An ion engine of this type was first tested in space in 1964. On that occasion, it provided .0009 kilogram (.002 pound) of thrust for 2 hours, 10 minutes. It was able to control the attitude of the attached instrument package. This ion engine is a gift from Electro-Optical Systems, Inc., the company that developed it. Project Orion [Illustration: 57. The Project Orion test vehicle was used to explore the feasibility of a unique type of propulsion which utilized successive nuclear explosions behind the rear pusher plate.] Project Orion was an attempt to solve the problems of propulsion for long-term manned journeys to other planets by creating an engine that would use successive nuclear explosions to propel very large space vehicles. The Orion spacecraft was designed to carry many small nuclear explosive systems which would be ejected sequentially from the rear of the vehicle. These units would explode some distance behind the spacecraft. The expanding debris, in the form of high-velocity, high-density plasma, would strike a pusher plate at the rear of the Orion vehicle. Work on Project Orion was halted in 1963 when the Limited Nuclear Test Ban Treaty, which prohibited atmospheric tests of the propulsion system, was signed. The Project Orion Test Vehicle—on display—demonstrated the basic principle of intermittent thrust from explosive charges. Test data provided by this model would have assisted engineers in developing the full-scale spacecraft. The test vehicle carried five high-explosive plastic charges which were ejected from the rear of the craft. Compressed nitrogen powered the ejection system. Each charge was attached to the vehicle by a .9-meter (3-foot) cord. A microswitch exploded the individual packages. The Project Orion Test Vehicle was first flown successfully in October 1959. From the Gulf Energy and Environmental Systems, Inc. The Plug-Nozzle Rocket Engine Although this engine is a liquid-propellant rocket, it substitutes a series of small combustion chambers and nozzles for the traditional single large chamber and nozzle to achieve additional thrust. This innovative combustion system features chambers and nozzles mounted on an annular ring at the base of the engine. Thrust is derived from the expansion of the exhaust gases against a large segmented plug in the center of the engine. Flight control is achieved by varying the amount of propellant introduced into the individual chamber sections. The engine on exhibit burned liquid oxygen and kerosene to provide a thrust of 22,680 kilograms (50,000 pounds). The plug-nose rocket engine was developed at the General Electric Company’s Malta Test Station in 1961. The engine on exhibit is from the New York State Atomic and Space Authority. Space Suits [Illustration: 58. Astronaut John Glenn is assisted with his suiting-up.]