Eligius IV

Eligius IV, also called the Mothership, is a mining ship and a space station previously owned by the Eligius Corporation. It was designed to be used for interstellar missions to mine asteroids or to search for habitable planets. The ship was built to house 500 people in indefinite cryo-stasis. As well as mining equipment, food to last for several weeks, a small water recycler, a dropship, and an assortment of weapons and military grade hardware for the guards. Including guns, missiles, and shock collars for inmates. It also has a fully equipped medical bay and a large long-term fuel supply.

On the side of the haul, it states "Powering a Better Tomorrow." This most likely refers to the prisoners mining a renewable source of energy to power utilities.

It is now a refuge for the sole survivors of the human race, who were originally planning on staying on the ship in stasis for a decade until the Earth would be habitable. However, when it was discovered Earth was now forever uninhabitable, Monty set the ship on a course for a new potential homeworld for humanity in another solar system before he died of old age after his wife. Which he discovered in the ship's computer files on the Eligius III mission after spending 30 years decrypting them.

History and Background
Sometime in the past, the Eligius Corporation sent out a mining mission into deep space with 300 prisoners, 25 guards and 12 crew members on board. The mission was supposed to be 24 years long.

After a mutiny led by Charmaine Diyoza on April 4, 2047, that killed the captain and the crew of the ship and destroyed one of the engines. The mutineers decided to return to Earth, but with one less engine working, the journey home would take decades. Therefore, the prisoners were put into cryosleep, and in 2156, Eligius IV finally returned to Earth.

Throughout the Series
6 years after Praimfaya, the Gagarin (A dropship from Eligius IV) landed on Earth, carrying Charmaine Diyoza and 22 other prisoners.
 * -|Season Five=

On the Ark, John Murphy saw the station in the distance. Raven tried to radio the ship, but there was no response. As a quest to solve the group's fuel problems they flew to Eligius IV and found 284 prisoners in cryo-sleep. One of them, Kodiak, was woken up by Rankin to find out the reason the alarm was triggered and was killed by Bellamy and Echo. Later in order to have leverage over the prisoners already on the ground, Raven and Murphy stayed aboard to control the other prisoners still in cryo-sleep. In the interval between Pandora's Box and Shifting Sands, the leaders of Eligius prisoners took the remaining people from the ship and brought them back to Earth, including Raven Reyes and John Murphy, thereby leaving the ship abandoned.

After the Shallow Valley was destroyed, Wonkru, Spacekru, and the Eligius prisoners, along with Clarke and Madi Griffin, decides to go to Eligius IV, where they were put into cryo-sleep. However, Monty and Harper decided to stay awake, and they later have a son named Jordan Green, who was put into cryo-sleep at the age of mid 20's. Monty and Harper both died of old age, many years later.

In the year 2281, Jordan wakes up both Clarke and Bellamy, and shows them everything about him and his parents, and a new world they can live on.

In Sanctum, Clarke, Bellamy and Jordan share Monty's video message about the New World with a few select members of their group including Murphy, Emori, Echo, Shaw, Abby and Raven. Everyone in the group meets at the mess hall to plan on their landing strategy. Bellamy and Clarke plan to approach their new residence peacefully this time round. Raven wants to go to the ground but Bellamy wants her remain in the mother ship while they go with Shaw since she's the only other pilot. The group call themselves Expedition 1 and flies on the transport ship to the moon.
 * -|Season Six=

While Clarke, Bellamy, Murphy, Echo, Miller, Jackson, Emori and Shaw go the ground, Abby, Raven, Octavia Blake and Jordan all stay on board the ship.

In Red Sun Rising, the normal life of awakened people gets interrupted when the Gagarin suddenly returns. They go in to check why their friends on the ground so soon. It turns out, the transport ship was hijacked. The four hijackers are wearing black suits and gas masks. They drop gas grenades, knocking out everyone in sight, before locking them all in the mess hall.

Luckily, Raven is in the cryo room. She quickly wakes up Diyoza and explains the situation. Diyoza comes up with a plan where she pretends to be asleep while two other intruders enter the chamber. She quickly grabs one of the hijacker's guns and kills both intruders instantly. She takes one of their radios to make demands to their leader on the other end, a woman named Faye. Since she doesn't know her friends are dead, Diyoza uses them as leverage. Faye agrees to let everyone free if Diyoza sends her husband back to her on the bridge. Since Diyoza has already killed them, she convinces Raven to put on the suit and pretend to be Faye's husband. However she notices a bullet hole on the suit and therefore, is not convinced that it is her husband and demands that they take off the mask. As fight breaks out, Madi jumps down from the vent and joins in. Faye gets shot in the mix and bleeds black blood. Madi points out that she is a nightblood. She then asks Raven for Clarke's whereabouts. After losing her friend, the last member of the group, Kaylee, surrenders and explains the situation they were fleeing on the ground. They agree to go back on the ground as the eclipse passes.

Location
The ship was built on Earth and in the 2040s it was launched to the asteroid Proxima 6, where it was based during its mission of mining Hythylodium. After the mutiny of the criminals, it was returned back to Earth orbit, where it was located all the time during the Battle for Eden.

Eligius IV is currently located in the orbit of Sanctum at coordinates 11.60, 212.85, 449.10, 11.27.

Alive
There were approx. 300 prisoners living on the ship, until they were woken from cryosleep in Shifting Sands. Murphy and Raven also briefly stayed there, until they were brought to the ground with the prisoners.

In Season 5 finale, 412 of survivors including prisoners, Spacekru, and Wonkru went back on the ship and put themselves into cryosleep except Monty and Harper. 125 years later, Jordan Green woke Bellamy and Clarke on Monty’s order before both Monty and Harper died, due to old age. Which left 411 inhabitants on board.

In "Sanctum", an exploratory team consisting of: Clarke, Bellamy, Murphy,  Echo, Emori, Shaw, Jackson and Miller went down to Sanctum. After the events of Red Sun Rising, a second team went down to Sanctum. Including: Raven, Abby, Octavia, Diyoza, Madi, Gaia and Jordan. Leaving 396 inhabitants on the ship

The remianing inhabitants on the ship include warriors, thieves, prisoners and other people. Russell doesn't seem to be fond of this.

Former Inhabitants
Those who left the ship to travel to Alpha.

Deceased
Those who died on the ship.

Notes and Trivia

 * There are at least four spaceships owned by the Eligius Corporation.
 * Eligius I was an unmanned ship, Eligius II was a failed mission, Eligius III was sent to a new world, and Eligius IV is a mining ship that used prisoners for manual labor on the asteroids.
 * After Season Four finale, showrunner Jason Rothenberg teased that the prisoners aboard the ship will, at first, be antagonists. Unlike the juvenile delinquents, these arrivals are "real hardened criminals" and will be a threat.
 * The prisoners were from before the first nuclear apocalypse and were in cryosleep.
 * They include: Charmaine Diyoza, a former military strategist; Paxton "Graveyard" McCreary, an enforcer from a powerful crime syndicate; and Vinson, a serial killer.
 * Miles Shaw was also aboard the ship, but unlike the others, he is not a prisoner and instead is an Eligius IV crew member.