NX class

The NX-class was a type of Explorer starship in the United Earth Starfleet in service during the mid-22nd century. The NX-class was commissioned as an exploratory vessel as a medium for the new warp 5 engine that would form the basis of Humans first reach into the galaxy.

The first six ships of the class were named after the NASA space shuttle orbiters of the late 20th century.

22nd century
The NX-class was to be medium of the revolutionary warp 5 engine. The Warp Five Complex was dedicated by Doctors Zefram Cochrane and Henry Archer in 2119 on Earth. 

On June 1, 2140, Commodore Maxwell Forrest approved the design of the NX-class. 

By 2143, the NX Project was underway. Prior to the NX Project, Human ships were incapable of exceeding warp factor 2. A series of NX prototypes, their design mirroring the [[Phoenix warp ship prototype, were launched. NX-Delta, commanded by Duvall, successfully broke the warp 3 barrier in 2144.

Enterprise was the first NX-class starship built, registry NX-01. The ship was launched ahead of schedule in 2151, under the command of Captain Jonathan Archer, to transport the Klingon courier Klaang back to Qo'noS. Due to the early launch of the Enterprise, several systems—most notably the starship weapon systems—had not yet been completed. These weapon systems were completed in the field at a later date. 

With a series of successful early missions, Starfleet decided to proceed with building further NX class ships. By 2151, three more NX class ships were in the early design stages. Construction of the unnamed NX-02 had begun by the time the Xindi attacked Earth in 2153. The ship, later named Columbia, was completed in November of 2154 and launched under the command of Captain Erika Hernandez. 

In August 2155, the Challenger and Discovery were completed and commissioned. Several months later, the Atlantis and Endeavour entered service. Between mid-2155 and mid-2156, the Columbia, Challenger, Discovery, and Atlantis were destroyed or lost as a result of Romulan attacks. The Endeavour, equipped with countermeasures to the Romulan arrenhe'hwiua telecapture technology, battled with the Romulans at Altair VI. 

In 2156, Enterprise underwent a 180-day refit. The ship was fitted with a secondary hull, essentially becoming a new ship class. The newly-refitted Enterprise saw more combat against the Romulan Star Empire during the Earth-Romulan War. 

NX-class production would later be restarted by 2159. Captain Picard remembered 15 or 16 ships of this class having been built. Some of them would be Intrepid,  Avenger, and Currie (NX-16). 

Following the end of the Earth-Romulan War, Enterprise was decommissed in 2161. With Endeavour refitted to what Admiral Jonathan Archer had designated standard, no NX-class starship remained in service. 

Alterate events
In another version of history, the NX-class starships did not follow the naming lineage of NASA orbiters, and more ships survived the end of the Earth-Romulan War. These ships subsequently entered service as Federation starships. 

25th century
In 2409, the Starfleet Corps of Engineers built the USS Utopia in the Utopia Planitia Fleet Yards as a replica of the NX-class. The ship entered service as a light escort during the Federation-Klingon War of 2405-2410. While the exterior was a careful replica of the original Earth starship class, its technology was state-of-the-art. 

Mirror universe
In the mirror universe, these were known as NX class battleships. There were at least 9 ships in service by January 2155. Most of these were refitted with advanced weapons from the USS Defiant (NCC-1764) in the same year. 

Specifications
When first launched, the NX-class was meagerly equipped with plasma cannons and spatial torpedoes. Instead of a tractor beam, it used special grappling cables. The first of the NX-class, the Enterprise had three phase cannons in storage, but it wasn't until midway through their first year that they were equipped. During the Xindi superweapon crisis, the Enterprise got retrofitted with twelve phase cannons and the newly developed photonic torpedoes. With these armanents, as well as improved hull plating, it was able to defeat three Klingon birds-of-prey.

After saving Earth from the Xindi superweapon, the NX-class received another upgrade including an upgraded navigational deflector, an improved computer interface, pulsed phase cannons, dorsal and ventral torpedo launchers, and polarised hull plating that had 12 percent greater performance than previous versions.

In 2159, these vessels were equipped with phase banks and four torpedo launcher banks.

Known vessels

 * Enterprise (NX-01)
 * Columbia (NX-02)
 * Challenger (NX-03)
 * Excalibur (NX-03)
 * Discovery (NX-04)
 * USS Constellation (NX-04)
 * Atlantis (NX-05)
 * USS Endeavour (NX-06)
 * USS Defiant
 * Lexington
 * Intrepid (NX-07)
 * Avenger (NX-09)
 * Currie (NX-16)
 * USS Utopia (NCC-2151-01)

Mirror universe vessels

 * ISS Enterprise (NX-01)
 * ISS Columbia (NX-02)
 * ISS Avenger (NX-09)
 * ISS Akagi
 * ISS Bismarck
 * ISS Broadsword
 * ISS Dauntless
 * ISS Interceptor
 * ISS Invincible
 * ISS Khan's Wrath