The Ark

The Ark (formally Ark Station) was the orbital home for the humans who's ancestors escaped the nuclear apocalypse on Earth 97 years ago.

Life-support on the Ark was failing, and even the best repair estimates had the work taking longer than the system could keep the population alive. As both a means of lessening the load on the system, and testing the survivability of Earth, the Ark sent the one hundred to Earth in an Exodus ship.

Season One
Approximately one year before the start of the the first episode, it had been discovered by Jake Griffin that The Ark's oxygen system was failing, which was the reason that the 100 were sent to earth. This problem presumably continues to worsen as the season progresses. In the episode Unity Day, an exodus ship is launched, severely damaging the Ark. In the episode, We Are Grounders (Part 2), Jaha sends all except the original Ark Station to earth. These stations brake apart in the atmosphere, but at least one section is know to have survived the fall.

Components
The major divisions of the Ark were functionally named stations

Government & Science Station
The Government & Science Station (Go Sci for short) is the large primary ring of the Ark. Go-Sci—and the Ark’s other ring stations—rotate to create artificial gravity using centripetal force.

Go-Sci is the location of the key command and operations sections of the Ark. It was also left behind in orbit when the rest of the Ark was de-orbited.

Ark Station Medical
Ark Station Medical, is located within Go Sci Station. Doctor Abigail Griffin worked there as the Ark’s senior medical officer. She was assisted by Doctor Jackson.

Earth Monitoring Station
Earth Monitoring Station is located within Go Sci Station. This was where “the 100” wrist monitors were tracked, and where Chancellor Jaha initiated station separation, allowing everyone else to attempt reentry to Earth.

Agro Station
Agro Station (aka Farm Station) was the Ark’s agricultural facility. It grew soy used as food by the inhabitants, and was also known for moonshine. (“Earth Kills”, mentioned) One of three stations evacuated after losing power during the Unity Day mutiny.

Jasper Jordan and Monty Green are both from Agro Station, and used their agricultural knowledge to grow “stuff”.

Alpha Station
Little is known about this station but it was separated from the Ark, while descending to Earth, it's status is unknown.

Arrow Station
This station forms the center-line of the Ark, through Go Sci, and looks like an arrow. It was separated from the Ark, while descending to Earth, it's status is unknown.

Factory Station
Factory Station, presumably manufactured items, needed by the Ark, from recycled materials and/or broken components. The Blake family lived there until Octavia Blake was discovered. Later, Bellamy worked there as a janitor. (named in “Earth Skills”)

Hydra Station
Hydra Station, often pronounced “Hydro” Station, and thus possibly water related. I.E. reclamation (and possibly aquaculture). One of three stations evacuated after losing power during the Unity Day mutiny.

Mecha Station
The Ark’s mechanical facilities were located here. Unknown to most, one of the station’s maintenance bays housed a 130-year-old escape pod salvaged from Mir-3 in 2102. One of three stations evacuated after losing power during the Unity Day mutiny.

Cuyler Ridley worked in Mecha Station, and Raven Reyes was from there.

The station’s hull has a Brazilian flag painted on it, implying that much of Mecha Station was converted from the original Brazilian national station.

Mecha Station was the only station without casualties from the Ark separation, reentry, and landing.

Prison Station
Also known as the Sky Box, it was the fourth station that lost power during the Unity Day mutiny. (It was not mentioned if it was also evacuated.)

Power Station

 * Based on the names, “Power” Station may be the nickname for Tesla Station.

Little is known about this station, as it was only named once (as stations reported ready for Ark separation and atmospheric reentry. Presumably it generated the majority of the electrical power used on the Ark.

Tesla Station

 * Based on the names, Tesla Station may be the formal name for “Power” Station.

Little is known about Tesla Station, but it was shown on computer displays as one of the stations that separated from the Ark, and descended to Earth, it's status is unknown.

Station Sections
Other divisions of the Ark, include station sections and docks, with alpha-numeric designations:
 * Section 17 – location of the room where The Culling took place.
 * Section No. B-17 – the location of both Cuyler Ridley’s, and Bellamy Blake’s living quarters according to profiles shown onscreen.
 * B dock – The location that the 100’s Exodus ship was launched from.

Other

 * Space shuttles – At least two shuttles can be seen docked to the Ark.
 * Dropships – Dedicated reentry vehicles, allowing return to Earth.
 * Exodus ship – A large 100-person dropship.
 * After using one Exodus ship to send down the 100, and losing another to Diana Sydney’s mutiny, the Ark’s dropship capacity was reduced to 600 people.

Thrusters are what keep the Ark in Earth's orbit.
 * Thruster - normal used to keep the Ark in its proper orbit, since even in low-Earth orbit, there is enough atmospheric friction to slow orbits over long periods of time. Each component station had thrusters, and Chancellor Jaha came up with the idea to use the thrusters to make most of the Ark itself a large "dropship".

Precursors
The Ark was constructed by merging together 12 national space stations, two of which have been named.
 * Mir-3 – Russian national space station, one of 12 combined to form the Ark. Salvaged in 2102.
 * Shenzhen – Chinese national space station, one of 12 combined to form the Ark.

History
The Ark was the orbital home that humans had survived on for 97 years, while Earth lay uninhabitable. The original survivors numbered over 400, spread across the space stations of 13 nations. Of those 13 stations one was lost to conflict before the remaining 12 joined forces. Those survivors combined the 12 remaining stations and thousands of satellites into The Ark, and their population grew to 2658, stretching life support to the breaking point.

Due to the resource scarcity, all adult criminals were punished with death, and juvenile offenders were imprisoned until they turn 18, and were either freed or executed. As a way of both testing the recovery of Earth, and reducing the population using up life support, 100 juvenile offenders had been sent to Earth.

Not knowing if the 100 were alive or dead, still facing inadequate life support, and with only enough dropships for 700; the Ark was forced to cull an additional 320 sacrificial volunteers, bringing the population living on board to 2237.

12 Nations

 * Main article: 12 Nations.

The individual space stations of 12 nations were combined to form the Ark. Their national flags are paraded as part of the Ark's Unity Day celebrations. The known station names are listed with 12 nations below.

13th Station
According to Finn, the 13th Space Station was destroyed in a conflict and the remaining stations decided to work together in order to obtain peace. Which country it belonged to is unknown.