Space Station Nitrogen Supply System Based on Stored Chemicals

The Space Station will require a method of supplying nitrogen (N₂) for Space Station leakage makeup and repressurization. Life Systems working with the National Aeronautics and Space Administration (NASA) has developed a Nitrogen Supply System (NSS) based on the catalytic dissociation of hydrazine (N₂ H₄) into a mixture of hydrogen (H₂) and nitrogen (N₂) and their subsequent separation. A preprototype NSS has undergone developmental testing and is capable of producing an average of 4.4 kg/day (9.6 lb/day) of N₂. The design integrates a hydrazine catalytic dissociator, three ammonia (NH₃) dissociation stages and four H₂ separation stages into a 28 kg (62 lb), 21 dm³ (0.76 ft³) module. The Nitrogen supply by hydrazine dissociation has a lower launch weight than other nitrogen supply techniques. It also has the advantages that the hydrazine will be readily available at the Space Station since it is required for satellite refueling as well as the probable fuel source for the Space Station, and the product hydrogen will be available for other Space Station consumers (e.g., attitude control, laboratory needs and carbon dioxide reduction). This paper reviews the design, configuration, operation and performance characteristics of the preprototype NSS.