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Space Elevator May Become Reality
mojotek writes: "The NASA Institute for Advanced Concepts has a study(15Mb pdf) about the feasibility of a "Space Elevator" comprised of a 22,000 mile long cable built out of carbon nanotubes. In theory, it would be able to carry loads of 20 tons to space without using a single rocket engine. Sounded way too sci-fi for my taste at first, but this article at TechTV actually helped fill in the holes."
Not to dismiss the elevator out of hand, but wouldn't research into efficient space vehicle propulsion yield better long term results?
Not really, because the "efficient" propulsion systems probably won't be able to lift a rocket off the ground. E.g. the DS-1 ion engine, high efficiency but only about 0.1N of thrust - or nuclear engines that would be too dirty to run in the biosphere, but would work fine in interplanetary space.
If a space elevator could be built, the cost of lifting payloads into space could drop dramatically, and that would create a lot more incentive for companies to develop these efficient space-only engines.
But the weight to payload ratio sucks pretty hard. I imagine the up-front construction costs would be a lot higher than the cost of building rockets. So even if it's cheaper after, say, 10,000 uses, we might not see anyone wanting to build it.
You see? You see? Your stupid minds! Stupid! Stupid!
No, you don't need a counterweight. If the cable is long enough so that the center of mass is in geostationary orbit it will just hang there by itself.
Thats a good idea, but... How do you purpose to keep the platform suspended? Is it hanging "off" the satelite? If so, won't its weight drag the satelite into a lower orbit, eventually destroying it? Or is the satelite going to be continuously firing retro-rockets, which would need enormous amounts of fuel, thereby negating the purpose of the elevator? Not to mention the wind blowing said platform around.
It doesn't drop off exponentially, it drops off as the inverse square. This is an awful lot different from exponential. The universe would be much different if the force of gravity was proportional to e^(-r) ;)