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See my previous post - I don't think it's all a case of momentum transfer.

I don't think it's all a case of momentum transfer

No, we'll have to get Michael Faraday or someone else with the common touch to 'splain this.

See my previous post - I don't think it's all a case of momentum transfer.

Unfortunately, the energy you pick up by spinning a wire in an electric field results in a drag on the wire. You can use the energy you've picked up to send out photons or something to make a drive - but entropy being what it is, you end up with a net loss.

There are good things and bad things about this idea. The good things are that it's within current material technologies, and it 'works' in the sense that you can indeed use it to boost a payload. I don't think there's any particular challenge in working out the orbital mechanics for the 'catch' and so on. And there are at least two viable methods for replenishing the lost momentum.

Unfortunately, neither of the methods are particularly palatable. One involves sending someone (or something) out to the asteroid belt to boost rocks down to where the string could catch them. That can be a really good idea if the rocks are things you want (nickel-iron, for example), though you've still got to get them through the atmosphere to be useful - at least until near-Earth factories are set up. However, right now it's a pretty impressive challenge to get out to the asteroids and snag a few. The good thing about that is the rocks can be moved in-system relatively slowly, and that's where such things as solar sails or mass drivers can help.

The other method of replenishing the momentum would be to use nuclear propulsion. If it weren't for the political/emotional issues with that, it would be pretty viable. Just think, there could be web postings of the schedule when people should walk outside to see the flash of a nuclear bomb going off a hundred miles overhead.

Oh, there is the problem of wiping out all the satellite systems, but in the (ahem) few years until this became viable, you could replace the current satellites with shielded ones.

I'd love to see this, but I'm not holding my breath.