Propellant Gelation for Green In-Space Propulsion

Concerns in recent years about the toxicity and safe handling of the storable class of propellants have led to efforts in greener monopropellants and bi-propellants. CFDRC has worked with researchers in designing and synthesizing propellants called ionic liquids. These are generally not as high-performing as traditional storables and still have toxicity issues. Other work by CFDRC and Army researchers (among others) has demonstrated that gelling of liquid propellants, even toxic hypergols, can enhance their insensitive munitions (IM) properties to a significant degree. Besides the IM benefits, gelling of the fuel allows the suspension of ultrafine particles that both densify the propellant and add to the combustion energy, and thereby the specific impulse. CFDRC proposes to combine these research elements into a comprehensive assessment in Phase I to determine the degree to which the gelation of innovative propellant combinations can enhance the system benefits, including performance, safety, and launch costs. Then in Phase II, the desired propellants will be obtained or synthesized, and then gelled. A liquid apogee motor-class thruster will be fabricated and the gelled propellants will be hot-fired in the thruster for evaluation. The end Phase II will focus on identification of opportunities to transition and integrate this technology into NASA, DoD and commercial product lines, with special emphasis on NASA secondary payload propulsion applications.