With Earth now uninhabitable, transhumanity survives in a variety of off-world habitats. There are two major types of these habitats: settlements on planets or large moons, such as those on Luna, Mars, Venus, Europa, or Titan, and space habitats that are built on or near an asteroid or other useful source of raw materials. Most of these space habitats spin themselves to provide gravity, with Earth and Mars gravity being the two most common choices. There are also a large number of zero-g or microgravity habitats, consisting of either non-spinning habitats or stations built into small asteroids or moons.

Planetary Settlements

The Martian and Lunar city-states and other planetary settlements contain environments most familiar to refugees from Earth. This similarity is one reason that two-thirds of all infomorph refugees live on Mars, Luna, or Titan. The exact type of settlements depends on the planet or moon on which they are located, with some being far more similar to Earth cities than others. Most Lunar settlements, like those on Ganymede, Mercury, Titan, and Callisto, consist of a network of subsurface tunnels and chambers excavated with plasma drills. These tunnel settlements differ slightly from one world to the next. In most of these tunnel cities, the floors of all open areas and many dwellings are composed of genetically modified grass designed for both comfort and durability, with light panels covering the ceiling providing bright full-spectrum lighting.
A few of these buried cities further enhance their natural appearance with the addition of trees and, in some cases, specially engineered ecosystems, in both public areas and private dwellings. A few of these urban tunnel forests and jungles are home to numerous flowering vines and bright tropical butterflies. In a small number of settlements on both Titan and Luna, colonies of small monkeys and parrots with metabolisms and habits modified for modern ideas of cleanliness and sanitation thrive, giving some of these tunnel cities the feel of a buried jungle.
All of the older or more prosperous tunnel cities also contain large open areas that are typically between one and twenty hectares, with ceilings at least ten meters high. Some are parks, others are public plazas, but all offer the residents of the tunnel cities a chance to experience open spaces. Also, with the exception of Mercury, all of these tunnel cities are on moons where gravity is no more than one-sixth of a g. Some of these open spaces are constructed with roofs between thirty and one hundred meters high and are designed so that residents can use them for flying by strapping on a pair of specially-designed wings.
The cloud cities of Venus are among the most unusual habitats in the solar system. Their exotic nature is enhanced by the chance to observe the many recently introduced floating and flying life forms modified to live in the clouds. Though located almost fifty kilometers above the most deadly environment in the solar system, life in these cloud cities is among the most Earth-like anywhere in the solar system, with gravity, temperatures, and atmospheric pressure all being very near normal Earth levels.
By contrast, the settlements on Mars look the most like the cities of lost Earth, built on the surface rather than underground or in the skies. Some of the more recent settlements are designed for use by inhabitants in ruster morphs or synthmorphs and feature no life support. Older Martian cities and other settlements are typically covered with low domes of flexible polycarbonate and filled with a completely breathable, if somewhat low pressure, atmosphere. Some, however, are collections of sealed skyscrapers, connected by skywalks and tunnels. If current terraforming efforts continue on schedule, the last sealed Martian cities will be opened to a Martian atmosphere breathable by all morphs within sixty years.
The most unusual planetary settlements are the ocean cities of Europa. These are among the most exotic locations in the entire solar system and are quite disorienting for individuals not used to underwater cities. From a distance, most appear to be complex Christmas tree ornaments hanging down one hundred meters or more below the ice crust above. A few are built deeper, plunging under the icy surface near the various hydrothermal vents that host the native Europan life clusters.
Many of the residents of the Europan cities find them familiar because they previously lived in one of the underwater cities on Earth and so were used to both the conditions and to living in an aquatic-adapted body. Europan cities all contain sealed buildings with normal atmosphere, both because some activities work best in air instead of water and because the cities often host visitors without gills. However, these regions make up only ten percent or so of most of these cities. The remainder looks vaguely similar to many zero-g habitats, except that the structures are considerably sturdier and are located underwater. Buildings are designed to be accessible in all three dimensions, so going from one floor to another usually involves swimming out a large opening in the wall and down a level. In almost all of these aquatic cities, large fusion generators heat the surrounding water, so that the entire city exists in a region of water that is far warmer than the surrounding frigid Europan sea.

