Why would there be apparent evidence of extraterrestrials having landed on the Moon without much sound evidence of extraterrestrials visiting the Earth?
The Moon would be an excellent location at which to leave an 'alert' beacon, to send a message back to ET thzt the intelligent life on the parent planet of the Moon has finally stepped over the threshhold and into space.
From the story, I gather they wouldn't be looking for evidence of extraterrestrials who actually landed on the Moon, but for tiny bits of debris from their activities in space which drifted for eons between the stars (or even between the galaxies), finally entering our solar system and crashing into the Moon. Possible of course, but it sounds very, very far-fetched to me! Almost a waste of time. Now if you see a big chunk of something on the Moon's surface, that's different. But who wants to waste their life examining every grain of sand on the Moon looking for something that had to be made by ET?
A lunar insertion and landing might be a lot easier than
entering earths atmosphere and returning to orbit.
Why just the cost of fuel alone....
Besides you wouldn't have to worry about interuptions or
men in black.