You may be right, mathsy.

I personally never understood how a satellite hanging in orbit is supposed to support the weight of a cable reaching to Earth, let alone a payload crawling up it. Wouldn't the downward force drag it out of orbit?

What if you stretched a cable from the earth to the moon? :-P

Wow, good point. We'd reel the moon into us.

Well, it's more likely that the cable would snap, but we might be able to pull it a little bit. And that would screw up all the oceans and stuff.

Color me stupid, but I still don't understand how a counterweight is any different than a satellite in orbit, as far as the fact that it's not attached to anything, and therefore free to decelerate (and lose altitude and fall as a result) if a force is applied to it.

Well, Arthur C. Clarke sure thought it would work. He also thought we'd have intelligent AIs and the ability to send people to Saturn by 2001.

It works by always keeping the forces in balance. The satellite starts in geosynchronous orbit. It should stay there whether it weighs 100 kg or 100,000kg, right?

Then imagine you attach a km of cable pointing towards the earth - the satellite's center of gravity will change, so you also put some cable pointing away from earth with enough weight on it to bring the center of gravity back again.

Continue this process until you get tired, or one end reaches the planet, then tie it around a rock so you can find it again.

(They may not build it this way, this is just a concept thing)

Then imagine you attach a km of cable pointing towards the earth - the satellite's center of gravity will change, so you also put some cable pointing away from earth with enough weight on it to bring the center of gravity back again.

Problem with this is that the side going towards earth is under much stronger gravitational forces than the side away from earth.  So you have to have an extremely massive thing on the side away.

The problem only gets worse as you get closer and closer to earth.

Everyone also seems to be neglecting the affect of weather and wind currents near the surface of the earth.  While these wouldn't be massive forces on a cable, unless the circumference was very large, it would still be great enough to jerk and jostle the satelite around which isn't under the same influences in the vaccuum of space.  The tension that we created by a counter mass would have to be quite large to minimize these sudden accelerations.

  Looking at it in this way, I don't see how any orbit could be maintained without the satelite(?) having a thruster system to constantly counter the forces that it receives from the earth side.