An Apollo lunar module prototype on display at the Kansas Cosmosphere:
Looking at this piece of history, it’s amazing that its builders could get this to hold an atmosphere for its occupants — but this is very nearly the same design that flew on the Apollo lunar missions. The only significant difference is the shape of the forward hatch — this one has a nearly-round shape (for commonality with the docking port hatch), while the as-flown forward hatch is roughly square. It turned out that the round hatch didn’t give a suited astronaut enough room to pass through with his life support backpack on.
