The space elevator (off topic):
Many years ago, in more cheerful times I was following our moon mission and did some arithmetic in my head and concluded that a trip to the moon cost more than the number of dollar bills set end to end that would reach there in a straight line. That gave me an idea. If one took a long enough cable one could attach one end to the earth and let the other end extend out into space where it would be held up by centrifugal force from the earth’s rotation. It would be sort of like the Indian rope trick. The cable would have to be tapered of course since at the beginning successively higher points would have to support greater weight.
When I finally did the calculation it seemed to me that using steel would require a cable so thick that the whole thing would outweigh the earth. Perhaps I was a bit pessimistic, but when I thought about what it would be like were the contraption ever to break it gave me pause. But before serenity returned to my fevered brain I wrote NASA with a, “How’s about it?” I got a form reply.
But now we have nanotechnology. It began really with the buckyball. It is a bunch of carbon atoms arranged like the geodesic dome invented by Buckminster Fuller. Making the things was easy. They are found in ordinary soot. Developing commercial uses was slow. Then somebody discovered the nanotube. It is carbon arranged in tiny tubes. The engineering difficulties were still considerable. Then came graphene. It is a single sheet of graphite of considerable extent, large enough to cover a computer monitor screen for instance. And it is prodigiously strong for its weight. The last time I had numbers it seemed to me that the cable into space was still not feasible. But others are more sanguine. In fact I see they are now experimenting with a way to power the vehicle.
When I described this to my father he said that part was easy, you just pulled on the bottom. When I asked for clarification he said there used to be a toy that was a monkey on a string. You would hold the string vertically in your hands. The string seemed to go through the monkey, but actually there were two strings that entered the monkey and wound on spools of different diameter. Suitable mechanics made it look like the monkey climbed the string when you pulled the ends apart.
I thought it would be simple enough to have two cables side by side and use them to conduct electricity. But current schemes (This is off topic, so forget the reference.) use a laser to activate a photocell on the vehicle that then climbs with an electric motor. Apparently the expected resistance of the cable or wear on the cable would be too much.
They are thinking that such a device would cause a major change in the economics of spaceflight. An electric motor delivers its power a lot cheaper than a giant rocket.
But now I am thinking, why stop there? If you can put one up you can put up any number. Somewhere along the cable gravity and centrifugal force must balance. High enough and it would pitch you into earth orbit or out to the stars. But somewhere there must be a level where letting go gives you a toss and lands you elsewhere on the earth. If you arrange it so that there happens to be another cable there, you just climb back down again. I suppose you would need a smallish rocket to maneuver into the right trajectory upon departure and into synchrony with the arrival site, but it would not take nearly the power that an ordinary transport jet uses and power would be needed for minutes not hours.
That would mean saving what we now burn as jet fuel. It would mean not putting a shroud of burned nitrogen in the stratosphere. It would mean that we would not need to have gasoline powered cars to keep the petroleum running so jet fuel is cheap enough for the super rich. It would mean no more shrieking jet takeoffs.
In many ways it would be a jolly good thing.
Until it breaks, of course.
Where are those Luddites when we need them?
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