My position is that any planet in the solar system, or in the universe for that fact, has the possibility of holding an EM Field around it. Such as the sun, any number of the planets in our solar system;however weak or strong they may be.
This, in turn, leads to langrange points-One's that Elon Musk is planning on using for the interplanetary transport system.
I'm not quite sure that you understand what a Lagrange point is, because it has absolutely nothing to do with electromagnetism and everything to do with gravity (which, as of this writing, we still have no real conclusively proved way to connect the two yet). To understand Lagrange points the first thing that you have to understand is that normally the speed an object in orbit is directly linked to it's orbital distance. This is because (and I'm going to steal some graphics from xkcd right now), space is
not like this:
but instead is like this:
(To get a grasp of how fast we have to move even in a low orbit in space, if you stood at the edge of a football field and fired a rifle bullet towards the other end zone at the same time the ISS passed right over you it would have crossed the whole field before the bullet even made it 10 yards). Because of this you can't ever be in the same orbit as something unless you have the same speed, and any attempts to "catch up" to something would just result in your altitude moving you into a higher orbit, which actually slows you down due to some weirdness which is the second thing that you need to know; that when you are in orbit a "lower" altitude rotates you around the object you are orbiting faster than a "higher" one (think back to if you ever spun around in a chair as a kid and pulled your arms/legs in to speed up and then stretched them out to slow down; same physical concept applies here [if you haven't done it before then get yourself a spinny chair and do it now, I won't judge you]). As such in space if you want to "catch up" to something in the same orbit as you the actual process involves first slowing down (thus dropping to a lower orbit that lets you move "faster" around the planet than the target does) and then burning to speed up (thus moving you back to your original altitude to intercept). It's backwards seeming and weird, but that's the way it works.
Now what Lagrange points are are special exceptions that happen when you complicate the problem a little bit from our original assumption. Previously everything I've been saying just assumes you are orbiting around one single body, but in the real world you're actually largely affected by two; the planet you are orbiting directly (say Earth), and the bigger orbit around the Sun. Now let's say I want to build a space station somewhere between the Earth and the Sun so I can fill up my rocket ships there. Obviously i can't keep the station perfectly still without it moving through space, without some speed to give it an orbit around the sun it'll get sucked in! But that's not all, we have a second problem as well. Remember that objects in "lower" orbits move around the object they are orbiting faster than objects in higher orbits? If I just build my spaceport at a lower orbit around the Sun than Earth is at it will therefore quickly "pass" us in orbit around the sun and take off on it's own, rendering it fairly useless if I want to be able to reliably fill up my spaceships there. If I put the spaceport at one of the 5 "Lagrange points" though, then something nice happens; the gravitational forces from the bigger object (the sun) and those from the smaller object (the earth), work against (or with) each other a little bit to change the effective altitude of my orbit, thus causing a change in the "speed" of the orbit at that point to perfectly match that of the smaller object. In other words, if I put my spaceport at any of the Sun-Earth Lagrange points, then it ends up having an orbital time around the sun of 1 year, which is exactly the same as the earth's! This means that we can always be sure that our spaceport is only a short distance away from the earth where we need it to be so we can refuel our spaceships, without it wandering off on it's own due to taking a different amount of time to rotate around the sun than the earth does.
As you can see, this doesn't have anything at all to do with the electromagnetic force at all (barring some sort unified field theory that we haven't gotten around to showing good evidence for yet that unifies them at a low level), and is wholly confined to the forces of gravity, velocity, and momentum.
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