The first capsules had windows in the walls, because that is where windows go in buildings. Guests spent their voyages with their necks twisted, looking sideways at a planet that seemed to hang beside them.
The station’s crews worked out the better answer decades ago with the cupola: put the window on the side facing the Earth, and let people look down. Our dome takes that idea and gives it to four people at once. It is eighty centimetres across, made of seven panes of fused silica four layers deep, and it is set into the floor of the cabin so the planet is where your body expects the ground to be.
Each pane has its own shutter, against micrometeoroids and against the sun. They open one at a time after the engines stop, which is why every guest remembers the first pane.