Nitrous Oxide Ethane Ethylene Engine

The Nitrous Oxide Ethane-Ethylene (NEE) engine is a proposed technology designed to provide spacecraft with non-toxic non-cryogenic high-performance propulsion. With the NEE engine, nitrous oxide is used as an autogenously pressurizing oxidizer, and a mixture of ethane and ethylene is used in the same manner as fuel. Initially, the ethane and ethylene mixture have the same vapor pressure as the nitrous oxide. By utilizing the autogenous pressurization capabilities of these propellants instead of an additional pressurization system greater system simplicity and reliability can be attained. Achievable specific impulse with pure N2O is about 315 s, which can be raised above 325 s by dissolving some O2 in the N2O. Catalytic ignition can be achieved by using a ruthenium reactor to exothermically dissociate N2O. Since both propellants can exist as a liquid in the same temperature range, no thermal separation is required, and the two propellants can be stored together in compact common bulkhead tanks, and freezing is not an issue down to -90C. Pioneer Astronautics has demonstrated monopropellant nitrous oxide thrusters with a specific impulse of 190 s. Using such nitrous oxide monopropellant engines for low thrust RCS together with the NEE for ??V and larger thrust reaction control propulsion, it will be possible to build spacecraft propulsion systems that are completely storable and non-toxic, with only two propellant fluids required. In the proposed program, we will demonstrate a NEE engine.

NEE propulsion would have many commercial spacecraft applications. The NEE would enable the first non-toxic storable stage, and as such would find many customers who would value it as a cost-effective alternative to the current choice of toxic hypergol or cryogenic propulsion. With its high performance and indefinite space storability, the NEE engine would be ideal as a lunar ascent/descent reaction control propulsion system. The NEE is particularly advantageous if used on manned spacecraft such as the lunar ascent/descent vehicle, the MPCV, or vehicles used in conjunction with manned spacecraft (such as free-flying inspection telerobots used in support of the ISS or MPCV), as in that case the N2O can be used for NEE bipropellant ??V propulsion, nitrous oxide monopropellant low-thrust RCS, and to provide a storable reserve supply of crew breathing gas.

Non-NASA commercial applications would include myriad of the propulsion chores for small satellites and large satellites as well, if designers of larger satellites wanted to take advantage of the compactness and non-toxicity of the NEE propulsion system. The NEE engine could be used for onboard spacecraft propulsion or for dedicated upper and transfer stages supporting every type of mission. The NEE engine is the highest performing non-toxic storable propellant combination that exists, and with a performance that matches the increasingly shunned toxic hypergols, is sure to find many customers in every niche from microsatellites to missiles and launch vehicles.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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