Yes, the "telescope to the moon"-idea comes up again and again. I use the argument, that the mirror of such a contraption should be around 50 times the diameter of the HST's mirror to make a descent stage one single pixel on a camera equal to the HST's best.
And it would have to be outside the atmosphere as well, adding to the impracticality of such a thing. Far better to do what LRO did and send a much smaller telescope much, much closer.
