Trying to predict the future is a discouraging and hazardous occupation. If by some miracle a prophet could describe the future exactly as it was going to take place, his predictions would sound so absurd that people everyone would laugh him to scorn. The only thing we can be sure of about the future is that it will be absolutely fantastic. So, if what I say now seems to you to be very reasonable, then I will have failed completely. Only if what I tell you appears absolutely unbelievable have we any chance of visualizing the future as it really will happen.
Arthur C. ClarkeOne orbit, with a radius of 42,000 kilometers, has a period of exactly 24 hours. A body in such an orbit, if its plane coincided with that of the Earth's equator, would revolve with the Earth and would thus be stationary above the same spot on the planet. It would remain fixed in the sky of a whole hemisphere ... [to] provide coverage to half the globe, and for a world service three would be required, though more could be readily utilized. (1945) [Predidicting geosynchronous communication satellites]
Arthur C. ClarkeMars is the next frontier, what the Wild West was, what America was 500 years ago. It's time to strike out anew....Mars is where the action is for the next thousand years....The characteristic of human nature, and perhaps our simian branch of the family, is curiosity and exploration. When we stop doing that, we won't be humans anymore. I've seen far more in my lifetime than I ever dreamed. Many of our problems on Earth can only be solved by space technology....The next step is in space. It's inevitable.
Arthur C. Clarke