Design and Fabrication of a Mars Ascent Vehicle Reaction Control System

Sample return missions generally have the largest velocity change (Delta;V) requirements for a mission to a given body such as Mars. For every pound of Mars liftoff mass removed from the return vehicle, in this case a Mars ascent vehicle (MAV), 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 Mars gravity well will have a huge impact on the amount of mass that must be lifted off the Earthrsquo;s surface. A leading design for a MAV is baselining the use of a hybrid rocket for primary propulsion and nitrogen cold gas thrusters for the reaction control system. Studies have showed that above a certain threshold, monopropellant systems become more mass-efficient. An in-house trade study has showed that for total impulses above 140 Nmiddot;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 Nmiddot;s. Furthermore, as the total impulse requirement increases, the mass advantage of the foam-based hydrazine system increases significantly. In this project, Ultramet will design, fabricate, and thoroughly bench test a foam-based ignition system for hydrazine.