A hand-held distress signal rocket as carried on board all types of sea-going vessel. For use, the end caps and safety pin are removed, the firing lever is operated and the rocket flies to a height of at least 300 meters. The flare is ejected and drifts below its parachute for at least 40 seconds. The discharger is made of plastic, the rocket body of aluminum.
A rocket is a projectile driven by reaction (jet) propulsion that carries its own propellants. A rocket is therefore independent of Earth's atmosphere in terms of both thrust and oxidizer. In addition to their chief use to power space vehicles and missiles, rockets are also used for supersonic and assisted take-off airplane propulsion, and sounding rockets are used for scientific investigation of the upper atmosphere.
The first rockets – of the firework type, cardboard tubes containing gunpowder – were made in 13th-century China, and the idea quickly spread to the West. Their military use was limited, guns being superior, until they were developed by William Congreve. Later Congreve rockets mounted the guide stick alongside the central axis; and William Hale eliminated it altogether, placing curved vanes in the exhaust stream, thus stabilizing the rocket's motion by causing it to rotate on its axis.
The twentieth century saw the introduction of new fuels and oxidants, for example, a mixture of nitrocellulose and nitroglycerin for solid-fuel rockets, or ethanol and liquid oxygen for the more efficient liquid-fuel rockets. The first liquid fuel rocket (see liquid-propellant rocket engine) was made by Robert Goddard who also invented the practical multistage. In World War II Germany, and afterward in the United States, Wernher von Braun made vast improvements in rocket design. Other propulsion methods, such as ion propulsion, have been developed.