There will be no gain of energy from the flyby.. If the source magnet is fixed. Thus I was wondering just how energy can be taken by a satellite in the socalled slingshot flyby of Jupiter to propell it further from the Sun... That gravity and magnetism are different forces should not alter the basic premise that energy gained by a fall is recovered during the climb... or visa versa.. Didn?t we discuss this before? The space probe flyby borrows energy from Jupiter?s motions, so the probe speeds up while father Zeus slows down (infinitesimally). The Jupiter-probe system conserves energy. Philip. This is another potential GS proof: An Earth flyby will not cause any speed change, since the Earth has no kinetic energy to transfer! [Is anyone keeping track of all these?] Robert