BIOS-3 was a closed ecosystem at the Institute of Biophysics in Krasnoyarsk, Siberia, in what was then the Soviet Union.

Construction began in 1965, and was completed in 1972. BIOS-3 consisted of a 315-cubic-metre habitat suitable for up to three persons. Chlorella algae, which photosynthesise, were used to recycle air breathed by humans, absorbing carbon dioxide and replenishing it with oxygen. The algae were cultivated in stacked tanks under artificial light. To achieve a balance of oxygen and carbon dioxide, one human needed 8 square metres of exposed Chlorella. Water and nutrients were stored in advance and were also recycled. By 1968, system efficiency had reached 85 percent by recycling water.

BIOS-3 facilities were used to conduct 10 manned closure experiments with one to three man crew. The longest experiment with a three man crew lasted 180 days (in 1972-1973). The facilities were used at least until 1984, and are apparently still available for experiments (as of 2004).

External links

• History of BIOS-3
• Comparison of BIOS-3 and Biosphere 2