Space architectures capable of supporting a permanent human presence on Mars are extraordinarily complex, with many different interdependent systems.

I've led a life of such structured discipline and always had a goal in mind of knowing what I was doing, from West Point to the Air Force combat, MIT, looking for new things to study and get involved in. And then I got into the space program, and how disciplined can you get?

I am excited to think that the development of commercial capabilities to send humans into low Earth orbit will likely result in so many more Earthlings being able to experience the transformative power of space flight.

There's a historical milestone in the fact that our Apollo 11 landing on the moon took place a mere 66 years after the Wright Brothers' first flight.

We really didn't devote a lot of time to investigating the scariest aspects of our flight. It was more challenging and productive to concentrate on the remedies, and leave things that couldn't be solved to happen without thinking about them. There is a morbid human curiosity associated with tragic death-producing events. Though naturally, this needs to be kept in perspective.

I feel we need to remind the world about the Apollo missions and that we can still do impossible things.

I'm not in favor of just taking short-term isolated situations and depleting our resources to keep our climate just the way it is today.