I fully expected that, by the end of the century, we would have achieved substantially more than we actually did.

I believe that every human has a finite number of heartbeats. I don't intend to waste any of mine running around doing exercises.

Science has not yet mastered prophecy. We predict too much for the next year and yet far too little for the next 10.

The one thing I regret was that my work required an enormous amount of my time, and a lot of travel.

People love conspiracy theories.

Geologists have a saying - rocks remember.

I'm substantially concerned about the policy directions of the space agency. We have a situation in the U.S. where the White House and Congress are at odds over what the future direction should be. They're sort of playing a game and NASA is the shuttlecock that they're hitting back and forth.