What would it take to go from a manned human return to the Moon to a self-sustaining colony?
When we look at modern society today, there is practically no city that is self-sufficient. Metals are produced in one part of the world, paper somewhere else, cell phones yet somewhere else. The list could go on.
But this situation exists because no city truly needs to be self-sufficient. People can purchase goods from wherever they can be produced at the best price and quality.
So, are there no places on Earth that are self-sufficient? Actually, there are.