I was the first Navy, Marine or Air Force person who had been an astronaut to return back to the Air Force. I had certain expectations about what would be a reasonable and desirable position to be assigned to after my years of service.

As someone who flew two space capsules and twice landed in the ocean, I can attest from personal experience how much logistics work is needed to get you home.

When you're in a spacecraft, you need to know what things you can touch and what things you shouldn't touch!

The moon I see now is the same moon I saw before. Except that before, when I looked at it, it was in anticipation of what it would be like when I got there. That's behind me now.

The best way to study Mars is with two hands, eyes and ears of a geologist, first at a moon orbiting Mars... and then on the surface.

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.

By refocusing our space program on Mars for America's future, we can restore the sense of wonder and adventure in space exploration that we knew in the summer of 1969. We won the moon race; now it's time for us to live and work on Mars, first on its moons and then on its surface.