Simple Semi-Analytic Model for Optimized Interplanetary Low-Thrust Trajectories Using Solar Electric Propulsion

Abstract

This paper describes a simple semi-analytic model for mass-optimized interplanetary solar electric low-thrust trajectories. A description is given of a model that accurately and quickly determines the performance of circular-coplanar low-thrust transfers with a series of simple empirical and physics-based relationships that can be implemented easily in a spreadsheet. The model takes flight time, departure and arrival velocity, initial power, initial mass, and propulsion-system efficiency as inputs and produces the optimum specific impulse, , final mass, and burn time that correspond to the mass-optimum trajectory as outputs. The development methodology is described, governing variables and fundamental relationships are identified, and a model is presented that efficiently calculates these parameters for a wide range of low-thrust trajectories. Models are presented for Earth-Jupiter/Trojan asteroid, Earth-Mars, Mars-Earth, Earth-Venus, and Earth-Main-Belt asteroid transfers using solar electric propulsion. The results show good agreement for estimates of both delivered mass () and optimum specific impulse (). This model is well suited to classroom instruction, concurrent engineering, and the initial development of new mission concepts.