For me, I am driven by two main philosophies, know more today about the world than I knew yesterday. And along the way, lessen the suffering of others. You'd be surprised how far that gets you.

It could be that these other civilizations, if they are far more advanced intellectually than we are, would not even measure our existence as a blip on the intelligence radar. They could be so advanced that we are to them what worms are to us.

If you need to invoke your academic pedigree or job title for people to believe what you say, then you need a better argument.

What are the lessons to be learned from this journey of the mind through the universe? That humans are emotionally fragile, perennially gullible, hopelessly ignorant masters of an insignificantly small speck in the cosmos. Have a nice day.

NASA has spin-offs, and it's a huge and very impressive list, including accurate and affordable LASIK eye surgery.

I love the smell of the universe in the morning.

We didn't go to the moon to explore or because it was in our DNA or because we're Americans. We went because we were at war and we felt a threat.