Test Shaft 09
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Test Shaft 09 can be considered as a "timeline" level, as it reveals many details about Aperture Science's background and evolution, from its establishment in the late 1940s to some time before the end of the pre-GLaDOS era, in the late 1980s, through explicit visuals and the prerecorded messages by Cave Johnson and occasionally his assistant Caroline.
As part of the Enrichment Shafts built in the immense salt mine purchased by Cave Johnson in 1944, Test Shaft 09 was used to test several experiments from the early 1950s to the late 1980s, many being described by Johnson through prerecorded interphone messages, not necessarily involving teleportation, often with ominous results, and spread through six Enrichment Spheres (the seventh apparently not used), as well as several other unseen Test Chambers:
- In the Enrichment Spheres: Experiments with the Mobility Gels (in the Co-op Test Shaft as well) coupled with prototypes of the Handheld Portal Device, from the 50s to the 80s. Testing starts in a 50s area at the bottom of the Shaft and goes ascending in height as well as time to end up in the 80s, then finally the modern facility again. Thus during the ~35 years of building of the Shaft, each area was left as it was when built and never modernized when the next area was completed.
- In the condemned Test Chambers near the 50s reception area:
- Injection of praying mantis DNA to Test Subjects, turning them into Mantis Men. The experiment would also required Test Subjects to fight the existing Mantis Men.
- Experiment having a Test Subject's blood replaced with pure gasoline by shooting at them with an invisible laser.
- Experiment having Test Subject's excrements temporarily turning into coal.
- Experiment during which a superconductor is turned up at its highest setting and pointed at a Test Subject, with unknown results, the best-case scenario said to have the Test Subject getting some superpowers, or, in the worst case, some tumors, which Aperture is said to remove.
- Experiment having a Test Subject's blood replaced by peanut water for a few minutes, which cannot be performed if the Test Subject is allergic to peanuts. Johnson states a new type of Nobel Prize will have to be invented just for them if the experiment succeeds.
- Experiment having a Test Subject's percentage of body water brought from 60% to 20 or 30% when being hit with jet engines.
- Teleportation experiment which may have a Test Subject's skin removed after the teleportation process. Before the test, Test Subject are asked to remember what type of skin they have in case it is removed during teleportation, and Cave promises Test Subjects will be sewn right back into it.
- Unknown experiment in the icebreaker Borealis in a large drydock located near the previous Test Chambers, which made the ship disappear and reappear in an Arctic region.
On June 15, 1961, Test Shaft 09 was condemned by vitrification when it was filled with unsafe quantities of cosmic ray spallation elements, until it was reopened in the early 1970s, to be used until the late 1980s. Anyone entering the area is warned to not look at, touch, ingest or engage conversation with any substances located beyond. In the 1990s, Cave Johnson is dead, access to the Mobility Gel supply is cut off, and the Enrichment Shafts are apparently disused, the main facility above, eventually supervised by GLaDOS, being used instead for testing.
As the Enrichment Shafts date from before GLaDOS' activation, she never monitored them before discovering Test Shaft 09 with Chell. Instead, prerecorded messages from Aperture CEO Cave Johnson and occasionally his assistant Caroline are used to guide Test Subjects.
What follows is a summary of Test Shaft 09's features. For the detailed layout, see below.
Test Shaft 09 has several known accesses:
- The Main Lift that connects each level to the surface, that was to be used by Test Subjects. Each level appears to be isolated from the other by a couple of horizontal sliding blast doors on each side of the elevator shaft covering the area.
- Two gargantuan hatches located at each end: the Abandonment Hatch, accessed by Chell from the "Tartaros" area at the very bottom, and the Transition Seal 02, located at the very top, leading to the modern facility and through which the Mobility Gel flow feeds into the facility.
- An underground train network connected to the eight other Test Shafts, located at the very bottom of the Shaft series.
 Reception and control complexes
Test Shaft 09 contains several complexes dedicated to office space, reception for Test Subjects, and access control to the Enrichment Spheres. These complexes can be distinguished by era: the reception complex for the Repulsion Gel spheres was completed in the early 1950s and reflects a time when Aperture (at that time marketing its products as "Aperture Science Innovators") was able to attract the best and brightest to test its exotic technologies. Instructional posters, Johnson's prerecorded messages and the awards seen in the case featured in the lobby suggest a time of pride and optimism for the company.
The complex for the Propulsion Gel spheres was completed in the early 1970s after Aperture suffered major financial and legal setbacks, as well as (according to Johnson) industry espionage by competitor Black Mesa. Offices are decorated in brown, yellow and orange paneling typical of 1970s America. Posters caution employees to notify their supervisors if they spot inspectors from any of a long list of government safety agencies. These tests were using hobos hired off the street and paid $60 per test.
The complex for the Conversion Gel spheres was completed in the early 1980s when Aperture had begun to replace its employees with robots, leaving the employees themselves to act as Test Subjects. Posters motivate human employees to accept their robotic replacements and give advice on how to deal with rogue artificial intelligences.
 Enrichment Spheres
Test Shaft 09 is mostly filled with 7 Enrichment Spheres - large geodesic asbestos and steel spheres located one above the other, and containing the original chambers used by Aperture Science Innovators for tests of its Mobility Gels in conjunction with ancestors of the modern Handheld Portal Device. Each sphere typically contains two Test Chambers supported by steel pylons and connected by catwalks. Spheres also contain offices and observation rooms around their periphery. Elevators provide transport between spheres.
Most of the testing spheres and the bottom of the shaft itself contain pools of highly corrosive toxic waste. The signs warning not to fall into the waste suggest it has been there from the start.
 Other Test Chambers
Experiments that did not require the space or modularity of the portal/gel tests were located in side chambers accessed by heavy doors near the '50s and '70s-era reception areas. Almost all of these chambers have been vitrified. Cave Johnson's prerecorded messages near these doors describe absurd side effects mentioned above. Of particular interest is an unsealed door leading to the drydock of the missing Borealis.
 Pumping Stations
The shaft also contains three Pumping Stations codenamed Alpha, Beta, and Gamma which pump the three Mobility Gels up the shaft and into various testing chambers (each bearing the color of its related gel), suggesting that a huge reserve of Mobility Gels must be located somewhere in the salt mine, as well as the main Pump Station located at the top of Test Shaft 09 and feeding the gel pipe network into the modern Enrichment Center. These stations were taken offline when the shaft was abandoned, but are reactivated by Chell during her journey, restoring the gel flow from the lowest levels to the modern facility. The stations are in surprisingly good repair given the amount of time passed since they were last maintained. The catwalks have decayed, but the pipe system has survived with only a few broken valves and leaking flanges.
