The Aeropan research rig is a location beyond the Brink in The Lost Frontier. It was the research station used by the Aeropans for the Dark Warrior Program long ago. However, it was eventually abandoned for unknown reasons, but still remained heavily protected. Whereas the rig appeared to be used for experimentation and research, the Aeropan barracks seemed to be used more for training and as a military base, though both facilities served similar experimental roles.
Later it is revealed that the rig was built over an eco core, a large device that controlled the flow of eco within the planet. After its prism, which combined and broke eco into its different colors, was knocked out of alignment, the catastrophic eco shortage occurred, causing Jak, Daxter, and Keira to search for it.
The research rig was originally built by the Aeropans over "strange formations", though at the time they could not penetrate what was beneath the surface. It is unknown whether they chose the location to build the rig because of this or despite it. However, there were also some faint readings of the rare light eco, which could suggest former. Despite Phoenix's claim that the rig was abandoned, when returned to it later, Keira discovered man-made excavations that went deep into the planet, so far as to reach the control panel for the eco core at the center of the planet. It is unknown whether the attempts to go beneath the surface were continued by the Aeropans after Phoenix left, though the rig was under tight security (though this was likely due to the advanced research for the Dark Warrior Program still present at the rig).
The Aeropans harnessed the power of a lot of old Precursor technology while stationed at the rig, among which included tapping eco power from the same Precursor idols Jak encountered along the Brink. It was later shown that the scientists were successful in doing so, manifested in the hyper mutant, which exhibited many of the same powers Jak acquired over the course of the game.
It is unknown why the Aeropans abandoned the research rig, though when Jak and Daxter visited it in the mission "Search for light eco", all machinery and equipment was still running such as computer monitors, security systems, holding cell transits, and dark eco experiments. Despite this, there were other clear signs of abandonment, the inside of the structure itself neglectfully dilapidated, covered in debris and cobwebs.
The Lost Frontier
When Keira initially studied the eco seeker, she discovered that it needed light eco to operate. Phoenix recalled its presence at the rig, and they successfully found the rig's main control room, with which they generated a single drop of light eco. Along the way, during the aforementioned mission, Jak and Daxter encountered franken apes identifiable as dark eco-infused versions of the silverback apes they encountered at Far Drop. Some of the apes, the ones that hadn't broken free, remained in a coma-like state inside experiment tanks being monitored by rows of computer terminals, though upon Jak's approach, they woke up and attacked.
Towards the end of the mission, Jak discovered an injection chair in a large, chasmic room identical to the one in Baron Praxis' fortress back in Haven City, under which Jak suffered as an experiment in Haven's own Dark Warrior Program. This caused Jak to experience a flashback, after which he was enraged by whoever committed the cruel experiments.
Although the apes were the only creatures with clear indications of being experimented on, there were also dark ghoul spider mutants. It is unknown whether or not they were subject to direct experiments, or infested the area and mutated as a result of exposure to dark eco.
At the end of the mission, after Keira acquired the light eco, Daxter lingered behind as they escaped, finding what he believed to be a candy machine, which was really a control panel. After aimlessly pushing a button, Daxter was grabbed by a robotic arm and placed into a containment cell, which was then dumped with a massive amount of liquid dark eco, transforming the ottsel into Dark Daxter. He then found his way into the rig's laser lab, and proceeded with the mission "Escape the laser lab".
After Daxter damaged a computer terminal, causing a leak in the authorization lab, the security system initiated "containment procedures", involving "thermal decontamination" which was a massive fiery laser that ravaged the lab through various corridors and hall ways. Daxter noted that the laser burned even dark eco mutants, including voltaic eels and ghoul spiders (as well as the same tripodbots that Jak encountered at Brink Island), leading Daxter to deduce that the lab was built to contain them (and thus experiment upon them).
After Daxter escaped the lab and returned to his usual form, he met up with Jak where the two found the Interceptor, designed for Aeropan test pilots and interception missions. They proceeded to steal the plane from the hangar and returned to the Phantom Blade.
Eco core and final boss
After retrieving the last coordinate sphere for the eco seeker and inserting the light eco, the seeker pointed back to the research rig. Phoenix recalled that the rig was built over strange, impenetrable formations, and thus they headed back to the rig, though they went in quietly and left the Phantom Blade behind with Klout to avoid detection.
Once there, Jak encountered a large shield that enclosed the rig, activated by the Aeropans due to their alertness to Jak's presence. The shield was generated by three generators placed around the rig, and was constantly repaired by repair tenders. Jak thus had to shoot them down and then take out the generators before he could land. After landing, they rode an elevator all the way down to the eco core, at the center of the planet, arriving at the control panel where Jak speculated the Precursors controlled it.
Although the control board initially looked dead, Jak was able to activate it by inducing eco energy, which was powerful enough to also wake the eco core itself. However, Keira was able to tell that it was malfunctioning, reading a massive unstable energy build up at the prism in the center, which was used to combine and break eco into different colors. Keira was afterwards able to put the prism back in alignment, fixing the core. However, she never got the chance to bring it back online slowly enough, resulting in an unsafe exposure to it.
Just then, Klout and a few pirates showed up, along with Skyheed himself. While initially mistaking it as a capture, Phoenix soon learned that Klout had betrayed him for money, thus giving knowledge of the core's location to the Aeropans. Skyheed ordered the group to be killed aside from Jak, as he wanted him "studied". After Jak refused to cooperate, the Aeropan duke ordered them to all be killed, at which point Keira swiftly hit a button on the control board which activated a shockwave of eco energy from the core, killing Klout, although Skyheed managed to avoid it.
