Magnetic Accelerator Cannon
From Halopedia, the Halo wiki
Summary
The Magnetic Accelerator Cannon or MAC gun is the standard main weapon of all UNSC cruisers, destroyers and frigates, and much larger versions are the main weapon onboard UNSC orbital defense stations. The MAC gun is stated as the UNSC's most powerful non-nuclear weapon.
The MAC gun uses a linear acceleration system, comprised of several superconducting coils. The coils are powered by a series of capacitors that store the tremendous energy neccesary to 600 ton ferric progectile with a depleted uranium core to 10% the speed of light, or roughly 30,000 kps. The main drawback to the shipboard MAC gun is the large amount of time it takes for the capacitors to reach full charge. This drawback has proven to be significant in combat against Covenant warships, since it has been shown that it requires several ship-scale MAC rounds to penetrate Covenant shields. An experimental version of the MAC gun has been developed, however, that is able to fire three successive rounds on one charge. A prototype of this weapon was mounted on the UNSC Pillar of Autumn. MAC guns exist on many different scales, ranging from the massive Mark V "Super" MAC guns onboard orbital defense platforms, to common shipboard MAC guns, and even down to the "Gauss" cannon mounted onboard the Warthog LRV.
Super MAC guns are loaded on defense platforms orbiting Reach, Earth, and other strategic locations that must be protected, and are much more powerful than normal MACs. The Orbital MAC guns (nicknamed "Super MAC" or "The Big Stick") which are capable of accelerating a 3000 ton ferric-tungsten round to 40% the speed of light and can reload in five seconds. These weapons are able to destroy a Covenant warship with a single shot (one projectile from a "Super" MAC gun will literally shatter a Covenant ship even with full shields) and are commonly placed in geosynchronous orbit around a planet over the location they are named after.
The one weakness of the orbital MAC guns is that the power stations that power them are located on the surface of the protected planet, and are thus susceptible to attack from Covenant ground forces. The pious nature of Covenant engagements have also presented a problem, since the Covenant are more than willing to sacrifice a number of ships in order to destroy one platform. This tactic was used during The Battle for Reach.
The MAC cannons can be found throughout the Halo universe, and play critical roles in many battles. The use of the MAC gun proved decisive when the Covenant fleet descended to Earth at the beginning of Halo 2, and was used as early on as Master Chief's first encounter with the Covenant, in which it was used to blow a hole into the ship through which Spartans could access.
Known MAC Guns
Athens Station
Cairo Station
Malta Station
Nassau Station
Naming Theory
One theory on the naming of of MAC Cannons is that they are named after the place they orbit above. For example the Cairo, Athens, and Malta all orbit above the Medeterrain Area.
