This is a cesium ion engine developed by the Electro-Optical Systems, Inc. as an experimental high-energy thruster for spacecraft. Ion engines produce extremely low thrusts over long periods of time, using electrically charged particles ejected out of the rear as a stream to provide thrust. This engine was successfully tested twice in space in flights of Air Force Blue Scout missiles in October and December 1964.
During the flights, each engine, weighing about five pounds, was carried to a maximum altitude of 1,200 nautical miles and produced thrusts of about .002 pounds (0.009 kilograms) for over two hours.
This engine was donated to the Smithsonian by Electro-Optical Systems in 1965.
Ellectro-Optical Systems, Inc.