THE EKRANOPLAN

in space in the form of rockets, which propel spacecraft by using jet thrust. Rockets carry the oxygen needed to burn their fuel. The fuel and oxygen-or a chemical containing oxygen-are mixed and burned, producing lots of hot gas. The gas rushes out of the rocket’s noz­zle as a fast jet, thrusting the rocket in the opposite direction.

Rocket-powered fighter planes were built in the 1940s, but they proved unpopular because of their short range and explosive fuel. Today, rockets are mainly used for launching spacecraft and missiles.

There are other ways of using jet power in space. Ed White made the first spacewalk by a U. S. astronaut during the Gemini 4 mission of 1965. He carried a gas gun called a handheld maneuvering unit (HHMU). As he floated in space, tied safely to the spacecraft by a tether, White squeezed the trigger to make gas squirt out of the gun. These tiny jets of gas were powerful enough to move him around. White found that he was able to maneuver easily with the gun, although it ran out of gas quickly. A similar device was tested during later Gemini missions. This time, the gun was supplied with gas by a hose from the spacecraft, so it worked longer.