Mercury

History will remember the inhabitants of [the twentieth] century as the people who went from Kitty Hawk to the moon in sixty-six years, only to languish for the next thirty in low-Earth orbit. At the core of the risk-free society is a self-indulgent failure of nerve.

— Buzz Aldrin, Apollo 11 astronaut

A species with all its eggs in one planetary basket risks becoming an omelet.

— Stephen Webb

Where Is Everybody (Copernicus Books, 2002)