Kevin, I agree that the earth's field is miniscule, but that wasn't really the mechanism for orbital change that I was proposing. I was really thinking (?) about the interactions between the earth and the sun's ( or another planet...Jupiter?) magnetic fields. The Earths field is not a classic dipole system, and continually changes with (solar) activity. My thought was maybe these changes could be utilised to very slowly change the crafts attitude and increase its apogee. The magnet/coil systems presently used to control attitude do interact with the earths field, but this is done to maintain a reasonably stable orbit. If the units could be operated to coincide with changes in the fields encountered in space then the orbit will change! The trick would be predicting when to operate the systems to give the desired result. This would be immensely complicated but I suppose dreams are free.
This link may be interest, it shows some of the research being done in this area. I'm sure there are others, NASA has some good stuff as well.
http://www.esa.int/esapub/bulletin/bulletin121/bul121b_laakso.pdf
Thanks for your previous reply.
Don Zl1THO