Aperture Science Sentry Turret

"Are you still there?"

- Aperture Science Sentry Turret

The Aperture Science Sentry Turret is a testing element and a fully autonomous weapon created by Aperture Science and featured in Portal and Portal 2. Sentry Turrets are used within Aperture Laboratories to protect restricted areas as well as in the testing of Military Androids and the Aperture Science Handheld Portal Device.

Overview
The Aperture Science Sentry Turret has a single red eye, sleek appearance and predominately white color scheme common to most Aperture Science technology. Sentry Turrets have only been seen in the Aperture Science Enrichment Center acting as guards in Test Chambers and maintenance areas.

Sentry Turrets often speak in a sweet child-like, artificial voice similar to GLaDOS and toilets within Aperture Laboratories. They have a strangely polite demeanor, which is in direct contrast with their deadly behavior. They will even forgive Chell for knocking them over. In one scene in Portal 2, a Sentry Turret stuck inside the Aperture Science Pipe Network attempts to get Chell and Wheatley's attention. At Wheatley's encouragement, Chell ignores it, but the Sentry Turret politely says "thanks anyway."

The Sentry Turrets are armed with dual machine guns, targeted with a visible laser beam. These weapons are normally hidden inside the body, during "sleep mode." When the Sentry Turret is alerted, they will deploy, and fire at any visible target (usually Test Subjects or intruders in the labs). When no target is in range, the Sentry will scan back and forth across the area, and return to sleep mode after several seconds if no further target is found.

Aperture-Brand Resolution Pellets, the bullets for a Sentry Turret's guns, are simply dumped into its hollow body, called the Shell Redistribution Chamber; this allows for an unusually large supply of ammunition for such a small device. Aperture-Brand Resolution Pellets are the only type of ammunition that is recommended for use with a Sentry Turret. In addition, bullets are not "fired" in the traditional sense. They are propelled, shell and all, with a spring-loaded mechanism called the Projectile Acceleration Cylinder, which is guarded by the Aperture Turret External Barrel. Since the whole bullet is fired, this allows up to 65% more bullet mass per bullet, the extra mass adding to the stopping power of the bullet.

The Personality Core of the Sentry Turret is located within the outer shell, above the guns. It is fitted with a Fire/No Fire Incident Resolution Chip, presumably to help the Turret distinguish when or when not to fire, an Empathy Generator and an Empathy Suppressor. Apparently, the Empathy Suppressor is of greater influence, as simply standing near a Sentry Turret may cause its Empathy Suppressor to accidentally activate, greatly reducing the Sentry Turret's feelings of empathy toward its foe.

The consumer version of the Sentry Turret is available in hundreds of different designer patterns and colors, including "Forest", "Desert", "Table", and "Evening at the Improv" (the latter two schemes being humorously named by Cave Johnson).

Tactics
Sentry Turrets, when idle, conceal their weapons under the two plates on either side of their body. When a gun spots a target it takes a moment to deploy its weapons to fire. A Sentry Turret's weapons are very powerful and are able to kill a human, such as Chell, after a few seconds of continuous fire.

However, Sentry Turrets can be easily spotted by the visible laser beam emitted from their eye at all times, making it easier to avoid them. When knocked over Sentry Turrets fire frantically in all directions before permanently deactivating. Like all other objects within Aperture Laboratories the Sentry Turret will disintegrate (and produce an unusual sound) if it passes through a Material Emancipation Grid.

Trivia

 * During Portal 2's chapter The Escape Chell passes through the production line for the commercial version of the Aperture Science Sentry Turret. The developer commentary states that originally, they would have had the sentry turret built and boxed, then passed into a machine directly below, that unboxes it, disassembles it, and then recycles the parts, meaning that the sentry never actually got shipped. They also would have included a massive pile of all the unrecycled packaging material, giving Aperture the most inefficient recycling system possible.
 * Some of the Sentry Turret's sounds were not used in the game, but can be found in Portal's Game Cache File, including "Hello" from Portal 2 teaser trailer and "Your business is appreciated", played when flushing the lavatory bowl in the Relaxation Vault.
 * The original Portal trailer also featured the Sentry Turrets using the same alarm sound effects as the Combine Sentry Gun, except the word "Searching", spoken with slightly modified voice from the final version. This was removed from the final version of the game.
 * In Portal 2, when Chell is ascending to the surface, the first stop involves four sentry turrets which do use the Combine Sentry Turret sound effects.
 * The hidden turret song also contains samples of the alarm.
 * Sentry Turrets will fire at rockets fired from a Rocket Sentry. This is not normally seen in-game, as they normally never encounter each other.
 * Sentry Turrets will also fire at various NPCs, such as zombies and headcrabs, if they are spawned through the console.
 * In Portal 2, Sentry Turrets will fire at Wheatley's monitors, vital to getting the Smash TV achievement.
 * Portal 2 features numerous Defective Aperture Science Sentry Turrets, either missing their casings or assembled incorrectly.
 * The achievement, 'No Hard Feelings', is earned by saving the Oracle Turret from the redemption conveyor belt leading to an incinerator. If you do so, the turret speaks several cryptic phrases, among them quoting Cave Johnson's 'Don't make lemonade' speech and mentioning Johnson's assistant Caroline.
 * Two unusual, non-defective turrets appear in Portal 2. The first is the "Animal King", used as part of a display to demonstrate some kind of non-human force dominating humanity. It also plays the bass tones during the opera at the end of the game. The second is a fat turret, which sings the opera. The fat turret may in fact be a reference to the opera saying "It's not over until the fat lady sings," in that the game isn't over until the fat turret sings.
 * The fat turret can be seen in the ending of co-op after Matthew Russell.
 * The fat turret can also be seen in the elevator that leaves before Chell's in Test Chamber 11.
 * Finally, in chamber 16, a hidden room near the entrance leads to four turrets playing a song while the fat turret watches. It can be accessed by using the Thermal Discouragement Beam in the room to destroy the turret guarding the grate.
 * The Sentry Turrets are powered by a compact fusion core. It can be seen on the caseless defective turrets, on their back.
 * The turret box states that one of the blue turrets was bought on January 25, 2010 by a person with an unreadable name. The reference to Michael Jackson can be seen on the posters.
 * In Portal 2, turret boxes indicated that turrets inside are blue, however, the machines in Manufacturing build and box white turrets.

List of appearances

 * Portal
 * ApertureScience.com
 * Portal: Still Alive
 * Portal ARG
 * PotatoFoolsDay ARG
 * Portal 2: Lab Rat
 * Portal 2
 * The Final Hours of Portal 2