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 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."

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

 * Some of the Sentry Turret's sounds were not used in the game, but can be found in Portal's Game Cache File. (For example: "Sorry we're closed", presumably when being disabled.)
 * The original Portal trailer also featured the Sentry Turrets using the same alarm sound effects as the Combine Sentry Turret. This was removed from the final version of the game.
 * In Portal 2, when Chell is ascending to the surface, the first stop involves 4 sentry turrets which do use the Combine Sentry Turret sound effects.
 * Sentry Turrets will also fire at rockets fired from a Rocket Sentry. This is not normally seen in-game, as they normally never encounter each other.
 * Unusually, Sentry Turrets will also fire at various NPCs, such as zombies and headcrabs.
 * In Portal 2, Sentry Turrets will fire at Wheatley's monitors.
 * In Portal 2, the Sentry Turret has a broken variant called the Crap Turret by Wheatley.
 * In the achievement 'No Hard Feelings' your aim is to save the Prometheus 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.
 * Amazingly, giant turrets do exist. One is seen during the ending, with a leopard skin-patterned skin. It is the same one as in the instructional video in the beginning, which showcases an animal king taking over.
 * Like the giant turret in the ending of Portal 2, there are also many types of turrets which can be found on the ending. One kind of turret is flat while another kind is fat. One even has a leopard-print pattern and a crown.
 * The fat turret can be seen in the ending of Co-op after Matthew Russell.

List of appearances

 * ApertureScience.com
 * Portal
 * Portal: Still Alive
 * Portal ARG
 * Portal 2: Lab Rat
 * Portal 2