Controlled Ecological Life Support Systems as Completely Closed Ecosystems in Space

Plant growth facilities used in space need to be highly reliable for the long term over plant life cycles with little manual control. Restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air. Excess leaf temperature would disorder the leaf’s physiological processes. The temperature increase would be greater at smaller regions, such as anthers and stigmata. Excess temperature in reproductive organs could also cause fertility impediments. There is a possibility that the aberration was caused by an excess increase in temperatures of reproductive organs such as anthers and stigmata under microgravity conditions. Low net photosynthetic rates would also retard plant growth at the reproductive growth stage as well as the vegetative growth stage. The higher air velocity above leaves reduced differences in the leaf surface temperature at the different gravity levels. The control of air movement is shown to be important to enhance the heat and gas exchanges between plants and the ambient air and consequently promote the growth of plants in a closed plant production system, especially with a large number of plants at a high density even on the earth. Proper air movement is essential to promote plant growth not only in the vegetative growth stages but also in the reproductive growth stages, especially in space.