It's very sad that there's going to be a hiatus in manned space flight from the U.S. The Shuttle was a fantastic, hugely complex vehicle. It was inevitable it would come to an end, but this is the opportunity for the commercial world to get involved. As the Shuttle era ends, another window of opportunity opens.

I was a frustrated astronaut all my life. I grew up at a time when space seemed to have no boundaries, and lots of us presumed humans would be living on the moon and landing on Mars.

I watched the moon landing as a boy, and I thought that was the most exciting thing ever, going into space, orbiting Earth and exploring other planets. That looked fantastic.