Sample return missions generally have the largest velocity change (ΔV) requirements for a mission to a given body, especially bodies with large gravity wells. For every gram of liftoff mass removed from the return vehicle, the incremental reduction in gross liftoff mass from Earth is several orders of magnitude greater. Consequently, any technology that can reduce the mass that must be lifted out of the target body’s gravity well will have a huge impact on the amount of mass that must be lifted off the Earth’s surface. For an ascent vehicle, regardless of whether a solid, liquid, or hybrid rocket is used, thrusters will be needed for the reaction control system. Studies have shown that above a certain threshold, monopropellant systems become more mass-efficient than cold gas systems. An in-house trade study has shown that for total impulses above 140 N·s, a traditional hydrazine system has less mass than a cold-gas system. The same study also showed that if a foam-based ignition system is used with hydrazine instead of a granular catalyst and external heaters, the breakeven point drops to just 44 N·s. Furthermore, as the total impulse requirement increases, the mass advantage of the foam-based hydrazine system increases significantly. In this project, Ultramet will build upon a recently completed effort in which a foam-based ignition system for hydrazine was designed, fabricated, and hot-fire tested. In particular, modifications will be made to the design to facilitate testing, and more extensive hot-fire testing will be performed.
Virtually any spacecraft or launch vehicle using monopropellant hydrazine can benefit directly from this technology. Applications include attitude control systems on spacecraft, reaction control systems on launch vehicles, and primary propulsion systems on smallsats and cubesats. Because the technology is fundamentally propellant-agnostic, it can be applied to virtually any monopropellant or non-hypergolic bipropellant system. Other applications include air heaters for hypersonic wind tunnels.
Non-NASA applications include attitude control thrusters on satellites, reaction control thrusters on launch vehicles, and primary propulsion systems on smallsats and cubesats. DoD applications include missile propulsion systems and air heaters for hypersonic wind tunnels. Other potential applications include auxiliary power units and emergency power units on aircraft.