To send humans back to the moon would not be advancing. It would be more than 50 years after the first moon landing when we got there, and we'd probably be welcomed by the Chinese. But we should return to the moon without astronauts and build, with robots, an international lunar base, so that we know how to build a base on Mars robotically.

The decision to go to the moon is now appreciated and associated with President Kennedy's speech, but somebody else had told him it was a good idea. It turned out to be a good commitment, but it was a unique situation.

Some things just can't be described. And stepping onto the moon was one of them.

As a youngster, I read of Buck Rogers and Flash Gordon. As a student, I wrote English reports on science fiction. And as a fighter pilot, I observed the selection of the Mercury astronauts. All this was fascinating, but I really didn't think I would ever be a part of it. It was only when my good friend Ed White was selected as a Gemini astronaut that I decided to join NASA as part of the Apollo program.

Climate has been changing for billions of years.

Everyone should take their hats off to Neil Armstrong. He is a humble guy who doesn't wave his own flag.

What comes after the moon? I think you can guess: Mars.