Skip to main content
3 of 3
added 1584 characters in body
uhoh
  • 151k
  • 56
  • 505
  • 1.6k

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.

See also

uhoh
  • 151k
  • 56
  • 505
  • 1.6k