Photon torpedo
The photon torpedo, (also known as "photorps" and "photons") an imaginary weapon of science fiction, is a space torpedo armed with an matter/antimatter bomb. The concept is frequently mentioned within the fictional Star Trek, where these weapons are often part of a starship's and space station's armaments.
Photon torpedoes are launched from specific launchers. The Intrepid class starship has four launchers, two forward and two rear of the spoon-shaped saucer. These launchers can fire more than one torpedo at once. A photon torpedo is a rounded rectangle about three meters long, a meter wide, and half a meter in height. These launchers are also used to launch similarly shaped science probes and can perform burials in space.
Photon torpedoes are most useful for combat while ships are engaged in warp speed travel, as phasers, which are confined to the speed of light, are not usable.
The photon torpedo was first introduced during Star Trek: The Original Series. During the run of DS9, they began to be replaced by more powerful quantum torpedoes, and these have also been used in the more recent Star Trek films. The Romulans have never used photon torpedoes, instead relying on plasma torpedoes. Federation vessels also carry tricobalt devices which are a type of subspace weapon more powerful than photon torpedoes, but used against stationary targets.
Star Trek: Voyager had an ongoing story of a limited supply of photon torpedoes, as the necessary anti-matter was impossible to replicate.
For Federation Starfleet, there are a number of different versions of the photon torpedo with guided, un-guided, and high-speed versions. The Mark IV and Mark V torpedoes are micro torpedoes that are used aboard small ships like Danube class runabouts and shuttles.
A standard photon torpedo is said to hold about 1.5 kilograms of small pellets of anti-matter and about 1.5 kilograms of similar matter suspended in a magnetic field. Yield is reduced by including fewer pellets. The torpedoes do not have their own warp drive, but they do have a warp sustainer engine that can keep them going at faster than light speeds, if launched by a ship at those velocities.
During their mission, the starship Enterprise, NX-01, encountered two species that used photon torpedoes, the Klingons and Vissians. When the Enterprise was reassigned to the Delphic Expanse, Starfleet technicians installed these new torpedoes, which were called photonic torpedoes.