Plasma torpedo

"The Covenant cruiser came about to face them. Its plasma turrets glowed like angry red eyes."

- Description

The plasma turret, also known as a plasma cannon, is a weapon used by most Covenant warships. It fires magnetically guided bolts of plasma, referred to as plasma torpedoes, that can strike at exceedingly long ranges. Along with the pulse laser turret and energy projector, it is one of their primary ship-to-ship weapons. Upon contact, a plasma torpedo causes severe damage to the target, boiling armor or overloading shields. The weapon can be used in conjunction with pulse laser turrets and energy projectors to decimate entire UNSC fleets, and can be used in ground assaults as well.

Design details
The plasma turret itself is antenna-like in appearance and is installed on universal joints often located along the lateral sides of the ship. The beam is red, purple, or blue and short with a ball-like head and a trail. The turrets, from afar, usually appear as short spikes on the sides, the upper sides, and the bow of the vessel. On larger ships, the plasma is collected into visible lines located along the surface of the exterior hull before firing.

The size and power of the plasma turret depends on the vessel; the plasma turrets mounted on smaller ships such as corvettes are less powerful than those on larger vessels such as battlecruisers. In addition, the plasma turrets mounted on corvettes only appear to be able to fire their torpedoes in a straight line, while the tracking systems on larger warships are far more sophisticated.

Operation
Plasma is heated in a pinched magnetic field by energy supplied from the ship's pinch fusion reactors. The atoms that are on an appropriate trajectory between the Covenant starship and its target are then herded towards the mouth of the turret through a series of plasma conduits by magnetic pulses. Magnetic coils shape and guide the plasma, acting as a sophisticated focusing lens. When the weapon charges, a line of superheated plasma forms alongside the exterior plasma conduit adjoining the turret. Once fully charged, the plasma fires outward at its target. The torpedo is guided towards its target by a long-reaching magnetic field projected by the emitter. Upon impact, the torpedo penetrates most unshielded starships, burning through internal decks and structures, thus causing heavy damage on the target.

They are extraordinarily accurate; one of the only ways for UNSC ships to even temporarily avoid them is to use emergency thrusters to "dodge" incoming plasma torpedoes at the last moment. Particularly strong magnetospheres, such as those of gas giants, will disrupt the magnetic field holding the torpedo together, dissipating the plasma and rendering the torpedo harmless. The dust and vapor from missiles detonated close enough to the ship may also absorb the energy from a torpedo, rendering it harmless. When the damaged Ascendant Justice entered the atmosphere of Threshold, the massive wake of superheated gases trailing the ship scattered the plasma torpedoes fired by pursuing Covenant vessels.

The attacking ship must lower a section of its shield in order to fire the torpedo, otherwise it would detonate inside the protective barrier. John-117 used this weakness to temporarily blind a Covenant cruiser with a Longsword and to penetrate the shields of the Ascendant Justice.

Guidance
Plasma torpedoes can be manually guided from a weapons control station on the bridge, by using holographic "steering spheres" superimposed over a holographic display of the space surrounding the ship. The plasma torpedoes and steering solutions of an enemy ship are similarly shown on the display. Covenant corvettes also feature manned control stations from which each turret can be operated individually. The Covenant have also developed "counter guiding signals", a form of electronic countermeasure that disrupts the guidance control of an enemy ship's plasma torpedoes.

If the firing ship is destroyed, all plasma torpedoes guided by its magnetic fields are detonated prematurely or fly about aimlessly. However, it appears that torpedoes are sometimes able to hold together for a small amount of time, as demonstrated during the Fall of Reach, when fired torpedoes destroyed UNSC orbital defense platforms even after their firers had been destroyed.

Tactics
Volleys of plasma torpedoes are frequently the first attacks launched by Covenant fleets when engaging enemy forces at long range. They often decimate enemy ranks upon impact. They emit visible radiation, giving them an amber color but volleys are visually akin to solar flares due to the sheer number of torpedoes launched. It has been said a single volley can destroy a ship from bow to stern.

