During construction of Biosphere 2 in the late 1980s, the 480 cubic meter Test Module proved potable water generation, atmospheric sealing, mitigation of thermal expansion and contraction, and the behavior of agents in a closed ecological system. Three closures of the Test Module were conducted for the sum of one month, each supporting a single human inhabitant during which water and human waste were recycled, a healthy atmosphere and an agricultural area were sustained. A great deal was learned about the function of a human-in-the-loop, closed ecosystem as shared by Taber MacCallum at the SAM Symposium 2020 (#3 of 12).
A Space Analog for the Moon and Mars, or SAM will be built around the Test Module coupled to an airlock and hub, pressurized corridor and earth-bermed crew quarters. SAM is ideally located adjacent to an approximately half acre where a massive, indoor/outdoor Mars yard will be constructed for EVA and rover evaluation.
There is no single-run experiment that results in the ideal solution for providing breathable air, recycled water, food and waste reprocessing. Rather, we will see an unfolding of experiments, findings, and prototypes for decades to come. Much as farming evolved from the art of crop rotation to the science of genetically modified organisms, living on the Moon, Mars, and in free space will demand constant improvements in our systems as more humans move to off-world homes.