We didn't have practical model rockets in the '50s. The ones we made were very dangerous and the kids that played with them didn't have all their fingers, and sometimes were blind in one eye.

I spent about seven years during the Vietnam War flight-testing airplanes for the Air Force. And then I went in and I had a lot of fun building airplanes that people could build in their garages. And some 3,000 of those are flying. Of course, one of them is around-the-world Voyager.

We need affordable space travel to inspire our youth, to let them know that they can experience their dreams, can set significant goals and be in a position to lead all of us to future progress in exploration, discovery and fun. Thanks to the X Prize for the inspiration.

No one knows how to make going to orbit orders of magnitude safer and orders of magnitude more affordable.

To allow public access to orbit, we would need breakthroughs that would lower the cost by a lot more than an order of magnitude and increase safety by a factor of 100 as compared to every launch system used since the first manned space flight. I think airborne launch will be a significant part of the safety solution.

In the coming era of manned space exploration by the private sector, market forces will spur development and yield new, low-cost space technologies. If the history of private aviation is any guide, private development efforts will be safer, too.

NASA's myriad failures are in many ways the natural consequence of a catastrophic combination of bureaucracy, monopoly, and a calcifying aversion to the kind of risk necessary for innovation.