Phoenix, Jak, Daxter, and Keira used the diversion to ride the elevator back up, and retreated to the Phantom Blade to regroup. With the location of both the eco core and Far Drop known to the Aeropans, the Sky Pirates decided to take the fight straight to Aeropa.
The rig was lastly featured toward the end of the game during the final mission, "Take down the Behemoth". By now the core rose up from the ground, knocking over and destroying the research rig. The Behemoth was next to the core, drawing energy from the core. The crystal with which Skyheed used to soak up the energy was causing a cascade reaction: the more energy he soaked up, the stronger the crystal's reaction got. Keira deduced that if he kept it up, the resulting reaction would consume the entire planet. Jak proceeded to battle the Behemoth but failed to damage it to any considerable extent. This led Phoenix to sacrifice himself and the Phantom Blade by intercepting the energy flow, which was successful in damaging the Behemoth, leaving it vulnerable. However, this led to Phoenix and the Blade's demise. Jak proceeded to destroy the Behemoth, for Phoenix.
After the Behemoth stopped leeching from the core, it went back into balance again, beginning the end of the catastrophic eco shortage, and causing a vast reduction in storm and quake activity. Keira stated that eco vents around the world would start flowing again. Keira then mentioned that she and Tym had been decoding the symbols along the walls, discovering that there were more eco cores to explore.
The rig itself is a large structure situated in the middle of a small inlet off a break in the sea floor, typical of the Brink. Evidently, the structure goes deep into the planet, all the way down to the eco core, on top of which the rig was built. Evidence of the Precursor formations can be seen at the top of the foggy depths, and there are also other Precursor structures around the general area.
On either corner and at the apex of the inlet lies shield generators, and between these a small perimeter is formed by floating motion sensors (others are also placed at random spots around the area). It is unknown what these devices do, though they are easily destroyed with plane weapons. At the base of the generator near the apex of the inlet is a narrow runway that extends outward all the way to the rig, though this does not lead to an entrance of any sort. Instead, the entrance is located on the opposite side, with a series of large, floating blinking lights indicating the way.
At the base of each of the generators is a garage, out of which repair tenders are deployed (unless said garages are destroyed). Tenders continually patrol the area, though they have no weapons. The Phantom Blade docks to the west of the inlet, while the Precursor statue is placed just off the apex of the inlet, and the pirate radio tower is placed just behind the shield generator along the eastern corner.
After docking at the rig, you will immediately encounter clear signs of abandonment. Cob webs and dust cover computers, ape skeletons, and block entrances. Despite this, many of the computers still run. After this is a large, bottomless cavern decorated with large Precursor structures on the sides as well as holding cells to the left, which Jak uses to traverse the area and arrive to the next room.
Said room contains both an idol and a totem, as well as air vents along the top of the walls out of which franken apes ambush Jak. Other Precursor chattels could be found in this area, including a set of "stone" tablets, cultural figurines, and basket-like basins. After this is a room filled with computer terminals as well as incubation tanks wherein lie mutant apes, monitored by the computers.
The next area is nearly identical to that of the fortress in Haven City, containing an injection chair in the center of a bottomless room. Different, however, is the following area which contains a laser gate with rotating platforms, presenting a puzzle involving the totems. Following is the inside of a massive dark eco silo, in which there are several smaller silos, which are seemingly filled with yellow eco, as yellow gas leaks from the busted tops with which Jak can use his eco rocket jump power. At the bottom is a mass of fatal liquid dark eco.
Following is a chasmic cavern supported by Precursor structures, for which Jak must use the eco construct power to navigate. Following is another similar area, though the room is circular and water streams in from the sides. These two areas are separated by a gate which appears to be of Precursor origin. Next is a transit room that serves to transport holding cells. The rails for said transit are surprisingly still active, despite the area being abandoned.
After navigating the tops of these cells, Jak will reach a cavernous area littered with totems and patches for his construct power. Using these together presents a puzzle, after which Jak reaches the main control room. This is a large circular area, filled with control panels.
After Daxter transforms into Dark Daxter via a holding cell, he crashes through the rig and lands in the laser lab. The first area is a circular room at the center of which is a massive laser generator. There's also a computer terminal in this area as well as two power harvesters containing voltaic eels and tripodbots. The proceeding areas mainly consist of hallways with computer terminals until you reach an experiment lab, containing rooms, laser blockers, grated platforms, and busted walls exposing strong currents of water.
A narrow hallway connects this room to another nearly identical room. All along the way, the floors are embedded with small batteries which Daxter must flip to control the large laser, presenting a puzzle. This room connects to two other similar rooms before Daxter reaches the elevator at the very end. This elevator leads to a large hangar room, containing the Interceptor.
The eco core was situated below the research rig, and had to be accessed via an elevator that goes deep into the planet. After being activated, the eco core raised out of the ground, knocking over the rig. Before activation, the crystal was a dull purple color, though after activation it began to glow with dark eco. After the prism was put back into alignment and the core became functional again, it glowed with all the different colors of eco, representing its function as a device that combines and breaks ecos into their different colors.
This eco core is evidently only one of many eco cores, as Skyheed alluded to it as "one of the" major eco sources, and Keira and Tym concluded from studying the symbols engraved in the eco core's walls that there are multiple connections to "other" energy lines, including a "big one" over the Brink. While Keira stated that, due to the core's return to balance, eco vents "around the world" would start flowing again, it is assumed she meant the vents connected to this particular core as opposed to all vents in existence. Furthermore, while it would appear that this is the main eco core (considering it is at the center of the planet and was sufficient in restoring a proper eco balance in the world), the other cores do have quite some significance as Jak and Keira decided it was worth exploring beyond the Brink in search of them.