My vision is for a fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars - this is very important - so you don't have to carry the return fuel when you go there.

I'm increasingly inclined to think there should be some regulatory oversight, maybe at the national and international level just to make sure that we don't do something very foolish.

You need to be in the position where it is the cost of the fuel that actually matters and not the cost of building the rocket in the first place.

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.

Don't be afraid of new arenas.

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

Mars is the only place in the solar system where it's possible for life to become multi-planetarian.