Circling back to Solaris's author, I just read another of his books, "The Invincible," described as a "hard science fiction novel," which, fair enough. It reminded me a lot of Jules Verne, and a bit less of H.P. Lovecraft's "Mountains of Madness." The writing quality is absolutely ace (bearing in mind I read a translation from the original Polish), it seems less philosophical and more scientific-technical than Solaris (the films, haven't read the book). Some major scifi tropes (notably militaristic themes) are attributed to Lem, and recognizable in literally dozens of derivative works.
Interesting that Lem hated Tarkovsky's first screenplay for Solaris, as did the soviet authorities, so T had to go and write another.
I have a British Film Institute account for their online streaming thing, and Stalker is critic Mark Kermode's film of the week. Amused to notice that the crew ran out of booze (and other provisions) during filming and resorted to drinking cheap cologne mixed with sugar. Much drunkenness ensued. Tarkovsky sacked his art director on a charge of "behaving like a bastard".