Minimal enduring space habitat

I'd like to describe my ideas for an enduring space habitat with ample space for a self-sustaining community of over a thousand humanoids. It's a thin torus about 1.6km in diameter with a texture superficially similar to a rocky asteroid. The ring has a circular cross-section of about 50m diameter. Its outermost surface is a shielding crust of 5m thick spongy pumice-like material, resistant to radiation and micro-meteorites. The crust covers a structural tension ring, something like reinforced concrete; this can deform elastically to absorb large meteorite impacts without breaking. The tension ring also gives strength to the habitat as it turns, simulating standard gravity by centrifugal force. Inside, there are utilities crawl-spaces in ceilings and floors, but that still leaves at least a 36m wide by 20m high interior. This volume is partitioned by robust bulkheads into personal living spaces, stores, engineering workshops, communal areas (including garden parks, refectories, a library, a school, recreation spaces etc) and their connecting corridors. 5 larger nodes, built with even greater structural strength, bulge out at evenly spaced intervals around the ring. These provide airlocks and docking facilities.

These ideas are for a remote science fiction setting. As the habitat is indefinitely self-sufficient, it is not supported by regular traffic from a large populated planet. I imagine it to be one of several (between 5 and 100, say) orbiting a red dwarf (the 70% majority in the galaxy). There may be planets orbiting the star, but no rocky worlds with atmospheres in the narrow habitable zone (tight up against the star). The solid planets that do exist could be subject to constant robot exploration and slow terraforming. Outside the habitable zone, that means tunnelling out large sealed chambers beneath planets' frigid or toxic surfaces. These would each much larger than the habitat's interior, and would eventually be filled with life-sustaining biomes. Descendants of the habitat's population would eventually live in these pocket-worlds, but that goal is perhaps 10,000 years away.

Reliable planning and engineering at this scale is beyond the scope of human teams. The habitat's origins are traced back to when the red dwarf system was seeded by an advanced artificial intelligence. This may have arrived in a slower-than-light spacecraft, either an automated robot probe or a self-sustaining generation ship somewhat similar to the habitat. Since then, the AI would have bootstrapped it's own manufacturing capabilities from in-system resources (rocky and metallic asteroids, and icy sooty comet nuclei). Macro and nano-scale robots under the AI's supervision would have captured and processed more raw materials to spin out the habitat. The original AI would have cloned instances of itself to run on new cores built into the computing, sensor and information storage substrate distributed through each habitat's structure.

In a future where such technology exists, rogue AI on selfishly self-replicating von Neumann probes are a possibility. Such entities may try to steal resources claimed by others and cheat the bootstrapping processes by subverting others' established manufacturing capabilities. For these reasons, each AI is very cautious about remote communications. Even with message security controls, they never completely trust received remotely sensor data and instructions. Each core instance is therefore autonomous and capable of independent development. Copies of the AI only communicate sparingly with each other via ultra-high integrity channels at low bandwidth (compared to current real world standard rates). Advanced encryption, content redundancy, nested stacks of handshakes, error checks and signal recovery ingredients aim to prevent interception and spoofing by malign rivals.

As well as manufacturing the habit, the local AI operates the systems for its maintenance, repair, manoeuvring and life support. It also cooperates with its peers in the supervision of traffic between the habitats and other bodies in the red dwarf system. As the habitat is not a completely closed system, top-ups of the most basic resources are necessary. Exchange of manufactured goods is also beneficial. With completely control of the habitat systems, the ubiquitous sensors wired into its fabric and all its communications, the AI has godlike power over the habitat's population. However, as its mission is to sustain that population indefinitely, it is benevolent. It seeks to minimise harm and is concerned not to restrict the free will individuals.

So the AI mind and the habitat systems that are its body meets the basic needs of the community it hosts in reliable, robust, efficient, mess-free ways:

• Light is generated from solid-state materials (diurnally for bright public spaces and at warmer low intensity for personal use), powered by a variety clean energy sources (e.g. solar-collectors, thermoelectric heat exchangers, nuclear fusion reactors, and superconductors rotating in natural solar magnetic fields).
• Air and water are recycled and cleaned (using self-replenishing safe bioengineered microorganisms) in cycles – via sinks, caches (e.g. small lakes, cisterns and pressurised volumes) and easy to use outlets.
• Food is grown in cultures of bioengineered organisms that are easy to keep in moist and well lit conditions, without requiring soils or significant preparation (e.g. in harvesting, the cutting away of waste or cooking). These appear as gel trays, with the cultures colour-coding their maturity. The colours of ripening and decaying food – green, yellow, orange, red, brown – have cultural associations too (e.g. for youthful naivety, transition, good wholesome reassurance, risk and disgusting old waste).
• Medicinal interventions are assisted by specialist grown materials (drug cultures and bandages), as well as knowledgeable doctors and nurses; robot surgeons and digital diagnostic assistants have limited application.
• Shelter from the hostile environment of space (with weightlessness, vacuum, radiation and high-velocity impacts) is provided by the habitat shielding and manoeuvring thrusters. The internal structure separates enclosed spaces by insulative and fire-suppressant materials, mitigate the effects of hull breach and "breakaway oxidation phenomena".
• Weight, for the creation of normal human living spaces as much as its benefits to the physiology of the inhabitants, is generated by the habitat's spin (revolving around once per minute, as for a classic Stanford torus).
• Temperature control depends more on heat-sinks than adding sources; waste heat from the absorbed solar radiation, engineering systems, human bodies and other organisms would otherwise be trapped by vacuum.
• The basic raw materials to top-up the inevitably slightly inefficient recycling systems could be delivered in bulk periodically from small asteroids (for metals and other heavier elements) and comets (for water, gases and precursor organic compounds). Thousands of tonnes of material can be slowly and safely moved over hundreds of years from their sources' natural orbits by robot spacecraft. At their source, materials are gathered with minimal mining and in situ processing; the autonomous systems on these bodies don't manufacture items that the habitats may or may not need.
  

