Re: Cupola, Windows in space?
I am not a rocket scientist, but here's my guess.
Pressure is one part of it. The pressure exerted by the deep ocean on a submersible is many times higher than the pressure exerted by the atmosphere inside the station. However, the ocean pressure is inward relative to the submersible but outward relative to the space station. I seem to recall the shuttle is pressurized to less than one ATM to reduce the stress on the hull, and I would not be surprised if the ISS did the same thing.
The other thing is debris. At orbital velocities, even something as small as a paint chip carries a lot of kinetic energy. A piece of metal hit by such a particle could deform on impact, cushioning the blow, maybe even springing back to shape if the hit was small enough. Glass would be more likely to chip or crack. I imagine that the cupola resembles those on tanks and other armored vehicles is entirely on purpose.
In the event that a pane is damaged, it seems like it would be more easily covered if you only have to patch over one port to keep your atmosphere contained rather than a whole dome, too.