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.
A species with all its eggs in one planetary basket risks becoming an omelet.
To the memory of my friend and colleague, the star-seeker Robert Forward;
and to A.D., of course;
but most of all to the beauteous Barbara.