# What are the forces affecting superconducting MRI-magnet on low-earth orbit and could you accelerate a satellite with these forces?

In superconducting magnetic levitation the magnet levitates on top of the superconducting material (Meisner effect). In space, the electric current of the solar wind should create a magnetic field because of Faraday's Law of induction (positive particles accelerating against gravity to move away from Sun).

Suppose we pack an MRI machine superconducting magnet on a StarShip and turn it on after it has been released into circular orbit around Earth with some thruster control of the orientation of the craft and remote control of the magnet's orientation itself. How does the interaction of the superconducting magnet with the magnetic field in space affect the orbit of the craft? Is there a simulation tool to test this / calculate the amount of force?

Suppoce we pack 6 magnets and orient them as the planes of cube with gimbaled attachement. Would this allow us to generate thrust and rotational control by pushing against the magnetic field in space?

Anybody has a Jupyter Notebook about relevant physics or recommendations about a (free) simulation tool?

• I’m voting to close this question because it belongs on Physics SE. Nov 17, 2021 at 15:20
• I have made a few edits to improve the readability. Feel free to revert to the original text if my edits are incorrect. Nov 17, 2021 at 15:24
• @fasterthanlight "because it belongs on..." is not a close reason. "Is off-topic here" can be a close reason.
– uhoh
Nov 17, 2021 at 21:02
• It's only the last question that looks off-topic. The rest seems on-topic for me. Nov 18, 2021 at 9:35

There is a good question here, but there are also things that won't work.

"Can it be used for space propulsion" is certainly on-topic so I'll write a short answer to that...

Suppose we pack 6 magnets and orient them as the planes of cube with gimbaled attachment. Would this allow us to generate thrust...

No, see below

...and rotational control...

Yes!!!

See

Suppose we pack 6 magnets and orient them as the planes of cube with gimbaled attachment. Would this allow us to generate thrust and rotational control by pushing against the magnetic field in space?

No, not really.

In a small region of space, say a few tens of meters, a few hundred kilometers above the Earth, the Earth's field is extremely close to uniform; it points in essentially the same direction within this volume, with the same strength.

With a dipole field we can not "push" against a uniform field. There will be a torque and magnetotorquers were are all the time in spaceflight.

The reason maglev trains work, or the reason that you remember two permanent magnets with the same poles facing each other push away from each other, is that both are strongly nonuniform. The two dipoles will be strongly repulsive when they are close, and weaken as the distance increases just a little bit.

Maglev trains work by balancing forces produced by extremely strong gradients in field strength.

Think about it. You have a dipole permanent magnet in your hand, and you sit in Earth's nearly uniform magnetic field. You lay it on the table, you don't see it roll away because it's "pushing" on Earth's field, right?

The compass in a hiker's pocket doesn't scoot around on the table. It may twist and turn, but we don't have to hold it down to keep it from moving.

There's no measurable force because Earth's force's gradient is extremely weak, roughly 1% every 20 kilometers vertically.

So no, magnetic space propulsion is not really a thing.