Follow the evidence wherever it leads, and question everything.

Apart from the obvious advantages of having ice to melt, filter, then drink, you can also break apart the water's hydrogen from its oxygen. Use the hydrogen and some of the oxygen as active ingredients in rocket fuel and keep the rest of the oxygen for breathing. And in your spare time between space missions, you can always go ice skating on the frozen lake created with the extracted water.

Where did the concept of "without borders" come from? No one had that concept until you saw Earth from space, illustrated not by a mapmaker who's color-coding political boundaries; it's illustrated by nature itself and there's land, there's ocean, there's atmosphere.

Not only do we live among the stars, the stars live within us.

We live in a world where not everyone has the urge to help others... It is OK to encourage others to pull themselves up by the bootstraps, but if you do, just remember that some people have no boots.

I'm revealing information to people. I'm not creating it. And to the extent that people embrace it, I think they're empowered by it, because any time you have a bigger perspective today than you did yesterday, it's got to be only for the good of your mind, your body, your soul.

If we have the power to turn another planet into Earth, then we have the power to turn Earth back into Earth.