Bay Door Control

Bay Door Control (BDC) was responsible for opening and closing bay doors on the first Death Star. They checked all orders by departing crew and checks the flight plan with Flight Control. Only if valid does the officer in charge give the order to produce a force field in the bay, strong enough to hold in atmosphere but permeable for ships to cross. Afterward, the doors close and seal shut and the force field is turned off.

Text and facts from the “Bay Door Control” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.