Biosphere+2

Creating habitable, sustainable environments will be tough to do. Space craft and space

stations, for example, are artificial habitations built for a few people to survive in an

environment hostile to life. However, no one has yet designed a space craft as a sustainable

environment. Biosphere 2, however, a $150 million project constructed in the Arizona desert

in the early 1990’s, was intended as a self-sustaining ecosphere. The huge terrarium contained

3,000 species including a very small band of Homo sapiens.

An important goal of Biosphere 2 was to “Maintain resilient, persistent, complex and

evolving ecosystems.” Perhaps the most important lesson from this project is that creating a

self-sustaining ecosphere is a dauntingly complex problem. While Biosphere 2 remains the

most sophisticated life support system ever designed by humans, there are no longer any

pretenses about the elaborate terrarium being able to sustain human life in a synthetic

environment.3

In the two years the experiment ran researchers were unable to achieve an

equilibrium in the carbon dioxide (CO2) level; researchers did not foresee that excess CO2

would be generated by micro-organisms decomposing organic matter in Biosphere’s agricultural

soils. In addition to the CO2 problem, Biosphere’s “ocean” became acidic and the freshwater

supply salty. The crew worked overtime to ‘balance’ the system, adding bicarbonate to buffer

the water, cutting back plants to encourage more carbon-fixing growth, postponing composting

http://web.utk.edu/~mbentle1/MARS_TST_2_98.pdf

More on carbon dioxide and oxygen: http://phys.org/news/2015-02-silver-electrocatalysts-enable-long-term-space.html