# Magnetic / Inductive braking against planetary magnetic fields?

I'm familiar with the concept of aerobraking. Consider an object like a star, or a planet with strong magnetic field (Earth, Jupiter, probably all of the gas/ice giants?) Could a probe use some kind of electromagnet (or maybe magnetic induction), to push against the magnetic field as it gets close to the planet, similar to aerobraking, but much farther out?

(Also, is this an old, well known idea?)

Even if there was lower deceleration, the much longer reach of the magnetic field might make it viable for starting to slow down much earlier.

I was watching a speculative video on YouTube about how tethers push against the earth's magnetic field. In that video, the idea was for a space station or skyhook or satellite to gain momentum to prevent gradual orbital decay.

But it occurred to me it might work just fine for slowing down instead.

There is some existing work for magnetic sails, to decelerate against a solar wind, but I don't really see anything comparing it to aerobraking, nor anything that considered it at the level of a planetary magnetic field.

Maybe the idea works just great, except the hardware is simply too heavy to be practical? Or if using induction — maybe the problem is if you decelerate too much, you build up too much charge and zap your space probe?

• ps. I did find a "Terminator Tether" product on google; designed as a way to de-orbit a satellite at the end of its life cycle, rather than leaving it as space junk. ( google for www.tethers.com ) Mar 24, 2017 at 18:36
• A very interesting idea, not sure how viable though: the magnetic braking is fairly weak. OTOH the tether, per meter, is quite light and you should be able to pack a lot of it on the cheap. I'm quite curious how it compares, mass wise, to propulsive braking.
– SF.
Mar 24, 2017 at 19:22
• If you compare the earth magnetic field with the field of a coil with a diameter of 1 m, 100 turns and a current of 1 A, the earth field is huge in size but very weak in its intensity. You could try to suspend this coil in a way to allow visible movement of the coil when the direction of current is changed. It would not be easy because the field and the resulting force is so weak.
– Uwe
Mar 24, 2017 at 20:02
• You may find these two links helpful (Magnetic Monopole) en.wikipedia.org/wiki/Magnetic_monopole and phys.org/news/… Mar 24, 2017 at 20:36