It has been estimated that it takes a community of about 250,000 minimum to provide all the various goods and services in a diversified economy to be substantially independent of imports. When anyone speaks of their belief that a Lunar or Martian settlement of a few hundred persons can be autonomous, they are either being naive or are defining autonomy loosely. Such a small settlement might achieve 50-60% self-sufficiency, but a metropolis of a quarter million could be 95% self-sufficient. No wooden nickels, please! Let’s go for broke or quit kidding ourselves.