In future space travel and colonization, plants and other biological systems are expected to function as an integral part of life support, providing food, potable water, and oxygen. Plants are uniquely able to provide all these essential elements of life support because of the process of photosynthesis.

The idea that plants could rejuvenate air was first discovered by Joseph Priestly in 1771, when he found that plants could renew the air made 'bad' by animals. Later on, in 1782, Jean Senebier showed that the presence of the noxious gas produced by animals and by plants in darkness, stimulated production of 'purified' air in the light. What they had identified is that plants, in the presence of light, consume carbon dioxide and produce oxygen.

The photosynthetic process results in the release of molecular oxygen and the removal of carbon dioxide from the atmosphere - just what you would need when sealed up inside a box in space. The carbon dioxide is used to synthesize carbohydrates (food), and during the process, water is pulled through the plant and out the stomates in the leaves transpiration), producing potable water that can be collected by condensation