Airlocks serve as the entrance and exits to spaceships, whether it is docking with another ship or for extravehicular activity (EVA), without compromising the atmosphere of a spaceship. They consist of a hyperbaric chamber with a pair of airtight doors, one allowing access to the ship's interior and the other to the vacuum of space. The chamber can be pressurized and depressurized in a controlled fashion. A Viper launch tube constitutes a form of airlock with additional features for the rapid deployment of Vipers.
Airlocks obtain notoriety as a method of execution, particularly following the Fall of the Twelve Colonies.
Airlocks on Battlestars
Airlocks on Galactica have at multiple configurations, including one featuring an observation booth from where a depressurized airlock can be safely monitored by personnel. Some airlocks feature shared layouts as a launch tube's control room.
Uses Aboard Galactica
Cally and Galen Tyrol were trapped in airlock 12 on deck 14, after Galactica's computer automatically seals its blast doors due to pressure loss. In order to affect a rescue, the two had to be "airlocked" when the bulkhead was blown and the two crewmembers were summarily recovered via a nearby Raptor. Both survive the brief exposure, although Cally was seriously injured during the decompression (TRS: "A Day in the Life").
During Gaeta's Mutiny, Galen Tyrol directs Lee Adama, Kara Thrace, Laura Roslin and Gaius Baltar to the Secondary Storage Bay, so that Admiral William Adama and Colonel Saul Tigh may escape capture by Felix Gaeta's mutineers via a Raptor dispatched by the Rebel basestar. Tyrol recalls that the location possesses an abandoned and forgotten airlock damaged in the Battle of New Caprica, but brought back online by Tyrol for his plans. Roslin and Baltar abscond via the Raptor, while Tigh and Admiral Adama stay behind to defend the airlock and give Tyrol, Lee, and Thrace time to use the vents to escape into the bowels of Galactica (TRS: "The Oath", "Blood on the Scales").
During the Battle of the Colony, Galactica crashes its nose through the side of The Colony, allowing a strike team made up of Marines and Rebel Centurions egress through one of Galactica's bow airlocks. After rescuing Hera Agathon with assistance from Sharon "Boomer" Valerii, and subsequently linking up with Thrace's fireteam, the rescue team ingresses through the airlock (TRS: "Daybreak, Part II").
Use in Corporal Punishment
Ejecting a person from an airlock or launch tube is a common and easy execution method (TRS: "Flesh and Bone", "Collaborators") and the phrase "throwing someone out of an airlock" has gained some notoriety due to Laura Roslin's preference for spacing Cylon agents in this manner (TRS: "Flesh and Bone", "Lay Down Your Burdens, Part II"). Much to Gaius Baltar's dismay, Roslin suggested throwing Hera out an airlock, in order to prevent the Cylons from obtaining the hybrid (TRS: "Downloaded"). Although seen as a quick execution, whether it qualified as humane is open for debate given Adama's comment that human survival is possible for up to a minute in a vacuum (TRS: "A Day in the Life").