BIOS-3 consists of a 315 cubic metres (11,100 cu ft) underground steel structure[1] suitable for up to three persons, and was initially used for developing closed ecological human life-support ecosystems.
[citation needed] Chlorella algae were used to recycle air breathed by humans, absorbing carbon dioxide and replenishing it with oxygen through photosynthesis.
To achieve a balance of oxygen and carbon dioxide, one human needed 8 square metres (86 sq ft) of exposed Chlorella.
[7][8] In 1991, BIOS-3 became a part of the International Center for Closed Ecosystems, which was formed as a subdivision of Institute of Biophysics, Russian Academy of Sciences, Siberian Branch.
Closed ecosystems research focusing on growing plants and recycling waste was resumed in 2005 in cooperation with European Space Agency.