[inquest]

So in effect, the apparatus creates a huge magnetic sail for the solar wind to blow the thing to Mars. But then how do they get back to earth?

[Ahban]

I e-mailed one of the profs about this. He gave a highly technical answer. I forget the details but the gist of it was that you "tack" (tach?) back like a sailboat when the Earth is in a position relative to Mars so that Earth is not directly towards the Sun, but off at an angle. He said the field could be adjusted to allow for this sort of sideways pushing.