"Free" Power: Electrotether trailing Io.

[Rakaydos]

So, Someone check my concept here...

An electrotether interacts with movement through a planetary magnetic field, either pumping energy into the orbit to speed up, or generating electricity from slowing down.

The idea is to place an electrotether ion Io's Spheere of Influence, trailing Io. Draining power from it's own velocity arounf jupiter, it generates free power, as Io's own gravity accelerates the probe back up to Jovian orbital velocity.

I believe the power comes from Io's momentum (which is slowed by a mass hovering behind it in orbit) but the ratio is so huge that it might as well be neligable.

[Z-Man]

That's not impossible in principle. However, the other ingredient you need to extract energy via a tether is an ionosphere that is stationary more relative to the magnetic field than to your craft. I don't know whether there is enough of an ionosphere where you want to place the probe, but if there is, it will also be moving along with Io.