By 1931, after a few years' experience of flying scheduled airlines, those planes were operating at roughly 600 times the safety of the space shuttle. I look at safety not in terms of fatalities per passenger-mile, but when you get in and close the door, what is the risk of dying on this flight?

I don't see anything beneficial about the US spending 100 billion dollars to go back to the moon unless we learn something new that will help us go to the moons of Saturn okay and so we ought to use that to breed new breakthroughs and to test new breakthroughs and to fund it.

Virgin Galactic, which will be operating SpaceShipTwo, will be only one of several spacelines. The competitors for Virgin include the Russians, Bezos's Blue Origin, and possibly Rocketplane Kistler. And likely a couple of others who are smart enough not to tell people what they are doing!

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.

The criticism is, once I get something flying, I lose interest in it.

The next 15 years will see thousands of people leave the atmosphere on suborbital flights. My company's SS2 system might fly 100,000 people by 2024. If it is shown to be highly profitable, perhaps we will see 20,000 people traveling to orbit by 2035, and then thousands to the moon by 2050. If we make a courageous decision, like the program we kicked off for Apollo, we will see our grandchildren in outposts on other planets.

With any luck, by the time NASA's space probe hits Pluto, you'll be booking a spaceflight with a privately run suborbital airline.