Recently, I saw a post from Amit Gawande on a partial failure of an Indian space mission to the Moon (communication failure with the lander, orbiting part is still working). First, I was surprised that there was any national space program still active in lunar exploration. I think that the Lunar Prospector program in 1998 was the last effort from NASA to perform lunar research (oops! looking at this page, I guess there have been a few NASA missions since then…). Second, Amit mentions that it must be getting crowded on the lunar surface with all of the objects sent from Earth. While there may be a lot of debris in a small area, to me this is still just a fraction of the lunar surface. An alien visiting the Moon would still have quite a bit of undisturbed territory to explore…