It could happen in the Americas, Europe, Asia, Australasia, or Africa. In any of these places, a rocket could be propelling a satellite through the Earth's atmosphere and into outer space. But where did rocketry begin? Actually, rockets were invented in the 1200s, long before there was a United States or a Soviet Union.
It was the Chinese who first packed gunpowder into a cardboard cylinder. On the right, you see a thirteenth-century rocket launcher used by the Mongolians; on the left, a seventeenth-century Chinese rocket-arrow launcher. In 1687, an English scientist, Isaac Newton, explained the science of how rockets move. His explanation is known as the law of action and reaction.
A modern rocket is used to illustrate Newton's law. In this rocket, liquid hydrogen and oxygen are sent to the combustion chamber,….where they mix and ignite. The hot gases created by the ignition rush out of the nozzle (action), causing the rocket to move in the opposite irection (reaction).
In the early 1800s, when Francis Scott Key wrote about "the rockets' red glare" in "The Star-Spangled Banner," he meant the rockets that were then sometimes used to carry explosives in war. Later on, by the twentieth century, some scientists had begun to realize that rockets were one way that objects could be pushed through space.
The first to do so in detail, beginning in 1903, was a Russian, K.E. Tsiolkovsky. An American, Robert H. Goddard, continued that work and in 1926 sent up the first rocket of a new kind. Instead of gunpowder, he used gasoline and liquid oxygen.
For the next fifteen years, Goddard kept designing and shooting off better and better rockets. Of course, working on rockets that would be big enough and powerful enough to use in space has never stopped people from using them to carry weapons on Earth. During World War II, the Germans developed rockets big enough and powerful enough to bomb London.
After the war, both the United States and the Soviet Union began to develop large rockets for exploring space. On October 4, 1957, as shown here, the Soviet Union's Sputnik 1 took its place as the Earth's first artificial satellite. On January 31, 1958, the United States launched Explorer 1, and what we call the Space Age had begun. Since 1958, many countries have sent satellites into orbit, including Canada, Japan, and Indonesia.
Such satellites circling the earth can do many kinds of work. Communications satellites receive radio waves from one place, make them stronger, and send them to a completely different place.
Special weather satellites, like this one, take photographs of Earth and send them down in the form of radio waves. When these radio waves are received on Earth, weather people can create the satellite pictures we see on the news each night. For the first time in history, we can see the clouds covering all of the Earth and watch how they move. This makes it much easier to predict the weather.
For example, we can see large, circular cloud formations that make up hurricanes. Before 1960, we couldn't always tell when a hurricane might hit. Now, people can board up their homes and leave before it comes. Countless lives have been saved in this way.
Satellites can also take pictures of Earth itself when clouds aren't in the way. This makes it possible to make very exact maps. This is a shot of Italy's boot. Such pictures can also help tell the condition of forests and croplands. They can pinpoint trouble areas and the spread of plant diseases.
The ocean, and schools of fish in it, can be studied, too. This map was sent back to Earth by a satellite that keeps track of the ozone layer. The central dark violet area over Antarctica shows a deep hole in the ozone that protects Earth from some of the Sun's ultraviolet rays. This warns us to be more careful about the chemicals we put into our atmosphere.
Since 1981, the United States has had space shuttles--rocket ships that can be used over and over again. This is a space shuttle launch at night. Shuttles can carry satellites into space and place these satellites in orbit. Once in orbit, members of the space shuttle crew can repair, rescue, or retrieve damaged satellites.
So satellites tell us many things about Earth. What else can they do? They can move outward and skim by other worlds, or actually land on them. They are then called probes. The nearest other world is Earth's Moon, which is only a quarter-million miles (or 400,000 kilometers) away. In 1959, a lunar probe skimmed by the Moon and sent back pictures.
This was the first time human beings had seen the far side of the Moon, for it is always turned away from Earth. With each lunar shot, the probes came closer and closer to the Moon. This photograph of the far side of the Moon was taken by the Apollo 8 astronauts in December 1968. Finally, on July 20, 1969, a probe piloted by humans landed on the Moon.
Neil Armstrong, here seen in his lunar module on the lunar surface, became the first human being who ever stepped onto another world. No human being has yet gone farther than the Moon, but unpiloted probes have gone much farther.
In 1973 and 1974, a probe called Mariner 10 skimmed by the planet Mercury several times. At one time, it came within 203 miles (327 kilometers) of the surface. It took photographs as it went. Mercury is the planet that is closest to the Sun, and until then, it could only be seen as a tiny circle. The probe showed us most of Mercury's surface in full detail. It looked very much like our Moon, with many craters on it.
