This eco-community concept would be intended for use in some rather harsh environments that might be chosen for their economy or to really put notions and technologies of self-sufficiency to the ultimate test and would serve as a direct analogy to subterranean settlements likely employed on future lunar and planetary settlements. Relying on either a natural strata suitable for simple excavation by roadheader, employing a system of reinforced concrete shells in less stable strata, or even using a ‘built-up’ structure combining concrete shells with earth berming, Terra Firma would be a largely below-ground community complex employing a network of excavated and open (but optionally skylight-topped) avenues or ‘canals’ and circular or oval atriums linked by short tunnels. Individual residences would be based either on bay units surrounding large atriums or avenues –much like the residences in the Solar Circle concept- or they would be based on one to a few small and completely private circular atriums. The complex would be largely internally focused, its atriums and avenues offering the primary ‘outdoor’ space and being used extensively for garden cultivation and water features. This is especially well suited to regions of harsh winter or desert climate, allowing the below-grade space to cultivate a pleasant semi-tropical climate year round with the aid of both natural thermal mass and geothermal heat pumps. This simple strategy of below-grade dwellings was quite common in the past with many ancient examples in both the near-arctic and desert regions, some of community scale. In regions with more complex terrain, terraces may be used and it may be possible to repurpose existing abandoned quarries and strip mines as single large terraced ‘valleys’ or ‘crater’ forms with an option for some kind of very large area dome or tension roof enclosure. A truly subterranean version, perhaps called Sub-Terra, is also possible, but probably less likely in the Foundation phase and would only serve as a more extreme demonstration of extraterrestrial settlement.
Terra Firma would offer one of the closest and most realistic analogies to an extraterrestrial settlement possible in the Foundation phase, and yet would defy common perceptions of a ‘space’ habitat since it could be quite low-tech in aspect, especially when relying on straight excavated structure. This is a potentially very economical community concept since it takes advantage of real estate that would be undesirable for other uses and, where the natural rock strata allows, reduces most construction to just machine excavation. However, it would be a challenging community to establish because of the complications of great remoteness likely with the locations it would use. Because this community structure is so inwardly focused, the environment would cultivate a great sense of serenity and inhabitants would tend to feel a great deal of isolation (or insulation, depending on your perspective) from the outside world, though while a high degree of privacy would be offered by private atrium dwellings (which could be as large as desired), a relatively close-quarters environment would be the norm elsewhere favoring a socially well-knit community. However, there is also great potential in this type of community in the role of a ‘retreat’ themed resort owing to its great physical isolation. With an aspect rather like a monastery or, perhaps more accurately, the hide-out of a Bond movie villain, here the privacy offered could go beyond serenity, employed for the benefit of cultivating alternative lifestyles, exotic environments, or simply to provide a much higher security haven in an otherwise luxurious environment for celebrities or for business and political conferences.