Rocket Sentry

"The rocket really is the way to go."

- GLaDOS

The Rocket Sentry is an automated static defensive turret used in the Aperture Science Enrichment Center.

Appearance and Capabilities
Rocket Sentry turrets consist of a white-plated, spherical body mounted atop a robotic arm. Attached to a sliding panel is the rocket launcher and a sensor device that emits a blue-green laser for targeting. In addition, the turret has a large robotic "eye" in the center of the sphere that is used to indicate the current status of the turret (Green = idle, Yellow = targeting, Red = firing rocket).

The Rocket Sentry, either by the virtue of being mounted to the floor or having better armor, is unable to be destroyed by Chell. As their name would suggest, rocket sentries are armed with compact (but still lethal) rockets.

Unlike the Sentry Turrets, Rocket Sentries are unable to speak but rather produce a "lock-on" sound when they have found a target.

Tactics
After locking on, the sentry will always pause briefly, emit a loud electronic beep and then fire a single rocket after their eye turns from yellow to red. Rocket Turrets don't seem to be programed to track targets, since they will launch their rocket even if the target has moved. Thanks to this, Chell can "trick" rocket sentries into breaking inconvenient objects.

Behind the scenes
In the Portal commentary, Bill Van Buren states that the rocket sentries originally fired lasers. The team switched from lasers to rockets after they introduced the glass-breaking mechanic, mainly because glass shattering in a massive rocket explosion turned out to be a lot more satisfying than glass just slowly being melted by a laser. Originally, they also spoke, just like the Sentry Turrets. Because players often redirect the rockets with their backs to the turret, however, a distinct, uncluttered sound cue was required. The voice simply added too much noise to the rocket redirect mechanic.

Trivia

 * If the player places two portals behind and in front of the Rocket Sentry and make it fire into the portals, the rocket will fly through the portals until it hits the Rocket Sentry, and strangely vaporize.
 * Although Chell encounters quite a few turret sentries in the final few Test Chambers, the game features only two rocket sentries, both found in the abandoned portions of the Aperture Science Enrichment Center.

List of appearances

 * Portal