Torpedoes were primarily used in space combat as an alternative to directed energy weapons such as disruptors and phasers. Torpedoes could be configured before launch to fit various specifications. Normally a torpedo was equipped with a warhead, and the explosive yield of this warhead could vary depending on the type of torpedo. Torpedo launchers brought the weapon into the launch tube and allowed fire control from the ship's bridge, although a torpedo could be launched manually. (TNG: "Masks"; VOY: "Future's End, Part II") Most of the time a tactical officer was responsible for target acquisition and launch sequence.
The maximum effective range of a torpedo depended on its type. Range was dependent on propulsion and acquisition capabilities. Propulsion was categorized basically by whether the torpedo was warp-capable or used another method of propulsion. Some types of torpedoes were equipped with a self-destruction mechanism. For those types, if a torpedo needed to be aborted and destroyed, due to, for example ,a targeting acquisition problem, it could be destroyed.
The torpedo guided itself via internal sensors that could be configured by the tactical officer. (TNG: "Genesis") The advantage was that a firing pattern could be established whereby multiple torpedo launches could be coordinated to hit a single target and thus make the best use of every torpedo's explosive yield. (TNG: "Pen Pals") When necessary, the device's internal sensors could be replaced by specialized sensor packs, allowing for additional flexibility in use; for example, using a sensor pack designed to detect gaseous anomalies could enable a torpedo to lock onto impulse engine emissions. After configuration, the torpedo could be fired and would automatically acquire its target. (Star Trek VI: The Undiscovered Country) Some torpedoes featured advanced artificial intelligence to make the decisions about target acquisition, defensive maneuvers, etc. (VOY: "Warhead")
Torpedoes were used by different species and varied in type, appearance, explosive yield, and effective range. There were several types of torpedoes:
- Antimatter torpedo - an antimatter weapon, used by Kelemane's species
- Chroniton torpedo - a torpedo in temporal flux, used by the Krenim Imperium
- Gravimetric torpedo - a heavy weapon with a gravimetric charge, used by Starfleet
- Photon torpedo - the most common type of torpedo, used by multiple species
- Photonic torpedo - an antimatter weapon, used by Starfleet and the Vissians
- Plasma torpedo - used by Romulan, Cardassian, and Kazon forces
- Pulse wave torpedo - a torpedo used to disrupt anomalies
- Quantum torpedo - an advanced weapon, used by Starfleet, the Terran Rebellion, and the Cardassian Union
- Series 5 torpedo - an antimatter torpedo with artificial intelligence developed by the Druoda
- Spatial torpedo - Triton-class spatial torpedoes were used by Starfleet in the 22nd century
- Stratospheric torpedo - a torpedo used in planetary atmospheres, used by Starfleet and the Maquis
- Transphasic torpedo - an anti-Borg weapon, originally developed by Captain Kathryn Janeway in an alternate timeline