# Satellites and Magnetic Fields

I remember (long ago) a high school physics test question if satellites are affected by the earth’s magnetic field. Since then, I Googled it can induce about 0.2 volt increase*. But, is there an uncomplicated answer to how this doesn’t play havoc with sensitive instruments and circuitry?
(If not the induced potential per se, then what about a small induced current?)

*I wager it may actually induce voltage ranging from -0.2 to +0.2 volts?

ObDisclaimer: I don’t design satellites. I design satellite ground systems, so I know something about satellite design (mostly by sidelong exposure).

There is significant shielding that protects most of the electronics from induced current, even in event when there is significant electrical differential charging from near-earth charged particles. Magnetic induction is comparatively mild and easy to design around.

ETA: there’s even a satellite attitude control method that uses the Earth’s magnetic field to align the spacecraft as desired.

I don’t even design satellite ground systems, but I think the best approach to this would be to start by thinking about in what specific manner induced currents from orbiting in Earth’s magnetic fields could be naively hypothesized to influence sensitive electronics and sensors. I think for most of those it wouldn’t be that hard to then add in some details of the actual nature of a satellite to show that they’re not an issue.

Yes, a conductor moving through a magnetic field will induce a voltage. And that voltage will cause current to flow… but that current will result in a buildup of charge on opposite ends of the conductor, which will also induce a voltage, opposite of the induced one. It wouldn’t take very much built-up charge to completely cancel out the induced voltage, and that charge is going to have somewhere in the neighborhood of 45 minutes to build up (half an orbit, after which it’ll start flowing in the opposite direction, assuming that the satellite is designed to always keep the same end pointing towards the Earth and that it’s in a polar orbit, the worst-case scenario). Not-all-that-much charge divided by 45 minutes equals a very small current, most of which is going to be carried by the metal body of the satellite.

Isn’t the effect proportional to the length of the conductor as well - which means for the size of a typical satellite, there is even less of an effect?