"Solaris" the book is quite interesting. I can see why a movie would be problematic, especially in 1972, or even now, in the likely event the audience finds Crazy Ocean boring or has any sort of need for closure, as most humans do. This is probably why the filmmakers added something more than "I guess it's time to go," the End.
"Rendezvous with Rama" is comparatively dull: the alien vessel is encountered; characters and technology precise for the next situation arrive like clockwork; please buy the sequel. There, a set of three.
Both books have unknowns doing unknown things but the handling and implications are radically different.
tags #scifi