Nitrous Oxide Based Oxygen Supply System

Update:: Pioneer Astronautics was issued United States Patent Number 6,347,627 for the NOBOSS technology.

The Nitrous Oxide Based Oxygen Supply System (NOBOSS) is a method for storing oxygen and nitrogen for EVA breathing and mobility. Nitrous oxide, N2O, is a common storable chemical that potentially could be used as a convenient, low cost, lightweight, safe and reliable source of oxygen and nitrogen. A nitrous oxide atmosphere supply would have the following advantages: easier storage with greater density at much lower pressure, no cryogenic insulation problems, longer duration oxygen supplies with less weight, and much lower fire hazard than compressed or liquid oxygen. In the NOBOSS, nitrous oxide is decomposed via heating in a catalytic reactor, and as the decomposition is exothermic, the N2O will continue to decompose without further energy input. The NOBOSS can be used to supply breathing gas to existing 4.3 psi space suits by employing an air separation membrane or molecular sieve to eliminate the nitrogen. The waste nitrogen could then provide propellant gas for an MMU. Alternatively, the 2/3 nitrogen, 1/3 oxygen gas mixture produced by N2O dissociation is the ideal gas supply for an 8 psi space suit. In addition, expansion of stored liquid N2O produces cold gas that can be used to help cool a spacesuit.

Pioneer’s work on the NOBOSS was supported by SBIR funding from NASA Johnson Space Center.

Project Summary

The Nitrous Oxide Based Oxygen Supply System (NOBOSS) is a method for efficient generation of breathable gases for space, terrestrial, and marine applications. Nitrous oxide (N2O) is a common storable liquid that can be used as a convenient, low-cost, light-weight, safe, and reliable source of breathing gas. NOBOSS offers non-cryogenic storage with greater density at much lower pressure and much lower fire hazard than supply systems containing 100% oxygen. The primary advantage of nitrous oxide is the small volume and low mass of storage tanks to support long-duration breathing needs. Nitrous oxide liquid at 750 psi is about 3 times denser than compressed air or oxygen at 3,000 psi. Compared to high-pressure breathing gas cylinders, the same mass of N2O can be stored in one-third the volume with one-twelfth the storage cylinder mass.

Nitrous oxide can be decomposed thermally in the presence of a catalyst, and the exothermic dissociation continues without further energy input. The resulting product gas, following polish filtration of parts-per-million byproducts, is 33.3 percent oxygen (by volume) with balance nitrogen, suitable for breathing. The following reaction describes the dissociation of nitrous oxide to oxygen and nitrogen.

N2O → N2 + ½O2 + 81.8 kJoules

After initial in-house proof-of-concept testing, Pioneer developed the NOBOSS technology during NASA SBIR Phase I and II programs. A novel, light-weight, efficient catalytic reactor system incorporating simple pneumatic flow and thermal controls was built. Pioneer’s reactor design achieves virtually complete nitrous oxide dissociation with very low byproduct gas formation. The gas production system requires no external power after initial start up. The nitrous oxide feed pressure (about 750 psi at 20oC) is used to deliver gas to the system and provides motive force for cooling and downstream gas cleanup systems. Product gas is delivered to the user through a self-pressurized surge tank. A fully operational prototype backpack was built and demonstrated during the SBIR Phase II program.

Michael Rouen was the NASA Contracting Officer’s Technical Representative at Johnson Space Center for the NOBOSS project. Dr. Robert Zubrin was the Principal Investigator for Pioneer Astronautics. Mark Berggren was the lead engineer for Pioneer on the Phase II project.