I'm a huge fan of the film, having absorbed many details and minutia surrounding it's filming/effects, and I can't recall ever seeing or hearing anything related to where the Aries docked to pick up Floyd.Exactly! And the original poster doesn't help either Again: Orion is too big to accommodate another space ship in there.
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You would think that there must have been a discussion about it - between Kubrick/Clarke and/or effects team? Someone?
It's as mysterious as the monolith.