What if the craft itself had a magnet at the rear, with an equally sized magnet that you could either bring towards the craft to propel forward ....or controlling it away from the ships magnet to reduce the “push” between the two and eliminate the propulsion .... granted it would probably be long and the magnets would be tremendous in size. such a thing has to be possible to do in space, right? Controlling the distance between two giant magnets to propel a craft forward?

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    $\begingroup$ This is functionally no different than trying to fly by standing in a bucket and pulling upwards on the handle. $\endgroup$
    – TCAT117
    Mar 2, 2018 at 5:35
  • $\begingroup$ Yes, if it's used as a coilgun... en.wikipedia.org/wiki/Coilgun but this is far from what you describe. $\endgroup$ Mar 3, 2018 at 4:53
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    $\begingroup$ I'm voting to close this question as off-topic because it is really a misunderstanding of basic physics, not space exploration. $\endgroup$
    – Rory Alsop
    Mar 3, 2018 at 13:29

1 Answer 1


This can't work.

Please refer to the image below of my patented MagnaRocket.

enter image description here

The magnetic repulsion force pushing on the magnet at the rear of the MagnaRocket....also pushes back just as strongly on the magnet attached to the purple arms.

If you move the patented purple HingyArms to move the magnet closer, or further away, the magnetic force changes, but it still is the same on both magnets.

Net force...zero. Motion....zero.

(Note: MagnaRocket and HingyArms are not really patented)

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    $\begingroup$ What about the patent pending, magnetic carrot and stick. Where you have a metal rocket, and a magnet on the end of stick. The magnet attracts the rocket, but the stick (which is attached to the rocket) moves the magnet.... \s $\endgroup$ Mar 3, 2018 at 4:51

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