Is Biosphere 2 an open system?
It is a 3.14-acre (1.27-hectare) structure originally built to be an artificial, materially closed ecological system, or vivarium. It remains the largest closed ecological system ever created.
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What was the biggest reason for the failure of the Biosphere 2 experiment?
The failure, say several of Biosphere 2's current staff, lay in the lack of transparency—not the lack of oxygen. Scientists did, in fact, learn something important from what went wrong: the soil was too rich in organic matter, and its thriving bacteria gobbled up too much oxygen.