A battle in the Karos sector
The Karos Graveyard is an immense debris field located near the Galactic Core in the Shining Hinterlands.
Overview
Thousands of derelict vessels are scattered throughout the sector, ranging from decommissioned warships to the shattered wreck of the Progenitor Mothership, a vessel speculated to be larger than even Sajuuk itself.
This sector of space plays a pivotal role in both the Homeworld War and also the Vaygr War. Besides the Hiigarans most other races keep clear of this sector, both because of its automated guardians known as the Keepers, and also Pirate fleets which linger in the area, preying on unknowing vessels which venture into the area.
Exploration
The Homeworld War
During the Homeworld War, the Exiles were led to the Graveyard by Captain Elson, the leader of the Taiidan Rebellion. There, he used a communications relay hidden in one of the derelicts, known as the Junkyard Office, to send instructions to the rebellion.
It was at this time the Kushan found the automated defense systems, including a Corvette-class vessel named Junkyard Dog. After the signal was sent from the communication relay the Kushan fleet withdrew from the sector.
One of many derelict cruisers on Karos Graveyard
In the original Karos Graveyard site, there are several seemingly significant objects and derelicts. Shortly after arriving, the fleet's researchers believe they are ready to begin researching plans for "heavy guns". This could arguably be due to the Mothership's close proximity to an ancient derelict heavy cruiser of sorts when she exits hyperspace and enters the graveyard. This object is located just in front and below the Mothership's exit coordinate. Upon closer inspection, this vessel appears to carry nearly the exact weapon inventory of future Avatar-class Heavy Cruisers: two forward dual-ion cannon turrets and six heavy assault mass drivers. There is little doubt that behind the scenes, this massive ship was observed by crews aboard the Mothership and the fleet researchers would then endeavor to emulate it.
Another type of ship found on Karos
There are many other "heavy cruiser" derelicts throughout the graveyard as well as derelicts resembling "carriers," that are characterized by no armament, but a large bay toward the bow that could serve to build, launch and tender fighters, corvettes and frigates. Both the heavy cruiser and carrier derelicts display engines, curvatures and characteristics that are shockingly similar to Kushan ship design, despite the fact this is their first visit to the graveyard.
Derelict support frigate
Though not mentioned in the storyline, one theory is that this veritable derelict "fleet" could very well have been one or several ancient Hiigaran fleets that were defeated by the Taiidan in the first war. After being directed to exile the defeated Hiigarans rather than annihilate them, the Taiidan would no doubt have boarded the surrendered ships, interned the crews and disposed of their vessels to some sort of "graveyard." Another theory is that all ships present were part of a Hiigaran expeditionary fleet sent to uncover Progenitor secrets, possibly the remnant of the very fleet that recovered the Second Core. When it arrived, the fleet happened upon an ancient Progenitor tending vessel, the Junkyard Dog, and without discovering a way to defeat it, the fleet succumbed to the powerful guardian one ship at a time. When the Junkyard Dog captures a ship from the Mothership's fleet, it spirits it away to one of the many standing hyperspace gates. The ship, once captured by the Junkyard Dog, floats adrift in the same manner that the ancient derelicts do; its effect on both ancient and current captured ships is the same. Either way, the Karos Graveyard may very well be the final resting place of an ancient Hiigaran fleet.
Small derelict craft resembling minelayer corvette
Oddly, there are two other objects located at the graveyard of which only a single instance can be found. There is a single support frigate of "current" (as opposed to "ancient") Kushan ship design with green markings. It does not resemble any of the ships surrounding it and by the look of its yet pristine hull, it appears to have arrived at the graveyard fairly recently. It appears to still have some power as seen by the blinking lights on the forward antenna array, but the repair docking pads are not illuminated and the ship is assumed to be powered down and abandoned. How this ship even exists or how it arrived at Karos before the Mothership's fleet is currently unknown. There is also another single derelict: a small fighter class ship that resembles more of an insect with its long antennas. The explanations for the origin of this ship, why such a small, fragile fighter class ship even survived to make it to a graveyard to begin with and why there is only one present are also currently unknown. Attempts to contact or salvage these seemingly out-of-place vessels are unsuccessful by the Mothership's fleet.
Although they have clear ties to the past in some way, these objects are apparently insignificant to the Exile fleet and are absent from the storyline and any mission objective.
