Terraforming Planets & Habitats

This is a step by step projection of some of the check-lists and goals necessary for the eventual terraforming of planetary bodies in our solar system, and for constructing large and complex ecological habitats in orbital space. Intermediate objectives are arranged in order from the most basic to the more advanced and in-depth:

1. self-sufficient food and resource
acquisition
     - dome farming
     - pressurized exploration
     - automated mining
     - permanent housing units

2. established trade in resources and information
     - patents & formulas
     - precious metals & fertilizers
     - entertainment & documentaries
     - scientific research results

3. sustainable material industry & infrastructure
     - appropriate economic technology
     - closed-loop recovery & recycling
     - complete parts manufacturing
     - independently built spacecraft

4. survival outside without pressure suits or breathing masks
     - air pressure within normal limits
     - air composition reflects earth normal
     - oxygen & carbon dioxide acceptable
     - no poisonous trace elements

5. ecologically based food and fiber production
     - developing agricultural biome
     - acculturation of plants to environment
     - managing animals & pastoral habitat
     - naturally recycled waste products

6. base ecological web sustainable via stewardship
     - essentially integrated biome habitats
     - variety of interconnected ecosystems
     - develops robust diversity of species
     - growing "web of life" interactions

7. survivable pre-technological base culture(s)
     - attempts to support hunter-gatherers
     - vulnerable to catastrophic events
     - managed to overcome fragility
     - balanced to avoid over-exploitation

8. independently viable & evolving ecosystems
     - can survive & evolve without help
     - will diverge to create native ecology
     - humans comfortably at home
     - robotic supervision & maintenance

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Space Colonies:
There is a significant difference between planetary terraforming and constructing a habitat made to order. Atmosphere, gravity and lighting are assumed to be chosen and integrated in optimal proportions.

* Approximate weights will run roughly about 2.59 million metric tons/square mile, not counting the hub & docking facilities. The larger, ecology habitats can more nearly balance out this concern, while the smaller Stanford torus may come near to this in total, as if it had one mile of area.
* This "astronomical" weight is why the materials must come from the Moon and the asteroids, not from Earth. And that is just the intended goal weight, which is rarely met in construction, despite design constraints. Clearly, topographical variety can only be achieved through the liberal use of aerogels. Achieving balance along both the length and circumference of the cylinder may be a particular challenge, in order to prevent instability and wobbling during rotation.
* The weight target does not include the biomass and inhabitants that are introduced after the "habitat container" is finished. But it does include the sterile water, soil substrates and atmospheric components. It can take about 10 years to "terraform" the inside of a large habitat from scratch.
* Stable soil ecology is the most critical, and least understood, process to develop. Sterile soils must begin with various particle sizes and viscosity (sand, loess and clay), then introduce porous carbon, nitrogen and phosphates, and certain vitamins and minerals to activate nutrient availability.
* Fertile soils then require communities of bacteria, protozoa, algae, fungi, lichens, insects and small invertebrates to fully disintegrate and recycle plant detritus. Then, certain plant and animal communities, specific to the intended final biome, are needed for the complete reduction and recycling of animal wastes. At this point, you try to balance the ecosystem at large and maximize the carrying capacity. The introduction of larger species begins the final characterization of the biome's ecological identity and diversity.
* The human inhabitants will have to adapt their lifestyles to fit into the "natural" biome of the habitat, so as to minimize their disruptive influences and maintain the overall balances, while planning how much of the internal space they want to "civilize" for economic purposes. This is likely to be a continuing issue, as the impact of human civilization on artificial biomes has not been studied.
* Technically, a proper fully balanced biome should be capable of perpetual operations, including the support of a small population of "simple" human hunter-gatherers. But that would be an ideal case, and some provision for the maintenance of the mechanical habitat would need to be made, as well as for the availability of some kind of sophisticated knowledge retention and education facility.
* There may always be some requirements for replenishing small amounts of vital resources, whether nutrients or chemical elements. This is due to the unavoidable entropy of all systems. External energy, in the form of solar power or nuclear fuels, is probably the largest external requirement for the continual functioning of the colony.