Mission Capability Gains from Multi-Mode Propulsion Thrust Variations on a Variety Spacecraft Orbital Maneuvers

摘要

Many spacecraft today have two separate propulsion systems: a chemical system for large maneuvers and an electric propulsion system for minor adjustments. The concept of coupling an electric and chemical propulsion system is not necessarily new but few studies have been published which discuss having an integrated chemical and electrical propulsion system. The utilization of a multi-mode propulsion (MMP) system could reduce the amount of propellant required for maneuvers in addition to lowering overall propulsion system mass. MMP refers to a propulsion system that couples an electric and chemical propulsion system which utilizes the same propellant tank and piping. A fully coupled system provides many advantages over a spacecraft with a single chemical or electric propulsion system. To help quantify the potential benefits in the utilization of a MMP system three separate spacecraft missions were analyzed. The missions were chosen to be representative of potential spacecraft missions. These missions include an altitude change mission, a phase change mission and a plane change mission. Each mission had a fixed propellant mass and time constraint. A variety of thrust profiles were investigated that utilized a combination of electric and chemical propulsion to complete the maneuver within the mission constraints. The 'optimal' thrust profile for each mission was determined as the profile which completed the mission in the time constraint with the least amount of propellant. In all cases the utilization of the electric propulsion system decreased overall required propellant mass.