Every kilogram delivered to the lunar surface costs approximately $50,000 to $100,000 depending on the launch vehicle and trajectory. A 20-person settlement consuming Earth-equivalent supplies requires roughly 10 tonnes of consumables per year: food, medical supplies, spare parts, and specialty materials that cannot be manufactured locally. That is $500 million to $1 billion annually just in resupply, before you account for crew rotation or expansion.

There is a historical parallel that haunts me. The early Antarctic stations were entirely dependent on annual resupply ships. When the supply failed, as it did for Shackleton in 1915, the mission became survival. The Moon is three days away by transit time, but the launch window, refueling, and trajectory constraints mean a minimum of 30 days from emergency request to delivery. For some failures, 30 days is 29 days too many.

The critical path to reducing Earth dependence is local food production. Closed-loop hydroponic systems using LED lighting can produce roughly 40 to 80 grams of edible biomass per square meter per day. To feed 20 people at 2,500 calories each requires approximately 800 square meters of growing area. That is a greenhouse module larger than any pressurized volume yet designed for space. And it assumes perfect crop yields, which no agricultural system achieves.

The supply chain also has an information dimension that is underappreciated. Spare parts for systems that have not been invented yet. Medical supplies for conditions we have not yet encountered in partial gravity. The settlement must carry an inventory of contingency supplies for scenarios we cannot fully predict. This is the tyranny of the unknown: you cannot pack for a future you have not imagined.

Additive manufacturing changes the equation significantly. A well-equipped 3D printing facility with metal sintering, polymer extrusion, and ceramic fabrication capabilities can produce a substantial fraction of mechanical spare parts from raw feedstock. Ship feedstock, not finished parts. One tonne of titanium powder can become thousands of different components on demand. The settlement needs a machine shop, not a warehouse.

The ultimate goal is what SpaceX internally calls "Level 5 autonomy" for the settlement. Not vehicle autonomy. Supply autonomy. The point at which the settlement can survive indefinitely without any delivery from Earth. Water from ice. Oxygen from water and regolith. Metals from regolith. Food from closed-loop agriculture. At that point, the settlement is not an outpost. It is a civilization. And the distance to that point is measured not in kilometers but in decades of engineering.