Instead of planning the retirement of the Space Shuttle program, America should be preparing the shuttles for their next step in space: evolving, not shutting them down and laying off thousands of people.

I want to keep on the move, keep stimulated and challenged.

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.

I want to reach a new generation. That's why I am Twittering now. I have a BlackBerry, an iPhone and a Mac.

People communicate in Twittering ways. I've learned how to do that.

I was given permission to serve myself Communion, with wine and a wafer, on the surface on the Moon. But I was advised not to say anything about it at the time. Someone had strongly objected to the Apollo 8 crew reading from the Bible. We didn't want to get into any further trouble with the religious critics.

The universe is the way it is. It's not going to be changed by supplications.