Probes began to pass Venus in 1962. People have wondered for years what is beneath that planet's thick cloud cover. This gas balloon, dropped by a Soviet probe, transmitted data about the atmosphere, temperature, and wind movements on the surface of the planet. The thick atmosphere holds in heat so that Venus is very hot--hot enough to melt lead.
During the early 1900s, some astronomers thought they saw canals on the surface of Mars and speculated that intelligent beings might exist there. But beginning in 1965, probes passing near the planet sent back photographs like this one which showed no canals.
Instead, there were canyons, dead volcanoes, craters, and a very thin atmosphere. In 1976, two probes--Viking 1 and Viking 2--landed on Martian soil. This is a working model of the Viking lander, which features a soil sampler extending from the front and two camera "eyes" above it. These Viking probes tested the soil of Mars to see if simple life might exist there. Apparently none does.
This photograph of the Martian landscape was taken by the Viking 1 lander fifteen minutes before sunset. You can see part of the lander in the bottom of the picture. Because Mars is the planet most like Earth, everything we can do to understand it better might help us understand Earth better, too. So much for our neighbors. What lies beyond? Several probes, named Pioneer and Voyager, have gone past Mars to the farthest reaches of our solar system.
Beginning in 1973, they explored the giant planets that circle the Sun at great distances. They skimmed by Jupiter and its large natural satellites, or moons. On Io, Voyager 1 photographed a huge volcanic explosion. In this picture, the spectacular explosion appears just over Io's horizon.
Beyond Jupiter, these probes sent back close-up pictures of Saturn and its magnificent rings. The rings turned out to be full of complicated detail. Beyond Saturn, Voyager 2 has sent back photographs of even more distant Uranus. Aboard Voyager 2, which will continue beyond the solar system on out into our galaxy, is a recording of music and messages from Earth, just in case there are any extraterrestrials who care to listen.
In the future, a probe called Galileo will drop a package containing instruments on Jupiter, and for the first time we will be able to gather information about the inner regions of a giant planet's atmosphere. Closer to home, we are planning to build space stations between Earth and the Moon.
Such stations would give us a base for sending probes and people to other parts of the solar system. Satellites and probes give us eyes deep in space. Will we leave it at that? It's not likely. Many think we are getting closer and closer to the day when we may begin to colonize other worlds.
It was the Chinese who first packed gunpowder into a cardboard cylinder. On the right, you see a thirteenth-century rocket launcher used by the Mongolians; on the left, a seventeenth-century Chinese rocket-arrow launcher. In 1687, an English scientist, Isaac Newton, explained the science of how rockets move. His explanation is known as the law of action and reaction.
A modern rocket is used to illustrate Newton's law. In this rocket, liquid hydrogen and oxygen are sent to the combustion chamber,….where they mix and ignite. The hot gases created by the ignition rush out of the nozzle (action), causing the rocket to move in the opposite irection (reaction).
In the early 1800s, when Francis Scott Key wrote about "the rockets' red glare" in "The Star-Spangled Banner," he meant the rockets that were then sometimes used to carry explosives in war. Later on, by the twentieth century, some scientists had begun to realize that rockets were one way that objects could be pushed through space.
The first to do so in detail, beginning in 1903, was a Russian, K.E. Tsiolkovsky. An American, Robert H. Goddard, continued that work and in 1926 sent up the first rocket of a new kind. Instead of gunpowder, he used gasoline and liquid oxygen.
For the next fifteen years, Goddard kept designing and shooting off better and better rockets. Of course, working on rockets that would be big enough and powerful enough to use in space has never stopped people from using them to carry weapons on Earth. During World War II, the Germans developed rockets big enough and powerful enough to bomb London.
After the war, both the United States and the Soviet Union began to develop large rockets for exploring space. On October 4, 1957, as shown here, the Soviet Union's Sputnik 1 took its place as the Earth's first artificial satellite. On January 31, 1958, the United States launched Explorer 1, and what we call the Space Age had begun. Since 1958, many countries have sent satellites into orbit, including Canada, Japan, and Indonesia.
Such satellites circling the earth can do many kinds of work. Communications satellites receive radio waves from one place, make them stronger, and send them to a completely different place.
Special weather satellites, like this one, take photographs of Earth and send them down in the form of radio waves. When these radio waves are received on Earth, weather people can create the satellite pictures we see on the news each night. For the first time in history, we can see the clouds covering all of the Earth and watch how they move. This makes it much easier to predict the weather.
