Magnetic Accelerator Cannon

A MAC Cannon is a Magnetic Accelerator Cannon, from the storyline of Halo. For Advanced ship-based Cannons, they use Tungsten cores (Or Nickel-Iron Ferric slugs for station-based defenses), which are then fired using a system of magnetic fields down a long shaft. They are the only non-nuclear weapons that can destroy Covenant shields that the UNSC possess. 20 MAC Cannons were used to defend the planet Reach from Covenant invasion, but they soon fell as the Covenant destroyed the underground generators that powered them. The planet Earth had 16, but production was stepped up quickly after Halo: The Fall of Reach, bringing the total up to 30. Some of the more famed Super MAC Orbital Stations above Earth are: Cairo Station, Malta Station, and Athens Station, each geosynchronized above the city they are named for.

Cairo Station was the station abord which the Master Chief (John-117) and Sargeant Johnson (Avery Johnson) received awards, along with Miranda Keyes, daughter of the famed Captain Keyes. When the Covenant came out of Slipspace, they attacked each of these 3 stations. At one time in the middle of the battle, Malta Station seemed to have won the fight, as they reported: "Cairo, this is Malta. The Covenant are retreating! I can't believe it!" But, the Covenant soon demonstrated their new technique, involving placing a bomb in the station. Miranda Keyes soon discovered that there was a bomb on Cairo Station, and the Master Chief ran to find it, defused it with Cortana's help, and destroyed one of the Covenants own Capital ships with it, before falling to Miranda Keyes' ship and taking "the fight to the surface."

Athens Station met the same fate as Malta Station, approximately 60 seconds after Malta's incident.