Properties Investigation of High-MON Oxidizers for Use in Deep Space Exploration

Rocket propulsion for deep space applications typically use liquid propellants for axial stage and attitude control systems. The most common propellants are hydrazine (N2H4) and monomethylhydrazine (MMH) (CH3N2H3) for the fuels, and nitrogen tetroxide (NTO) (N2O4) for the oxidizer. The freezing points of both hydrazine and NTO approach room temperature and require on-board electrical heaters for the propellant tanks. MMH has a much lower freezing point but is used with NTO as an oxidizer so propulsion systems still require significant heater power. MON-25, an oxidizer composed of NTO mixed with 25% nitric oxide (NO), has a freezing point comparable to MMH. MMH and MON-25 propellants can allow a thruster to operate at -40°C. However, the properties of MON-25 have not been fully defined, specifically at temperatures below 5°C . This project will further characterize the properties of MON-25 and MON-30 oxidizers so they can be used with confidence at cold temperatures in space flight systems. These propellants will save considerable power required for propellant heaters, which will permit larger science payload and enhance the mission capability of deep space probes. The low-temperature oxidizers may also find use in lunar landing and ascent systems where sunlight is intermittent or absent.