Elevator and Escalator Consulting Engineers
The aim of mankind since first becoming aware of its own existence on the planet Earth has been to escape from Earth. Early mythology and many religions envision a heaven hovering far above our planet where, hopefully, we might enjoy an afterlife. Ideally, we could obtain this heaven within our lifetimes rather than leave it to the somewhat chancy possibility that our supposed good deeds would safely get us there. So it is only natural that those of us in the elevator industry should contemplate an elevator to heaven. And indeed this has been, in one form or another, the gist of a few novels.
How practical is an “Elevator to Heaven”? Perhaps not too practical in terms of reaching a religious heaven but certainly conceptually possible as a means of taking us high enough to escape the Earth's gravity. Let's have a look at how to do it.
First, we stretch a long cable from the surface of the Earth to a heavy object about one hundred thousand miles above the earth. The centrifugal force on the object keeps the cable taut. Then, as in Jack and the Beanstalk, we can climb up the cable and get, if not to heaven, at least a bit closer.
As you might expect, there are some problems. The cable itself at its midpoint will have trouble supporting “its own weight”. (In fact the stress at the midpoint would result from gravity pulling down to the Earth and the heavy object at the other end pulling away from the Earth.) So we need a special cable. Ideally the cable would be made of light-weight material and would be tapered so that it would be strongest at the midpoint of its length where the highest stress is exerted and weakest at the ends where the stress is minimal. What makes the idea worth considering today is that we have some materials such as carbon nanotubes and Kevlar (Dupont synthetic organic fibre) that are both strong and light. Moreover we can conceive of ways of making our tapered cable of these materials.
Jumping ahead (and skipping past a couple of decades of research, trial and error) we now have our cable stretching into space. The next task is to construct a cab that will travel up and down the cable so as to transport people and materials. The cab would ideally be driven by solar power converted to electricity with storage batteries to allow for operation during the “night”, The driving machine would grip the cable with clamping rollers which when turned would move the cab up or down. This is all doable even with our present somewhat limited technology. This completes our elevator.
This space elevator is a convenient way of supplying or constructing space vehicles without such impediments as launch sites and heavy fuel loads. As well, since the top end of our elevator is already some one hundred thousand miles we could consider adding another elevator tied to the moon and extending into space so that exchanges could be made between the two elevators. The moon elevator would have a somewhat similar cable length: perhaps one hundred and fifty to two hundred and fifty thousand miles long.
Actually the concept of a space elevator is quite practical and may well come to fruition in this century. Then we can truly say “I have slipped the surly bonds of Earth ... put out my hand, and touched the face of God”.
“The physics of the space elevator” P. K. Aravind