When you have a transportation system that the price of propellant is essentially negligible something is very wrong. If you look at any other transportation system, a car, a motorcycle, a train, an oil tanker, an airliner, you name it; about a quarter to a third of the operating cost is buying the propellant.

Everything looks nonsensical before it works.

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.

I have a hunch the most important reason we're going to space is not known now.

When you have a transportation system that the price of propellant is essentially negligible something is very wrong. If you look at any other transportation system, a car, a motorcycle, a train, an oil tanker, an airliner, you name it; about a quarter to a third of the operating cost is buying the propellant.

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.