ScienceDaily (Dec. 25, 2003) — A team of engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif, successfully tested a new ion propulsion engine design, one of several candidate propulsion technologies under study by NASA's Project Prometheus.

The event marked the first performance test of the Nuclear Electric Xenon Ion System (NEXIS) engine at the high-efficiency, high-power, and high-thrust operating conditions needed for use in large-scale nuclear electric propulsion applications.

The NEXIS engine was powered using commercial electrical power. Ion engines used on NASA's proposed Jupiter Icy Moons Orbiter (JIMO) will draw power from an onboard nuclear reactor. The ion engines, or electric thrusters, would propel the orbiter around three of the icy moons orbiting Jupiter, Ganymede, Callisto and Europa, to conduct extensive, close-range examinations and to determine their potential for sustaining life.

"On the very first day of performance testing, the NEXIS thruster demonstrated one of the highest efficiencies of any xenon ion thruster ever tested," said Dr. James Polk, the principal investigator for the test at JPL. "We expect the NEXIS design to demonstrate both the performance and projected lifetime necessary for the proposed Jupiter mission," he said.

The test was conducted December 12. It used the same vacuum chamber, where the Deep Space 1 ion thruster set the all time endurance record of 30,352 hours (nearly 3.5 years) of continuous operation. The NEXIS engine operated at more than 20 kilowatts, nearly 10 times that of the Deep Space 1 thruster. It is designed to process two metric tons of propellant, 10 times the capability of Deep Space 1, and operate for 10 years, two to three times the Deep Space 1 thruster life.

Team members working on the NEXIS engine also helped develop the first ion engine ever flown on NASA's highly successful Deep Space 1 mission. It validated 12 high-risk advanced technologies, among them the use of the first ion engine in space.

"The NEXIS thruster is a larger, high performance descendant of the Deep Space 1 thruster that achieves its extraordinary life by replacing the metal, previously used in key components, with advanced, carbon based materials," said Tom Randolph, NEXIS program manager at JPL.

Unlike the short, high-thrust burns of most chemical rocket engines, the ion engine emits only a faint blue glow of electrically charged atoms of xenon, the same gas found in photo flash tubes and in many lighthouse bulbs. The thrust from the engine is as gentle as the force exerted by a sheet of paper held in the palm of your hand. However, over the long haul, the engine can deliver 20 times as much thrust per kilogram of fuel than traditional rockets.

"This test, in combination with the recent successful test of the High Power Electric Propulsion ion engine at NASA's Glenn Research Center, Cleveland, is another example of the progress we are making in developing the technologies needed to support flagship space exploration missions throughout the solar system and beyond," said Alan Newhouse, Director, Project Prometheus. "We have challenged our team with difficult performance goals and they are demonstrating their ability to be creative in overcoming technical challenges."

NASA's Project Prometheus is making strategic investments in space nuclear fission power and electric propulsion technologies. The technology may enable a new class of missions to the outer Solar System, with capabilities far beyond those possible with current power and propulsion systems. The JIMO mission could launch during the next decade and provide NASA significantly improved scientific and telecommunications capabilities and mission design options. Instead of generating only hundreds of watts of electricity like the Cassini or Galileo missions, which used radioisotope thermoelectric generators, JIMO could have up to tens of thousands of watts of power, increasing the potential science return many times over.

A team of engineers from JPL; Aerojet, Redmond, Wash.; Boeing Electron Dynamic Devices, Torrance, Calif.; NASA's Marshall Space Flight Center, Huntsville, Ala.; Colorado State University, Fort Collins, Colo.; Georgia Institute of Technology, Atlanta; and the Aerospace Corporation, Los Angeles is developing the NEXIS.

For more information about Project Prometheus on the Internet, visit: http://spacescience.nasa.gov/missions/prometheus.htm

For information about JIMO on the Internet, visit: http://www.jpl.nasa.gov/jimo/

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