Advanced ion propulsion systems for affordable deep-space missions

Abstract

A key feature of future deep-space science missions will be the need for significantly greater on-board propulsion capability. To meet this need, ion propulsion based on the technology that flew on NASA's Deep Space 1 spacecraft has now entered the mainstream of propulsion options available for deep-space missions. The next most likely science mission to use ion propulsion is the comet nucleus sample return (CNSR) mission. CNSR has recently been identified by the Solar System Exploration Subcommittee as the highest priority new mission for NASA's Exploration of the Solar System theme. Ion propulsion for CNSR enables the use of a smaller, less expensive launch vehicle, and significantly shortens the overall trip time. A trade study for CNSR was performed to identify engine and system technology improvements, which provide the greatest mission benefits for the lowest additional risk. This trade study indicated that the maximum specific impulse of the ion engine should be increased from 3100 to 3800 s and that the maximum engine input power should be increased from 2.3 to 3.2 kW . Simultaneously the engine total propellant throughput capability must be increased from the 80-kg NSTAR design point to approximately 180 kg . A focused technology program to make these advances is underway.