Bunker Door

Bunker Door is a slow, double-and-a-half-sized airlock, that can be controlled with Automation signal, but cannot be used by dupes manually. Like Bunker Tiles, it does not take any damage from meteors, so it can be used to protect the surface against Meteor Showers using a Meteor Scanner. The door takes 44 seconds to open and 39 seconds to close when powered. It will still open and close without power, but it will take approximately 400 seconds. Thus they require at least 2 Scanners to close in time when powered and cannot close in time when unpowered. Using unpowered doors might be enough when rockets are considered, but detrimental when protecting Solar Panels, since it takes longer than a cycle to reset their state.

Tips

Bunker doors can support buildings, and thus allow to stack rockets on top of each other safely.
Bunker doors do not change state until the animations finishes, e.g. a closing bunker door will still let meteor/light through until it fully closes.
Once open, even the edges do not block rockets, so you can put 2 of them next to each other to have a 8 tile door.

Bugs

The opening/closing animation is not recorded during a save. This means if the game was to be reloaded midway through the opening animation, the animation will reset and will take another 45 seconds to open.