If the warp engine is the heart of a starship, the bridge is the brain. Here the captain holds sway, directing the course and actions of the vessel. From the bridge, she/he and his senior officers can, if they need to, control every system on the ship. On most Starfleet ships, the bridge is located on the very top of the ship (of the saucer section, if the ship has one).
On most ships it can be removed in Toto at a spacedock or similar facility and be replaced with a new one, thus facilitating upgrades and maintenance. Because of its importance to the ship, the bridge is always one of a ships emergency environmental support shelters and even if both primary and emergency life support systems fail, the bridges separate systems can maintain a class M environment for 72 hours. Even if a total environmental systems failure occurs, two emergency modules provide lighting and atmosphere for 24 hours.
The major sections of most bridges include the captains’ chair, viewscreen, duty stations, captains’ ready room, and conference lounge (a.k.a. :Observation lounge). Not all ships may have all these systems; the Danube class vessel has no viewscreen, for example. Some may have even more systems; The Ascendant-class and Republic-class of Starships have expanded bridges with multiple redundant and specialized systems and stations. The Republic has expanded flight control stations, no captains’ chair, but instead replaces the central command area with a hemi-circle control area where senior officers stand and watch through a tri-fractured viewscreen. The Ascendant class is similar to an Intrepid-class bridge, but larger, mimicking the Sovereign and Frontier-class vessels also in design, with three redundant tactical stations, expanded engineering and science open ‘compartments’ on port and starboard side, an aft situation area open compartment to the aft that contains the Master System control display and related systems, including damage and auxiliary weapons diagnostic stations. The Ascendant-class viewscreen is a huge concave structure at the fore section of the bridge, giving people a nigh-panoramic view of situations.
Ships, which have saucer separation or multi-vector assault mode capabilities, need one or more secondary bridges so that the captain (or other officer) can operate the engineering section of the ship effectively. These are known as auxiliary control rooms or battle bridges. Although smaller than a standard bridge, an auxiliary control room has standard engineering, Flight Control, and Ops stations, and an enhanced Tactical station. In some cases, it als0 has several unique stations, including defense Communications, Defense Systems Engineering, Technology Assessment, Computer Systems, and Engagement Damage Intelligence. An auxiliary control room serves as a secondary command center in the event the main bridge is damaged or incapacitated.