Physico-chemical processes can perform the two latter tasks, but only biological processes can perform all three. Biological systems utilize plants and microorganisms to perform these life support tasks in a process termed bioregeneration. An BLSS is a tightly controlled system, using crops to perform life support functions, under the restrictions of minimizing volume, mass, energy, and labor. Research on human life support began in the 1950's with oxygen regeneration using algae. The KSC-ALS philosophy is to use biological subsystems to recycle material through an ALS system.
Humans take in oxygen, food and water, and expel carbon dioxide and organic waste.
Plants utilize carbon dioxide, produce food, release oxygen, and purify water. Inedible plant material and human waste are degraded by microorganisms to recycle nutrients for plants in a process termed resource recovery. Integration of component systems is the key to the project . This chamber was formerly a hypobaric test facility for the Mercury and Gemini Space Programs. It was installed in the Life Science Support facility in 1986 and retrofitted for plant growth.