Dear Mark

I really enjoyed reading your post on space elevators - you've obviously considered the technological details in some depth.

I think I first came across the idea of a space elevator in Arthur C. Clarke's novel "The Fountains Of Paradise". From what I remember, it seems like the major problem is finding a material that won't sag under its own weight when you make it into a cable that's thousands of miles long.

I guess that carbon nanotubes weren't even on the horizon when Clarke wrote the novel in 1978. The space elevator is a good example of something that might have been labelled (forgive the pun) a "pie in the sky" idea in its day because some vital piece of supporting technology that could have made it feasible (in this case, related to the material science) simply did not exist. But it's a testament to Clarke's vision that this idea has survived and continues to be considered.

Best

Gordon