Engine Helps Satellites Blast Off With Less Fuel (Forwarded)

Georgia Institute of Technology

For more information contact:

Megan McRainey, Institute Communications & Public Affairs
404-894-6016

February 22, 2007

Engine Helps Satellites Blast Off With Less Fuel

Engine lets satellites take more hardware into orbit, reposition more easily

ATLANTA -- Georgia Tech researchers have developed a new protoype engine
that allows satellites to take off with less fuel, opening the door for deep
space missions, lower launch costs and more payload in orbit.

The efficient satellite engine uses up to 40 percent less fuel by running on
solar power while in space and by fine-tuning exhaust velocity. Satellites
using the Georgia Tech engine to blast off can carry more payload thanks to
the mass freed up by the smaller amount of fuel needed for the trip into
orbit. Or, if engineers wanted to use the reduced fuel load another way, the
satellite could be launched more cheaply by using a smaller launch vehicle.

The fuel-efficiency improvements could also give satellites expanded
capabilities, such as more maneuverability once in orbit or the ability to
serve as a refueling or towing vehicle.

The Georgia Tech project, lead by Dr. Mitchell Walker, an assistant
professor in the Daniel Guggenheim School of Aerospace Engineering, was
funded by a grant from the U.S. Air Force. The project team made significant
experimental modifications to one of five donated satellite engines from
aircraft engine manufacturer Pratt & Whitney to create the final prototype.

The key to the engine improvements, said Walker, is the ability to optimize
the use of available power, very similar to the transmission in a car. A
traditional chemical rocket engine (attached to a satellite ready for
launch) runs at maximum exhaust velocity until it reaches orbit, i.e. first
gear.

The new Georgia Tech engine allows ground control units to adjust the
engine's operating gear based on the immediate propulsive need of the
satellite. The engine operates in first gear to maximize acceleration during
orbit transfers and then shifts to fifth gear once in the desired orbit.
This allows the engine to burn at full capacity only during key moments and
conserve fuel.

"You can really tailor the exhaust velocity to what you need from the
ground," Walker said.

The Georgia Tech engine operates with an efficient ion propulsion system.
Xenon (a noble gas) atoms are injected into the discharge chamber. The atoms
are ionized, (electrons are stripped from their outer shell), which forms
xenon ions. The light electrons are constrained by the magnetic field while
the heavy ions are accelerated out into space by an electric field,
propelling the satellite to high speeds.

Tech's significant improvement to existing xenon propulsion systems is a new
electric and magnetic field design that helps better control the exhaust
particles, Walker said. Ground control units can then exercise this control
remotely to conserve fuel.

The satellite engine is almost ready for military applications, but may be
several years away from commercial use, Walker added.

Related Links

* Daniel Guggenheim School of Aerospace Engineering
http://www.ae.gatech.edu/
* Dr. Mitchell Walker
http://www.ae.gatech.edu/people/mwalker/

IMAGE CAPTIONS:

[Image 1:
http://www.gatech.edu/upload/pr/tzb60588.jpg (1.14MB)]
Georgia Techs new engine uses a novel electric and magnetic field design
that helps better control the exhaust particles. Ground control units can
then exercise this control remotely to conserve fuel.

[Image 2:
http://www.gatech.edu/upload/pr/tib60588.jpg (1.04MB)]
Dr. Mitchell Walker, an assistant professor in the Daniel Guggenheim School
of Aerospace Engineering, tests an engine.