Work completed to date within the NASA CELSS program suggests that the technologies needed for growing plants in the space environment are sufficiently well understood to allow an early application that would enhance the quality of life for the crew while they are in space. Specifically, the growth of salad vegetables on Space Station Freedom, and during other long duration missions, can provide psychological and dietary benefits to crewmembers. For this reason, a unit capable of producing 600 grams of edible salad vegetables, enough for one salad three times a week for a crew of four is being planned at the NASA Ames Research Center with the involvement of university scientists and engineers. Although the growth requirements for specific plants are well established, providing these requirements within the constraints of the space environment will demand preliminary space flight tests of selected technologies, and of some plant growth behaviors.
This paper describes the plant growth requirements for specific salad vegetables, and the candidate subsystem technologies which are under consideration to achieve the plant growth requirements. Various subsystem options for nutrient delivery, lighting, water vapor condensation and recovery, and environmental control are assessed, and prototype design concepts which integrate these technologies into a production unit are presented. The potential application of Salad Machine technologies to future CELSS modules is also addressed.