energy as a crucial enabler but water breakthroughs as the key to scalable city-building.

The analysis, published in Frontiers in Space Technologies, references recent findings of water ice at the lunar poles and cites figures from industry and exploration, including leading figures in the field.

Solar power near the poles could underpin a lunar economy, with towers potentially generating around 3 gigawatts to drive mining, construction, and other industries.

Near-continuous sunlight on crater rims makes large-scale electricity generation feasible, supporting a lunar economy and even AI data centers near sunny peaks.

Projects envision kilometric photovoltaic towers delivering roughly 3 gigawatts of electricity without resorting to nuclear power.

Not all lunar ice is retrievable; the extractable fraction depends on how ice is embedded in regolith, and practical recovery rates remain unknown until ground truth is established.

Sustainable lunar use requires governance and regulation of water resources, not a free-for-all extraction model.

The piece is authored by Dr. Martin Elvis of the Harvard-Smithsonian Center for Astrophysics, framing feasibility questions around water availability and reuse.

Feasibility hinges on precise totals and distribution of lunar water, and on achieving high recycling efficiencies (ideally above 99.5%).

International cooperation is essential to manage lunar water resources and avoid a competitive scramble that could jeopardize sustainable exploration.