4 ms·

I completely agree that Biosphere 2 was a great experiment. But at no time was Biosphere 2 a functioning independent biosphere -- it was a slowly decaying stati

by michael1999 3y ago

I completely agree that Biosphere 2 was a great experiment. But at no time was Biosphere 2 a functioning independent biosphere -- it was a slowly decaying station. I think it is likely that we could eventually make one work. But that is a long way from "demonstrated feasible". If you struggle to manage respiration, food is not your problem. "The oxygen inside the facility, which began at 20.9%, fell at a steady pace and after 16 months was down to 14.5%." "Daily fluctuation of carbon dioxide dynamics was typically 600 ppm because of the strong drawdown during sunlight hours by plant photosynthesis, followed by a similar rise during the nighttime when system respiration dominated. As expected, there was also a strong seasonal signature to CO2 levels, with wintertime levels as high as 4,000–4,500 ppm and summertime levels near 1,000 ppm."

yellowapple 3y ago
From the same source: > Since some biospherians were starting to have symptoms like sleep apnea and fatigue, Walford and the medical team decided to boost oxygen with injections in January and August 1993. The oxygen decline and minimal response of the crew indicated that changes in air pressure are what trigger human adaptation responses. These studies enhanced the biomedical research program. > [...] > The respiration rate was faster than the photosynthesis (possibly in part due to relatively low light penetration through the glazed structure and the fact that Biosphere 2 started with a small but rapidly increasing plant biomass) resulting in a slow decrease of oxygen. A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont–Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen. > [...] > After Biosphere 2's first mission, extensive research and system improvements were undertaken, including sealing concrete to prevent the uptake of carbon dioxide. Long story short: it was primarily an issue with the concrete absorbing the carbon dioxide (which otherwise would've been converted back into oxygen), lowering overall air pressure. Said issue was fixed by the second mission.

yellowapple 3y ago

From the same source: > Since some biospherians were starting to have symptoms like sleep apnea and fatigue, Walford and the medical team decided to boost oxygen with injections in January and August 1993. The oxygen decline and minimal response of the crew indicated that changes in air pressure are what trigger human adaptation responses. These studies enhanced the biomedical research program. > [...] > The respiration rate was faster than the photosynthesis (possibly in part due to relatively low light penetration through the glazed structure and the fact that Biosphere 2 started with a small but rapidly increasing plant biomass) resulting in a slow decrease of oxygen. A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont–Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen. > [...] > After Biosphere 2's first mission, extensive research and system improvements were undertaken, including sealing concrete to prevent the uptake of carbon dioxide. Long story short: it was primarily an issue with the concrete absorbing the carbon dioxide (which otherwise would've been converted back into oxygen), lowering overall air pressure. Said issue was fixed by the second mission.