[No Truce With Kings]

I wonder what the principle is behind the thrust.

Electro-magnetic repulsion. Pump a current through a loop. Result, a magnetic field. Put one magnetic field in proximity with a second (the tethered system and the Earth's magnetic field). Depending on polarity you either get repulsion or attraction. The total thrust is very small, but since there is very little resistance, you still move away from the Earth or towards the Earth with every orbit.

Buck Rogers stuff that is for real. The only thing is ya gotta be patient.

[Young Werther]

Same principal as the "Everlasting Flashlight" advertised on TV. The Faraday effect occurs when coils and stators interact to create current flow. The flashlight stores the energy in an inductive or capacative device and voila light with no batteries.

$19.95 plus shipping and handling and you too can generate EMP. Electro motive propulsion!!!!