LOX Olefin Rocket Propulsion for Deep Space

The LOX Olefin engine (LOXO or LOX/LC2H4 or LOX/LC3H6) is a proposed technology designed to provide interplanetary spacecraft with high specific impulse, space storable propulsion. With the LOXO engine, the combination of liquid oxygen with sub-cooled liquid ethylene or liquid propylene as a rocket propellant enables development of compact lightweight high performance stages with isothermal common bulkhead propellant tanks. This could enable energetic deep space delta-V maneuvers. Currently, space missions requiring energetic delta V maneuvers weeks or months after launch are limited to use of moderate Isp conventional stored hypergolic propellants, typically achieving performance of 310-320 seconds. The much more energetic LOX/LH2 combination has the decided disadvantage of low density, and is not considered suitable for long term storage in space because of thermal management issues with the extremely cold (20K) LH2. The LOXO propulsion system represents an important midway step that combines the advantages and avoids the major flaws of both of these extremes. Theoretical Isp for this propellant combination over 390 seconds has been calculated using AFALS chemical equilibrium code. With an achievable in-space thermal management system, LOXO is a good candidate for deep space propulsion, with performance greatly surpassing current options for mission planners.