Why crash asteroids on the Moon when its surface is covered in impact craters from ancient strikes. The moon is geologically dead and has no atmosphere, so anything kicked up in those old impacts should still be around.
Hmm, interesting. I was thinking that we could mine fresh debris from the asteroids themselves, in concentrated form. Plus saving the earth, of course.
GP's point is that plenty of asteroids have crashed into the moon in a recent enough time frame that the debris is still "fresh". After all, there's not much erosion on the moon.
