I would say "this is what you would get as an illustration for sci-fi work (be it movie, story, magazine or book cover) in times before Star Wars". E.g. note the "countdown" element. I'd have to check if this guy made Polish covers for Daeniken's books or "Fantastyka" magazine (LOL, my Dad subscribed it, we even had the first issue, rare early sci-fi stuff here), as this ESB poster looks strangely familiar...
One thing that puzzles me is that this guy was probably already exposed to Star Wars (he did ANH poster), so... ?