Abstract
This paper presents an analysis of multimode spacecraft propulsion systems using decomposed monopropellants in both chemical and electric propulsion modes, enabling both efficient high-thrust and high-specific-impulse maneuvers. Traditional monopropellants such as hydrazine and hydrogen peroxide are evaluated alongside modern green alternatives, including ammonium-dinitramide-based LMP-103S and hydroxylammonium-nitrate-based SHP-163 and FAM-110A. The study investigates how decomposition products from these propellants perform in multimode systems with an arcjet, Hall effect, and gridded ion thruster electric mode. Two modeling approaches are used to estimate performance: a mass-averaged model based on available empirical data and an ionization limits model that assesses theoretical performance based on the ionization energies of the decomposition products. The ionization model indicates that propellants with high concentrations of low-mass species perform poorly in electric thrusters due to high ionization energy demands with hydrazine requiring over 77% more power than SHP-163 and over 141% more than hydrogen peroxide. Results show that Hall effect thrusters provide the best balance between [Formula: see text] and thrust, yielding 9.4 to 35.5% more delta-[Formula: see text]. The mass-averaged model showed that LMP-103S provided the highest system-level delta-[Formula: see text] for a 250 kg spacecraft, with gains of 1.2, 2.5, 6.0, and 13.5% over hydrazine, SHP-163, FAM-110A, and hydrogen peroxide, respectively.