The Vaygr War
During the Vaygr War the Pride of Hiigara found the Oracle, which led it from Gehenna to the Karos Graveyard, where the Mothership fleet received data from the Karos Lighthouse. However when the Mothership fleet attempted to make a hyperspace jump, they were inhibited by Quantum Wave Form irregularities, trapping the Mothership fleet between a flotilla of Progenitor Movers and a Vaygr armada. The Hiigaran fleet managed to destroy the Derelicts, making hyperspace travel possible again. The third battle to occur in the Karos Graveyard took place near the Dreadnought Berth, where the Keeper Destroyer spoke to the Hiigarans in the Progenitor language, and later attacked the Mothership fleet when trying to defend the Progenitor Dreadnaught. Eventually the Keeper was trapped in the power core of the Progenitor Mothership, and self-destructed soon after the Hiigarans left the Karos Graveyard with the Dreadnaught.
Graveyard Defenses
The Karos Graveyard possessed many AI controlled vessels designated to defend or their territory or various objects.
Junkyard Dog
Main article: Junkyard Dog The Exiles encountered the Junkyard Dog during their first incursion into the Graveyard. The Dog was a small, corvette-sized vessel that operated in a manner similar to that of a salvage corvette, except the Dog could latch onto and control any size vessel, from frigates to heavy cruisers. As it is only a corvette, it can be overcome with an active Gravity Well Generator.
Autogun
Main article: Autogun The sector of the Graveyard patrolled by the Junkyard Dog was also guarded by a large number of stationary autoguns, small immobile mass driver units that fired on any non-Progenitor active craft within range. There were two varieties of autogun: large and small. The large units contained two mass drivers, and did more damage than the smaller version, which held only one cannon. Their armor is fairly weak; a Revelation-class Destroyer can take it down with just its Ion Cannons.
Movers
Main article: Progenitor Mover As the Oracle led the Hiigarans into previously-unexplored sections of the Graveyard during the Vaygr War, the Pride of Hiigara discovered many defenses that hadn't existed in the area of their original visit or later explorations. Among these new defenses were the Movers, AI-controlled Progenitor constructs. A derelict Mover was captured and reverse-engineered by Fleet Research, and proved useful at eliminating the quantum waveform-destabilizing radiation anomalies located throughout the derelict Engineering section of the Progenitor Mothership that housed the Dreadnought and the Hyperspace Foundry.
The Keepers
Main article: Progenitor Keeper As the Mothership fleet prepared to recover the Dreadnought, they ran afoul of the most potent defenses discovered in the Graveyard to date: the Progenitor Keepers. Equipped with high-powered engines and twin heavy ion cannons, these lethal AI constructs proved as maneuverable as a frigate and nearly as damaging as a Qwaar-Jet-class Heavy Cruiser. Their purpose was to protect Progenitor artifacts from various "interlopers" and to stop anyone from reawakening Sajuuk. The only way these vessels could be destroyed was when massive energy was released, or as a result of self-destruction. If they suffered any kind of damage, they would simply jump away and return with full health.
Background objects
The background structures as seen in level 6 of Homeworld
Far larger than any of the ancient vessels scattered throughout the graveyard, dwarfing even the progenitor mothership, are a number of vast derelict structures seen in the backgrounds of all the levels that occur within the graveyard in Homeworld2, namely levels 6, 7 and 8. A string of similar sized derelicts are also visible at Tanis, in the first level of Homeworld2. Level 13 of Homeworld also occurred in the graveyard, but in another part of it, and thus the background structures seen there are presumably different.
Since the structures are part of the background images of each level, they look equally large and are always seen from the same angle regardless of where the camera is positioned, making it impossible to directly estimate their size in-game. However this can be estimated another way. In the cutscene between levels 6 and 7 of Homeworld a simulation of the breakup of the progenitor mothership is shown. The V-shaped spread of the derelicts in level 6 can clearly be seen in the right-most part of the simulation, as can be evidenced in this screenshot -
In-game these derelicts are spread out over a distance of about 60km. The distance from the 'lighthouse' (where the oracle takes the player in level 6) to the dreadnought berth (indicated in the screenshot) is visibly about ten times larger, giving us a distance estimate of five or six hundred kilometres. The dreadnought berth is located close to the second of the giant, ring-shaped structures. With this in mind we can estimate each of the 'rings' to be several hundred km across, 300-400km would seem to be a reasonable guess. If all the rings were once part of one long, continuous structure, then it must have been a giant cylinder as much as several thousand km long. It can only be speculated what the purpose of such a megastructure would have been. Possibly it was a giant orbital habitat, such as an O'Neill cylinder which would have been spun up to provide artificial gravity on its inner surface, thus providing a large living space. Although on this scale a more similar example could be the Halo rings from the Halo series. The builders of these vast, ancient structures can only be speculated at. Strangely, fleet intelligence doesn't comment at all on their origins but is instead focused on investigating the progenitor mothership. Whether these structures were built by the progenitors or an even more ancient race, possibly including the builders of the Ghost Ship from the original Homeworld or the Naggarok from Cataclysm, is also unknown.