We are so used to living on a planetary surface that is is a wrench for us even to consider continuing our normal human activities in another location. If, however, the human race has now reached the technical capability to carry on some of its industrial activities in space, we should indulge in the mental exercise of “comparative planetology.”

We should ask, critically and with appeal to the numbers, whether the best site for a growing advancing industrial society is Earth, the Moon, Mars, Some other planet or somewhere else entirely.

Surprisingly, the answer will be inescapable: the best site is: “somewhere else entirely.”

-Gerard Kitchen O’Neill