Space Habitats

With the exception of the private habitats of the wealthy and powerful described below, the vast majority of space habitats hold between twenty-five hundred and one million inhabitants. Almost two-thirds of these habitats were built during the first seven years after the Fall, when huge portions of the system’s surviving infrastructure were used to create habitats suitable for hundreds of millions of infugees.
During this era, several thousand torus habitats and cluster colonies were created throughout the solar system. Many of these habitats were created by automated mining machinery that had been repurposed to create colonies. Due to the limitations of these automated mining rigs, most these habitats were small, holding between one thousand and one hundred thousand inhabitants. Twenty percent of the system’s inhabitants live in such habitats. During the past decade, various small organizations, cults, and subcultures have left the larger habitats they lived in and created their own small habitats, few of which were designed to hold more than ten thousand residents.
The development of the new nanotech Hamilton cylinders has lead to a new interest in large habitats and in habitats that can easily expand in size to accommodate an increasing population. The expense and difficulty involved in expanding existing habitats or building new ones is one of the principle reasons that more than forty million infomorph refugees still do not posses morphs. Although neither of the existing Hamilton cylinders has finished growing, they are both highly regarded by their residents. This same technology is also likely to produce a low-cost method for creating small habitats, where the creators merely need to seed an asteroid with the appropriate advanced nanotech generators and wait a few months.


At the opposite extreme from the Hamilton cylinders are the infamous scum barges. Most are spacecraft built before or during the Fall that were used to help with the early stages of the evacuation, ferrying people away from the doomed Earth. Many of these refugee ships were unable to find anywhere to unload their human cargo, becoming a sort of permanent traveling refugee camp, sometimes succumbing to mutinies. They eventually joined up with pre-existing scum ships and swarms, adopting their nomadic, free-wheeling, anarchistic lifestyle. In contrast to egocasting or the faster and more efficient fusion drive ships, so-called scum barges offer a floating city alternative to space travel. These ships function as roving black markets and carnivals of the bizarre—lawless zones where anyone can find whatever they want or need for the right rep or price.
Most scum barges have fusion-powered plasma drives and hold between two hundred and five thousand inhabitants. The worst barges are exceptionally overcrowded, with aging life-support systems struggling to maintain a breathable (but still foul-smelling) atmosphere under the strain of too many passengers. The larger and more prosperous scum barges are often fitted with various modern conveniences, including large cornucopia machines and vast stores of pirated manufacturing templates. Some are thriving utopianist enclaves, while others are mobile dens of smugglers and thieves that would have been destroyed long ago except for the fact that large and powerful organizations find their existence occasionally useful. Living conditions on the scum barges range from overcrowded refugee camps to thriving, egalitarian, but non-wealthy anarchist enclaves, to relatively modern habitats outfitted in barbaric splendor by highly successful organized crime gangs.

