ArcJet Systems

ArcJet Systems is a location in the Commonwealth in 2287. Once a large facility for a pre-War military and civilian aerospace contractor, it now lays abandoned.

Background
In 2075, ArcJet began working on a nuclear-powered rocket, the XMB booster engine, in hopes of convincing the United States Space Administration to award them the lucrative contract for their Mars Shot Project. Despite the risk of starting work before the contract, it paid off when the USSA gave them both the contract for the booster engine and the contract for a deep range transmitter. Both projects were completed before 2077. However, ArcJet only received payment for the deep range transmitter project, as the rocket was delayed before the Great War due to increasing military conflicts. CEO Thomas Reinhardt promised the USSA to finish both projects by July 2077, a year before the expected launch date.

Eager to deliver on its first agency contract, Reinhardt hired Dr. Rory McClellan, a private military contractor, to lead the development of the XMB booster engine. Reinhardt also ordered the head of security, Sam Brent, to double the facility's security and install automated security systems. By December, both of their projects were on schedule, and even under budget, and the USSA was discussing the possibility of other future projects.

In February 2076, the XMB suffered a setback when it was discovered that it was hundreds of tons over the weight allowance demanded by USSA, setting them potentially three to six months behind schedule. Reinhardt also became increasingly paranoid about security, having turrets installed in the office areas and requiring everyone to wear special identification badges or risk being fired upon. In July, the USSA announced the Mars Shot Project to the public, resulting in an increase of popularity and media coverage at ArcJet, causing Reinhardt to lie about their progress. In November, McClellan was able to fix the engine's weight issue, allowing ArcJet to finalize the project.

By 2077, ArcJet was able to complete the deep range transmitter project, allowing them to earn the proceeds from their contract. In February 2077, ArcJet planned to hold a press event to show off the first USSA testfire of the XMB booster engine. However, before the event, a reporter somehow managed to sneak into the core engine room and was accidentally vaporized by an engine test. The press event was canceled and Reinhardt ordered Sam Brent to cover the death up to prevent them from losing their contract. By September, the USSA warned Reinhardt that they may have to delay the Mars Shot Project due to the conflicts overseas.

In October, Dr. McClellan discovered the coverup of the dead reporter and told Reinhardt he was going to inform the police. Reinhardt responded by threatening to kill McClellan and his family if he told anyone. Despite this, McClellan still planned to take the video evidence to the press. It is unknown if he ever followed up on this, as the Great War occurred that same month.

Layout
The layout of the building differs, depending on whether or not the Call to Arms quest has been started. Before starting the quest, the building will only consist of the main lobby and a corridor leading to a collapsed room. Once the quest has been started then the whole building will be accessible and infested by synths.

Upper floors
The upper floors of the building have suffered massive internal damage, making it a maze of collapsed floors and ceilings. This area consists of the main lobby area, offices, restrooms, data storage, and board rooms.

After passing the lab control room is a lobby defended by two ceiling-mounted machinegun turrets and a handful of synths. This lobby gives access to several rooms which contain a weapons workbench, an armor workbench and a chemistry station. In the room with the chemistry station, an Expert locked terminal can be used to unlock a nearby Expert locked safe. In the eastern room, some stairs are leading up to the office area.

The office area is first accessed through the CEO's office, in which the Tesla Science Magazine issue #1 can be found. The corridors are heavily defended by four ceiling-mounted turrets although they can be deactivated from a terminal located in the first room on the lefthand side. In the northwest corner, a collapsed floor gives access to the receptionist area where an Advanced locked safe can be found and where stairs lead down to the ArcJet engine core.

ArcJet engine core
Beneath the main building is a large rocket engine test chamber. The XMB booster engine can be found suspended from the ceiling. At the bottom of the chamber is a facilities terminal inside a small control room that can be used to restore auxiliary power. The engine is still functional and can be activated by pressing the start button in this control room once power is restored. The engine will test fire and the intense flames from it will turn all synths inside the chamber to piles of ash. This can only be done once and cannot be repeated.

Due to collapsed stairs, the only way to access the top section of the chamber is to ride the elevator. At the top are the main control room and multiple synth enemies. Here one can find the deep range transmitter and an elevator to the surface.

