What are you going to do with astronauts who first reach the surface of Mars and then turn around and rocket back home-ward? What are they going to do, write their memoirs? Would they go again? Having them repeat the voyage, in my view, is dim-witted. Why don't they stay there on Mars?

We need the next generation to be motivated and to push technological boundaries, to seek out new innovations.

I understand that Detroit was a pretty rough place to grow up in the '70s and '80s.

Retain the vision for space exploration. If we turn our backs on the vision again, we're going to have to live in a secondary position in human space flight for the rest of the century.

The society of life on Mars, or the challenge of making Mars more livable, will have significant benefits on our attempts to modify and change in some ways the environment here on Earth.

The big companies are the private industry. But they're faced with a short-term need to show a profit in short-term.

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