A Diversity of Floating Worlds

The use of cornucopia machines and smart materials means that the interiors of all but the poorest and most destitute habitats can be reshaped according to the whims of their inhabitants. When the number of inhabitants is small enough or their aesthetics are uniform enough to all share the same tastes, the results can be both unique and strange. Large-scale fads occasionally sweep through even the largest and most cosmopolitan habitats, making some of the bigger colonies almost as odd.
Several habitats closely resemble terrestrial jungles, with an entire rainforest canopy growing from the slowly rotating outer shell and all dwellings and pieces of high technology nestled in the branches or hollows of these vast gene-engineered trees. In these living marvels, genetically engineered monkeys, iguanas, and tree sloths wander amidst the inhabitants—some of these creatures are wild animals, while others are controlled by AI servitors and act as maintenance or observation drones. Some habitats resemble other scenes from old Earth, including more than a dozen water-filled habitats hosting some of the aquatic inhabitants of the now-destroyed underwater cities. In most of these marine habitats, the actual buildings are either placed amidst a living coral reef filled with fish and other creatures or are actually built into the coral reef itself. There are many other habitats duplicating other environments, such as Afrique—a large Cole habitat with a population of two hundred thousand, where the habitat is made to resemble the African savanna. In Afrique, the two ends of the habitat are shaped into snow-capped mountains, and the inhabitants mostly live in several large cities built in the savannah. While nostalgia for Earth is a powerful force in habitat design, there are many other options. A few exotic habitats resemble fantastic cities from various vidgames or older forms of entertainment, including a handful of small and eccentric habitats where the inhabitants all appear as strange humanoid alien beings. In many, the inhabitants have cosmetically modified themselves to fit in with the setting.
One of the most common differences between small and large habitats is that the residents of smaller stations often share a common ideology or sense of aesthetics, and so are far more eccentric. Some of the more unusual habitats range from dimly lit, spooky landscapes filled with perpetually leafless trees, thick, continually regenerating cobwebs, and other similar macabre touches to gleaming colonies that are shining citadels of quartz and steel. Some are huge interconnected arcologies where any sort of personal privacy is rare, while in others every family or even every person has a separate dwelling that is rarely seen by outsiders. Since the populations of these stations are relatively small and the vast majority are not major economic centers, travel to and from these smaller habitats is infrequent, which further increases their insularity and idiosyncrasies.

The Largest Habitats

Extropia, the huge Martian city-states, and some of the largest Lunar stations hold between one million and twenty million inhabitants. There are many smaller settlements containing between one hundred thousand and one million residents. These habitats are considerably less idiosyncratic and exotic than the smaller habitats. Almost all contain a cosmopolitan and diverse population from a wide variety of subcultures. Because of this diversity and the difficulty of forming any sort of consensus with a large population, these settlements tend to be reminiscent of the cities of Earth. All of them have their own unique character and feel, but the differences between one habitat and another are rarely overwhelming. In addition, all of these stations are large enough to hold offices for all of the major hypercorps, who further promote uniformity by providing the same services from identical hypercorp offices. Since most of these habitats are major centers of commerce, travel between them is frequent, so there are various facilities for travelers such as hotels and sports clubs that help reduce the disorientation of travel by offering identical experiences, regardless of their location.

Microgravity Habitats

Zero-g habitats are very different from those that use rotational gravity. Most consist of networks of tunnels drilled through the asteroids—similar to the tunnel cities of Luna and Titan—but some are considerably more exotic. Like most other habitats, almost all microgravity colonies are built in, on, or next to one or more asteroids containing a large amount of useful raw materials. They typically feature a gravity less than 0.01 g that has very little effect on the daily lives of the inhabitants. Near-weightless environments allow for some interesting and unusual habitat designs as there is no up or down, enabling the creation of structures that would be too fragile even in low gravity. The habitats of Nova York and Nguyen’s Compact are both examples of this, among many others.

Private Habitats

The most rare and exotic of all of the types of habitats are the luxurious private ones owned by exceedingly wealthy or high rep individuals. Most private habitats are small but still give each of the residents several thousand cubic meters of personal space.
A typical private habitat is either a cylinder one hundred fifty meters in diameter (the minimum necessary to produce Mars gravity at a rate of rotation slow enough to avoid problems in all morphs) and between fifty and two hundred meters long, or a zero-g sphere one hundred to two hundred meters in diameter. These habitats are always tethered to a small collection of raw materials, consisting of chunks of silicate, nickel-iron, and water-containing carboniferous asteroids with a mass equal to at least that of the habitat. The majority of private habitats are inhabited by between half a dozen and three dozen morphs, some or most of which may be AI servants or, on rare occasions, indentured servants. Life in a private habitat is exceptionally lavish. Almost every surface is made of formatible smart materials and there are several large general-purpose cornucopia machines available for the use of every resident.
By using these nanofabricators and the smart materials to their fullest, residents can completely change the interior of the habitat in only a day or two—transforming a sterile and crystalline array of shining metal and glass buildings into a thriving forest, inhabited by a variety of wild animals. The mesh is filled with vids and XPs about the lives of the most famous residents of the solar system. Almost everyone has seen the interior of one of these vast space mansions many times, though only a tiny percentage of the inhabitants of the solar system will ever have a chance to actually visit such a location. Many gatecrashers, scavengers who travel to Earth, and others who engage in similarly daring endeavors hope to be able to obtain information or objects sufficiently valuable to allow them to retire to their own private habitat.

