A bit pedantic here.. I think you might be thinking about space tether propulsion. I don't know if that has been deployed yet. Magnetorquers, as in a device that uses magnets to rotate the satellite are very common in cubesats, you can buy it off the shelf
defrost|1 month ago
I first encountered space tethers in 1980 reading an Introduction to Engineering text where the example was given of unrolling a flat spool of thin metal through shaping rollers to extrude a very long boom with a spring on the end to stabilise the orientation of a satellite.
That was one of the first times I noodled about with the dynamics of a pendulum in a potential field.
These days, of course, there's a few more tricks that can be done with a dangling lasso, including interacting with the magnetic field via a looped current.
That aside, I was curious about traditional magnetorquers and their variations actively providing force in the magnetosphere.
The Earths magnetic field has a lot of diurnal pulsing .. the gravitational field is lumpy but stable.
There's a control challenge in getting a smooth desired response from a choppy field.
Cheer's for the lookout though, it hadn't occurred to me that some would be talking about magnetic force against the field using "space tether" as the base description - my background was more about the field equations than the physical implementation.
( Magnetorquers are also used in the US Navy for twisting controls inside a fully sealed container. )