NASA Research on Spirulina

Certain basic physiological needs must be met in order for human beings to stay alive. On earth, these needs are met by other life forms in conjunction with geochemical processes that effectively use human waste products in conjunction with energy from the sun to produce fresh supplies of food, oxygen, and clean water. In the artificial environment of a spacecraft, these materials must be provided, and human wastes removed, without relying on the natural resources of the earth's biosphere.