Development and Operation of a Space-Oriented Salad Machine ‘Phytoconveyer’;

Installation of a ‘salad machine’; in the International Space Station (ISS) will be the first step toward long-term biological regeneration of food during space missions. Salad crops have demonstrated promise for providing dietary supplements and psychosocial benefits. A cylindrical conveyer-type design (called the Phytoconveyer) under development exhibits high productivity and low energy and crew time demands. The overall dimensions are 54 × 59 × 40 cm. Power consumption is 0.25 kW and the volume of the plant growth chamber is 0.09 m³. The Phytoconveyer includes a cylindrical planting surface area comprised of six root modules. Each root module contains a porous tube wrapped in a fibrous ion-exchange resin substrate (BIONA V-3) enclosed within a black plastic cover with an open slot on the top for seed insertion. The total outer diameter of the root module is 5 cm. The Phytoconveyer uses an ‘ebb and flow’; delivery system to supply water to the six root modules in conjunction with a control program. Light is provided by red (660 nm) and blue (470 nm) LEDs on the internal surfaces of the spiral cylinder in a nine to one ratio (providing 350 μmol·m⁻²·s⁻¹ PAR 4 cm below the light source). The total illuminated crop area inside the Phytoconveyer is ca 0.4 m². In ground tests with a 24-hr photoperiod, the Phytoconveyer provided up to 300 g of fresh edible salad biomass every 4-5 days. The unit has been designed to be incorporated into the interior of the ISS Russian segment. This work has been supported by the Moscow office of the International Science and Technology Center (ISTC Project No. 2137).