Portal at Voi

The Portal at Voi, known to the scientific community as the Excession at Voi or simply the Excession and sometimes referred to as the Artifact, is a massive Forerunner construction in Kenya, Africa on Earth. It was designed to generate a slipspace portal to Installation 00. It was built across and eventually buried beneath an area that would come to encompass the town of Voi and the city of Mombasa, and it was uncovered by the Covenant during the Battle of Earth in late 2552. It can be activated by a specific keyship, that being the Covenant's "Forerunner Dreadnaught", and was so activated upon its unearthing. It was reactivated once more in March of 2555 with the help of Drifts Randomly, a Huragok that had worked on the Dreadnaught.

Ancient history
"Who will use this portal? Who will live to return here? And what will they think of this machine that I’ve buried? Those I have fought for, for so long. Those who, it is clear to me now, ultimately will and must inherit the Mantle. I can only hope that they will survive and upon returning, that they will find this portal and use it to travel to the Ark—in order that they might discover their rightful place in this galaxy, and the great responsibility they have finally inherited. They are the last of my children. They must reclaim their birthright."

- The Librarian thinks on the future of the portal and its use by humanity.

Shortly before the firing of the Halo Array, the Forerunner known as the Librarian ordered the construction of the portal beneath a savannah in what would later become Kenya. The Librarian knew that the portal would not be completed before the Halos were fired, and thus construction would continue for at least a century after Earth was reseeded. She had it built with the hope that humanity would one day use it to reap the benefits of the legacy the Forerunners left on the lesser Ark. A Gargantua-class transport sent by 343 Guilty Spark at her request, along with the necessary components mined from the Earth, was used to build the portal. At least two varieties of sentinels, Retrievers and Assemblers, were deployed from the transport and were also important to its construction.

When humans and other lifeforms were reintroduced to Earth, they emerged at the planet above the portal in Africa. However, work on it would continue for multiple generations. Its continual construction was witnessed by humans, including an African elder named N'chala, who was oblivious to its purpose and considered the sentinels to either be gods or to be under their direction. While the artifact was always designed to be partially buried in the earth, it eventually came to be entirely buried through unknown means.

Discovery
"Truth could've landed anywhere, but he committed all his forces here. East Africa. The ruins of New Mombasa. Then, they started digging."

- Miranda Keyes informs John-117 of the Covenant's excavation.

By at least the nineteenth century, the portal was originally entirely submerged beneath the land occupied by the city of Mombasa and the town of Voi, lying at least partially underneath a man-made lake. At some after the dawn of the twenty-fourth century, the UNSC's Office of Naval Intelligence discovered a small section of the portal structure located below the metropolis of New Mombasa, and constructed a major facility known as the ONI Alpha Site in the city in order to conduct covert research on the artifact. In 2551, toward the end of the Battle of Meridian, a luminary was discovered by the Covenant on the moon. Ths luminary would later be presented to the Prophet of Regret and reveal to him the location of the portal. In October of 2552, a seismic anomaly originating with the portal was discovered in a survey conducted by New Mombasa's urban infrastructure AI, the Superintendent, for Dr. Endesha, revealing the location and full extent of the structure to him. By November 17, 2552, the entire lake that lay over where it was buried had been vaporized by Covenant ships and the earth overtop of the artifact had been burned away by focused glassing to unveil it.

Following the Prophet of Regret's flight from the Sol system during the Battle of Earth, a massive Covenant fleet led by Jiralhanae arrived to swiftly take control of the battle from the Sangheili. These forces attempted to use the data gathered by the Superintendent to pinpoint the location of the artifact, but were eventually forced to discover its location on their own. On the same day, they started the uncovering of the artifact by glassing. By November 17, 2552, the entire lake that lay over where it was buried had been vaporized by Covenant ships and the earth overtop of the artifact had been burned away by focused glassing to unveil it. The Prophet of Truth landed the Forerunner Dreadnought on the structure, and an unusual electric storm formed above it. Before its activation, the prophet personally traveled to the Superintendent's data center deep underneath where New Mombasa used to be, now occupied by a number of Covenant Huragok, and observed a section of the artifact visible from the facility.

The UNSC attempted to attack the keyship, falsely presuming the portal to be the Ark itself, but was stopped by Covenant Type-27 Anti-Aircraft Cannons. A small force in the city of Voi, consisting of John-117, Thel 'Vadam, Marines, and factory workers from a Traxus Industries facility, neutralized an anti-aircraft battery to clear a path for three frigates and numerous Longswords. These then made several attacks on the Dreadnought with MAC cannons and ASGM-10 missiles, but to no effect. At that moment, the gateway finally activated, opening a large slipspace rift above the Portal which led to the real Ark. Truth and his fleet advanced through the rift and were pursued by the Fleet of Retribution and the UNSC Forward Unto Dawn.

Post-War Period
"There are more secrets locked under our feet than we dare speculate on."

- Doctor William Iqbal in a letter from the Department of Xenoarchaeological Studies at Edinburgh Universityto security-cleared faculty and onsite graduate students.

When Installation 04B was prematurely fired on December 11, 2552, it tore itself to pieces, doing an enormous amount of damage to the Ark. This sudden destruction caused the portal to collapse while the Forward Unto Dawn was still traveling through it back to Earth. The ship was torn in to two large pieces at this time and only the fore half made it back to Earth, crashing into the Indian Ocean. From that point onward, the portal remained inert and unaccessible. In 2553, civilian xenoarchaeologists were hired by the Office of Naval Intelligence to study the artifact. While closed, it was still drawing power from an unknown source and the majority of the passageways below it were still unexplored. It was suspected that the portal had additional as-of-yet undiscovered functions besides simply creating a gateway between Earth and the Ark.

