Das: Do you consider the paper on geostationary orbits your most important contribution?

Clarke: It’s definitely my most important contribution. And maybe in a generation or so the space elevator will be considered equally important.

Das: Ah, yes, the space elevator, another technology that Clarke has championed. The idea of a space elevator is basically a huge cable connecting the Earth to space, along which payloads can be launched using electromagnetic vehicles. The cable would be tethered to an object beyond the geostationary orbit, while having its center of mass in a geostationary orbit. Current plans call for a cable about 50 kilometers long. Clarke first wrote about the space elevator in his 1978 book, The Fountains of Paradise.

Clarke: I’m often asked when do I think the space elevator will be built. My answer is about 10 years after everyone stops laughing. Maybe 20 years. But I am pretty sure that the space elevator is an important element in future space travel.

Das: Can you elaborate a little more on the space elevator?

Clarke: The space elevator is exactly that, reaching from the Earth’s surface to the stationary orbit. Getting to space purely by electrical energy, and you recover it all on the way down…a very efficient economical system and the key to the planets. The chief expense of space travel when you build the space elevator is catering and in-flight movies.

Das: Now that private entrepreneurs are entering space exploration, do you think they will get into this? Like a Virgin Space thanks to Richard Branson, for example?

Clarke: I’m sure that there will be quite a few interesting rackets.

Das: So what do you think of private entrepreneurship in space exploration?

Clarke: It can never be fully private, because it is so expensive. Aircraft initially were funded by governments, and the same for the space elevator.

I don’t know if the Wright brothers realized how soon, relatively speaking, aircraft would pay for themselves.

Das: Clarke was born in 1917 and grew up in western England. He became interested in science as a youngster, when he started reading American science-fiction magazines. I asked whether he spent a lot of his pocket money on those magazines.

Clarke: Yes, these magazines cost the astronomical sum of thruppence… three pennies. I couldn’t always afford that….They had a tremendous influence on me, of course.

Das: Clarke was so interested in what he read that he started corresponding with some of the authors. I asked how he managed to contact Willy Ley and other science-fiction authors.

Clarke: I probably saw their addresses in the various magazines….I hope I still have most of the correspondence.

Das: Clarke published his first story in 1937. It was called “Travel by Wire!”