 Introduction area
In the Central AI Chamber at the end of the Portal 2 chapter The Escape, Wheatley plugs GLaDOS' memory to a potato, and put her with Chell in the elevator connected to the chamber. As GLaDOS explains to him who he really is and calls him a moron, he has a fit of rage, and smashes the elevator several times until it is set loose into the shaft. The next chapter, The Fall, opens as Chell and the now potato-powered GLaDOS fall into the 4375 meter-deep elevator shaft, an employee access to Test Shaft 09. During the fall, GLaDOS (now nicknamed "PotatOS") tells Chell more about Wheatley's background and how the fact that he is in charge of the facility is a catastrophe. At the end of the fall, the lowest part of the shaft appears to be destroyed and does not reach the floor; Chell and PotatOS fall onto the ground and Chell passes out. When she wakes up, she witnesses PotatOS being pecked by a crow that quickly takes her away (while it is the same model, it is unknown if it is the same bird that attacked Wheatley earlier), and the elevator dangling at the end of the destroyed shaft up above.
Chell then proceeds to an area that seems part ruined, part in construction, one of the two entrances to Test Shaft 09 to be used only by employees. Large pillars appear to support the modern facility above, and are marked with the number "09" and the name "Tartaros". In the Greek mythology, Tartarus is a large gloomy abyss used as a dungeon of torment and suffering that resides beneath the underworld, and where several Titans were sent by Zeus for punishment; this is paralleled here, with Chell being sent into a large gloomy abyss as punishment from Wheatley. "09" is probably related to this particular area of the mines, since the Enrichment Shaft located nearby bears the same number.
Aided by her ASHPD creating portals on the portalable surfaces, Chell proceeds through the area, which is still fully powered, with ongoing fires of carcasses of Sentry Turrets. Many red cranes can also be seen; many other pillars and cranes appear to extend very far under the facility, possibly in areas bearing other numbers. The whole area seems to be incomplete, as many scaffolds are still in place.
Chell then finds herself facing a wall barring the way to the "condemned testing area" of Test Shaft 09, condemned by vitrification on June 15, 1961, with three small shut doors. There two signs indicate the current status and condemnation date of the shaft mentioned above. Many "Keep out" and "Do not enter" signs are present. Conversion Gel pipes are also seen coming from above, disappearing farther into the rock. Thanks to her portal gun, Chell easily circumvents the wall, and proceeds through a narrow path along which a pipe runs, until she reaches the Abandonment Hatch.
 Abandonment Hatch
The Abandonment Hatch is a gargantuan metal hatch that seals Test Shaft 09 from that part of the facility. There the condemnation date is seen again. To open the hatch, two persons have four seconds to press the two "Hatch Reclusion Override" buttons each found in the two cabins located on left and right of the hatch, each with a countdown outside of them. As Chell is alone, she uses her portals to push both buttons. When the hatch opens, it reveals it was hiding only a small human-size door (along with a chair and knocked down stool), the rest of the hatch space being a mere wall, a rather (purposely) anticlimactic result. Beyond the door is a small corridor leading to another small door, itself leading to the very bottom of the proper Test Shaft 09.
 Gallery: Screenshots
 Gallery: Logos, signs and posters
 1950s levels: Repulsion Gel
The Mobility Gel tested in this level era is the Repulsion Gel.
 1952: Entrance Way, Lobby and Testing Lounge
The proper way to reach that part (i.e. the Test Subject way) is by arriving from the Main Lift from the surface. It will lead to the reception area (Sublevel 193), which is made of the Entrance Way, the Lobby and the Testing Lounge.
Chell however arrives directly into the shaft itself from the Abandonment Hatch (which is restricted to employees), where she can see the first two Enrichment Spheres, a sign warning not to fall into a lake of toxic waste filled with six small spheres and a destroyed "Aperture Science Innovators" metal logo that fell from above, and the building date, 1952, on a wall. While Chell proceeds, cables and debris detach from Sphere 01. A catwalk then leads to another level, where three doors leading to contaminated and vitrified areas are found. The first one, breached by the collapsed sealing, is an employee door leading to the Test Subject reception area, with breaker 135B that provides power to the latter (it bears the alphanumerics "B-09/S", used many times in the level). The second door leads to Test Chambers 1 to 200. It has a notice stating the experiment was discontinued, with the image of an Enrichment Sphere filled with cement, suggesting other spheres (maybe smaller like the ones in the water) could be located there, and that Aperture must have been running an incredible amount of other unknown experiments. The third door shows the existence of 8 other Test Shafts, as it leads to an underground train network linking them together. Near the door is also a notice with an Enrichment Sphere filled with cement, placed there for unknown reasons.
 Entrance Way
Back to the reception area, the Main Lift shaft is empty and condemned, and the elevator, located several hundreds of meters above, is out of order until a undetermined date. Back then in the 1950s, Test Subjects leaving the Main Lift would reach the Entrance Way and meet a sign with on it "Aperture Science Innovators" (Aperture's trademark, created in 1947, later renamed "Aperture Laboratories") and "Welcome to the future of tomorrow!" above, with a mountain skyline as a background, as well as a faded blue metal Aperture Science Innovators logo, the same as the one that fell into the shaft's bottom. A catwalk through the Entrance Way, carved into the rock, would lead to the Lobby and Testing Lounge. Aperture CEO Cave Johnson would greet [Test Subject]s with great enthusiasm, joined with his assistant Caroline, in the following prerecorded announcement, accompanied with an early rendition of the music heard in the Aperture Investment Opportunity videos and the television in Chell's chamber in the Extended Relaxation Center:
"- Cave: Welcome, gentlemen, to Aperture Science. Astronauts, war heroes, Olympians - you're here because we want the best, and you are it. So: Who is ready to make some science?
- Caroline: I am!
- Cave: Ha ha! Now, you already met one another on the limo ride over, so let me introduce myself: I'm Cave Johnson. I own the place. That eager voice you heard is the lovely Caroline, my assistant. Rest assured, she has transferred your honorarium to the charitable organization of your choice. Isn't that right, Caroline?
- Caroline: Yes sir, Mr. Johnson!
- Cave: She's the backbone of this facility. Pretty as a postcard, too. Sorry, fellas. She's married. To science."
Cave sounds very enthusiastic and eager, and has Caroline at his side. Back then, Aperture was using high profile and trained Test Subjects such as astronauts, war heroes, and Olympians, driven to the facility in a limousine, and whose honorariums were transferred to the charitable organization of their choice.
When Chell visits the place, the catwalk leading to the Lobby has been destroyed, and she must portal herself through the gap by using momentum and going through the Aperture Science Innovators sign, after the nuclear logo in its center falls on the ground after detaching itself.
Upon reaching the lobby, Test Subjects would be greeted by this message:
"There's a thousand tests performed every day here in our Enrichment Spheres. I can't personally oversee every one of them, so these prerecorded messages'll cover any questions you might have, and respond to any incidents that may occur in the course of your science adventure. Your test assignment will vary, depending on the manner in which you have bent the world to your will.
Those of you helping us test the Repulsion Gel today, just follow the blue line on the floor. Those of you who volunteered to be injected with praying mantis DNA, I've got some good news and some bad news. Bad news is we're postponing those tests indefinitely. Good news is we've got a much better test for you: fighting an army of Mantis Men. Pick up a rifle and follow the yellow line. You'll know when the test starts."
