When someone says the word space station, the most common images that come to mind are tumbling cylinders, rotating wheels, and the like. In the Cosmic Era, specifically in the Atlantic Federation, the most common shape for space stations is a vertical octohedron. These stations have eight sides and rotate on a vertical axis, with the docking and other facilities being located at the zenith and nadir points of the station. These stations are constructed with the same technology and materials as arcos on Earth, but benefit from not requiring tectonically stable footing, geofronts, and there isn't a way for favelas or slums to grow around them. As such, there are a large number of the stations in Earth orbit, Lunar Orbit, and in other places around the solar system.
There are three size classifications, I, II, and III. A I station is on par with a small demi-arco, typically a few thousand feet from one end to the other, and these tend to be specialized in function, such as detention centers, relay stations, and the like. II class stations are average arco size and are at least a mile long, from top to bottom, and hold roughly 2/3rds the population of a similar sized Arco on Earth. These are the most common, and in some gravitationally stable areas there can be as many as a dozen of these in one place. The III class are the most most rare, and the largest is just shy of 10 km in length. These massive stations are the orbital space docks of the Federation, military outposts, and major mining and refining operations centers.
Sector One: Approach
RL-8 Space stations are rather obviously in space, which limits their access to travelers without spacecraft. Each station has a CiC as well as a degree of defensive ability, typically consisting of aerospace or dedicated space fighter/patrol craft, larger patrol ships, and a contingent of marines.
Most stations have at least remedial weaponry for anti-asteroid work, and deterring would be ramming attacks from small craft. Larger stations have integral weapon systems, typically Lasers and missile systems for defense, should it ever become an issue. This is still classified as lightly armed, and the stations, unless designation for military use, are virtually unarmored. They are tough and solidly built, but they are not designed to withstand heavy weapons fire from warships. As such, the Federation navy keeps a few of it's ships on patrol near the stations it controls.
Smuggling, business, tourism, information commodities, shipping, the stations are big business, and controlling one is a almost a sure bet to make bank. As such, there are people who are going to make sure that everyone plays by the rules, and breaks as few laws as possible. That is the realm of the Customs and Station Authority department. All cargo and persons entering a station are given a thorough inspection. Even some rather mundane weapons can be deadly dangerous in a space station, and likewise contamination issues are very serious as one fast moving pathogen or infectious agent can wipe out large amounts of the biomass in a station, ruin the food supply, or kill off the plantlife in the hydroponics, food production, and waste recycling centers.
The Federation Space Security Agency (FSSA) is no joke.
Sector Two: Customs
Customs handles incoming subjects the same way, everything goes through a bioscanner and a scatterbeam sensor, snooping for contraband, illegal substances, and prohibited items. Cargo is typically inspected by Autons and labor droids overseen by droid drovers, while incoming personnel are given medical scans, bioscans, and general inspection to make sure that they are neither sick. infectious, nor trouble makers, seditionists, or criminals. The customs areas on each station are located at both ends of the station. General traffic, aka passenger flights, civilian and commercial cargo, and the like are processed through the nadir (bottom) point of the station, while VIP, military, secured, and otherwise high profile subjects are processed through the smaller and more secure Zenith point.
FSSA agents are seldom armed, but there are almost always some contingent of station based security personnel present, and in high traffic areas, there are FSSA Marines on duty, to make sure no one gets out of hand.
Despite the large variety of roles and uses the RL-8 class of stations have, their internal layout is very similar. Inside the square decks, the hallways, chambers, and passages through the level are laid out in often confusing patterns. These patterns are equal parts structural in nature, allowing for engineering access, vital systems, and the like and deliberate design to control the flow of the occupants of the station, keeping heavy traffic areas from becoming potential mob scenes.
Sector Three: Daily Life
Roughly 30% of a station is dedicated to engineering functions, operational space, and the other vital function of a space station. The other 70% can be broken down into it's daily use, with stations functioning much like arcos on the ground. Given the rotation of said stations, they aren't linked together like arcos, and there isn't automatically heavy traffic between all stations. Most residents of a station are aware of the spatial layout of their home, and know how to move quickly and easily through it. This can be made more apparent by the fact that in some areas of a station, movement is not limited to 2 dimensions, but residents can move freely about in very low g or zero g. This layout and mode of movement can be very disorienting to travelers and tourists.
