To appropriately respond to an emergency requires a very clear mind, to cooly analyze what the observations are and how to fix it.

We could have human intelligence in orbit around Mars, building things there.

Anything we can do in the near future that begins to stimulate the interest of people - seeing somebody down the street have an opportunity to go into space - buoys up the whole neighborhood.

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

Most people never believed in the real possibility of going to the moon, and neither did I until I was in my twenties.

When we can demonstrate that we can take off horizontally and put something into orbit, then we can begin to talk about increasing the amount of payload. But to say, 'I'm going to do that and put people into orbit' is a real leap.

I think humans will reach Mars, and I would like to see it happen in my lifetime.