Notable loot

 * Discarded ArcJet worklog – In the lab control room, on a desk next to a terminal and a globe in the middle of the room.
 * Technician's personal log - On the table with the Junk Jet.
 * ArcJet project manager's password - In the cabinet high up just to the right of the project manager's terminal in the engine core section, unlocks the nearby terminal.
 * Deep range transmitter – Quest item for Call to Arms, located on a synth in the upper floor control room after using the elevator in the rocket test area.
 * Tesla Science Magazine – On the table with the CEO's terminal. One has to pass the same locked door as for the Stealth Boy, but turn left instead and go up the stairs. It is in the first room one comes to.
 * Junk Jet – Engine core, in the control room at the base of the rocket, on a work table beside a holotape from the creator.
 * Stealth Boy – The first is past a Novice locked door to the left of a collapsed stairway in the small lobby with a broken, flooded floor. Once through the door, check behind the collapsed floor/ramp to the right to find the Stealth Boy sitting on a metal shelf.
 * Overdue book – Sitting on the large table in the meeting room, which is located on the second floor in the northeastern corner of the hallway where one encounters three machine gun turrets attached to the ceiling.
 * Two fusion cores – One in the generator room behind the rocket control room. A second is inside a generator, in a small warehouse to the north of ArcJet Systems. The warehouse is trapped with a landmine.
 * Fat Man – Sitting on a desk inside the north room (Marked with a '2' on the right side of the door) in the ArcJet engine core section. This can either be accessed going down from the top of the stairwell or by getting onto the railing as soon as one enters the area with the engine and jumping up to the walkway that leads to the room marked with a "2."

Related quests

 * Variable Removal: PAM has intel on a courser in the field. An unchecked courser can cause tremendous damage to the Railroad and the Sole Survivor is tasked with eliminating it.
 * Call to Arms: Paladin Danse asks the Sole Survivor to follow him to ArcJet Systems where he hopes to retrieve a Deep Range Transmitter to repair the Brotherhood of Steel communications array.

Appearances
ArcJet Systems appears only in Fallout 4. The ArcJet G-Force attraction is also sponsored by ArcJet in the Fallout 4 add-on Nuka-World.

Behind the scenes

 * The name ArcJet may be a reference to the Arcjet rocket, an engine produced by Aerojet by the same name.
 * Additionally, the company's name might be a reference to Aerojet itself (now Aerojet Rocketdyne).

Bugs

 * P.A.M. can give the missions to kill Coursers (Railroad) in this location but you won't have access to most areas yet due to another companion mission not being completed yet. This will leave you unable to finish the mission.
 * This can be fixed by using a power armor glitch. Simply face the broken door in third-person, aim your gun to push yourself into the door a little, hold the button to exit the power armor, then turn your back to the door. If done right, you will get out through the door. This will start Call to Arms and cause Paladin Danse to show up but attempt to leave. The quest cannot be finished this way, however.
 * If Call to Arms has not been started, you can enter ArcJet wearing power armor (preferably with a companion) and exploit being able to exit your power armor to enter the otherwise inaccessible portion. Go upstairs and head to the southeast corner of the building. You will see a way down to a safe and a piece of what looks to be upturned flooring directly ahead. Stay to the left and move up to and into the upturned flooring. Turn around to face North and you can exit your armor. You are now on the other side of this barrier and should be able to find and eliminate the courser. To get out, wait in one of the chairs in this area so your companion shows up. Go back to where you left your armor and have your companion enter it. Go to the left side of the blocking piece and start turning in circles while changing from first to third-person view. You should, with time, see into the CEO's office and be able to sit on the couch. Once you do so, you are now in the CEO's office and able to leave normally. With your companion in your armor, you will be able to get it back as soon as you leave the building.
 * In the Engine Core section, when you activate the rocket engine while the quest Call to Arms is not activated and Paladin Danse is not in the room, companions will get stuck in the observation room. Reloading an earlier save is the only way to fix them.
 * The project manager's terminal will show [EXPERT] to unlock, but the Sole Survivor will be unable to hack it with only rank 2 of the Hacker perk.