I was looking at some diagrams for the Apollo spacecraft, which I found to be interesting. It's clear that there's two separate enclosures that astronauts could reside in (the lunar module and command module). However, there is a massive rocket nozzle in between each habitable enclosure. This leads me to a few related questions.
Where and what kind of design was in place to allow the astronauts to safely move from enclosure to enclosure? How did the astronauts traverse them? Were there any restrictions? What sort of precautions and safety mechanisms were in place to keep the astronauts safe when a lower section of the craft was discarded through the various stages?