The concept of the replaceable bridge module originated during Star Trek V, 
when we were working with Herman Zimmerman on a new Enterprise bridge 
that was quite a bit different from the one seen in Star Trek IV. We 
rationalized that this was because the bridge, located at the top of the 
saucer, was a plug-in module designed for easy replacement. This would 
permit the shipÕs control systems to be upgraded, thereby extending the 
useful lifetime of a starship, and would make it easier to customize a 
particular ship for a specific type of mission. This concept also fits the fact 
that weÕve seen the main bridges of at least four different Miranda class 
starships, the Reliant (Star Trek II), the Saratoga (Star Trek IV), the Lantree 
(ÒUnnatural SelectionÓ), and the Brattain (ÒNight TerrorsÓ), each of which 
had a different bridge module.