For example, we can see large, circular cloud formations that make up hurricanes. Before 1960, we couldn't always tell when a hurricane might hit. Now, people can board up their homes and leave before it comes. Countless lives have been saved in this way.
Satellites can also take pictures of Earth itself when clouds aren't in the way. This makes it possible to make very exact maps. This is a shot of Italy's boot. Such pictures can also help tell the condition of forests and croplands. They can pinpoint trouble areas and the spread of plant diseases.
The ocean, and schools of fish in it, can be studied, too. This map was sent back to Earth by a satellite that keeps track of the ozone layer. The central dark violet area over Antarctica shows a deep hole in the ozone that protects Earth from some of the Sun's ultraviolet rays. This warns us to be more careful about the chemicals we put into our atmosphere.
Since 1981, the United States has had space shuttles--rocket ships that can be used over and over again. This is a space shuttle launch at night. Shuttles can carry satellites into space and place these satellites in orbit. Once in orbit, members of the space shuttle crew can repair, rescue, or retrieve damaged satellites.
So satellites tell us many things about Earth. What else can they do? They can move outward and skim by other worlds, or actually land on them. They are then called probes. The nearest other world is Earth's Moon, which is only a quarter-million miles (or 400,000 kilometers) away. In 1959, a lunar probe skimmed by the Moon and sent back pictures.
This was the first time human beings had seen the far side of the Moon, for it is always turned away from Earth. With each lunar shot, the probes came closer and closer to the Moon. This photograph of the far side of the Moon was taken by the Apollo 8 astronauts in December 1968. Finally, on July 20, 1969, a probe piloted by humans landed on the Moon.
Neil Armstrong, here seen in his lunar module on the lunar surface, became the first human being who ever stepped onto another world. No human being has yet gone farther than the Moon, but unpiloted probes have gone much farther.
In 1973 and 1974, a probe called Mariner 10 skimmed by the planet Mercury several times. At one time, it came within 203 miles (327 kilometers) of the surface. It took photographs as it went. Mercury is the planet that is closest to the Sun, and until then, it could only be seen as a tiny circle. The probe showed us most of Mercury's surface in full detail. It looked very much like our Moon, with many craters on it.
Probes began to pass Venus in 1962. People have wondered for years what is beneath that planet's thick cloud cover. This gas balloon, dropped by a Soviet probe, transmitted data about the atmosphere, temperature, and wind movements on the surface of the planet. The thick atmosphere holds in heat so that Venus is very hot--hot enough to melt lead.
During the early 1900s, some astronomers thought they saw canals on the surface of Mars and speculated that intelligent beings might exist there. But beginning in 1965, probes passing near the planet sent back photographs like this one which showed no canals.
Instead, there were canyons, dead volcanoes, craters, and a very thin atmosphere. In 1976, two probes--Viking 1 and Viking 2--landed on Martian soil. This is a working model of the Viking lander, which features a soil sampler extending from the front and two camera "eyes" above it. These Viking probes tested the soil of Mars to see if simple life might exist there. Apparently none does.
This photograph of the Martian landscape was taken by the Viking 1 lander fifteen minutes before sunset. You can see part of the lander in the bottom of the picture. Because Mars is the planet most like Earth, everything we can do to understand it better might help us understand Earth better, too. So much for our neighbors. What lies beyond? Several probes, named Pioneer and Voyager, have gone past Mars to the farthest reaches of our solar system.
Beginning in 1973, they explored the giant planets that circle the Sun at great distances. They skimmed by Jupiter and its large natural satellites, or moons. On Io, Voyager 1 photographed a huge volcanic explosion. In this picture, the spectacular explosion appears just over Io's horizon.
Beyond Jupiter, these probes sent back close-up pictures of Saturn and its magnificent rings. The rings turned out to be full of complicated detail. Beyond Saturn, Voyager 2 has sent back photographs of even more distant Uranus. Aboard Voyager 2, which will continue beyond the solar system on out into our galaxy, is a recording of music and messages from Earth, just in case there are any extraterrestrials who care to listen.
In the future, a probe called Galileo will drop a package containing instruments on Jupiter, and for the first time we will be able to gather information about the inner regions of a giant planet's atmosphere. Closer to home, we are planning to build space stations between Earth and the Moon.
Such stations would give us a base for sending probes and people to other parts of the solar system. Satellites and probes give us eyes deep in space. Will we leave it at that? It's not likely. Many think we are getting closer and closer to the day when we may begin to colonize other worlds.
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