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

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

“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,


For information about JIMO on the Internet, visit: