< 303
This article is about the X-303. For otheruses, see 303.
"This is Prometheus, otherwise known as the X-303."
Samantha Carter[src]

The X-303 was an interstellar spaceship built secretly on Earth using technology procured by Stargate Command.

Like its predecessor, the X-302 hyperspace fighter, the X-303 is exclusively of Tau'ri construction. Like the 302, it has Inertial dampeners, artificial gravity and an antigravity system that allows the vessel to hover in midair. Its Sublight engines are capable of boosting it from the surface into orbit in less than thirty seconds, and it also possesses a Naquadria-based hyperdrive. (SG1: "Prometheus", "Memento")

Unlike the 302, which is designed as a fighter-interceptor, the 303 was developed as a response to the Goa'uld Ha'tak, which is a mothership. It is the United States Air Force's first capital ship. However, it is still far smaller in scale than the Ha'tak. Its span consists of 17+ decks and is capable of carrying more than a hundred personnel, as well as eight 302s within its hangar bay. (SG1: "Grace")


The X-303 was built using both Earth-based and alien technology. Its design is based on that of an Earth naval aircraft carrier, having a long nose with a visible bridge area near the rear of the vessel.

The X-303 was capable of both sublight and hyperspace travel. It could reach up to half the speed of light at sublight speeds. Its hyperdrive, however, was unstable and thus unreliable, being based on Naquadria. The first test ended with the vessel stranded in an unknown area of space, and on the second attempt it overloaded and had to be ejected to save the ship.

For armament, the X-303 had an array of Railguns around the hull and missile launchers loaded with Naquadah-enhanced Nuclear warheads.



The elevator shack leading to the Prometheus' subterranean bay.

The X-303 was constructed in an underground hangar facility designated Area 37-92/NV, under the project name "Prometheus". Its development was so large an undertaking that maintaining its secrecy proved impossible, with information leaking to reporter Julia Donovan with the !nside Access news program. In an attempt to minimize the potential damage of the project's disclosure, the President of the United States agreed to give Donovan, her producer, and a camera crew a tour of the X-303, claiming the alien technology it incorporated was in fact salvaged from a UFO that crashed near Fairbanks, Alaska in 1978.

During the tour, the ship was taken over by the camera crew, actually rogue NID agents working at the behest of Colonel Frank Simmons. The agents successfully managed to steal the ship and take it into hyperspace before being overpowered by SG-1. However, the hyperdrive, which was configured for Simmons by the Goa'uld inhabiting Adrian Conrad, malfunctioned and transported the ship instead to an unknown destination. (SG1: "Prometheus")

O&#039;Neill class cruiser

An O'Neill-class ship above the Prometheus.

In what came to be the ship's first mission, the Asgard took the X-303 to the Othala in the hope that it could be used to trap the Replicators inside a time dilation field. During this mission, the Asgard also modified the ship's shields and engines to their maximum potential. After the successful completion of this mission, the Asgard provided shields for the ship in advance of its formal shakedown cruise as a gesture of gratitude. (SG1: "Unnatural Selection", "Disclosure")

Ultimately, the X-303 entered active service, taking the designator BC-303 and the name Prometheus. In this capacity, it served as the flagship of the Tau'ri fleet under the auspices of the Office of Homeworld Security, and received additional upgrades from the Asgard.

After nearly being in service for four years, Prometheus was eventually destroyed in the Battle of Tegalus which occurred in February 2006. Though plans were later made to construct an entire fleet of BC-303s, the introduction of the Daedalus-class battlecruisers rendered the craft obsolete, leaving the Prometheus as the sole vessel in its class. (SG1: "Enemy Mine", "Ethon", "Moebius, Part 1")

The design plans for the X-303 (without the Asgard upgrades) were provided to the Russian Federation in 2002 along with those for the X-302 hyperspace fighter; however, the Russians have apparently not constructed any such vessels.




A phone on Prometheus

Prometheus had a variety of means to communicate within and between ships. There were traditional telephones located in corridors and rooms throughout the ship for intra-ship communications. There was also the capacity to integrate the system to wireless radio headsets. The ship also has an intercom system for ship wide messages. It could be activated on the bridge by one of the stations and could also be triggered directly from the commander's chair. (SG1: "Prometheus", "Beachhead", "Prometheus Unbound")

The Prometheus was equipped for both audio and video communications outside the ship as well. Despite communications satellites being down, Prometheus was able to establish a secure video transmission directly to the Oval Office, which displayed on monitors above the main window/viewer display. A side viewer also displayed video communications that integrated with alien ships, such as the Asgard and Goa'uld. The ship could also broadcast audio-only messages on multiple frequencies, and included the additional feature of translating the broadcast into Goa'uld. The communications, however, couldn't penetrate Ancient shielding, as was evidenced upon the discovery of the caves of Avalon in the Glastonbury Tor. The Prometheus had two communications arrays symmetrically placed on the rear section of the ship. (SG1: "Memento", "Lost City, Part 2", "New Order, Part 2", "Avalon, Part 1", "Beachhead")

Inertial dampeners and artificial gravityEdit

The Prometheus had Inertial dampeners and artificial gravity technology, which gave its passengers a smooth ride, much like that taken within a fast elevator. When Julia Donovan's filming crew turned out to be rogue NID agents who stole the ship, Major Samantha Carter was trapped on a level which didn't have the artificial gravity systems in place and she experienced zero gravity when the ship was taken into space. (SG1: "Prometheus")



