This came up on my YouTube, you can watch here: https://www.youtube.com/watch?v=Z8ZhQPaw4r
Interesting, it's the Soviet answering to and picking up where 2001 - A Space Odyssey left off.
The plot, in a nutshell, revolves around a trio of astronauts in orbit about a planet that appears to be alive, and capable of reading their unconscious thoughts and returning them to the station in human form.
In a sense a little like "Stalker". And a bit of horror, in that your unconscious thoughts can take physical shape and haunt you...
Notes; that while Tarkovsky spends a lot building a mock-up of a space station, it's entirely irrelevant to the situation at hand, which is - in a nutshell - how can we make and sustain a meaningful contact with an alien species when we so poorly understand ourselves?
It's merely a backdrop to tell a very different sort of story.
It doesn't bog itself down with irrelevant science techno-babble to try and explain what's going on, it's merely the dynamic of a group of people that are in a situation they are at a loss to explain...
Noteworthy, the long traffic sequence, blood through veins, how we are as well a part of a larger organization we can’t expect to comprehend, as well the folly of man's vision, as evidenced by the illustration torn from "Don Quixote", that all this science, exploration, is a fool's errand...
Anyways, curious, Canon, but probably not for everyone. But I notice his "Mirror, Mirror" is also on YouTube, and so that might be my next watch...