Science is not there for you to cherry pick ... You can decide whether or not to believe in it but that doesn’t change the reality of an emergent scientific truth.

The caricature of science is that we hold tight to the theories we have, and shun challenges to them. That's just not true. In fact, we hold our highest rewards for those scientists who can prove others wrong. And by the way, they are famous in their own lifetimes. We don't wait until they're dead.

People say, oh we just need charismatic leaders to continue on to Mars. Now we've gone to the moon, of course Mars is next. No. Mars was never, of course, next. It is next if you think we went to the moon because we're explorers, but if you know we went to the moon because we were at war then we're never going to Mars. There's no military reason to do it, to justify the expenditure.

Today, scientists sound the alarm on other environmental dangers. Vested interests still hire their own scientists to confuse the issue. But in the end, nature, will not be fooled.

I wonder if, in fact, we have been observed by aliens and upon close examination of human conduct and human behavior they have concluded that there is no sign of intelligent life on Earth.

I believe that the manned space program can engage the public by advancing the space frontier. Every next mission takes you farther out in space than you were before, either technologically or in terms of distance.

Space only becomes ordinary when the frontier is no longer being breached.