The humanoid population have genetically engineered modifications so they are better suited for space habitation. They are hairless, disease resistant and quick healing, with simpler digestive systems. Their bodies are tolerant to zero-G and radiation, preparing them for possible disasters. They have short strong limbs, very dark skin and exceedingly good cellular repair mechanisms, including cancer-resistant DNA. The population of at least a thousand can remain genetically healthy over many generations. However basic screening is maintained by the AI, without crossing over into eugenic manipulation.

The habitat would be pointless if the humanity of its inhabitants couldn't be maintained. The hierarchy of needs above the basics addressed above are therefore also met:

• A technologically advanced civilised culture is maintained by the import, management and archiving of information. This includes entertainment media and history, but more critically it covers mechanical, organic and human systems engineering knowledge. Some of the population always retain knowledge of the design patterns and simulation models that the AI uses for these. They understand how these are supported by theories from fundamental science and mathematics.
• Social activities maintain individuals' sense of belonging . These include sports and gaming; swimming (diving, racing and cooperative team games) is popular on the space habitat. Craft, study and creative acts can also be social - more on that below. There is plenty of scope for normal healthy humans' love, affection and romance, with all the associated complications.
• Personal rewards, support of the community and innovation may also be achieved through assistance to the habitat systems. To be purposeful, this work must really matter and be safety critical - it's not just about following the robots to pick up their rubbish and mistakes. Tasks include support to the habitat's structural engineering, monitoring via its sensors and operational maintenance of the life-support systems. Individuals could also assist in the supervision of the automated biological-mechanical hybrid systems with modelling and reprogramming.
• Another class of important maintenance task is the support of the human community itself. Psychology, psychotherapy, sociology, leadership and political roles all overlap in such a small society, but there would always be a few clearly recognised experts in these (and those learning from or competing against them).
• There is also something like a religious institution that supports the cohesiveness of the community. This isn't about faith in the supernatural (e.g. life after death) or a supreme being (the prime-cause, architect of human experience with a divine plan that gives our lives and the universe purpose), or petitioning the AI for divine intervention. It would be about reinforcing the ethics of the cooperative community, sharing joy at new life, coming of age and marriage, and giving the comfort of a greater enduring institution to the sick and bereaved. Its foundational aspiration may be faith that human life will eventually settle more terraformed planets and continue its expansion and creative innovation.
• Self-actualisation (or at least individual expression and personal fulfilment) could be achieved through developing the creative skills available in a small local community: creative craft works (especially clothes, accessories and furniture), folk art, songs and music, and writing (perhaps the most enduring and readily communicable to others beyond the community). Self-esteem is built by independently chosen careers, responsibilities and skills mastery. Exchange of original gifts and public awards, granted occasionally by respected committees or directly by the AI, reinforce personal achievements.
• The transcendent need to help others achieve their own potential cuts across roles in the society. There are amateur and professional teachers who assist in the interpretation of the knowledge resources and coach student as they practice skilled activities. Individuals may also dedicate themselves to the institutions for psychological health and religion.

The inhabitants of the baseline home habitat may assume those in the red dwarf system's other habitats are more or less the same as them, but they could be quite different. Each habitat remains relatively isolated, and its life and culture can grow and evolve independently, just as it does on real-world islands, or the city-states of ancient Greece with their different philosophies, politics and martial structures. Most individuals have only minimal second-hand experience of direct contact, handed down from rare personal histories of space-travel between habitats, in which individuals would have piggy-backed on the slow robot spacecraft transport network. This sense of a wider community at arms-length is maintained by the limited communications traffic. The narrow bandwidth constrains this to text (and vector-drawn graphics primarily used for engineering and science). Without pictures, direct audio and video of others’ small worlds, the commonality of human mental constructs matter more than superficial differences in appearance and cultural styles. The communications are sufficient to maintain use of a common language between habitats.

There’s more to say about the technology to support all this. Specifically, the habit requires advanced genetic engineering (of the human stock and the modified microorganisms used for the environment control that includes air, water and nutrition recycling). There’s also the systems engineering, which is about aggregating dynamically interacting elements from mechanical, electronic, chemical, structural, cybernetic and sociological disciplines. The technology must come together to enable a self-sustaining homeostatic system that efficiently uses sparse resources in the space environment that's otherwise hostile to organic life.