Turrets are a special vehicle in Destiny.
Strategy and Usage
The turret is armed with twin rapid-fire rotary machine guns and a frontal energy screen. Turrets are designed to destroy vehicles or groups of enemies before they become a threat to the rest of the player's Fireteam during a Crucible Combined Arms match.
If the turret is fired for long enough, it will overheat and require some time to cool down. This is long enough for the enemy to take advantage of the player's inability to fire and converge on their location.