A 303's shields are pierced

The Tau'ri do not possess shields of their own design, instead utilizing reverse engineered Goa'uld shields, however, these shields were replaced with shields of Asgard origin, which were donated to them in thanks for the help the Tau'ri had provided the Asgard in their conflict against the Replicators. Asgard shielding was first equipped to the Prometheus and eventually the Daedalus-class, allowing the Tau'ri to better confront the warships of the Goa'uld. However, with the invasion of the Ori, the shields of the Prometheus proved virtually ineffective against the powerful weapons of the Ori. (SG1: "Disclosure", "Memento", "Ethon")

Landing gearEdit

The Prometheus had a tripodal landing gear system with one leg in the front of the ship and two in the rear. The slender midsection of the ship had no support. The ship needed to engage the deceleration thrusters in order to obtain a stationary point above the planet surface before landing. Most likely, the anti-gravity pod assisted in the landing process. The landing gear operated just like that on a jet airplane and could be retracted back into the body of the ship. (SG1: "Unnatural Selection", "Memento", "Prometheus Unbound")

Escape podsEdit

The 303 also has an unknown number of escape pods. (SG1: "Grace")


Sublight enginesEdit


Prometheus' sublight engines

Sublight engines enabled the Prometheus to accelerate to 110,000 miles per second, which was over half the speed of light (186,000 miles per second). An ignition module had to have been calibrated to within a 1% margin of error in order for the engines to start. If outside this margin, the module would burn out, and the engines would fail to start. Sublight engines placed the Prometheus in Earth's orbit in less than 30 seconds. (SG1: "Prometheus")

The control relay for the sublight engines was located on Deck 8. Sublight engines have varying output, which is controlled through the ship's helm. One such output was referred to as "emergency thrust" and was used when the Prometheus left Antarctica to meet Anubis's fleet in Earth's orbit. (SG1: "Lost City, Part 2")



The Prometheus' original naquadria reactor core

The hyperdrive engines were first powered by the powerful, but highly unstable, mineral called Naquadria in the form of a Naquadria reactor core. A buffer was installed to prevent the reactor from going critical due to Naquadria's inherent instability. Later, new hyperdrive technology was installed by the Asgard. Between that time, however, the ship operated on a temporary adaptation of a hyperdrive engine from an Al'kesh. The rectangular hyperdrive nacelles were seen on either side of the ship's rear section. The hyperdrive engines glowed blue when activated. (SG1: "Memento", "Grace", "Covenant", "Endgame", "Gemini", "Prometheus Unbound")

Hyperdrive control systems were protected with codes, but these codes could be overridden by someone who was familiar with the crystals used in these control systems. An engine coolant system ran through the length of the slender midsection of the ship and into the rear where the engines were located. Spatial gases could interfere with the even flow of power to the hyperdrive emitters and thus prevent a hyperspace window from becoming fully formed. When the power to the hyperdrive emitter was reduced, it was possible to create a partial shift into hyperspace which could take the ship out of the surrounding space-time temporarily. (SG1: "Prometheus", "Grace", "Prometheus Unbound")

If the Prometheus were ever called upon to take a trip to the Pegasus galaxy using its Asgard hyperdrive engines, it would take approximately 18 days, as this is the amount of time that Daedalus-class ships are able to make the trip with their Asgard hyperdrive engines. (SGA: "The Intruder") (SG1: "Ripple Effect")

Anti-gravity podEdit

The Anti-Gravity Pod was housed in the lower portion of the rear of the ship, as labeled on the Venting Sequence display. The Prometheus most likely used this feature in entering and exiting its subterranean bay on Earth, in softening an off-world landing, and in hovering or maintaining a stationary position above the ground as it did in Antarctica in order to protect SG-1's Tel'tak during Anubis's attack. (SG1: "Lost City, Part 2", "Grace")

Deceleration thrustersEdit

Deceleration thrusters were used to slow the Prometheus down. They were situated on the front side of the large rectangular hyperdrive engine sections and were seen being used by SG-1 when they landed on the planet Hala. (SG1: "Unnatural Selection")




The Prometheus opens fire.

The 303s have 16 Railguns, which have become standard on F-302 fighter-interceptors and all Daedalus-class vessels for ship-to-ship combat. Just a few shots are able to take out a Death Glider relatively quickly and deal damage to Al'kesh and Ha'taks. (SG1: "Prometheus Unbound", "Ethon")

Missile batteriesEdit

The 303s have 12 missile batteries and Naquadah enhanced Nuclear warheads. These missiles are able to take out a Death Glider relatively quickly and deal a large amount of damage to Al'kesh and Ha'taks. However, Ori shields are significantly more difficult, practically impossible, to pierce. (SG1: "Prometheus Unbound", "Ethon")

References and notesEdit

  1. 1.0 1.1 1.2 1.3 Stargate SG-1: The DVD Collection 2
    Some issues of The DVD Collection magazine are known to contain errors with respect to the dimensions they provide for spaceships. Dimensions for the same class of ship may vary between issues. The dimensions given in an issue may contradict how the ship visually appears on screen. The dimensions of two ships which appear similarly sized on screen may be given different measurements in The DVD Collection magazines. However, as the DVD Collection Magazines are officially licensed by MGM (and thus considered canon) Stargate Wiki includes them, while noting the apparent discrepancies in instances where they occur. See policy and List of spaceships by size for more information.

External linksEdit

Tau'ri spaceship classes
Fighters ( X-301 )  · ( X-302 )  · F-302
Battlecruisers ( X-303 )  · BC-303  · BC-304
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