The message suggests a very brisk and busy era for Aperture, with a thousand tests performed every day in the Enrichment Spheres. Test Subjects would test the newly created Repulsion Gel, but also be injected mantis DNA, turning them into Mantis Men (postponed for some reason), which would also be fought by other Test Subjects as part of another test. The message asks Test Subjects sent to fighting Mantis Men to pick up a rifle and follow a yellow line, but it cannot be found anywhere, the only path being to Enrichment Sphere 01 or three unrelated Test Chambers.
The Lobby is a room with black marble and a maroon carpet on the floor, and wooden panes on the walls. Four lamps with spherical lampshades hang from the ceiling. A sign asks Test Subjects to go to the small desk nearby and sign in with the receptionist before proceeding to the Lounge. Next to the Lobby is an elongated operator room filled with several desks equipped with typewriters and phones, probably used for registering candidates.
 Testing Lounge
The Testing Lounge is accessed through a folded red curtain. Its floor is fully covered with maroon carpet, and it is filled with large conformable beige armchairs, as well as several ashtrays. It also has six spherical lamps on the ceiling. Of note is the large portrait of a young and brisk Cave Johnson placed between two cases. One of the cases has been broken and emptied; the other is filled with many items giving information about Aperture's background and evolution: four trophies, including the Spirit of Idaho 1955 award for the promotion of Potato Science, by the National Potato Board; the Shower Curtain Salesman of 1943 award for Aperture Fixtures; and two "Contractor of the Year - Runner Up" awards from the US Department of Defense, dated 1952 and 1954 (an unseen 1953 award can also be found in the game files). The case also includes the main page of the newspaper The Up Pioneer Press, dated from a Thursday of January 1944, showing that Johnson purchased salt mines in Upper Michigan, where and above which the Aperture Science Enrichment Center will eventually be built, retconning the facility's location from Cleveland to Michigan. Under a picture of the mine, Johnson is quoted "The Future is Here, and it's Under the Earth's Crust". Finally, four framed awards can be seen: the Best New Science Company award 1947 given to Aperture Science by the Science and Business Institute of America; another Spirit of Idaho award by the National Potato Board Award for the promotion of Potato Science, undated; the Shower Curtain Salesman of 1943 award given to Cave Johnson for Aperture Fixtures; and finally an award for rank #2 for Aperture Science in the Top 100 Applied Science Companies 1949.
After leaving the Testing Lounge to the shaft proper, Test Subjects would go to an elevator operated by an attendant. Upstairs, a catwalk, now collapsed, would lead either to the small elevator going inside Enrichment Sphere 01, Pump Station Alpha, or three condemned Test Chambers, two vitrified (one of which filled with cement), the other apparently not condemned, but inaccessible regardless. Near each door leading to these chambers is an interphone, which when powered will give the following prerecorded messages by Johnson about what tests they involve:
"- If you've cut yourself at all in the course of these tests, you might have noticed that your blood is pure gasoline. That's normal. We've been shooting you with an invisible laser that's supposed to turn blood into gasoline, so all that means is, it's working.
- If you need to go to the bathroom after this next series of tests, please let a test associate know, because in all likelihood, whatever comes out of you is going to be coal. Only temporary, so do not worry. If it persists for a week, though, start worrying and come see us, because that's not supposed to happen.
- Just a heads up: We're gonna have a superconductor turned up full blast and pointed at you for the duration of this next test. I'll be honest, we're throwing science at the wall here to see what sticks. No idea what it'll do. Probably nothing. Best-case scenario, you might get some superpowers. Worst case, some tumors, which we'll cut out."
These tests imply strong recklessness from Aperture, suggesting the team didn't really know what they were doing.
 Pump Station Alpha
The first of the three Mobility Gel Pump Stations found in Test Shaft 09, probably also built in 1952, is used to pump Repulsion Gel. It is activated by a switch on a console in a booth located at the lowest level, with a screen showing the six spheres used in Test Shaft 09. The booth contains three motivational posters: "Know your... Allergens" ("pollen", "animal dander", "plastics", "anti-matter"), "Know your... Hazardous Materials" ("Don't touch anything unfamiliar"), and "Know your... Chemical Hazards" ("Do not inhale fumes - no matter how good they smell"). Above on a catwalk leading back to the shaft can be found a safety poster saying "Together we can make 1956 the lowest unexpected casualty annum ever!".
After powering back Pump Station Alpha, Chell portals herself near the small elevator leading to Enrichment Sphere 01 to begin her introduction to Aperture's Mobility Gels. At the entrance of the elevator is introduced an early iteration of the Material Emancipation Grill, the first of several early iterations of familiar Aperture technology that can be found in the shaft.
Before entering the elevator, Test Subjects would hear the following overenthusiastic message:
"They say great science is built on the shoulders of giants. Not here. At Aperture, we do all our science from scratch. No hand holding."
This references the metaphor "Standing on the shoulders of giants", meaning "One who develops future intellectual pursuits by understanding the research and works created by notable thinkers of the past".
 1953: Enrichment Sphere 01
The elevator leads to a dark Sphere 01. When it stops, the sphere is lit up, revealing a "You are here" sign showing a partial plan of the Enrichment Shaft complex, although it incorrectly shows Test Shaft 09 with 9 spheres instead of 7. Test Subjects were welcomed by that Cave Johnson announcement:
"Alright, let's get started. This first test involves something the lab boys call "Repulsion Gel."
You're not part of the control group, by the way. You get the gel. Last poor son of a gun got blue paint. Hahaha. All joking aside, that did happen - broke every bone in his legs. Tragic. But informative. Or so I'm told."
Again, Cave is rather reckless and nonchalant about something grave happening, typical of the cynical writing style of the Portal story arc. Furthermore, The "paint" may be a reference to the concept behind the Mobility Gels, i.e. the paint from Tag: The Power of Paint. In Tag, the blue paint allows its user to walk on walls and ceilings covered by it (which originally also was to be featured in Portal 2 as the Adhesion Gel).
 Test Chamber 01
Outside this first Test Chamber can be found a building date, 1953, and a sign stating that "This test is unsolvable without an Aperture Science Portable Quantum Tunneling Device. If you have not received one, please find a test associate before participating in any Shaft 09 Enrichment Activities", with in the center the picture of a Test Subject bearing a huge Handheld Portal Device prototype.
Inside the Test Chamber are introduced early iterations of familiar Aperture technologies, paired with the use of the Repulsion Gel: an early Weighted Storage Cube used with an early 1500 Megawatt Heavy Duty Super-Colliding Super Button and an early Switch, used to release the Cube through an early Vital Apparatus Vent. A short story about the Repulsion Gel is also found on a sign at the entrance of the Test Chamber, near the early iteration of the squared testing element sign, named "Aperture Science Fact Placard #00D45-01R - Repulsion Gel": "Did you know Repulsion Gel was Aperture's first attempt to create a dietetic pudding substitute?", followed by Repulsion Gel in a spoon, then "It's true. The gel is a sweeter, slightly less non-toxic form of fiberglass insulation that causes subsequently-ingested food items to bounce off the lining of a dieter's distended stomach and out his or her mouth! (For various reasons, this product was pulled from shelves.)", the under it, in small letters: "For more information, consult the following Fact Placards: Aperture Science Fact Placard #0012344-22R - 'Repulsion Gel, Lawsuits Concerning' / Aperture Science Fact Placard #0012321-23R - 'Repulsion Gel, Public Outrage Over'" After the test has been performed, the following message is played:
"The lab boys just informed me that I should not have mentioned the control group. They're telling me I oughtta stop making these prerecorded messages. That gave me an idea: make more prerecorded messages. I pay the bills here, I can talk about the control group all damn day."
