# Can I avoid a magnetar with an electromagnet?

Magnetars are generally accepted as existing. Wikipedia suggests that the magnetic forces are strong enough to kill you.

I am assuming that virtually any spacecraft would have some magnetic properties vastly in excess of that its inhabitants. A steel hulled spaceship would thus be attracted to the magnetar long before its inhabitants would be threatened.

This brings up the question of avoiding a magnetar. Obviously, a spaceship with propulsion could just use its engines to offset the force from the magnetar. Given that the force between to magnets is proportional to the magnitudes of the magnetic poles, could we use an electromagnet to offset the intrinsic magnetism of the spaceship? The magnetar would essentially behave like a giant point source of magnetism at a distance. The electromagnet would need to be "pointed" at the magnetar to offset the force. Depending on the rotational velocity of the magnetar this could be challenging. As long as the spacecraft was not highly magnetic the electromagnet would not need to be significant in size.

The electromagnet would work if you were still far away enough that you could overcome the force, but you'd probably want to cool superconducting coils sufficiently and insulate them from incident radiation and heat from your ship.

If you tried to use copper coils, you'd need a lot of electrical power because of the $I^2R$ losses, and then they would melt because there's no way to cool them sufficiently in space.

Instead, I'd use the Meissner effect and just bounce off the magnetic field of that pesky magnetar, or any sufficiently strong magnetic field gradient. Maybe even use it for propulsion if someone hasn't patented that already.

It's the size of the gradient of the field that you need to pay attention to. There is no net repulsion from a uniform field if you have become superconducting in a low-field volume of space. But beware - you must cool your superconductors down before you get into a high field region, otherwise you'll get stuck with a strongly magnetized ship. You could use that for propulsion too!

I suppose you could use thrusting maneuvers to rotate from attractive to repulsive orientation if you had very strong attitude thrusters. This sounds like the beginning of a cool video game - especially if you start visualizing the field lines in real time in VR. Wait - shhh... don't tell anyone :)

Image from Wired article

Why do I suddenly get the feeling I've been duped into advertising something?

• I'm doing the math and plotting now for a spacecraft trying to deflect itself from a Magnetar... stay tuned!
– uhoh
May 21 '16 at 12:46
• It seems I haven't yet, I should get back to this.
– uhoh
Jan 21 '21 at 23:32