''This is Chapter 4 of the [[SolSeed book]].''
=== Orbiting mini-worlds ===
Habitats in space, as defined by images that NASA shows us, are traditionally sterile white boxes and tubes with little life other than their human occupants. The only green, or color of any kind, is to be found in some ultra-processed space food we may see the astronauts carefully imbibing, doing their level best to avoid polluting the limited air supply with floating crumbs. If there is any plant life in the public imagination of space, it is also strictly for food (as in the typical depiction of a greenhouse adjoining a future Mars base) and its growth is carefully regimented and constrained.
Such was not always the case. In the 1970s, in the afterglow of our first successful mission to another world, Gerard O'Neill and others developed an ambitious vision of huge orbiting colonies with complete self-sustaining ecosystems inside. Humans would live in ordinary houses built on the inside surfaces of giant spinning spheres and cylinders (the spin creating the effect of a roughly Earth-equivalent gravity or perhaps somewhat less). They would lead lives much like those of their Earthbound brethren, though they would only have to glance at the upside-down forests and rivers arching overhead to remind themselves of where they were.
Many people were disappointed that these ideas did not gain more traction and work their way into NASA's planning, but that doesn't mean the dream is dead. The International Space Station is the largest structure ever built in orbit, and it will doubtless serve as a stepping-stone to far larger ones, whether built by governments or new private space-station manufacturers like Bigelow Aerospace. There is a revived interest in visiting the asteroids, at first only for mining and perhaps to test methods of diverting a potential biosphere-killer like the one whose impact killed the dinosaurs, but these could be the first steps toward hollowing out such a giant rock, filling it with air, and seeding life inside.
It's hard to be optimistic, though, when you think about the size of such a bubble world in comparison to the sum total of all previous objects we've sent into space. Millions of tons of shielding alone would have to go into the design, for defense against damaging solar and cosmic radiation. O'Neill proposed huge mass drivers to launch material from the Moon that would go into shielding, oxygen, and the beginnings of soil for the new colonies' plant life. To date, we've never done any construction work in space, unless you count snapping together pre-built space station modules; it seems too great a leap from where we are today to go straight to establishing a mining rig and other major installations on the Moon. So what stepping-stones can we envision that would take us in that direction?
=== Biospheres 3, 4, 5, etc ===
You've probably heard of the Biosphere 2 experiment: a large glass-walled building containing several miniature ecosystems, completely airtight, with the only input from outside being sunlight. Eight "Biospherians" spent two years inside this sealed structure, researching how well this microcosm of Earth's biosphere could maintain itself, with one main goal being to see if such a system could provide life support for spacecraft and space colonies.
The experiment is best known for its failures, both sociological and technical (particularly oxygen getting absorbed by the concrete supports to the point where it became somewhat difficult to breathe). But that doesn't make it less surprising that few significant efforts have been made since then to study how to get it right. After all, technological life-support systems (air and water purification, oxygen generation, etc) often have single points of failure and can be difficult to repair. By contrast, each element, or niche, of an ecosystem is composed of many self-repairing organisms, making it much more robust, reducing the likelihood that problems will escalate into disaster.
Research in this area may be a key area where SolSeed can make a contribution. Two of the Biospherians started a company, Paragon Space Development Corporation, that has created very small closed-ecosystem experiments for the International Space Station and is planning to send a living flower to the Moon. NASA also has a "bioregenerative life support" research division, relatively poorly funded but with at least one project underway at the University of Arizona to develop a space-rated crop-growing module. Perhaps we can study and expand on their work, starting small as they have, helping this nascent research community work its way up to a closed system that we can more confidently send humans into (which may be a better way than what Biosphere 2 attempted, trying to get it all right on the first try).
Of course, there are many other challenges associated with moving such a self-sustaining habitat into space. Many proposals exist for moving matter from Earth's surface to orbit more cheaply, from single-stage scramjets to space elevators, in addition to mass drivers and even ultra-high-altitude balloons and airships. There is no reason why SolSeed couldn't contribute to these endeavors as well, once we have the resources. But keep in mind that what separates the SolSeed Movement from other groups interested in space travel is our ethic of "going to space for the sake of all life." Given that, it may make the most sense to focus our energies primarily on the more biological and ecological aspects of the project, rather than on hardware engineering.
=== Terraforming/ecopoeisis: a multi-species joint venture ===
: Three scientific meetings on the topic of making a second home on Mars were held, and at one of them, Robert Haynes, a distinguished geneticist from Toronto, coined the word ''ecopoeisis''--literally, "the making of a home"--for the practice of transforming an otherwise uninhabitable environment into a place fit for life to evolve naturally. I prefer it to the word ''terraforming,'' often used when considering this act for planets. Ecopoeisis is more general. Terraforming has the homocentric flavor of a planetary-scale technological fix.
::: ~ James Lovelock, ''The Ages of Gaia,'' p. 186
: "One generation plants the trees; the next gets the shade."
::: ~ Chinese proverb
Let's imagine that in fifty or a hundred years, our efforts to bring life into space have borne fruit, and there are several miniature biospheres floating around Earth or elsewhere in the Solar System. But the first generation of people living inside these hollow spheres and cylinders is growing nostalgic for the wide-open skies and distant horizons of Earth, and their descendants may find the same longing through watching videos or VR simulations of their ancestral home. It's time to consider a life-bringing project of more ambitious scope.
Transforming an entire planetary surface to support multicellular life is a massive undertaking by any measure. On Earth, it took many millions of years for photosynthesizing bacteria to produce the oxygenated atmosphere that provides the essential energy source for animal life. Practically speaking, humans are unlikely to develop the patience to embark on such a glacially slow transformative process. Clearly, we will need to find some means of artificially accelerating the creation of a habitable environment, both to help gather support for the project, and to reduce the risk that humanity itself won't be around long enough to finish the job. Proposals for how to do this range from simple, low-tech ideas (scattering black dust on polar caps to absorb heat and melt the ice) to grandiose construction projects (huge mirrors to reflect sunlight onto or away from a planet, or a world-enclosing "tent" held up by miles-high poles to keep air from escaping to space), to what might be described as life-supporting violence (crashing comets into the surface to get more water, or setting off hydrogen bombs underground to release volatile elements).
But the time from the beginning of a terraforming/ecopoeisis project to the time when humans can walk the new landscape unprotected by spacesuits is likely to be many decades no matter what we do. In his Mars novels, Kim Stanley Robinson posits a longevity treatment that allows some of his characters to live through the whole process, but we can't count on such a breakthrough to occur in real life, so we must contend with the probability that a project begun by one generation of humans must be completed by another. Indeed, there is a great risk that people who won't accept this will take drastic measures to speed up the process, and create a dangerously unstable planetary environment as a result, one that is all too likely to collapse back into uninhabitability with even greater speed. So to set up a terraforming project on a sustainable basis, we must study the great multigenerational projects of the past, like the construction of cathedrals or the Great Wall of China, to see what lessons we can draw from them about keeping people motivated when working toward a result they will not live to see.
Of course, construction projects may not be the best metaphor for the whole process of ecopoeisis, though of course they fit just fine if you're building a world-tent. Robinson and others have suggested that ecopoeisis is actually a form of large-scale gardening. There are many possible quibbles with this metaphor--particularly the notion that humans are in charge of the whole thing, when the goal is to grow a planetary wilderness that sustains itself with as little ongoing human intervention as possible--but the emotional resonance of the concept is a good one.