What goes around comes around...

Message A while back I made the comment on a space newsgroup that one wouldn't have to worry about the pellets coming back because the exhaust velocity would be in excess of solar escape velocity. Someone posted to say that was crazy, and that there'd be no reason to make the enormous investment in energy necessary to accelerate the reaction mass to solar escape. I don't know that they were looking at the specific exhaust velocityproposed in the High Frontier studies that got published or just expressing their own opinion. I've noticed thetendency of many to substitute their own opinions for many of the recommendations published in the NASA-sponsored studies. I posted to say that I was working off of memory, and allowed that I might have misremembered what I read and perhaps it was only stated that the exhaust velocity was in excess of Earth escape. That might satisfy many, as at least the pellets would leave cislunar space. But if the exhaust was only just barely in excess of Earth escape, I suppose the scenario you raise could come about. Does anybody know the specifics of the mass-driver tug exhaust velocity?