Johnson does not like having people telling him what to do, also referenced for instance in the memos revealed during the Portal ARG, in which Cave complains about the "bean counters".
 Test Chamber 02
The next Test Chamber was originally to be reached through several catwalks, but since they have collapsed, Chell must use her Portal Gun instead to reach the other side. Its construction appears to have started in 1953 and ended in 1956. Before entering, the following message is played:
"For this next test, we put nanoparticles in the gel. In layman's terms, that's a billion little gizmos that are gonna travel into your bloodstream and pump experimental genes and RNA molecules and so forth into your tumors.
Now, maybe you don't have any tumors. Well, don't worry. If you sat on a folding chair in the lobby and weren't wearing lead underpants, we took care of that too."
In this Test Chamber, the Repulsion Gel is said to have been injected with an additive said to cure tumors. It is unknown what "lobby" Cave is referring to, but the Lobby found at the bottom of the Shaft has no folding chairs. The "lead underpants" would also suggest this lobby (or at least its folding chairs) is irradiated.
A more elaborate test is proposed, with an early Unstationary Scaffold used to take hold of a Cube, as well as two walls covered in Repulsion Gel, having Test Subjects to bounce from one to the other to reach another Cube. These two Cubes are to be used on a Supper Button, triggering portalable panels, allowing Test Subjects to exit. Outside, the following message is played:
"Oh, in case you got covered in that Repulsion Gel, here's some advice the lab boys gave me: DO NOT get covered in the Repulsion Gel.
We haven't entirely nailed down what element it is yet, but I'll tell you this: it's a lively one, and it does NOT like the human skeleton."
It is easy to have Chell covered with the Repulsion Gel, although it has no effect on her health an any point of the game; it is possible these effects have waned over the decades. Then an elevator leads to Sphere 02.
 1957: Enrichment Sphere 02
In this sphere built in 1957 Test Subjects were introduced by the following message, revealing that the spheres are made of asbestos to keep out the rats:
"All these science spheres are made of asbestos, by the way. Keeps out the rats. Let us know if you feel a shortness of breath, a persistent dry cough or your heart stopping. Because that's not part of the test. That's asbestos.
Good news is, the lab boys say the symptoms of asbestos poisoning show a median latency of 44.6 years, so if you're thirty or older, you're laughing. Worst case scenario, you miss out on a few rounds of Canasta, plus you forwarded the cause of science by three centuries. I punch those numbers into my calculator, it makes a happy face."
Again, Chell does not seem to have any of these symptoms anywhere later in the game.
 Test Chamber 01
Test Chamber 01 cannot be used as it collapsed on the wall, forcing Chell to reach the bottom of the Sphere then reach the second Test Chamber with portals.
 Test Chamber 02
Outside this chamber can be seen the date 1957, though it cannot be seen from the start elevator, but can at the end one.
Despite the original entrance of the chamber being condemned, Chell starts testing in the proper place, and is met with the following message:
"Ha! I like your style. You make up your own rules, just like me. Bean counters said I couldn't fire a man just for being in a wheelchair. Did it anyway. Ramps are expensive."
The message suggests the proper entrance has always been condemned, since Johnson shows appreciation in the way the Test Subject reaches the Test Chamber through another way. Here Cave also shows his complete disregard for rules and lack of empathy, firing someone in a wheelchair, just because wheelchair ramps are expensive.
This Test Chamber involves using a Repulsion Gel dispenser to portal the gel in the needed places, then make a long jump to the exit. As the first Test Chamber is destroyed, the test is already over after that, and Chell proceeds to Sphere 03, before hearing the following:
"Just a heads-up: That coffee we gave you earlier had fluorescent calcium in it so we can track the neuronal activity in your brain. There's a slight chance the calcium could harden and vitrify your frontal lobe. Anyway, don't stress yourself thinking about it. I'm serious. Visualizing the scenario while under stress actually triggers the reaction."
Chell did not drink any coffee earlier, so it is normal she does not have these rather grave symptoms.
This Test Chamber was originally built with a modern design, as seen in the Repulsion Gel video shown at E3 2010.
 1958: Enrichment Sphere 03
This Sphere starts with the following message:
"Now, if you're part of Control Group Kepler-Seven, we implanted a tiny microchip about the size of a postcard into your skull. Most likely you've forgotten it's even there, but if it starts vibrating and beeping during this next test, let us know, because that means it's about to hit five hundred degrees, so we're gonna need to go ahead and get that out of you pretty fast."
It seems that the control groups have nicknames, in this case "Kepler-Seven". Of note is that Enrichment Sphere 06 was originally named "Hotel Kepler". Furthermore, the microchip Test Subjects would be implanted into seems highly unstable.
 Test Chamber 27
Outside the first Test Chamber (numbered "27" for some reason) can be seen the building date 1958. Inside, the test involves precise timing, as water brought through a Conversion Gel pipe makes the Repulsion Gel go away, preventing the Test Subject to jump on it.
In the next room, the following message is heard:
"I'm telling 'em, keep your pants on.
Alright, this next test may involve trace amounts of time travel. So, word of advice: If you meet yourself on the testing track, don't make eye contact. Lab boys tell me that'll wipe out time. Entirely. Forward and backward! So do both of yourselves a favor and just let that handsome devil go about his business."
On the wall can also be seen a sign with the following words: "Remember! If a future you tries to warn you about this test, don't listen."
The next area is set above Test Chamber 27, and the Repulsion Gel dispenser must be used to reach the next chamber. Nearby is a safety sign reminding that accidents hurt "you" ("you will be hurt"), "coworkers" ("don't endanger others"), "the company" ("replacements are costly"), and "science" ("investigations impede progress").
Cave's warning and the sign on the wall suggest Aperture had mastered time travel in the 1950s. However no apparent "trace amount of time travel" is seen at any time.
 Test Chamber 28
When reaching the catwalks below Test Chamber 28, the following message is heard:
"If you're hearing this, it means you're taking a long time on the catwalks between tests. The lab boys say that might be a fear reaction.
I'm no psychiatrist, but coming from a bunch of eggheads who wouldn't recognize the thrill of danger if it walked up and snapped their little pink bras, that sounds like 'projection'.
THEY didn't fly into space, storm a beach, or bring back the gold. No sir, we did! It's you and me against the world, son! I like your grit! Hustle could use some work, though. Now let's solve this thing!"
Cave likes Test Subjects whoever they are, and publicly discredits his colleagues.
Test Chamber 28 was also built in 1958. Inside can be found an early Weighted Storage Cube in a large glass case, which must be broken after the Cube is covered in Repulsion Gel and starts bouncing around the chamber. After being released, it must be caught and washed to be used on a button that will trigger the exit platform, then covered in gel again to release the platform.
