We want to explore. We’re curious people. Look back over history, people have put their lives at stake to go out and explore … We believe in what we’re doing. Now it’s time to go.

— Eileen Collins, STS-114 commander, a few days before the re-launch of the Space Shuttle program, reported on Space.com, 11 July 2005.

Of all investments into the future, the conquest of space demands the greatest efforts and the longest-term commitment . . . but it also offers the greatest reward: none less than a universe.

— Daniel Christlein

As we got further and further away, it (the Earth) dimished in size. Finally it shrank to the size of a marble, the most beautiful you can imagine. That beautiful, warm, living object looked so fragile, so delicate, that if you touched it with a finger it would crumble and fall apart. Seeing this has to change a man.

— James B. Irwin, Apollo 15.