a 1,900 square meter rainforest, an 850 square meter ocean with a coral reef, a 450 square meter mangrove wetland, a 1,300 square meter savannah grassland, and a 1,400 square meter fog desert (above).I remember thinking that the biomes seem to have been chosen by how cool they are -- why a coral reef? -- but I suppose they had to pick something. Heating and cooling were by passive solar power, with a small natural gas plant for electricity.
The discovery of the small difference between rate of respiration and rate of photosynthesis depended on the extremely low leak rate of Biosphere 2. . . . had Biosphere 2 leaked as much as other closed ecological test chambers, the wash-out effect of outside air mixing in would have concealed the entire imbalanceThe best guess as to what went wrong with the atmosphere was a combination of exposed concrete, which soaked up oxygen, and soil bacteria. Soil bacteria live in fiendishly complex communities of hundreds of species, and despite a ton of research over the past 20 years (climate change, you know) we still don't understand them very well; what happened to Biosphere 2 certainly seems within the range of their behavior.
The biospherians also had trouble raising enough food, which is hardly surprising given their 1/2 acre farm. They all lost weight, one of them over 50 pounds. But plenty of explorers have gone hungry before, and, again, what planetary mission wouldn't have an emergency reserve? There was a lot of hype when one of the biospherians left for medical treatment and then went back in with a duffle bag, which critics said was probably full of food. The biospherians said it was mainly mail, along with plans and some tools, but even if it was food it was just one duffle bag. Not much over two years.
Before the first closure mission was half over, the group had split into two factions and people who had been intimate friends had become implacable enemies, barely on speaking terms.The second attempt at a biosphere mission was actually sabotaged by two people from the first mission who, for reasons never explained, opened the air lock and smashed one of the glass windows. But the first biospherians did manage to stay inside for the whole two years, to my amazement. Sadly for them, the various scandals and blow-ups over those two yeas meant that their leaving was greeted very differently from their entering.
And the Biosphere II facility has contributed at least one piece of very important science: it was proved here that high atmospheric CO2 levels cause acidification of the ocean, and that this can kill coral.
Interesting video here.