Exploration is wired into our brains. If we can see the horizon, we want to know what's beyond.

Standing on the Moon looking back at Earth - this lovely place you just came from - you see all the colours, and you know what they represent. Having left the water planet, with all that water brings to Earth in terms of colour and abudance life, the absence of water and atmosphere on the desolate surface of the Moon gives rise to a stark contrast.

Monumental achievements by humanity should be done by major organizations as much together as possible.

I was the first Navy, Marine or Air Force person who had been an astronaut to return back to the Air Force. I had certain expectations about what would be a reasonable and desirable position to be assigned to after my years of service.

The energy varies with the square of the velocity, so if you need five times the velocity, that's 25 times the energy.

Space tourism is a logical outgrowth of the adventure tourist market.

The first human beings to land on Mars should not come back to Earth. They should be the beginning of a build-up of a colony/settlement, I call it a 'permanence'.