[Edwina Lee (OP)]

Is it possible to use the earth's magnetic field to move around in space, or even take off from earth?

What about using generated magnetic or electric fields to alter orbits ?  Is it already being done?

[Colin2B]

Is it possible to use the earth's magnetic field to move around in space, or even take off from earth?

The earth’s magnetic field is very weak compared to the force required to move a spaceship. It can move a magnetised needle on a low friction support, but anything heavier like a bar magnet on a desk doesn’t move. Also even a weak bar magnet will easily overpower the earth’s field and influence a compass needle
As we get further from earth the earth’s magnetic field gets weaker, but a magnet will still be able to align along the field see

Notice how the magnet is stronger than the earth’s magnetic field.

[evan_au]

Large satellites use gyroscopes to maintain their orientation in space.

Gyroscopes are a bit too heavy for tiny satellites, so small satellites in Low-Earth orbit generate a magnetic field, and work off the Earth's magnetic field (as illustrated by the astronaut).
- Unfortuantely, this won't give you propulsion, only orientation.
See: https://en.wikipedia.org/wiki/Magnetorquer
https://en.wikipedia.org/wiki/Control_moment_gyroscope

Is it possible to use the earth's magnetic field to move around in space

Yes, in a very limited way.

It has been suggested as a way to de-orbit old satellites in Low Earth Orbit, or to boost the orbit of satellites in Low-Earth Orbit, or even generate electricity in Low-Earth Orbit, using an electrodynamic tether.
- This has been tested from the Space Shuttle
- You don't get something for nothing; if you generate electricity, you lose orbital height; if you want to gain orbital height, you have to inject electricity
- I think the main concern is that a (say) 10km tether hanging in space would be a major obstacle to satellites in passing orbits. I think it would destroy too many satellites, and increase space shrapnel.
See: https://en.wikipedia.org/wiki/Space_tether

Is it possible to use the earth's magnetic field to ...take off from earth?

I can't see how this is possible - the Earth's magnetic field is too weak.

It is conceivable that a superconducting accelerator built in a vacuum tunnel up the side of a high mountain could launch satellites into orbit - but the mountain would need to be very high to get above most of Earth's atmosphere.

[Petrochemicals]

I assume the energy you are hoping to create is due to your movement through the field ? This is a law of physics that escapes me at the minute but it had something to do with an airplane oving through the earths magnetic field and how much charge it would create its also constrained by energy conservation, basically you have to put energy in to the movement to get the electrical energy out.

Is it possible to use the earth's magnetic field to move around in space, or even take off from earth?

The earth’s magnetic field is very weak compared to the force required to move a spaceship. It can move a magnetised needle on a low friction support, but anything heavier like a bar magnet on a desk doesn’t move. Also even a weak bar magnet will easily overpower the earth’s field and influence a compass needle
As we get further from earth the earth’s magnetic field gets weaker, but a magnet will still be able to align along the field see

Notice how the magnet is stronger than the earth’s magnetic field.

How about the radiation fields ?

[evan_au]

How about the radiation fields ?

The Sun's radiation has been used experimentally to move spacecraft, with a solar sail:
https://en.wikipedia.org/wiki/Solar_sail

Cosmic rays carry a massive momentum for nucleus. However, they arrive randomly from all directions, so they are not very useful for controlled propulsion.

LEO (Low Earth Orbit) is shielded from most of the Sun's Solar wind by the Earth's magnetosphere. What remains is mostly low-density charged particles spiraling down the Earth's magnetic field lines towards the north & south magnetic poles. Since this doesn't provide a very consistent thrust to a satellite in orbit, it's hard to see how to use this for propulsion.
See: https://en.wikipedia.org/wiki/Magnetosphere#Earth's_magnetosphere

[Edwina Lee (OP)]

Suppose ions are shot into the orbits of space-debris. Would the debris pick up the ions?
If so, would they not act as a brake against their orbital speed in earth's magnetic field?

[Petrochemicals]

How about the radiation fields ?

The Sun's radiation has been used experimentally to move spacecraft, with a solar sail:
https://en.wikipedia.org/wiki/Solar_sail

Cosmic rays carry a massive momentum for nucleus. However, they arrive randomly from all directions, so they are not very useful for controlled propulsion.

LEO (Low Earth Orbit) is shielded from most of the Sun's Solar wind by the Earth's magnetosphere. What remains is mostly low-density charged particles spiraling down the Earth's magnetic field lines towards the north & south magnetic poles. Since this doesn't provide a very consistent thrust to a satellite in orbit, it's hard to see how to use this for propulsion.
See: https://en.wikipedia.org/wiki/Magnetosphere#Earth's_magnetosphere

I was thinking about the VanAllen radiation belts really Evan.