Scientific truth is not what any one scientist puts forth. It can be that, but it is generally not. It is the sum of multiple studies that all lean in the same direction in their results conducted by different people at different times of different nationalities with different competitive urges who all end up getting the same result. Then you have an emerging scientific truth, and then you put that in the textbooks, and that will never be shown to be wrong later on.

The atoms of our bodies are traceable to stars that manufactured them in their cores and exploded these enriched ingredients across our galaxy, billions of years ago. For this reason, we are biologically connected to every other living thing in the world. We are chemically connected to all molecules on Earth. And we are atomically connected to all atoms in the universe. We are not figuratively, but literally stardust.

The day we stop exploring is the day we commit ourselves to live in a stagnant world, devoid of curiosity, empty of dreams.

For me, one of the most fertile consequences of the space program is the extent to which it stimulates people to innovate because they want to create a different tomorrow than what they're living in today. And it's that culture of innovation that spawns entirely new economies.

I'd bet almost anything that life from another planet, if formed independently from life on Earth, would be more different from all species of Earth life than any two species of Earth life are from each other.

I'd like - inviting aliens and have them observe what we do because so much of what we do that we take for granted will just be weird or extraordinary or just plain dumb when observed by an alien from another civilization.

I am proud to be part of a species where a subset of its members willingly put their lives at risk to push the boundaries of our existence.