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CAN PLANTS AND HUMANS CO-EXIST IN A SMALL ENCLOSED SPACE?

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The Biospheric Test Module was constructed in 1986 as a testbed for the experimental earth colony of the monumental Biosphere 2 Facility. The Test Module was also a closed ecological environment, on a much smaller scale (480 m3 compared to Biosphere 2’s 204,000 m3). Closed-loop experiments took place between 1988-1989, two years before the first experiments took place in Biosphere 2. The purpose of the Test Module was to observe the changes in atmospheric composition in an enclosed environment, and to measure the adverse effects of a closed system on life support systems and human occupants.

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The Test Module was divided into two volumes: the first was the biochamber, which included the human habitat quarters, food production, data collection and monitoring devices, and mechanicals. The second chamber was the facility’s “lung” tank, a variable volume chamber that controlled the interior pressure of the biochamber in accordance with temperature and external barometric changes. For example, as the outside barometric pressure decreased, the lung expanded so as to offset the pressure difference between inside and outside. This dynamic volumetric-barometric relationship reduced the chance of the Test Module exploding or imploding. The biochamber structure itself was a steel space frame with double laminated glazing and allowed for an average of 65 percent photosynthetic solar radiation to pass into the structure. The Test Module’s monitoring system was a sophisticated system to measure changes in pressure, temperature, and atmospheric composition.

The data monitoring system uploaded information to the Space Biosphere Ventures (SBV) command center outside the Test Module. From the SBV Mission Control building, scientists were able to observe information about the atmosphere and organic composition inside the Test Module. Several early experiments revealed problems regarding sensory output, including that of “noise” that altered chemical concentrations in the atmosphere. The iterative process of calibration reduced the anomalies in measurements and secured the Test Module for long-term human habitability. The water system of the Test Module was composed of three subsystems: the generation of potable water, the generation of plant irrigation water, and recycling of waste water in a closed loop. These subsystems were solved relatively quickly in comparison to the life support systems inside the structure. The balance between oxygen for humans and carbon dioxide for plants was the key relationship, but the production of toxins also influenced the balance of air recycling and treatment. Utilizing gas chromatography mass spectrometry (GCMS), scientists could measure eleven key gases in the atmosphere and change systems to balance atmospheric production towards human and plant cohabitation.

The Test Module was considered a “success” because its scope of experimentation was limited so as to justify the possibility of Biosphere 2 for an enclosed human habitat. Since there were fewer variables to consider over a smaller scale, control of bioregenerative systems was plausible, especially in comparison to Biosphere 2. Based on the results of Biosphere 2 and its Test Module, scale became an important issue in enclosed systems. As systems became larger, they could emulate Biosphere 1 (the Earth), but new challenges would arise as the large increase in the inflow of data made the process of balancing the organic composition of an atmosphere more difficult.

Conversely, unanticipated toxic buildups can occur more easily in small-scale systems like the Test Module, following the metaphor of increased cultivation in a petri dish. The Test Module also resonates with the construction mock-up in contemporary design practice and construction, with the mockup yielding unanticipated problems in the feasibility of structures and enclosure. Because these mockups are an abstraction of a full structure—as is the case with the Test Module in relation to Biosphere 2—they cannot foretell all the possible changes present in a scalar shift.

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KEYWORDS: Bioregenerative Systems, Gas Chromatography Mass Spectrometry, Lung Chamber

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KEY FAILURES

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TEST MODULE: Although no failures occurred, the scope of the Test Module was deceiving in its implementation in the much larger monumental earth colony of Biosphere.

If the Test Module were to be ‘successful,’ it should have integrated a forecast of the measurable effect of upscaling the facility in size. 

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