I had a suspicion that SMART-1's trajectory would be interesting because of the ion engine, and I wasn't disappointed. In fact, I was kind of amazed...

The engine has a thrust of 0.2 millimeters/second2, which, if you'll forgive the analogy, is about the thrust you'd experience after a heavy Mexican dinner. It'll spiral out from the Earth on the first leg, then dive through a Lagrange point (usefully described as a "Weak Stability Boundary") to make the change to an orbit that can be captured by the Moon...just barely. That answers one question I had, how to brake into lunar orbit with that tiny engine. In the second phase it'll spiral inward to a circular lunar orbit.

Damn, that's fine navigatin'! The same techniques could be used with solar sails, I'd reckon.

Thanks again!