Source: Firewall Resources for the Newly Revived [Link]
If you’re here, chances are that you've spent a long time in cold storage or simulspace. Welcome back to the world of the physical. That also means you’re probably used to life back on Earth before the Fall. It would be an understatement to say that a lot has changed. You will need time to get used to life out here. It’s natural for you to feel excited, even euphoric, at the moment. You have survived and persevered where so many did not.
It also is entirely natural for feelings of sadness, unease, guilt, and even fear to set in once you start to grasp the reality of what you lost in your old life and just how different your new one is. Just know that you don’t have to go through it alone and that there isn't anything wrong with you. We have counselors available and we hope that you will form bonds with your fellow egos in this orientation.
Some of you will be going on to other stations and colonies shortly after you are medically cleared, so we’re going to take the time to go over the fundamentals of life in space. We don’t want to overwhelm you, but it is important that you be equipped with knowledge that is both essential and helpful. If something we discuss is unclear or confusing, don’t hesitate to stop and ask questions.

New Homes on the Frontier

Source: Lectures on Space Habitat Systems Engineering & Design, Prof. Iona Stormgren, Titan Tech [Link]
By modern standards, the first space habitats—Salyut, Mir, the International Space Station—were crude pressure vessels (they were called “tin cans,” even back then) barely capable of protecting their crews against a hostile space environment. Those initial attempts at sustaining human life beyond Earth’s atmosphere taught our predecessors crucial lessons, though. They learned how to build large structures in microgravity as well as how to avoid the degrading effects of atomic oxygen, radiation exposure, and micrometeoroid impacts on exposed materials. They realized just how ill-suited the baseline human body is for long durations in space. Without these lessons, the Fall would have been the end of human civilization.
The first stations at the Earth-Luna Lagrange points and in orbit around Mars took advantage of more efficient waste removal and recycling of air and water. They could even grow some of their own food in plant growth chambers or hydroponics bays. Advanced solar arrays concentrated the sun’s rays on smaller panels with higher conversion efficiency, increasing available power and greatly reducing the structural requirements of these stations. They were still fundamentally dependent on terrestrial industry for major components and long-term sustainability, however. These outposts were typically public-private partnerships that allowed scientific research, industrial R&D, and government-backed exploration projects to carry on simultaneously.
The expansion of hypercorps into space to escape the increasingly intractable socioeconomic and ecological problems on Earth pushed the situation to the next level. Combined with the development of advanced biotechnologies, machine intelligence, and the space elevator, space habitat construction entered a kind of second generation. Humanity had—as long dreamed of by engineers and literary prognosticators alike—the situational awareness of the space environment, the technological means of mitigating its worst effects, and the economic drive to establish the first habitats truly independent of Earth. While the resupply of consumables (such as water and oxygen) was still required, infrastructure was available for local resource utilization. Once it became cheaper to mine volatiles from near-Earth objects or permanently shadowed craters on Luna, the proverbial cord was cut. Design considerations were dominated more by the mission requirements of each specific habitat and local needs rather than the payload size and lift capacity of a booster launching from Earth.
Mining operations tended to favor clusters and beehives, as they made the most efficient use of existing materials and available structures. Surface stations on Mars and Luna increasingly adopted dome structures because a large surface area could be quickly enclosed, pressurized, and made available for development akin to cities on Earth. The first torus habitats were built at the Lagrange points to accommodate research and manufacturing that required gravity. The inherent volumetric limitations of the torus design led to the construction of O'Neill cylinders and Bernal spheres that allowed permanent habitation for even Earth-born immigrants.
The third generation of space habitat design and development was initiated with the availability of nanotech assemblers and digital consciousness. While third-generation development stalled during and after the Fall, the demand for new habitats to alleviate congestion on existing platforms and the emergence of widely disparate transhuman factions have incubated space habitat designs previously unimaginable.
Saturn’s famous Hamilton cylinders are, perhaps, the best example of this because of their ability to self-assemble and reconfigure to the size and needs of large populations.
Though many post-Fall habitats have sought to recreate the lost Earth through cityscapes and nature preserves, much of transhumanity has instead chosen to adapt itself to the local environment and build homes accordingly. Coronal habitats represent one extreme, designed specifically to shelter the suryas, salamanders, and their rare visitors from the Sun’s direct fury. Processor loci inhabited solely by AGIs and infomorphs can be said to represent another. Nearly any configuration imaginable is possible when the only constraints are the laws of thermodynamics and the availability of economic resources.


