NASA’s Project Prometheus recently reached an important
milestone with the first successful test of an engine that
could lead to revolutionary propulsion capabilities for space
exploration missions throughout the solar system and beyond.
The test involved a High Power Electric Propulsion (HiPEP)
ion engine. The event marked the first in a series of
performance tests to demonstrate new high-velocity and high-
power thrust needed for use in nuclear electric propulsion
(NEP) applications.
“The initial test went extremely well,” said Dr. John Foster,
the primary investigator of the HiPEP ion engine at NASA’s
Glenn Research Center (GRC), Cleveland. “The test involved
the largest microwave ion thruster ever built. The use of
microwaves for ionization would enable very long-life
thrusters for probing the universe,” he said.
The test was conducted in a vacuum chamber at GRC. The HiPEP
ion engine was operated at power levels up to 12 kilowatts
and over an equivalent range of exhaust velocities from
60,000 to 80,000 meters per second. The thruster is being
designed to provide seven-to-ten-year lifetimes at high fuel
efficiencies of more than 6,000-seconds specific impulse; a
measure of how much thrust is generated per pound of fuel.
This is a contrast to Space Shuttle main engines, which have
a specific impulse of 460 seconds.
The HiPEP thruster operates by ionizing xenon gas with
microwaves. At the rear of the engine is a pair of
rectangular metal grids that are charged with 6,000 volts of
electric potential. The force of this electric field exerts a
strong electrostatic pull on the xenon ions, accelerating
them and producing the thrust that propels the spacecraft.
The rectangular shape, a departure from the cylindrical ion
thrusters used before, was designed to allow for an increase
in engine power and performance by means of stretching the
engine. The use of microwaves should provide much longer life
and ion-production capability compared to current state-of-
the-art technologies.
This new class of NEP thrusters will offer substantial
performance advantages over the ion engine flown on Deep
Space 1 in 1999. Overall improvements include up to a factor
of 10 or more in power; a factor of two to three in fuel
efficiency; a factor of four to five in grid voltage; a
factor of five to eight in thruster lifetime; and a 30
percent improvement in overall thruster efficiency. GRC
engineers will continue testing and development of this
particular thruster model, culminating in performance tests
at full power levels of 25 kilowatts.
“This test represents a huge leap in demonstrating the
potential for advanced ion technologies, which could propel
flagship space exploration missions throughout the solar
system and beyond,” said Alan Newhouse, Director, Project
Prometheus. “We commend the work of Glenn and the other NASA
Centers supporting this ambitious program.”
HiPEP is one of several candidate propulsion technologies
under study by Project Prometheus for possible use on the
first proposed flight mission, the Jupiter Icy Moons Orbiter
(JIMO). Powered by a small nuclear reactor, electric
thrusters would propel the JIMO spacecraft as it conducts
close-range observations of Jupiter’s three icy moons,
Ganymede, Callisto and Europa. The three moons could contain
water, and where there is water, there is the possibility of
life.
Development of the HiPEP ion engine is being carried out by a
team of engineers from GRC; Aerojet, Redmond, Wash.; Boeing
Electron Dynamic Devices, Torrance, Calif.; Ohio Aerospace
Institute, Cleveland; University of Michigan, Ann Arbor,
Mich.; Colorado State University, Fort Collins, Colo.; and
the University of Wisconsin, Madison, Wis.
For information about NASA on the Internet, visit:
For more information about NASA’s Glenn Research Center,
visit:
For more information about Project Prometheus on the
Internet, visit:
http://spacescience.nasa.gov/missions/prometheus.htm
Information about JIMO is available on the Internet at:
