NUTRIENT DELIVERY TESTBED-1: DESIGN OF A FLIGHT EXPERIMENT FOR ASSESSING NUTRIENT DELIVERY SYSTEM EFFECTIVENESS UNDER μ-GRAVITY CONDITIONS

Suitable and effective nutrient delivery systems will be required for both long-duration studies of plant growth and for implementation of bioregenerative life support technologies involving crop production in closed micro-gravity environments. Such environments are anticipated onboard a Space Station. The development of such systems hinges on acquiring the scientific and engineering knowledge necessary to design for micro-gravity operations. We have completed the preliminary design of a flight experiment called the Nutrient Delivery Testbed-1 (NDT-1) which will provide a substantial amount of information about the behavior of such systems in the space environment. The NDT-1 package includes a computer control subsystem, two motor-driven nutrient solution reservoirs, a nutrient solution composition monitoring subsystem, a solution sampling subsystem, three different nutrient delivery systems, and a plant surrogate. The plant surrogate both simulates root uptake of nutrient elements and provides a measurement of element availability to plant roots. Unlike plants, the behavior of the surrogate is not affected by gravity or a lack thereof, and is entirely reproducible, thus allowing us to directly measure the effectiveness of each of the nutrient delivery system designs. The NDT-1 package will be housed in two middeck lockers, connected by umbilicals during operation. This experiment will allow us to evaluate nutrient delivery effectiveness in a series of tests to be conducted aboard the Space Shuttle in 1996.