Source: Lectures on Space Habitat Systems Engineering & Design, Prof. Emeritus Jack Carlson, Titan Tech [Link]
The basic needs of corporeal beings are food, water, and shelter, so the old Earth saying goes. While the first two are either negotiable or cheap with uploading, advanced biomods, cybernetics, and cornucopia machines, the universe is still a pretty dangerous place. Every day, someone somewhere is dealing with a coronal mass ejection, or the problem of heat rejection into a vacuum, or collision damage from some kind of debris, or the effects of galactic cosmic radiation. For every solution we think we've come up with to maintain our supposed technological immortality, there is something out there that can defeat it. Whatever we do, then, for food and water, we still need shelter. It’s our armor against the universe. Without our space stations, warrens, beehives, cylinders, and everything else, all of us would have been at the mercy of the TITANs. That is, if we hadn't drowned in our own filth on the homeworld first. Some of you are old enough to know what I’m talking about or experienced it yourself. I knew we were finished if we didn't get off that rock, so that’s just what I did.
I traded my youth for the chance to build domes on Luna. As soon as that contract was up, I hopped out to the Belt and worked on the first Cole habitats in return for zero-g biomods. From there, I rode the wave out to Titan and I've been here ever since. I know all you want to hear about is the Hamilton cylinders, but bear with me. You've got to understand where we came from if you’re going to be any good at taking us into the future. A good habitat engineer understands the threats out there and devises a strategy for avoiding unnecessary risk as well as mitigating those you have to accept to satisfy the requirements of the project. Lest you idealists forget, we build habitats for a reason. Unless you ever get rich or lucky enough to do your own thing, habitats aren't there for our own personal edification. A quality product is one that meets your stakeholders’ requirements, simple as that. If you can’t handle that, go take your chances at Locus. Still with me? Good. One of the things you’ll have to learn once you get beyond Titan’s warm embrace is how to deal with old codgers like me. I've been building space stations since before the Fall and I’ll keep doing it long after some of you do something stupid and get your stack popped. Don’t think it can’t happen to you. I knew a guy whose work team got fried by a gamma-ray burst from God-knows-where.
The basic purpose of any habitat is to keep its inhabitants alive and safe from whatever is outside. The coronals are a perfect example, even though I think they’re a bit crazy. Giant honking electromagnetic field generators surrounding an immense core of water, all to protect a zero-g cluster at the center. That’s ultimately just physics and engineering, though. Figuring out why you would build something like that in the first place is what really drives the problem. That’s the key to defining the trade space for your design, satisfying your project’s sponsors, and delivering the best product.
Let’s consider a few examples. Building a colony is all about keeping the most people alive in the volume available for the least amount of resources consumed. Ask yourself, “what is the target population?” I’m not just talking about numbers of bodies. What level of gravity will they require? How much water, air, and food will they consume? How will you provide those consumables? How much radiation protection do they need? What local resources are available to meet these needs? Building an O'Neill cylinder out at the Earth-Luna L5 point gives you a lot of pressurized volume, a relatively simple way to provide artificial gravity, and fairly effective protection against even cosmic rays, but requires a significant outlay of initial resources to build the damn thing and sustain regular resupply.
