Advanced ion propulsion for space exploration

Ion propulsion is one of the numerous technologies proposed for the Space Exploration Initiative. To operate at the megawatt power levels required for Martian cargo and/or piloted missions, ion propulsion must evolve from present technologies. The principles of operation and a brief historical review of this form of propulsion are described. Also presented are the performance of present 50-cm diameter inert gas ion thrusters at power levels and specific impulse values up to 19 kW and 9300 seconds, respectively. These thrusters are applicable to orbit transfer vehicles, planetary probes, and other precursor missions.