Before the exit elevator, the following message, in which Johnson gets angry, is heard:
"Science isn't about WHY. It's about WHY NOT. Why is so much of our science dangerous? Why not marry safe science if you love it so much. In fact, why not invent a special safety door that won't hit you on the butt on the way out, because you are fired.
Not you, Test Subject, you're doing fine.
Yes, you. Box. Your stuff. Out the front door. Parking lot. Car. Goodbye."
Despite being a prerecorded message, Cave seems genuinely mad. Of note is that the lines until "because you are fired" were reused from a memo revealed during the Portal ARG, in a completely different context.
Catching the gel-covered Cube before it hits the ground unlocks the "Schrodinger's Catch" achievement.
 Elevator access
Right after leaving the Sphere elevator, the following message is heard, concluding the test series performed in the 1950s:
"- Cave: Congratulations! The simple fact that you're standing here listening to me means you've made a glorious contribution to science.
As founder and CEO of Aperture Science, I thank you for your participation and hope we can count on you for another round of tests.
We're not gonna release this stuff into the wild until it's good and damn ready, so as long as you keep yourself in top physical form, there'll always be a limo waiting for you.
Say goodbye, Caroline.
- Caroline: Goodbye, Caroline.
- Cave: She is a gem. "
This closes the 1950s area on the same enthusiast and optimistic tone in which it started.
Four Spheres can be seen from here: the two last from the 1950s below, and the two from the 1970s above.
The access to the Main Lift follows, with a small lounge in the same style as that of the Testing Lounge featured at the bottom of the shaft, with another portrait of a brisk Cave Johnson, as well as a sign thanking Test Subjects for their participation. Inside the elevator shaft can be seen that the area is at a 4000 m depth.
 Gallery: Screenshots
 Gallery: Logos, signs and posters
Modified "fire diamond" sign seen on Mobility Gel tanks outside the Pumping Stations, stating the tank contents are safe.
Fourth poster, "Know your... Anti-Matter Risks", cut from the final game. The image was kept for a sign seen above Test Chamber 27 in Sphere 03.
Early exit sign, anachronistically based on a real-life modern exit symbol designed in 1979.
 1970s levels: Propulsion Gel
Of note is that the timeline jumps from the late 1950s to the early 1970s, as the Shaft was condemned in 1961 to be reopened in the early 1970s.
 1971: Pump Station Beta
As the Main Lift is disabled, Chell must portal herself from the 1950s exit area to the next set of Spheres, starting with Pump Station Beta, built in 1971, and pumping Propulsion and Repulsion Gels.
Inside Pump Station Beta, Chell portals herself to the top of the deep room and powers back the two pumps in rooms made in a typical 70s style, with wooden walls and an orange tiled floor, as well as typical white and orange 70s objects.
 1971: Entrance Way
Reaching the area where Test Subjects would arrive from the Main Lift in the 1970s, Chell can hear the original welcome message:
"- Cave: Greetings, friend. I'm Cave Johnson, CEO of Aperture Science - you might know us as a vital participant in the 1968 Senate Hearings on missing astronauts. And you've most likely used one of the many products we invented. But that other people have somehow managed to steal from us. Black Mesa can eat my bankrupt--
- Caroline: Sir, the testing?
- Cave: Right. Now, you might be asking yourself, 'Cave, just how difficult are these tests? What was in that phone book of a contract I signed? Am I in danger?
Let me answer those questions with a question: Who wants to make sixty dollars? Cash.
You can also feel free to relax for up to 20 minutes in the waiting room, which is a damn sight more comfortable than the park benches most of you were sleeping on when we found you.
So. Welcome to Aperture. You're here because we want the best, and you're it. Nope. Couldn't keep a straight face.
Anyway, don't smudge up the glass down there. In fact, why don't you just go ahead and not touch anything unless it's test related."
About ten years after the Shaft was condemned, it appears that Aperture has suffered major issues: astronauts hired for testing in the 50s appear to have disappeared, leading to Senate Hearings about their disappearances; Aperture also seems to have been victim of industry espionage by competitor Black Mesa; finally, these issues appear to have led Aperture to hire Test Subjects off the street, paying as low as $60 to risk their lives in the Test Chambers. Cave also repeats the sentence said in the 50s, "You're here because we want the best, and you are it", except that now he does not believe in it, since the new Test Subjects are no longer the best.
In a welcome area very similar to the one seen in the 50s, upon leaving the Main Lift Test Subjects would be met with a large yellow sign with on it "Welcome to Aperture / Where the science is theoretical ...but your $60 is fact!". Beyond is a large faded orange metal logo shows that at that time the "Aperture Science Innovators" brand had been changed to simply "Aperture". Test Subjects would go through the aperture of that Aperture logo to board the elevator leading to Enrichment Sphere 04, after leaving the ground with a platform started from the Control Room on the left. Left of the platform is a sign showing the way to the Test Subject Waiting Area, with on it the words "Keep to the left / Do not litter / Do not loiter / Do not touch glass.".
The Main Lift access is still condemned, and inside can be seen a 3975 m depth. The wall left of the elevator access is heavily damaged, and the catwalk originally tied to it was damaged as well, preventing from reaching an office above. Chell portals herself to that office, and accesses a corridor from a door located behind a large computer.
 Borealis’ drydock
In the corridor can be found four doors leading to vitrified Test Chambers, one of them having been blasted on the floor. Each of the three shut doors has an interphone, which when powered will give the following prerecorded messages by Johnson about what crazy tests they involve, reminiscent of what was heard at the bottom of the Shaft:
"- If you're allergic to peanuts, you might want to tell somebody now, because this next test may turn your blood into peanut water for a few minutes. On the bright side, if we can make this happen, they're gonna have to invent a new type of Nobel Prize to give us, so hang in there.
- The average human male is about sixty percent water. Far as we're concerned, that's a little extravagant. So if you feel a bit dehydrated in this next test, that's normal. We're gonna hit you with some jet engines, and see if we can't get you down to twenty or thirty percent.
- All right. We're working on a little teleportation experiment. Now, this doesn't work with all skin types, so try to remember which skin is yours, and if it doesn't teleport along with you, we'll do what we can to sew you right back into it."
The opened door leads to a large and empty drydock that used to house the Borealis before the experiment performed there made it disappear to an Arctic location. A barrier prevents from going into the drydock itself, and several life preservers bearing the ship's name are scattered on the floor. The drydock was also vitrified, as seen on the blasted door by noclipping.
 Control Room and Test Subject Waiting Area
 Test Subject Waiting Area
Back into the welcome area, below the office leading to the Borealis’ drydock is a two-story building. The ground floor is for Test Subject reception. The entrance hall features the portrait of an older Cave Johnson from the 1970s, now with sideburns. The Test Subject Waiting Area follows, in which Test Subjects had to take a numbered waiting ticket before being called for testing (when it was last used, the next ticket was 426, while the next Test Subject to go was 23). Two images on the wall also promote the promised $60. The floor also houses two offices with plants that dried out long ago. One office features a poster asking Aperture employees to alert their supervisor if they see the following: OSHA Inspector, Dept of Energy Inspector, GAO accountant, undercover police officer, Nuclear Regulatory Commissioner, FEMA Coordinator, ordinary police officer, journalist, Public Works Inspector, MSHA Mine Inspector, ATF / FBI / US Marshal.