Mining operations are mainly concerned about accessing and producing raw materials. A small outfit with razor-thin margins is probably going to stick to breaking up rubble piles and small metallic globs that get lost in hypercorp overhead budgets. If they can’t afford biomods for zero g, you’re looking at a tin can spun on a tether for minimal gravity. More established operations working on larger objects have the resources and the time to provide more permanent housing for their workers. Even then, they’re looking to save costs. Typically, they’ll cap the boreholes and seal the walls with an impermeable plastic membrane or rock melt. Clear the dust, pressurize the volume, and you've got a standard beehive.
Waystations exist solely so interplanetary spacecraft don’t have to carry all the fuel they need to get to a given destination. Even with increasingly more efficient propulsion systems available, no one wants to carry reaction mass and the containment for said reaction mass if they don’t have to. Quite a few infomorph habitats keep themselves going by providing this function. They get to stay out in the middle-of-nowhere and do whatever it is they do in simulspace. The best part for them is that other people pay for it since they provide a valuable service. For unmanned cargo resupply, we’re talking minimalistic structure, enough radiation and micrometeoroid shielding to keep things from breaking down, along with huge fuel tanks floating in space. Maybe a sunshield if they’re storing cryogenics. Only a handful of these places provide amenities for passengers, since most people that go for physical embarkation prefer a fast ride on a fusion drive.
Industrial facilities, like shipyards and factories, aren't much different than waystations, in terms of engineering. The majority of the structure will be dedicated to microgravity manufacturing processes, which are almost always highly automated. It’s all about processing the raw input, typically ores and volatiles from the mines, into useful products. The actual habitat portion of the facility depends on who or what the business operations are there to sustain. Cluster habitats are pretty popular because they’re modular, reconfigurable, and fairly cheap. Biotech facilities stand out, though. It’s still pretty hard to do bioengineering in either vacuum or microgravity. Torus habitats are not uncommon because they provide artificial gravity, but are smaller and cheaper than the big cylinders or spheres.
Building a research station is all about putting the mind of someone who’s trying to figure something out where that something is. Location, location, location! If you want to study the space whales, that’s what the coronal habitats are for. If you want to learn about the aquatic lifeforms of Europa or Enceladus, you get to live in what amounts to a fancy submarine. If you want to study Venusian geology without being incinerated by the heat and pressure that limited the first probes to seconds of lifetime, then aerostats hovering above those layers of hellish atmosphere are where you are least likely to die. Cosmic astrophysicists want to be as far the hell away from all the electronic noise and light the rest of us make, so a lot of them are heading out to the Kuiper Belt to dig holes for their sensors in the ice or establishing zero-g observatories on highly inclined, highly eccentric orbits. Get the picture?
Even giving the science types their due, most of what I've been yammering about is stuff that actually does some sort of good. You also have to keep in mind that, even considering we’re still clawing our way back from near-extinction, there are still plenty of people out there with more wealth than sense—and who are looking for ways to show that. Before anyone asks, yes, I’m talking about MeatHab. You've also got people that want to play at being a mermaid and simulspace just isn't good enough. Beyond the absurd, there’s also the uplift habitats with environments optimized to suit lifeforms that never existed in nature. Remember, it all comes down to what your customer wants and what they can afford. As the engineer, it’s your job to make the trades.

