Assessment of Multimode Spacecraft Micropropulsion Systems

Abstract

Multimode spacecraft micropropulsion systems that 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 butane propellant and ionic liquid chemical monopropellant modes are investigated alongside pulsed plasma, electrospray, and ion electric thruster modes. These systems are studied by varying electric propulsion usage percent and calculating the payload mass fraction and thruster burn time for missions requiring 250, 500, and delta-V. Systems involving chemical monopropellants have the highest payload mass fractions for a reference mission of delta-V and 6U-sized CubeSat, where 1U is a volume, for electric propulsion usage below 70% of total delta-V; whereas for higher electric propulsion usage, cold-gas thrusters deliver a higher payload mass fraction due to lower system inert mass. Due to the combination of a shared propellant for both propulsive modes, low inert mass, high electric thrust, and specific impulse near optimum for the system, the monopropellant/electrospray system has the highest mission capability in terms of delta-V for missions lasting less than 150 days.