In 2555, scientists exploring Installation 07 discovered a countdown sequence and it was determined that it was originating from the Ark. It suddenly became pf paramount importance that the portal be reactivated. The UNSC reached out to the Swords of Sanghelios and a Huragok named Drifts Randomly that had worked onboard the Forerunner Dreadnaught was brought to Earth. After a few days, it was able to open the portal using data from the keyship it had internalized. A joint UNSC and Swords of Sanghelios team was sent through the portal to prevent the activation of the Halo Array. The countdown was part of a ploy by the Ark's monitor, 000 Tragic Solitude, to make the humans on Earth reactivate the portal so that he could send Retriever Sentinels to mine the Sol system for materials to repair damage done to his installation. Many Retrievers poured through the portal and the UNSC Home Fleet engaged them in battle. Operation: FAR STORM successfully prevented Solitude's plan from coming to fruition, however, and the sentinels were recalled. Afterwards, the UNSC used the now-active portal to send researchers to the Ark.

Appearances
The storm was first seen in the Halo 3 Announcement Trailer, when the camera shows the artifact being uncovered and activated. The storm lies directly over it, lightning bolts are seen flashing out of the clouds, and the formation seems to have an eye, like a hurricane would. When the portal is activated, the beam travels up through this eye and disappears.

In the level Crow's Nest, when a player looks up at some of the computer monitors, you will see a map of the local area. The map will have a mass of clouds beginning to show a swirling motion around the area. When you enter the level Tsavo Highway, you can see a doughnut-shaped mass of clouds above the artifact that the Covenant are excavating. When you proceed to the level The Storm, the storm has intensified and grown. The clouds now bring rain to the area, and certain parts of the cloud glow as if cloud-to-cloud lightning is occurring. At a point in the level The Storm, a group of UNSC Marines are present around a radio. Intel comes over the communications channel and says, "...winds inside the storm have been clocked at over 200 kilometers per hour." When Truth activates the Portal, the solid blue beam shoots up into the cloud formation's eye and opens the portal to the Ark.

After the portal is opened, and the level Floodgate begins, the remains of the clouds are seen broken up and swirling around the portal in the sky, having been disrupted by the opening of the portal itself.

At the end of Halo 3 where Lord Hood is making his concluding tribute speech about the Human-Covenant War and the Marines who died in the strife and war, one can see the now-inactive Portal when the Phantom comes to transfer the Arbiter to the Shadow of Intent.

The artifact is also seen in the ending cinematic of Halo 3: ODST, where a fleet of Covenant ships are excavating the object.

Size
Before Halo: The Essential Visual Guide established a definite diameter for the Portal, there was some confusion as to its size. This was due to a conflict between the in-game sizes of the Forerunner Dreadnought in Halo 2 and Halo 3, the latter depicting the ship as being far smaller than its former incarnation.

Based on the map geometry in Halo 3, the Portal can be estimated to be approximately 25 kilometers in diameter. However, this figure is contradicted by the geography of the Portal's surroundings; as evidenced by Halo 3 and Halo 3: ODST, the structure stretches from the edge of the metropolis of New Mombasa all the way to the edge of Voi, a distance well over 100 kilometers.

The canonical size of the Portal is derived by referencing the in-game measurements of the Forerunner Dreadnought from Halo 2. The sizes of the Portal and the Dreadnought in Halo 3 are taken as a liberty due to engine limitations; generating map geometry for over a 10,700 km2 area would be extremely taxing, if not impossible, within the game engine.

It should be noted that these estimations are centered around the the size of the excavated portion of the Portal. The extent of the underground installations surrounding it is still unknown.

Trivia

 * In the "Behind the Scenes" section on the Halo 2 Collectors Edition, there is a sketch of the Portal upon activation.
 * When the frontal half of the came back to Earth through the portal, instead of exiting it above the structure where the Slipspace rift would be, it ended up exiting in Earth's orbit, due to the portal being closed. This indicates that from the Ark, one-way access through the portal was possible, even if the portal was closed.
 * The 14 monoliths/petals that lift up after activation of the portal is another reference to the number 7 (7+7=14). The entire structure seems to be constructed of seven identical parts, with seven pairs of monoliths/petals. The Portal is 117 kilometers in diameter, a direct reference to John-117.
 * It has been further stated by Bungie that at one point, during story conception, the area that ended up being the Portal had originally been intended to be the Ark itself. Interestingly, the UNSC assumes the portal is the Ark as it nears activation, particularly during the levels Tsavo Highway and The Storm.
 * The monoliths/petals bear a striking resemblance to the monoliths around the Atmosphere Processor from the film Aliens.
 * The portal mechanism encountered in the first chapter of Spartan Ops Episode 7 shares a near identical design to that of the Voi portal; with monoliths that withdraw downward when the portal is deactivated. Presumably it is a similar technology on a much smaller scale.

List of appearances

 * Halo 3
 * Halo 3: ODST
 * Halo Legends
 * Origins
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Human Weakness
 * From the Office of Dr. William Arthur Iqbal
 * Halo: Silentium
 * Halo: Rebirth
 * Halo: Broken Circle
 * Halo 2: Anniversary
 * Terminals
 * Halo: New Blood
 * Halo: Spartan Strike
 * ''Halo: Hunters in the Dark