“By the year 2000 we will undoubtedly have a sizable operation on the Moon, we will have achieved a manned Mars landing and it’s entirely possible we will have flown with men to the outer planets.”

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

Crash programs fail because they are based on theory that, with nine women pregnant, you can get a baby in a month.

To simply dismiss the concept of God as being unscientific is to violate the very objectivity of science itself.

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.

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.

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.

The best computer is a man, and it’s the only one that can be mass-produced by unskilled labor.

It was very successful, but it fell on the wrong planet.

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

I find it as difficult to understand a scientist who does not acknowledge the presence of a superior rationality behind the existence of the universe as it is to comprehend a theologian who would deny the advances of science.

I believe in an immortal soul. Science has proved that nothing disintegrates into nothingness. Life and soul, therefore, cannot disintegrate into nothingness, and so are immortal.

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.

If we were to start today on an organized and well-supported space program I believe a practical passenger rocket can be built and tested within ten years.

I’m convinced that before the year 2000 is over, the first child will have been born on the moon.

I believe that the time has arrived for medical investigation of the problems of manned rocket flight, for it will not be the engineering problems but rather the limits of the human frame that will make the final decision as to whether manned space flight will eventually become a reality.

With our present knowledge, we can respond to the challenge of stellar space flight solely with intellectual concepts and purely hypothetical analysis. Hardware solutions are still entirely beyond our reach and far, far away.

It’s murder to doubt yourself in life. It took until I was 45 to get to that point.

Don’t ever aim doubt at yourself. Laugh at yourself, but don’t doubt yourself.

Doubt is not below knowledge, but above it.

A little doubt is better than total credulity.

My main thing is to prove all the doubters wrong.

There has been a lot of self-doubt and unwelcome events in my life.

The play will invariably be different and stronger, and much more fulfilling and richer on all counts. There’s no doubt in my mind about it.

I hope you never doubt again that even when you are in pain, that you are a miracle, that every part of you is incredible.