Aurora Unit 313

Aurora Unit 313 is a Galactic Federation Aurora Unit that was stolen by Space Pirates from the G.F.S. Valhalla, under the orders of Dark Samus. Like all Aurora Units, it is a type of artificially-intelligent computer used to control Federation facilities and starships. As it was being removed from the Valhalla, it left behind a final message to the Federation, detailing what was occurring. It was taken to Phaaze, where it was implanted into the planet and corrupted by Phazon. As a result, Dark Samus was able to control the planet and all of its powers - including the Leviathans (this allowed her to launch them wherever and whenever she wished). During this time, however, Aurora Unit 313 became symbiotically linked with the planet.

After Dark Samus is defeated by Samus Aran on Phaaze, she merges with the Aurora Unit, forcing Samus to battle it. To destroy it, Samus must first attack the open holes from which its tentacles emerge in order to stun it, then open the hatch on its head with the Grapple Lasso to reach its core and overload it with Phazon energy. Once this is done, the cable connecting it to the ground will break and reveal its weak point. It will fly around the arena during this part of the fight. At this point, Samus must attack the weak point where the cord once was.

Once Samus destroys it, Dark Samus is finally defeated. The destruction of the Aurora Unit begins a chain reaction, caused by the symbiosis of Phaaze and the AU, that ultimately culminates in Phaaze exploding.

313 also appears in a Diorama in the game's Extras menu. (See Gallery)

First form

 * A purple laser shot from the eye, which is easy to evade by jumping and side-stepping.
 * Sometimes the AU will stay on the ground and four cannons will shoot small energy balls.
 * The AU will often extend Phazon sensors that will shoot Phazon balls if they are not destroyed.
 * As a last resort the AU will call Dark Echoes to assist it.

Second Form

 * This is an attack from the Metroid Prime Core: the destructive energy wave. Shooting the node that projects the energy wave stops it and stuns the AU.
 * Another of its attacks are four lasers which will be unleashed by the AU in a way so the lasers arch and fall. At this time, only the area below the machine is safe.
 * The AU's central "eye" will glow blue and fire one or two blasts of Phazon. When the attack finishes the AU will be stunned. This attack is also used by Quadraxis when its head is separated from the body.
 * This attack consists of the AU spinning and flying around the room. An extremely accurate Screw Attack into the AU's weakspot will stop this.

Valhalla message
On the G.F.S. Valhalla, there is a terminal in the final room of the station that displays a message from the invasion of the Valhalla. This message can only be seen by entering the code "78356". This code can be seen on a PDA device belonging to a deceased Federation Marine in the same room. The Aurora Unit 313 describes how the Federation were unable to repel the attacks of the Space Pirates upon the ship, and how 313 was forcefully taken from the Valhalla. Near the end of the transmission, 313's voice fades, as it is somehow shut down. With its last words it reveals the Pirate's intentions for stealing the Aurora Unit:

"Data log entry 2467.3. This will be the last communication of the G.F.S. Valhalla. Our efforts to repel the Space Pirate boarding force have failed. They have successfully removed the primary mounting structure around our stasis tank. It is obvious now that they intend to extract us from the Valhalla. It is vital that the Federation receive this transmission.

...Severing main power...

A large bioform is creating a wormhole...

...Implant into...

Sentient planet which is the source of all Phazon.

...Darkness coming."

Music

 * This is the music heard when battling the first form of Aurora Unit 313:.
 * This is the music heard when battling the second form of Aurora Unit 313:.

Trivia

 * After the network in SkyTown is restored, the corrupted AU 313 is displayed on the many breakable monitors all over the place instead of 217. Despite this, the scan states that it is displaying 217. This may indicate that the four lasers that protrude from the base of 313 are actually a pre-existing combat mode, in other words, it is possible that all Auroras already have combat settings for use in a crisis. The image also seems to have a few vertebrae of 313's 'spinal column'. which seems to suggest that the 'spinal column' is also a normal part of the Aurora Unit, possibly as a way for them to connect to machinery when separated from their tanks.
 * Unused GF records refer to 313 as female, although the AU's voice is clearly masculine. To confuse gender matters even more, direct scanning refers to him/her as neither. It is possible that 313 has a gender-neutral configuration, which some AUs are said to have.
 * The "cable" is similar in appearance to a spinal column. While its most likely purpose is for support, it may also be a reference to how 313 is "symbiotically connected" to Phaaze. In anatomy, the spinal cord inside the backbone is connected to the brain, and aids in the movements and reflex actions of the body. In this case, the head of the Aurora Unit could be representing the brain, the cable of 313 the spine, and Phaaze the body which 313 is able to control to launch Leviathans. It is also plausible that the spine is to induce a sense of fear of death, as skeletal features (predominately spines and skulls) are often used to represent mortality in media.
 * When corrupted, 313 seems to resemble the Phazon Core of a Leviathan, including the cord that connects each to the larger organism. This could be to highlight the similarities between the two, since both control a larger, Phazon-producing organism that is destroyed when they are.
 * 313 shares many similarities with Mother Brain. This is seen in the purple energy laser that resembles Mother Brain's eye beam in Metroid: Zero Mission or the Hyper Beam in Super Metroid, the red spheres of energy that resemble the Rinka defense system and Cannons. 313's eye is also larger than the eyes of the other Aurora Units and bears more resemblance to Mother Brain's eye, and 313 bears much more resemblance to Mother Brain than the other Aurora Units. Also, when the hatch in the Aurora Unit is opened, a brain-like object is shown within. Upon closer inspection the brain-like object appears to have spikes sticking out of it, much like Mother Brain.
 * The theme of 313 is a remix of Darkness, arranged in a way that resembles Zebetite, Mother Brain's theme from Metroid: Zero Mission. The "cable" that connects 313 to the floor in its first phase resembles the neck of Mother Brain's body from Super Metroid. 313's death is also similar to Mother Brain's death in Super Metroid: both shrivel and die, and their death results in the explosion of a planet.
 * Ian Olsen modeled and skinned 313.
 * 313's floating head resembles a Metroid. It has a similar body shape and two pairs of mandibles like that of any Metroid.
 * Unused scans for Aurora Unit 313 mentioned that it had an abnormally high aggression potential even before Dark Samus and the Space Pirates stole it.