Science does not have a moral dimension. It is like a knife. If you give it to a surgeon or a murderer, each will use it differently.

Our sun is one of a 100 billion stars in our galaxy. Our galaxy is one of billions of galaxies populating the universe. It would be the height of presumption to think that we are the only living thing in that enormous immensity.

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.

Looking back, nothing seems so simple than a utopian vision realised.

Everybody knows what the moon is, everybody knows what this decade is, and everybody can tell a live astronaut who returned from the moon from one who didn't

The greatest gain from space travel consists in the extension of our knowledge. In a hundred years this newly won knowledge will pay huge and unexpected dividends.

Man is not made for space. But with the help of biologists and medical doctors, he can be prepared and accommodated.