World Book at NASA for Students
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Image to right: A two-stage rocket carries one or more rocket engines in each part, or stage. When the fuel in the first stage is gone, it falls away. Then the second stage carries the load to where it is going. Credit: World Book diagram
How Rockets Work
Most rockets today produce power by burning a fuel. These rockets are called chemical rockets. Rockets burn a mixture of chemicals called propellant. Rocket propellant is made of a fuel, such as gasoline, kerosene, or liquid hydrogen, and a substance that supplies oxygen. This supply of oxygen makes the fuel burn and allows the rocket to work in space, where there is no air.
A chemical rocket burns fuel in a combustion, or burning, chamber. The burning creates gas that rapidly expands, or spreads out. The gas spreads out in all directions inside the rocket. However, the gas that flows to the back of the rocket gets out through a nozzle. This escaping gas pushes the rocket forward.
Most space rockets have two or three sections called stages. These rockets are called multistage rockets. Each stage has a rocket engine and propellant. The first stage, called the booster, launches the rocket. After the first stage has burned its propellant, the rocket drops that section and uses the second stage. The rocket uses one stage after another in this way.
Multistage rockets are used for long flights near the Earth and for flights into space. They can reach higher speeds than rockets that have only one stage. A multistage rocket can reach higher speeds because it lightens its weight by dropping stages as it uses up propellant. A three-stage rocket can fly about three times faster than a single-stage rocket carrying the same amount of fuel.
Uses of Rockets
People use rockets mostly for scientific research, space travel, and war. Rockets are also used to launch unmanned spacecraft and satellites into a circular path, called an orbit, around the Earth. These rockets are called carrier rockets or launch vehicles. Scientists use rockets for exploration and research in the atmosphere -- the air around Earth -- and in space. Rockets can carry scientific instruments that gather information about the atmosphere. Rockets also lift satellites into orbit around the Earth. These satellites take pictures of the Earth's weather. They gather other information for scientific study, too. Some rockets also carry instruments far out in space to study other planets. Some satellites are used to send telephone messages over long distances.
Rockets also provide the power for spacecraft. The Saturn V rocket, which carried astronauts to the moon, was the most powerful launch vehicle ever built by the United States. It is no longer used.
Rockets used in war vary in size. They range from small battlefield rockets to guided missiles -- giant rockets that can fly across an ocean. Small rocket launchers called bazookas are carried by soldiers in battle. Armies use larger rockets to shoot explosives far behind enemy lines and to shoot down enemy aircraft. Fighter airplanes carry guided missiles to attack other planes and ground targets. Navy ships use guided missiles to attack other ships, targets on land, and planes. Rockets can also be used in war to launch and power intercontinental ballistic missiles (ICBM's). ICBM's are guided missiles that can travel as far as 9,200 miles (15,000 kilometers). They are used to bomb enemy targets with nuclear explosives.
History
Scientists believe the Chinese invented rockets, but no one knows exactly when. Historians describe "arrows of flying fire" that were used by Chinese armies about 800 years ago. They believe these "arrows" were rockets. About 100 years later, the use of rockets had spread throughout much of Asia and Europe. These first rockets burned a mixture of charcoal and chemicals called black powder.
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Image to left: Rockets that made history. Credit: World Book illustration
In 1926, American rocket scientist Robert H. Goddard made the first successful liquid-propellant rocket. It climbed 184 feet (56 meters) into the air at a speed of about 60 miles (97 kilometers) per hour.
During World War II (1939-1945), German rocket scientists developed the powerful V-2 guided missile. Germany bombed London and Antwerp, Belgium, with hundreds of V-2's during the last months of the war. American forces captured many V-2 missiles and sent them to the United States for use in research.
The first high-altitude rockets made in the United States were designed and built during World War II. These rockets rose up to 75 miles (121 kilometers) in the air.
On Oct. 14, 1947, Captain Charles E. Yeager of the U.S. Air Force made the first flight that was faster than sound. He flew a rocket-powered airplane called the X-1. In the 1960's, a rocket-powered airplane called the X-15 reached a speed of 4,520 miles (7,272 kilometers) per hour. This was more than six times the speed of sound.
The space age began on Oct. 4, 1957, when the Soviet Union used a rocket to launch Sputnik 1, the first artificial satellite. On Jan. 31, 1958, the U.S. Army launched the first American satellite, Explorer 1, into orbit. On April 12, 1961, a Soviet rocket put a person, cosmonaut Major Yuri A. Gagarin, into orbit around the Earth for the first time. On May 5, 1961, a rocket launched Commander Alan B. Shepard, Jr., the first American to travel in space. On April 12, 1981, the United States launched the rocket-powered Columbia, the first space shuttle to orbit the Earth. On Feb. 1, 2003, the Columbia, like the Challenger in 1986, broke apart, killing all crewmembers.
How to cite this article: To cite this article, World Book recommends the following format: "Rocket." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.
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