The engineering core is the third area that the Lone Wanderer encounters aboard the Mothership, and serves as a hub between numerous other locations aboard the ship, including the steamworks, hangar, cryo lab, robot assembly, cargo hold, maintenance level and engine room. Here, the player character can also find several other captives who will assist them aboard the ship. As one progresses through the main quest, the Engineering Core changes. Defenses are put up and barricades are made by the other captives; eventually a broken Nuka-Cola vending machine will show up; a teleporter to the Bridge appears near the steamworks entrance, down a corridor to the left of the Nuka-Cola machine; and a terrified alien will appear and plead for its life, only to be shot by Paulson.
The Engineering Core is one of the few rooms still available to explore after the quest This Galaxy Ain't Big Enough... is complete, as most other rooms beyond it will become inaccessible. At this point, aliens will also begin to spawn occasionally in the room.
The central power for Mothership Zeta is at the center of the map. The lower level surrounding the core contains little of interest.
Lower Observation Deck
The lower level is far smaller than the top level. It has a small room where Toshiro Kago sits most of the time with a large window that displays the reaches of space. There is a table opposite Kago and a foot locker near that. Across the from the windows is a hallway that has some garbage in the middle of it. Through this hallway, one reaches the main part of the lower floor. This has a main energy pillar in the middle of it, surrounded by capacitors. Also on this floor underneath the stairs is a bed for the player character to sleep on.
Upper Observation Deck
In Kago's room is a staircase that leads up the second level. This staircase opens to a room with random junk strewn about on tables, beds, and the floor. Going through a door on the right will take the player character to the main area with the energy pillar from the first level. This is the area where most of the captives roam. Going straight, the player character will head into the cryo research area, going to the right will let them into the maintenance level, robot assembly, or the engine rooms and going to the left will take them to the hangar or cargo hold.
- There are alien captive recorded logs 5, 6, 7 and 8, beside each frozen captive.
- Two Buttercup toys appear. The first appears downstairs on a table near the makeshift bed where Toshiro Kago usually sits, after two of the generators are destroyed. The second appears upstairs on the table between the between the pre-War bed and the teleporter to the observation deck, after visiting the engine room and all three generators are destroyed.
- 26 alien power cells can be found here in a box along with a Nuka-Cola Quantum.
- Three Nuka-Cola Quantums appear in crates. Two after exploring all of the rooms branching from the engineering core and destroying two generators, the third after all generators are down.
- One mini nuke appears in the chair next to the workbench in the room that leads to the decompression chamber after exploring all of the rooms branching from the engineering core and destroying two of the generators.
- One Nuka-grenade in a bucket, on the right side of a control panel, in the room leading towards the decompressing chamber.
- Spacesuit - Found on Colonel Hartigan's corpse.
- Winterized medic armor (minus helmet) - Worn by Elliott Tercorien.
- Paulson's outfit and revolver - Worn/carried by Paulson.
- Samurai armor worn by Toshiro Kago.
- Once the player character has started destroying generators, the area opposite the stairwell of the cryo lab will start being progressively cluttered with loot and world items (Wasteland and alien). The area actually gets so cluttered that some items might need to be removed before others turn up. The whole room will also progressively exhibit signs of malfunctions and disrepair.
- Everything needed to craft weapons from all seven schematics can be found here and the cryo lab, with the exception of a deathclaw hand. The workbench itself (which of course looks nothing like a regular workbench) can be found in the room north of the main hub, to the left of the door leading to the decompression chamber.
- Some safe places to store loot during the main quest are:
- In the room with a makeshift bed. The footlocker on the far right when looking into space is a safe place to store items.
- The toolbox next to the alien workbench.
- The alien container on the bottom floor of engineering furthest from the NPCs. It is too far away for them to steal from during Among the Stars and a break in the upper level railing allows one to quickly drop down on top of it while unable to jump (encumbered).
- The overturned Nuka-Cola machine.
- As the player character walks up the stairs above the bedding, if they look down when reaching the top, they can see a miniature drone holding a teddy bear.
- If the player character the Child at Heart perk, after thawing the cryotubes, one will get the option to ask Sally if she has "any good stuff hidden away." She will give the player character access to room near the teleporter to the bridge, which contains three containers of alien items normally blocked by an energy barrier. Note, however, that if the player character talks to Sally again while she is leading them to the room, she will stop and talk to them and will not open the room; the dialogue option will also no longer be available.
- Sitting on a box at the top of the stairs is a teddy bear holding a beer and wearing brass knuckles.
- Sally can sometimes be seen drinking beer in the area above the makeshift bed.
The teleporters on this deck may stop working, while displaying the appearance of a fully active teleporter. This can be a serious game glitch permanently trapping the player character on the ship. [verified]