Habitat Types

Source: A Mercenary’s Guide to the Offworld Colonies [Link]
I don’t care how many brush wars are listed on your resume, working a security detail or launching an infiltration op is an entirely different paradigm when you’re dealing with space habitats instead of hugging the dirt. Not only do you have to consider minor inconveniences like lack of gravity, but the proximity to hostile environments means that a simple hull breach could take out your entire squad in seconds. Every habitat used by transhumanity has an entirely different layout configuration and accompanying set of concerns when it comes to security and offensive ops. Air support and perimeter free-fire zones are going to do nothing for you in a close-quarters beehive skirmish, and in a Cole bubble or O'Neill cylinder your enemy may be directly overhead. This part of the primer will introduce you to the basics of each colony type.
The most common space habitats are familiar types that were used over many decades in transhuman space colonization efforts: tin cans, toruses, O'Neill cylinders, beehives, Cole bubbles, clusters, and the Reagan cylinders (more commonly called sarcophagus habs) used by the Jovian. However, experimentation and the special needs of a variety of environments have led to a number of more exotic habitat types.

Exotic and Variant Habitat Types

Transhumanity and its varied exotic interests and morphologies have a habit of inventing interesting new ways of carving out a home. Some of the habitats below are uncommon now, but they may be more common in transhumanity's future.

Biological Habitats

The success and attention given to the Hamilton cylinders and more artistic station designs such as MeatHab has sparked a number of new projects to design and grow habitats with a biological (infra) structure. One group of nano-ecologists is attempting to grow the first “Dyson tree” on an apohele asteroid; they have already grown a substantial forest of intertwined roots and trunks, each sustaining a breathable atmosphere and living ecosystem inside. A neo-octopi art collective in the Belt is almost finished with their modified Bernal sphere design that is in fact a massive neogenetic organism adapted from jellyfish genetics. This small station is intended to be microgravity, with an aquatic interior. Another group recently completed their proof-of-concept of a cluster hab grown from modified “space coral.” Most of these biological habitats are small in size and scope, housing hundreds at most, usually only dozens. As their success continues, we are likely to see more interesting and unique designs.


The carousel is a new design now under construction. Also known as a beaded torus, this habitat is constructed from domes that are chained together in a circle shape around a central hub. An array of support spokes, some containing elevators, connects the domes to the hub, which is a non-rotating spaceport. The domes have a flat base (the rim of the wheel), with the top pointing towards the hub. Spin gravity and landscaping provide a natural-seeming environment for the dome interiors, while mirrors around the hub focus sunlight. Each dome has its own life support systems, meaning that if one fails the residents can still escape to another. The first carousel, Infinite Loop in the Saturnian Trojans, already has two functioning domes, with four more planned.

Disc Habitats

Disc habitats are an uncommon design. They are essentially flat enclosed discs, spun for gravity, like a filled-in torus or a slice of an O'Neill cylinder. The best known, Mahogany in the Uranian system, is somewhat atypical in that it has an axial light source and spaceport facilities along its rim. Most discs have a light source running in a ring around the rim, allowing for an axial spaceport, or, if they’re close to the sun, windows. Discs are otherwise similar to toruses and O'Neill cylinders in terms of their systems.

