Phoenix-class colonial support vessel

Phoenix-Class Colony Ship The Phoenix-class Colony Ship  is a ship classification within the United Nations Space Command. The Phoenix-class starship, among others, are often modified into warships such as the, which is a modified Phoenix converted for wartime-use towards the newly encountered Covenant alien alliance. The refitted ships carry vehicles, troops, and supplies as support for ground forces. It also carries the resources necessary to build bases.

The UNSC Skidbladnir was the Phoenix-class Colony Ship which colonized Harvest.

Function
The Phoenix-class is 2.5 km long, making it one of the largest known UNSC ships in the organization's naval history.

The Phoenix-class ships were designed to transport thousands of colonists from Earth, or one of the other Inner Colonies, as well as terraforming equipment to alter the existing atmosphere and/or biosphere to become compatible with human habitation. Once the terraforming is completed, the colonists settle the planet. On at least one instance, a colony ship was decommissioned to aid in the development of a colony. On Harvest, the Skidbladnir's fusion reactor was used to power the first settlement, Utgard and its data processing storage housing the Agricultural Operations AI, Mack was also utilized. The ship's AI, Loki, became the Planetary Security Intelligence, sharing a core with Mack, covertly monitoring the colony for trouble for the UNSC. Whether this was a common fate for colony ships during the colonization of other worlds is unknown.

Once converted, a Phoenix-class ship can become an extremely effective troop transport and orbital support ship, carrying thousands of Marines, significant supplies and equipment, and, if equipped with a Magnetic Accelerator Cannon during conversion, is able to attack ground targets from orbit in support of ground operations. It can also use Pelican and Albatross dropships and Pods to deploy ground forces and establish bases of operation. It is even able to participate in atmosphere to a degree. However, despite the conversion of the Phoenix-class from a Colony transport ship to a warship, it is still underpowered as far as most warships go; the super-structure of the Spirit of Fire is vulnerable to light pulse laser fire, and despite the addition of armor plating, the outer edges of the hull were ripped away when the ship nearly collided with a Covenant Destroyer of about the same size. The Magnetic Accelerator Cannon can fire multiple times consecutively, but each round is less powerful than the cannons used by other UNSC warships.

Trivia

 * The name Phoenix may be a reference to Bungie's canceled game of the same name, or, more likely, the name is derived from an Ensemble prototype which pitched humans against invading Martians in a War of the Worlds style, which was titled Phoenix.