Well, impacts. I suppose that a vertical hit at interplanetary speeds (or earth-orbit speeds, that high up) will leave a nicely clean hole, but think of the eno

Well, impacts. I suppose that a vertical hit at interplanetary speeds (or earth-orbit speeds, that high up) will leave a nicely clean hole, but think of the enormous cut made by something coming in on a trajectory that would slingshot close to the moon surface if the bubble wasn't there. Sure, with technology indistinguishable from magic you could still do it, but i don't known if there would still be much incentive for building the bubble left in that case.