Outer Planet Exploration with Advanced Radioisotope Electric Propulsion

Abstract In response to a request by the NASA Deep Space Exploration Technology Program, NASA Glenn Research center conducted a study to identify advanced technology options to perform a Pluto/Kuiper mission without depending on a 2004 Jupiter Gravity Assist, but still arriving before 2020. A concept using a direct trajectory with small, sub-kilowatt ion thrusters and Stirling radioisotope power systems was shown to allow the same or smaller launch vehicle class as the chemical 2004 baseline and allow a launch slip and still flyby in the 2014 to 2020 timeframe. With this promising result the study was expanded to use a radioisotope power source for small electrically propelled orbiter spacecraft for outer planet targets such as Uranus, Neptune, and Pluto. Introduction Outer planet exploration is experiencing new interest with the open competition for a Pluto flyby mission. Voyager 2 conducted flybys of all the outer planets from Jupiter outward, except for Pluto, giving us a short glimpse of these mysterious planets and their many moons. At the request of the NASA Deep Space Exploration Technology Program, an examination of advanced power and propulsion technologies to allow a post 2004 launch of a fast Pluto flyby (missing the 2004 launched Jupiter gravity assist opportunity) was undertaken at Glenn Research Center (GRC). It was found that with the use of small, advanced 8 cm ion thrusters and Stirling radioisotope power systems, both under development at GRC, it was possible to launch the Pluto/Kuiper mission as late as 2012.