Sci-fi from the 80s or before where they go to the dark side of the moon and steal an alien ship

[Raven]

A friend asked me about finding a book. They said it was probably 80s or before (possibly as old as the 50s) and the premise of the book was that a group of people traveled to the dark side of the moon, found out the truth about aliens and ended up stealing one of their ships to get away.

I haven't found anything on Google or any of the other sites and while it's ringing a bell I can't remember the full thing. I'm pretty sure it was one of those ones that gets talked about, but I haven't found the right combination of search factors to get the name.

Thank you in advance for your help.