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.

I believe that research, that you can claim that you're doing research only if half of the people, and I'm talking about half of the experts, believe that the goal is impossible.

NASA is doing nothing but development. They're not doing research in manned spaceflight at all and I see no reason for them to do that because we already know that it will work and we already know exactly how it will work.

There was a wonderful little short four-year time period when marvelous things happened. It started in 1908, when the Wright brothers flew in Paris, and everybody said, 'Ooh, hey, I can do that.' There's only a few people that have flown in early 1908. In four years, 39 countries had hundreds of airplanes, thousands of pilots.

In 12 or 15 years, there will be routine, affordable space tourism not just in the U.S. but in a lot of countries.

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.

A NASA-funded study estimates that if the price of a ticket to space approached $100,000, close to a million people would buy one. That's a $100 billion industry. Microsoft cofounder Paul Allen gave me $20 million in startup funding to go after that market.