Sorry, I realize that this isn't a lot to go on, but here goes...
This was a book I read in late 80s or early 90s and was supposed to be the first book in a series. The book or the next in series may have been scheduled for 1989.
As I remember, the bulk of the story occurs in a star system that humans have recently discovered. The system contains a very large alien device (perhaps a space station). A previous human visited the device and had his memory erased, leaving him in an almost baby-like state.
I think the story revolves around two protagonists who arrived in the system after the first human was wiped (I could be wrong about this point). They try to decide how to proceed, and some major plot point towards the end of the book causes one or both of them to decide to go to the alien artifact.