Let's not spend resources that we don't need to be sending astronauts back to the moon. Let's not spend expensive resources on bringing people who have reached Mars back again. Prepare them to become a growing colony.

My first inclination is to be a bit skeptical about the claims that human-produced carbon dioxide is the direct contributor to global warming.

I'm sure that there are places in the deserts in Australia that could be similar to where we might want to go on Mars.

History will remember the inhabitants of this century as the people who went from Kitty Hawk to the moon in 66 years, only to languish for the next 30 in low Earth orbit. At the core of the risk-free society is a self-indulgent failure of nerve.

A mind concerned about danger is a clouded mind. It's paralyzing.

There should be an international lunar base. That is certainly doable.

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?