Assessment of Multi-Mode spacecraft micropropulsion systems

Multi-mode spacecraft micropropulsion systems which include a high-thrust chemical mode and high-specific impulse electric mode are assessed with specific reference to cubesat-sized satellite applications. Both cold gas Freon-14 propellant and ionic liquid chemical monopropellant modes were investigated alongside pulsed plasma, electrospray, and helicon electric thruster modes. Systems involving chemical monopropellants have the highest payload mass fractions for a reference mission of a 500 m/s delta-V and 6U sized cubesat for electric propulsion usage below 55% of total delta-V. For higher electric propulsion usage, cold gas thrusters delivered a higher payload mass fraction due to lower system inert mass. Due to the combination of utilizing a common propellant for both propulsive modes, low inert mass, and high electric thrust, the cold-gas chemical/helicon-type electric combination had the highest mission flexibility, able to achieve a delta-V 10% lower than that of the largest delta-V system, but at roughly 500 days less burn time. A System utilizing a monopropellant thruster and electrospray thruster can achieve the largest delta-V, but with a burn time of over 600 days. This same system, however, can achieve the largest delta-V for missions requiring a thrust time of less than roughly 10 days.