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.

Everything looks nonsensical before it works.

I like to call the difference between research and development. Some people use that interchangeably. They'll say R&D. They're two totally different things.

Space travel is the only technology that is more dangerous and more expensive now than it was in its first year. Fifty years after Yuri Gagarin, the space shuttle ended up being more dangerous and more expensive to fly than those first throwaway rockets, even though large portions of it were reusable. It's absurd.

Testing leads to failure, and failure leads to understanding

We didn't know the importance of home computers before the Internet. We had them mostly for fun, then the Internet came along and was enabled by all the PCs out there.

We'll go back to the moon by not learning anything new.