Semianalytic Approach for Optimal Configuration of Electric Propulsion Spacecraft

Abstract

Electric propulsion is a spacecraft propulsion technology offering higher exhaust velocities and higher thrust efficiency than classical chemical rockets. Such technology allows for high total impulse missions with reduced propellant mass consumption, but it requires a power generation system that becomes heavier and heavier with thrust magnitude. As a result, the design of an electric propulsion mission cannot ignore the spacecraft mass breakdown because it might happen that power generation system, propellant, and other spacecraft subsystems result in a too low or even null payload mass fraction. The paper presents a semianalytic optimization of the design of an electric powered spacecraft identifying those missions more suited for a given thruster and/or power generation system technology. The relations presented, moreover, can also be used to identify the best thruster for delivering a given payload mass into a target orbit in a prescribed time. A basic spacecraft mass breakdown and analytic closed form approximations are used to identify spacecraft optimal configurations intended as the best combinations of power level, thruster characteristics, and thrust duration resulting in the maximum payload mass fraction achievable for a given electric propulsion mission.