When I review my travels among the astronauts, my mind's eye goes first to the Houston shopping mall where Alan Bean sat for hours after returning from space, just eating ice cream and watching the people swirl around him, enraptured by the simple yet miraculous fact they they were there and alive in that moment, and so was he.

Had (President) Kennedy turned to his advisers and wailed, "What can we beat the Russians at?" and if someone had cried "Backgammon!" at that point, Apollo would never have happened.

Was Apollo worth all the effort and expense? If it had been about the Moon, the answer would be no, but it wasn't, it was about the Earth. The answer is yes. The only thing I can't see in all this is a rationale for going back. Unless we could find a way to take everyone.

Apollo has something to teach us as we enter a new century of genetic modification, artificial intelligence, nanotechnology. It's a cautionary tale about that most fundamentally human of human tragedies .. wanting something so badly that you end up destroying it.