> what's the state of solar powered magnetorquers these days?

Academic. We don't currently have a pressing need for reactionless thrust in the magnetosphere. Each of semiconductors, launch vehicles and telecommunications standards are moving faster than satellites last.

Thanks for the reply.

> Each of semiconductors, launch vehicles and telecommunications standards are moving faster than satellites last.

That's certainly a pragmatic cost based argument for not using them in the fast moving world of commercial magnetosphere constellations.

> Academic.

I feel they've moved past academic and transitioned to deployed .. at some evolution of implementation. Not commercially relevant is certainly one state of play.

I guess I was more interested in the nonlinear control issue in a field of highly variable intensity.