 Control Room
The Control Room room above is not connected to the waiting area, and was presumably accessed from catwalk stairs now missing. There are further desks, and in a small room the Elevator Control button that operates the platform leading to Sphere 04's elevator.
There Chell reunites with PotatOS, being pecked by the bird in its nest after the latter grabbed her in the Tartaros area, showing it was able somehow to follow Chell inside the shaft. PotatOS asks Chell to kill the bird as she is "good at murder", but it escapes when she approaches. PotatOS tells Chell how important it is that Wheatley is disconnected. The AI then bargains to be taken with Chell, since she states she must replace Wheatley before he completely destroys the facility. Chell sticks one of her ASHPD's appendages into the potato, in the process releasing the Elevator Control button hidden in the nest. Shortly after, PotatOS "passes out". As Chell cannot activate the button and be on the platform at the same time, she portals herself to it, going again through the Aperture logo before reaching the platform from the other side through momentum.
 1972: Enrichment Sphere 04
This starts the seventh chapter, The Reunion, and tests with both the Repulsion and Propulsion Gels.
At the start, the following message is heard:
"- Cave: The testing area's just up ahead. The quicker you get through, the quicker you'll get your sixty bucks.
Caroline, are the compensation vouchers ready?
Caroline: Yes sir, Mr. Johnson!"
PotatOS oddly reacts to the message, answering to Johnson the same words as that of Caroline. After realizing what just happened, PotatOS suffers a panic attack and shorts out temporarily. This is the first clue of a connection between GLaDOS and Caroline.
 Test Chamber 01
This chamber, dated 1972, requires coupling the Propulsion Gel with a ramp. A pylon has fallen into the chamber, partially destroying a wall. At the end can be seen a large sign, reminding several things to Test Subjects: "Do not: leave your belongings here / loiter for more than twenty minutes / touch the glass", and "Do: wear a shirt and shoes at all times / move quickly through your test track / not forget to not touch the glass".
On the catwalks between Test Chamber 01 and 02 can be seen a sign ask to remember the following: "If you see an orange jumpsuit, hit the red button", with a the image of Test Subject with a bindle seemingly escaping. Nearby Chell has the ability to portal herself to Test Chamber 01's observation room, where a portrait of Cave and Caroline at his side can be found, unlocking the Achievement "Portrait of a Lady". To this, PotatOS comments "Those people, in the portrait. They look so familiar...". Behind the couple is a bookshelf, and on the left what may be the statue of an unknown individual. In the room, two posters previously seen in the Test Subject Waiting Area can be found.
 Test Chamber 02
In this chamber, also dated 1972, the Propulsion Gel must be combined with the Repulsion Gel. At the end of the chamber, the following message is heard:
"Great job, astronaut, war hero, and/or Olympian! With your help, we're gonna [tape cuts out - actually change the world]
This on? [thump thump] Hey. Listen up down there. That thing's called an elevator. Not a bathroom."
Here it appears that a tape from the 50s was reused and that there was a mix-up with the tapes, as at that time astronauts, war heroes and Olympians are no longer hired as Test Subjects. This is evidenced by the tape cutting out before the end of the sentence, Cave then asking Test Subjects to not defecate in the elevator, more appropriate for hobos hired off the street.
PotatOS comments she swears she knows the voice.
 1976: Enrichment Sphere 05
 Test Chamber 05
At the start of the sole chamber found in Sphere 05, dated 1976, the following message is heard:
"If you're interested in an additional sixty dollars, flag down a test associate and let 'em know. You could walk out of here with a hundred and twenty weighing down your bindle if you let us take you apart, put some science stuff in you, then put you back together good as new."
Here Johnson bargains for a few more dollars, promising dangerous operations to Test Subjects.
The chamber requires the Propulsion Gel to be combined with the Repulsion Gel through a set of different platforms, combined with a Cube, portals, and a ramp. This is very reminiscent to the later levels of Tag: The Power of Paint, from which the Mobility Gels were inspired.
At the end of the Sphere, the following message is heard:
"In case you're interested, there's still some positions available for that bonus opportunity I mentioned earlier. Again: all you gotta do is let us disassemble you. We're not banging rocks together here. We know how to put a man back together.
So that's a complete reassembly. New vitals. Spit-shine on the old ones. Plus we're scooping out tumors. Frankly, you oughtta be paying us."
Cave insists again on the previous opportunity of being disassembled then reassembled, suggesting Aperture was also working on artificial organs.
 1978: Elevator access
This section, dated 1978, marks the end of the 1970s levels. Above, the Test Subject Waiting Area for the Conversion Gel can be seen. On the catwalk out of Sphere 05, the following message is heard:
"Thank you - I can't believe I'm thanking these people - for staggering your way through Aperture Science's Propulsion Gel testing. You've made some real contributions to society for a change, and for that, humanity is grateful.
If you had any belongings, please pick them up now. We don't want old newspapers and sticks cluttering up the building.
For many of you, I realize 60 dollars is an unprecedented windfall, so don't go spending it all on... I don't know. Caroline, what do these people buy? Tattered hats? Beard dirt?"
This end message is similar to the one heard at the end of the 50s, but much less respectful, and rather disdainful.
The catwalk leads to a L-shaped corridor ending at the Main Lift access. Near the first corner, a sign reads "Thank you for not loitering longer than 20 minutes". Left of the elevator access, and facing three chairs, is a small booth in which a chair, a desk, a phone and a portable TV can be found. On its side, the following sign reads "All forms must be filled out legibly and completely before eligible to recieve [sic] payment of $60", showing "$60" was changed from another sum. The elevator access is still condemned, and on it can be found the same "out of service" sign found in the 1950s Entrance Way.
Chell portals herself on catwalks above, and beyond a heavy door she is back in the shaft. Catwalks used to lead to Pump Station Gamma, but as they are destroyed, Chell portals herself beyond the gap.
 Gallery: Screenshots
Isolated view of the models making up Enrichment Sphere 04, viewed in Hammer.
 Gallery: Logos, signs and posters
 1980s levels: Conversion Gel
The Mobility Gel tested in this level era is the Conversion Gel.
 1982: Pump Station Gamma
Scaffoldings can be seen outside and above the Pump Station, dated 1982, suggesting some elements were never completed.
Inside the station, PotatOS wonders who this Caroline might be, and if she might have killed her. She suddenly stops, troubled, and tells Chell she is doing great job, then stops speaking after saying she needs to think.
The Pump Station is made of three pumps, one for each Mobility Gel, which Chell restarts at the console. The 1980s are conveyed through white-colored devices, and a white-colored wall decorated with a light-blue colored line at the top. As the pumps are leaking, Gel particles are spread in several places in the pump station. As the only way to exit the station is by reaching its upper level, Chell uses the leaked Gels to her advantage to portal herself on top of the station as the catwalks leading to it are gone, and avoids eight deadly pistons in the process.
