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How did soil microorganisms contribute to the oxygen problem in Biosphere 2?
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Biosphere 2
Biosphere 2, located in Oracle, Arizona, U.S., shown in 2008. The facility was originally developed to study survivability and assess whether humans were capable of building and living in self-sustaining colonies in outer space. It was later used as a scientific research facility.
During the first mission of Biosphere 2, the crew observed a significant and concerning decline in oxygen levels, which dropped from approximately 20.9 percent to 14.2 percent over 17 months.
While reduced photosynthesis due to cloud cover was a contributing factor, researchers later attributed the oxygen depletion primarily to soil microorganisms. These microorganisms consumed oxygen and released carbon dioxide through their metabolic processes, effectively depleting the atmosphere of the sealed facility.1