Eg, vintage photos such as these?: Interesting photos of Moon: "Vintage NASA Photographs 1964-1972"
What I think we really need to do is figure out how to make direct observations better. Can we enhance telescopic captures further? The ripple that has been observed is concerning in that there may be a kind of field of force or image overlaid over the Moon so as to eliminate our being able to see what is going on there. So, so, so many strange things about the Moon that we just ignore because of it's ever-presence and commonness.