PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
PASADENA, CALIF. 91109  TELEPHONE (818) 354-5011 
http://www.jpl.nasa.gov

PHOTO CAPTION                             JPL 27568 
                                          Ion Engine 

These images of a xenon ion engine prototype, photographed 
through a port of the vacuum chamber where it was being tested at 
NASA's Jet Propulsion Laboratory, shows the faint blue glow of 
charged atoms being emitted from the engine. This prototype will 
provide data for successive ion engines to be used in future 
space missions. 

Now that the engine has been ground-validated by the test, a 
similar engine will power the New Millennium Program's first 
mission, Deep Space 1, designed to provide space validation for 
this and other important technologies. DS1 will use the xenon ion 
engine in a test mission to encounter an asteroid, Mars and a 
comet. 

The engine, weighing 17.6 pounds (8 kilograms), is 15.7 inches 
(40 centimeters) in diameter and 15.7 inches long. The actual 
thrust comes from accelerating and expelling positively charged 
xenon atoms, or ions. While the ions are fired in great numbers 
out the thruster at more than 110,000 kilometers (68,000 miles) 
per hour, their mass is so low that the engine produces a gentle 
thrust of only 90 millinewtons (20-thousandths of a pound). Thus, 
it requires patience to accumulate the great speeds which ion 
propulsion is capable of achieving. 
                           
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