Nitrogen dynamics in the CELSS Breadboard facility at Kennedy Space Center

For the past 9 years, the Breadboard Project at Kennedy Space Center has studied the feasibility of using crop plants in bioregenerative life support systems for long-duration space missions. Nitrogen (N) has been emphasized in nutrient balance studies because it is a major plant nutrient, undergoes biogenic and abiogenic transformations, and is often limiting to plant growth under field conditions. Nitrogen budgets have been calculated from experimental results to quantify utilization and losses associated with specific crop production systems. The Breadboard Project has recently completed a 418-day potato crop study using recycled nutrient solution to evaluate the impact of continuous production on life support functions. A continuous production system is desirable in maintaining N balance within a solution because crop uptake rates vary dramatically depending upon the stage of crop development. Strategies for recycling N using biological techniques (e.g., biomass degradation with microbial bioreactors) have required that the production system be modified to distribute inputs more evenly over time. Recovery of N is dependent on the form of N entering the bioreactor and the desired output. Aerobic and anaerobic bioreactors for the recovery of N from waste streams and its transformation into a form usable by higher plants are being designed and tested.