Hamilton Cylinders

At first glance, the three Hamilton cylinders in the Saturnian and Uranian systems do not appear much different externally from an O'Neill cylinder. Both are based on the premise of providing a large pressurized volume and a wide surface area with artificial gravity provided by rotation. However, the O'Neill cylinder is largely a fixed construct upon completion. Applying nanotechnology on a broad scale, the Hamilton cylinder is intended to actually grow with its population over time.
The exterior shell of a Hamilton habitat is a silicate polymer composite structure that both forms the vacuum seal and provides the structural skeleton for the habitat. A middle layer of nanofabricators and bioreactors absorbs waste from the interior biosphere and combines it with material collected by the resource harvesters. This is used to replenish the outer shell, replace the habitat’s nanomachines, and sustain the water, nitrogen, and carbon cycles present inside.
Past a permeable insulation layer is the “neural strata”—a widely distributed nanocomputer network governed by neural networking algorithms and adaptive learning protocols. This system is the “brain” of the Hamilton cylinder and controls the entire process, automatically adjusting the habitat’s ecology, size, and functions according to the needs of its inhabitants. As nanoprocessors fail, they automatically fall out of the system for recycling and replacement. Also, this means there is no single point of failure for the control system, as every piece contains the algorithmic map of the whole. Mesh access nodes provide an interface between the neural strata and the more conventional information systems available to residents.
The biosphere layer consists of organic soil material that provides a habitable surface at Earth normal gravity, while the remainder of the interior is pressurized at one atmosphere. Solar tubes mounted on a central spar along the rotational axis provide a day/night cycle by electrochemiluminescence. This allows the use of the entire cylinder wall area for habitation. Power is provided by fusion reactors using locally sourced deuterium and tritium.
The initial construction and development phases required almost constant resource harvesting of ice and silicates from the rings of Saturn and Uranus and captured asteroids, as well as complex organic materials from Titan. However, the environment on the completed Hamilton cylinders is as close to an entirely closed-loop system as transhumanity has yet devised. Most of the resource harvesting in the present day is for fueling the fusion reactors and the personal activities of the cylinders’ residents. There is some talk that the next generation of Hamilton cylinder could be suitable for use as a space ark to explore extrasolar systems via sub-light travel.

Matrioshka Sphere

Matrioshkas are a new and unproven design, still deemed an experiment by old hands at habitat ops. Matrioshkas feature a large central reactor surrounded by concentric spheres of decks, each run in part by waste heat from the systems of the inner spheres. Beyond this novel energy distribution model, matrioshkas are otherwise similar to cluster habs, except with the modules stacked on top of each other like the decks of a ship. Two types of Matrioshkas have been tried; one spun for gravity, like a layered Bernal sphere, and another maintained as a microgravity environment.

Processor Locus

Processor habitats are essentially floating computers in space. They are not intended for habitation by biological life, instead populated entirely by AGIs and infomorphs. Processor habs have the usual cloud of support structures that accompany most habitats: drones, refineries, factories, defense satellites, and so on. The actual habitat units consist of one or more massively shielded processor blocks. These form a mesh in which a large number of minds can run, often in a simulspace.
The environments inside of a processor hab vary a great deal. Some offer simulspaces that are relatively comfortable for transhuman-born infomorphs, where humanoid or animal-like avatars can interact in a world that provides an illusion of physicality. Others are surreal and disorienting, with simple simulspaces consisting entirely of interactions between geometric shapes ranging in complexity from basic polyhedrons to wild fractal clouds. In a habitat called the Flea Circus, one of the processor modules actually contains a miniature city in a cavity only a few meters wide, yet appearing as a vast metropolis relative to the nanoscale robotic avatars used by the populace for social interaction.
Processor habitats fall outside the realm of operatives in our line of business. Security and infiltration concerns are almost exclusively relevant to electronic intrusion experts.

Spacecraft Habitats and Swarms

Many spacecraft essentially function as permanent or semipermanent habitats. This is particularly true of large, long haul spacecraft, which are in essence mobile tin can habitats, and nomadic swarms that serve as mobile colonies. In fact, many tin can habs and swarm modules are built from repurposed bulk freighters or other large craft. The primary difference is that all but the largest spacecraft are not designed for sustainability the way habitats are. Spacecraft typically lack the fleets of robotic harvesters and large, internal green spaces that make habs self sufficient. A spacecraft’s job is to move from point A to point B. Refurbishment, resupply, and harvesting or purchase of raw materials then happens at point B.
From a security perspective, spacecraft colonies are just like many other stations, except they’re mobile. Most are microgravity environments, with a few maintaining small toruses with light gravity. Accessing, securing, and otherwise manipulating these environments is thus quite similar to defending or infiltrating a cluster, tin can, or torus habitat.

Further Reading

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