Main->Readings->5th Grade Readings->Human Spaceflight->Part 1
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We live in an age when spaceflight is almost ordinary. Our telephones, television, and computer networks all depend on satellites orbiting the Earth. Shuttles go into space every few months. Rockets go up even more often. Hundreds of human beings have gone into space, and we have sent unmanned probes to explore all but one of the Solar System planets. Yet even as late as 1955, a few years before the first human being went into space, most people would have laughed at the possibility of these events. Most people thought of space-ships and trips to other planets as silly daydreams.
Spaceflight seemed impossible for some very good reasons. For one thing, just to get out into the beginning of space, an object has to have enough power to be able to escape gravity's pull. It has to push upward harder than gravity pulls downward. Up until the mid-1950s, there was no kind of engine that could produce nearly enough power to do that. So power was a problem that had to be solved before we could even think of going into space.
Another problem was how to maneuver, or move around, in airless space. Up past the atmosphere, there was no air, only vacuum, and a space craft couldn't use flaps or rudders the way an airplane does. There was nothing to push against, so once a space-ship was moving in vacuum it seemed as if it would have to keep moving forever.
Re-entry, or coming back through Earth's atmosphere to Earth, was a third problem. When an object is orbiting the Earth, it is very high up. If you bring it down, what will keep it from turning into something like a meteor? Meteors burn up because of their great speed and the friction of the Earth's air. Even though air is a gas, the meteor is moving so fast that it rubs against the air molecules fast enough to make a great deal of heat. How could we keep spacecraft from burning up and crashing when they came back to Earth?
Even if you could get a spacecraft into space, move it around, and bring it back, how would human passengers cope? Could they stand the force of take-off? When a rocket accelerates, or builds up speed, the force is many times the pull of gravity. Maybe that force would tear human beings apart. So acceleration and take-off were a problem.
Or, if humans could stand the stress of take-off, what about weightlessness in free fall? When a ship is orbiting the Earth, it is falling free in space and humans would feel as if they had no weight. Could the human body take that? It seems funny to ask the question now, when we know that humans can be weightless for long periods of time, but back then no one knew the answer because we had never experienced weightlessness, so it seemed a serious problem to us back then.
For these reasons and many more, spaceflight seemed impossible to us. Yet little by little, human beings began to solve these problems.
In the late 1800s, for instance, a Russian mathematician and teacher by the name of Konstantin Tsiolkovsky realized that a rocket engine could be used to solve the problem of power. We had known for centuries that for every action there is an equal and opposite reaction, thanks to Isaac Newton's laws of motion, but Tsiolkovsky was the first to realize that the tremendous thrust of a rocket when it sends its propellant shooting out was strong enough to power a rocket. Tsiolkovsky worked out the mathematics and showed that a big enough rocket with enough fuel could push itself right off Earth, against gravity's pull.
While he was at it, he did some more mathematics and solved the problem of maneuvering in vacuum. He realized, because of Newton's laws of motion, that a burst from a rocket on one side of a spacecraft would push the craft in the opposite direction. You didn't need flaps or rudders at all, just small rockets. So at the same time he solved the problems of power and maneuvering.
Another scientist who contributed to the possibility of going into space was the American scientist Robert Goddard. In the early 1900s, he did experiments with rockets, testing them with different kinds of fuels to see how fast and how high he could make them go. He even tested them in vacuum and proved what some people still doubted in spite of Tsiolkovsky's work, that a rocket would work in airlessness. Dr. Goddard sent up the world's first liquid-powered rocket, on March 16, 1926. This rocket, fueled by liquid oxygen and gasoline, climbed 41 feet, traveled 184 feet in 2.5 seconds. and landed in a cabbage patch.
Robert Goddard 1926
Picture courtesy of NASA
David P. Stern, "Robert
Goddard and his Rockets,"
From Stargazers to Starships
Goddard Space Flight Center
January 11, 2000, accessed July 19, 2000
http://www-spof.gsfc.nasa.gov/stargaze/Sgoddard.htm
Meanwhile back in post World War I Germany, physicist Hermann Oberth published a book on the theories of space travel, "The Rocket into Interplanetary Space." His ideas excited many people and inspired the German rocket program.
Some more improvements in rocket science happened because of World War II. The German country used rockets called V-2s which could be launched in Germany and come down and explode as far away as England. They used liquid oxygen and alcohol as their fuel, and when launched they got up to speeds as high as 3,500 miles an hour and altitudes as high as 60 miles up--almost in space. They weren't intended to be used for space exploration; they were flying bombs. They caused much death and destruction. Yet because they solved many of the problems of spaceflight, they advanced the understanding of spaceflight. In fact, after Germany had lost the war, many of the V-2s and the scientists who had designed them moved to the United States and the Soviet Union, where they became part of those nations' research on rocketry.
V-2 rocket
Picture courtesy of NASA
Von Braun: Germany
Liftoff to Space Exploration
April 3, 2000, accessed July 19, 2000
http://liftoff.msfc.nasa.gov/Academy/History/vonBraun/germany.html
After the war, the United States and the Soviet Union were in competition with one another for world power, and they saw spaceflight as one way of gaining more power and defending themselves against each other. Therefore, they put a great deal of money, time and effort into producing and testing rockets, hoping to be the first to put an object into orbit. Though this research was pushed by competition and fear, it made spaceflight into a real possibility instead of a crazy daydream.
Go on to Part 2: Starting the Race: Sputnik
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This page last modified on August 15, 2002