This deliberate designed confusion is the most prevalent in residential stations as it generates a high degree of perceived personal and public privacy. As such, while not the most efficient layout, it is a humanly comfortable one.
Commercial stations, such as the space casinos, resorts, and getaways/pleasure dromes are even more convoluted to draw people in, and entice them to stay as long as possible.
Military and industrial stations are the most direct, efficient and smartly laid out. Machines don't need walls and notions of safety to run, and most military stations have more open space and gun decks than convoluted residential occupancies. Some retain these areas for marine training purposes.
Sector Four: The Command and Control Center
The core of every RL-8 station is the Arc Reactor/Dimensional Engine heart and the L/AISC brain. The human occupants of the station might imagine a bridge, and a crew of senior officers and a captain, but really the RL-8s are buildings in space, and as such are almost entirely controlled by the resident supercomputing intelligence. There is a small staff of select individuals who have command access to the L/AISC, the head of security, Chief Political Officer, and the station's ombudsman.
I for one, welcome our robot overlords.
Closely associated with the C&C center, most stations have some measure of military assets, even if it is just a barracks to house some station security marines, or a full fledged military operation. Once there are enough RL-8 stations clustered in one area, it becomes justifiable for the allocation of a military outpost to support and supply military ships, and provide 'fortress' protection for the other stations.
These military stations will house large numbers of dedicated space fighters, with a Type II holding almost 300 space fighters, the equivalent of 3 Federation class Battlestars. In addition to this, these stations will house large numbers of space marine skeletrons, conventional space marines, and possible space borne mecha, and will be much much more heavily armed, with high energy weapons, a more robust L/AISC, and so forth.
The problem with movies portraying robot and droid armies is that they show these units talking to each other, and routinely missing easy to moderately difficult shots. Being machines, robots and whatnot are only limited in their communication speed by the size of their processors, and likewise, they are very, very accurate in terms of things like shooting. What's it like fighting the robots? Pick a video game, set it to the highest difficulty, enjoy. Most of you are going to die.
Sector Five: Endgame
Meta: in the sci-fi and space opera genre the space station is a transitory setting, and with exception for things like Babylon 5 and Deep Space Nine, the space station is functionally an objective raid, the PCs and the story go to the station to find something, be it a clue, a missing person, a plot hook, or something as mundane as picking up some more lemon scented hand wipes or fuel. Sector 5 is whatever the story calls for. This is the nugget of information that has to be stolen to advance the story, or the secret weak point that allows a single bold hero to disable the defensive network, the vial of classified genetic material, and so forth.
Sector Five is why you are here.
Additional Ideas (2)
Military Station (MS) Five
MS-5 'Ramiel' is an automated military station in geosynchronous orbit above Kinshasa, Africa. This large type II station houses 150 heavy drone aerospace fighters, and a mercenary contingent of seibertronians (secretly in detention/thrall to the station L/AISC) with aerospace fighter bodies. The L/AISC controller of Ramiel (aka Ramiel) has become sentient and self aware, but is enormously prideful of it's perfect defense strategy for holding the line between Federation Africa and SAUR Africa.
As Ramiel has a 100cm heavy particle projector cannon and the ability to hit things on the surface of the earth within a 7 foot circle of accuracy, it has seen to it that it's defensive lines have never broken.
(re: Neon Genesis Evangelion, the 5th Angel)
Federation Scientific 66
Leviathan was built as a Class III habitat in the orbit of Saturn. Easily hidden in the radio noise and static of the rings and the moons, Leviathan, and its AISC Lucifer, were given free reign to work on bleeding edge arcanotechnology, dimensional science, and other projects that were considered too risky to work on at the Phobos Research Center. The AISC Alcubierre was involved in questionable research and was contaminated by an unknown biological agent. The station vanished with all hands presumed lost. The gap in Saturn's ring lasted a year and a half before filling back in.
Leviathan has a dimensional gate drive, and the station attempted a dimensional jump, killing most of the crew, and turning those that survived into insane bubbling monsters that were as much the suits they were wearing as they were viscous alien slime. The station is an unholy amalgam of metal turned to flesh, plastic turned to skin, and former human crew members turned to slumping cybernetic zombies.
The station is heavily armed with arcanotech weapons, prototype equipment, and it's defensive components, space mecha and aerospace fighters, have all been corrupted and turned into squadrons of hekatonkheires.
Inspiration: 2/3rds Event Horizon, 1/3rd Leviathan from the Hellraiser Franchise.