Before exiting the station, a poster can be seen, promoting robot workers replacing human employees and encouraging the latter to volunteer for testing. It starts with the sentence "Karla the complainer says... ‘My new boss is a robot!’". Right after, "But did you know?" introduces the three following sentences: "Robots are SMARTER than you", "Robots work HARDER than you", "Robots are BETTER than you". Under is a picture of "Karla the complainer" sitting at a desk, with standing in front of her her "new boss", a robot wearing a tie and holding a cup. "Volunteer for testing today" is written under the image.
Back into the shaft, the crow can be found flying off from the catwalk, making PotatOS scream and asking Chell to kill it. Spheres 05, 06 and 07 can be seen. The catwalk would lead to the next Test Subject Waiting Area, and as usual, as it is destroyed, Chell portals herself beyond the gap by using spilled Propulsion Gel inside the Pump Station.
During this era, the current "Aperture Laboratories" brand was introduced. The Portal 2 game files reveal that a model for a large and damaged metal version of that logo variant was to be seen somewhere, in a similar fashion to that of the previous era levels, but it was ultimately scrapped, although it replaces the 70s logo in a Portal 2 70s style poster.
 Combataton Testing Area
Under the Test Subject Waiting Area can be found a small platform with a door leading to a vitrified "Combataton Testing Area" with a warning saying "Remain still if you are targeted". It is unknown what is behind this door.
 1981: Test Subject Waiting Area
This is where the Aperture employees would wait before testing. Above the main building can be seen two other inaccessible buildings. Upon entering the Waiting Area, dated 1981, the following message is heard:
"Welcome to the Enrichment Center. [cough]
Since making test participation mandatory for all employees, the quality of our Test Subjects has risen dramatically. Employee retention, however, has not.
[cough] As a result, you may have heard we're gonna phase out human testing. There's still a few things left to wrap up, though.
The bean counters told me we literally could not afford to buy seven dollars worth of moon rocks, much less seventy million. Bought 'em anyway. Ground 'em up, mixed em into a gel.
And guess what? Ground up moon rocks are pure poison. I am deathly ill.
Still, it turns out they're a great portal conductor. So now we're gonna see if jumping in and out of these new portals can somehow leech the lunar poison out of a man's bloodstream. When life gives you lemons, make lemonade. [coughs] Let's all stay positive and do some science.
That said, I would really appreciate it if you could test as fast as possible. Caroline, please bring me more pain pills."
Now Aperture is not even able to hire hobos off the street anymore, and is forced to recruit among its employees, replacing them (as evidenced by several posters) by robots, which also sees the numbers of employees diminishing, while their quality is higher than that of hobos. Human testing however is said to be soon phased out, but that experiments with the Conversion Gel, made of ground moon rocks, must first take place. The rocks are however poisonous, and have poisoned Johnson, retconning the original nature of its poisoning, which originally was with mercury. "When life gives you lemons, make lemonade." is a common phrase, and Johnson will get back to it at the end of the latest test.
Inside, a small sign "Enrich yourself today - volunteer for testing" is found. The area is dimly-lit with a cold light. The overall colors are greyish-blue and white, and is closer in design to the offices of the modern Enrichment Center. Another sign, titled "Know your paradoxes (!) in the event of a rogue AI", is found. It advises employees to "1. Stand Still, 2. Remain calm, 3. Scream ‘This statement is false! New mission: Refuse this mission! Does a set of all sets contain itself?’".
The Waiting Area, below, is accessed through a smashed window. It appears Aperture employees volunteering for testing would come through a door smaller than in the two previous areas (while it likely connects to the Main Lift as well, though it is not directly seen here). Next is the last portrait of Cave Johnson, appearing older and ill. Left is a door leading to the proper Waiting Area, right is a door to the Control Room, a small office where a button opening the door to the next sphere is found. There the "Karla the complainer" poster is seen again, along with another similar poster with "Remember... robots don't sleep", followed by "They can test and do your job" and the picture of a robot worker testing and sorting paperwork very fast behind a desk at the same time, finally followed by the words "Volunteer for testing today". Inside the Waiting Area can be found a poster titled "Aperture Science - Let's work together", with a robot worker and human employee wearing labcoats and walking hand in hand in front of a sunset, the sun being Aperture Science's aperture logo. The room contains several chairs, and a projector directed toward a white screen, on which motivational videos or other things were probably played. A catwalk leads to Enrichment Sphere 06, and a warning sign reads: "Please do NOT test if: - You are allergic to lunar sediment and/or starch; - You have fulfilled your monthly self-election quota; - You are confident enough in your work performance to unvolunteer from the test self-election process". There is no fizzler before the elevator; an unseen one is used instead in the elevator tube.
 1982 - 1986: Enrichment Sphere 06
Built from 1982 to 1986, it consists of a single Test Chamber, filling half of the sphere, though the numbers 01 and 02 are seen on two columns. It is the only Sphere testing the Conversion Gel, which is not used with the conjunction of any other gel. The ceiling is uncompleted, allowing to see Sphere 07 above.
After Chell completes the test, the latest pre-recorded message is heard, in which a demented Johnson has his now infamous rant about the lemons, to which PotatOS reacts enthusiastically (it has since become a famous Internet meme), and putting someone's brain into a computer, one of the hints that Caroline's mind was used to create GLaDOS:
"All right, I've been thinking. When life gives you lemons? Don't make lemonade. Make life take the lemons back! Get mad! 'I don't want your damn lemons! What am I supposed to do with these?
Demand to see life's manager! Make life rue the day it thought it could give Cave Johnson lemons! Do you know who I am? I'm the man who's going to burn your house down! With the lemons! I'm going to get my engineers to invent a combustible lemon that burns your house down! [heavy cough]
The point is: If we can store music on a compact disc, why can't we store a man's intelligence and personality on one? So I have the engineers figuring that out now.
Brain Mapping. Artificial Intelligence. We should have been working on it thirty years ago. I will say this - and I'm gonna say it on tape so everybody hears it a hundred times a day: If I die before you people can pour me into a computer, I want Caroline to run this place. [cough]
Now she'll argue. She'll say she can't. She's modest like that. But you make her. [cough]
Hell, put her in my computer. I don't care.
Allright, test's over. [cough] You can head on back to your desk."
 Enrichment Sphere 07
The seventh and last Enrichment Sphere cannot be visited and appears to be not connected to any part of the shaft, except for Conversion Gel tubes going through it from the Pump Station to Sphere 06. It is not present on the screens of the three consoles operating the Pump Stations, suggesting it was never used in Mobility Gel testing.
 1982: Elevator access
The elevator access, dated 1982, starts with a sign thanking employees for volunteering, followed by the words "Please return to your desk and await further opportunities", a small booth, then a small door to the Main Lift shaft, which is now accessible. The depth is now 3000 m. Since the elevator is out of order, Chell portals herself up the shaft. The elevator is stuck at around 2912 m. Chell finally leaves the elevator shaft through a maintenance door, located slightly above 2900 m, to get back into Test Shaft 09, now at its uppermost level, at a set of platforms built over Sphere 07. After PotatOS attempts to cheer Chell up, the latter goes through a set of several platforms by using leaking pipes of each Mobility Gel (somehow replacing the inaccessible last sphere in a last test), to finally arrive in the main Gel Pump Station through a maintenance shaft.
