Overview
- Researchers Martin Elvis and Jonathan C. McDowell published a model in Frontiers in Space Technologies that combines published polar-ice estimates with consumption and recycling losses to quantify how long supplies would last.
- Using a very generous one‑billion‑tonne ice assumption and current ISS-like 98% water recovery, the model finds a one‑million person settlement would exhaust that supply in about 100–120 years.
- Sustaining a million residents for the long term would require recovery rates far above current practice — the paper estimates greater than about 99.75% recycling — or sustained, large-scale imports or discovery of much more exploitable ice.
- The authors judge energy is a lesser constraint because polar solar arrays could plausibly deliver the multi-gigawatt power a large settlement needs, but they warn that food production and life support drive the water demand math.
- The study highlights wide uncertainty in how much water is actually recoverable from permanently shadowed regions, calls for in‑situ measurements and deeper drilling, and says governance for allocating lunar water will be a key political challenge.