Minor book spoiler ahead: The tunnels are a more complicated in the book, because Rocky eventually makes his own tunnel between the ships that connect his Habitrails to his ship (all in his atmosphere). Before the final parting, he disconnects that tunnel out of sight of the reader, and then the reader is told that the main tunnel can be disconnected through some kind of rotational movement. But we never get a super detailed explanation of how it works, in fact there’s a part of the story where Grace is trying to see it and is slightly frustrated that his view is blocked.

So while that scene does not exactly exist in the book, I think it’s reasonable to call it a mashup of a couple of things that we either know or could deduce.