The same forces of nature which enable us to fly to the stars, enable us also to destroy our star.

Get me a broom. I'll sweep my own office.

The logistic requirements for a large, elaborate mission to Mars are no greater that those for a minor military operation extending over a limited theatre of war.

All one can really leave one's children is what's inside their heads. Education, in other words, and not earthly possessions, is the ultimate legacy, the only thing that cannot be taken away.

Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go - and he'll do plenty well when he gets there.

What we will have attained when Neil Armstrong steps down upon the moon is a completely new step in the evolution of man.

In 1492 Columbus knew less about the far Atlantic than we do about the heavens, yet he chose not to sail with a flotilla of less than three ships. . . . So it is with interplanetary exploration: it must be done on the grand scale.