Optimism, pessimism, f**k that; we're going to make it happen. As God is my bloody witness, I'm hell-bent on making it work.

The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable.

The biggest mistake, in general, I've made, is to put too much of a weighting on someone's talent and not enough on their personality. And I've made that mistake several times. I think it actually matters whether somebody has a good heart, it really does. I've made the mistake of thinking that it's sometimes just about the brain.

It's a fixer-upper of a planet but we could make it work.

The thing that's worth doing is trying to improve our understanding of the world and gain a better appreciation of the universe and not to worry too much about there being no meaning. And, you know, try and enjoy yourself. Because, actually, life's pretty good. It really is.

It's not as though we can keep burning coal in our power plants. Coal is a finite resource, too. We must find alternatives, and it's a better idea to find alternatives sooner then wait until we run out of coal, and in the meantime, put God knows how many trillions of tons of CO2 that used to be buried underground into the atmosphere.

The extension of life beyond Earth is the most important thing we can do as a species.