 Gallery: Screenshots
 Gallery: Logos, signs and posters
"Future you" sign, 80s style, removed from the final game, with a variant of the 50s text: "Remember: If a future you tries to warn you about this experiment, do not listen.".
Notice for the cut Geothermal Power Plant 3: "Employees are reminded that there is NOTHING OF INTEREST present in the geothermal power wing. Any employees investigating further will be TERMINATED IMMEDIATELY due to the complete lack of anything of note present therein.", also removed from the final game.
 Gel Pump Station
The Gel Pump Station pumps Mobility Gels from below into the modern facility. Larger than the three previous ones, it also contains Transition Seal 02, the other hatch sealing off access to the shaft, and leading to the modern facility. The hatch can be opened with a Hatch Override button located in a booth to which Chell portals herself. Inside, the "paradoxes" sign first seen in the 80s Test Subject Waiting Area is seen again, and PotatOS suggests they use paradoxes to defeat Wheatley.
Upon opening Transition Seal 02, the Mobility Gel connection to the modern facility is restored, and a platform lowers to receive Chell and PotatOS. While ascending, the A.I. talks again about her plans to overthrown Wheatley.
Then they find herselves right under the modern facility, which appears to rest not only on giant numbered pillars but on giant numbered springs as well, reminiscent of the real-world NORAD facility. Upon going back into the modern facility, they come across the 1961 vitrification order from that side. After passing through a modern Emancipation Grill, they take a modern elevator bringing them back into the modern facility.
Upon leaving the elevator, the duo quickly reunites with Wheatley through his screens, and discover the newly built "boxes with legs", the Frankenturrets, starting the game's eighth chapter, The Itch.
 Gallery: Screenshots
 Gallery: Logos, signs and posters
 Behind the scenes
- Since the article is very long, many BTS facts have been placed near their related subjects for better reading.
- The Enrichment Shafts are what remains of the canceled game F-STOP, which originally was to be a prequel to Portal 2 set during Cave Johnson's era, hence the old-fashioned design of the area. It was not to feature portals, and Johnson was to be a protagonist later turning antagonist, a role adapted for Wheatley in the final game.
- As a relic of F-STOP, the Test Shaft 09 chapters serve as a "timeline" level, visually telling the backstory of Aperture Science with signs, props, materials and many dates relayed through Johnson's messages and the area's visuals. According to Laura Dubuk, the 50s area was made to show that Aperture was very brisk at that time, with warm colors and high-quality quality; Cave Johnson and his staff were just starting out in their enterprise and everyone was eager to do science. This contrasts with the stark, cavernous environment outside and the materials seen in the 70s and 80s, where the materials become cheaper, with an abundance of plastic and linoleum showing that Aperture had fallen on harder times and could no longer build high-quality offices for its workers. Furthermore, many of the new dates and events pertaining to Aperture's history revealed in the chapters significantly alter the original Aperture timeline revealed prior Portal 2’s release on ApertureScience.com.
- Test Shaft 09 also introduces several striking elements in the Portal story arc:
- The Mobility Gels, reused from an old NPC ("npc_surface") and the paint created for the student game Tag: The Power of Paint, much like the portal concept was reused from Narbacular Drop, with several changes applied to their properties (and the Adhesion Gel removed, while creating the Conversion Gel), as well as replacing the paint gun, and have the ASHPD redirect the Gels with its portals instead, as said by Ted Rivera.
- Caroline, Cave Johnson's assistant whose personality was transferred into GLaDOS. Her role originally was envisioned as a put-upon scientist named Greg, but the team considered wasteful to hire an actor for just one or two lines, hence reusing GLaDOS' voice actress Ellen McLain, which allowed the team to elaborate on GLaDOS' backstory.
- NASA's Apollo and Shuttle programs, CERN's particle accelerators (both modern and obsolete), industrial robots, derelict Soviet space shuttles, overgrown temples, Brussels metro stations (which was built in the 70s, hence the striking 70s design), seedy American motels, junkyards filled with rocketry equipment, Chinese apartment blocks under construction, Polish shipyards, neutrino detectors deep underground in nickel mines, corporate headquarters from a variety of eras, commercial nuclear reactors, experimental fusion reactors, rain-sodden book depositories in Detroit, peculiar cameras, forgotten space probes, etc. This is well rendered in the Enrichment Shafts, frozen in several points of time.
- The last sign seen during Chell and PotatOS' fall to Test Shaft 09 indicates 4375 m; as seen when Chell wakes up, the very bottom is lower than that. However, when adding up the different heights featured in Test Shaft 09, a total of ~3660 m only is found; thus one of the two depths is incorrect. (This is deduced thanks to the depth numbers seen in the Main Lift shaft: the depth seen on top of the 6th sphere is 2975 m, a sphere is ~87 m in height, the first sphere has around a sphere's height under it, there is ~50 m between the 50s and 70s spheres, and ~25 m between the 70s and 80s ones)
- The game files reveal several logos, signs and posters not appearing in-game, as well as codenames to be used for each sphere, each time starting with a NATO phonetic alphabet code word. The names are, in sphere order (given by the texture file names "underground sphere 00#"): "Whiskey-Hubble", "Bravo Volta", "Oscar Darwin", "Tango Franklin", "Juliet Planck", "Hotel Kepler", and "November Brahe". "Zulu Bunsen" also works the same way, as "Zulu" is the code word for "Z". The cut signs however were not necessarily to all appear in Test Shaft 09, as they are remains of F-STOP, which would feature differences unknown so far.
- Scott Dalton, the size of the Abandonment Hatch was a happy accident. For the team, the connection between old Aperture and new Aperture had to be a big set piece. The first model built was about five times bigger than the team expected, but they started to like it. They joked that it should be a bullet point on the Portal 2 box: "Features the biggest door in games ever!". They then decided it would be fun to play with the player's expectations and put a puny looking door behind it, along with a few small props. Furthermore, the Hatch was at some point to be opened with four buttons, reduced to two in the final game, as seen in concept art.
- While the Tartaros-themed Portal 2 menu clearly shows Sentry Turrets with their eyes turned on burning in the fires, in-game they are barely recognizable, with not even their eyes visible.
- Several sounds of Caroline dialogue can be found in the game files, notably some involving her seemingly being forced into becoming GLaDOS by what may be Cave. It is unknown where they were to be heard.
 List of appearances
- PotatoFoolsDay ARG (First appearance)
- Portal 2
- The Final Hours of Portal 2
- Lego Dimensions (Non-canonical appearance)
- ↑ 1.0 1.1 Aperture Laboratories lithograph by Laura Dubuk at the Valve Store
- ↑ Portal 2 Collector's Edition Guide
- ↑ Eric Kirchmer's Blogger
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Portal 2 commentary
- ↑ Borealis blueprint
- ↑ 6.0 6.1
- ↑ ApertureScience.com
- ↑ Cave Johnson / Combustible Lemons on Know Your Meme
- ↑ 9.0 9.1 The Final Hours of Portal 2
Central AI Chamber (3)
|Portal 2 journey||Succeeded by|
Wheatley's testing track