Occasionally, plasma torpedoes can miss their target and fail to reacquire them if the target is moving towards the launcher at an oblique angle and high speed, such as the offensive maneuver conducted by John-117 to evade the fire of the Covenant ships at Alpha Halo during the Skirmish over Threshold, or also if the movement of the craft is erratic such as the way Keyes evaded the torpedoes during the Keyes Loop by detonating the ship's emergency thrusters seconds before impact. Even though they are considered very accurate against capital ships and space stations, they can frequently be evaded by smaller craft, such as Pelican dropships and Longswords.

Enhancement and variation
As with virtually all of their technology, the Covenant themselves only understand a fraction of the underlying science involved with the operation of the plasma turret. As a result, despite their overwhelming power against human ships, the Covenant's methods of using their weapons systems are highly inefficient, relying on crude brute-force calculations and causing wasteful energy expenditure due to their slow operation; this is also why the turrets glow before firing. When in control of the Covenant ship Ascendant Justice, UNSC AI Cortana was able to use the vessel's plasma turrets to their full potential; she created an entirely new system to control the plasma, using electromagnetic pulses to direct the plasma atoms into precision beams within a microsecond. This enabled her to use the weapons with far greater power and precision than the Covenant themselves, cutting through Covenant vessels like a scalpel, not unlike an energy projector. According to Cortana, she could have improved the plasma turrets even further had the Covenant ship possessed better electromagnetic systems.

The magnetic coils used in a MAC gun can be used to shape and guide the plasma fired by a plasma turret; this was seen before the Massacre at Eridanus Secundus, when the 's magnetic coils were used to guide plasma generated by the Ascendant Justice's plasma turrets.

Production notes
Halo: Mortal Dictata erroneously refers to the plasma torpedoes of the battlecruiser Pious Inquisitor as if they were physical objects stored aboard the vessel in a dedicated "torpedo bay". However, there is no tangible component to the munitions, as the plasma cannon generates the "torpedo" from an amorphous supply of plasma upon firing.

Terminology
While the term "plasma torpedo" is used throughout the novels, the weapons used to fire the torpedoes are only identified as "plasma turrets" in Halo: First Strike, which also describes their operational mechanisms in detail. Halo Waypoint's article for the Song of Retribution introduces a distinction between the assault carrier's "Anterior Plasma Cannons" and "Plasma Torpedo Silo Network", listing these weapon systems as the ship's secondary and tertiary armament, respectively. This distinction is curious, as the novels only describe the Covenant using three layers of starship weaponry: energy projectors, plasma torpedoes and pulse lasers. However, the term "plasma cannon" is also used in reference to Covenant warships' secondary armament throughout Halo: The Essential Visual Guide, and in Halo: Contact Harvest, a "heavy plasma cannon" (most often referred to only as a "plasma cannon") is listed as the Rapid Conversion ' s main weapon system.

Halo: Combat Evolved, Halo 3 and Halo: Reach depict Covenant starships firing blue or blue-purple bolts of plasma which are seemingly unguided. Meanwhile, the novels consistently describe plasma torpedoes as being red as well as highly maneuverable. Given these differences, it is possible that at least some of the plasma weapons depicted in the games are in fact representative of the "plasma cannons" listed in the Song of Retribution ' s arsenal rather than plasma torpedoes. This is supported by a line by Captain Keyes in Halo: The Flood, in which he implies that a single plasma torpedo could reduce the into "free-floating molecules"; despite this Halo: Combat Evolved depicts the Autumn being struck by numerous blue plasma bolts without being destroyed. While it may be that the Covenant considerably reduced the power of their torpedoes out of fear of accidentally damaging Halo, Keyes' line would suggest the plasma weapons in question are not plasma torpedoes at all.

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * Halo 2
 * Halo: Ghosts of Onyx
 * Halo 3
 * Halo Wars: Genesis
 * Halo Wars
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * The Impossible Life and the Possible Death of Preston J. Cole
 * Halo: Reach
 * Halo: Fall of Reach
 * Covenant
 * Invasion
 * Halo: Combat Evolved Anniversary
 * Halo: Mortal Dictata
 * Halo: Escalation
 * Halo 2 Anniversary