问题描述：
办板报用的，急得不行了
还有中文翻译，不要word直接翻译的 ,词不要太难，我初2
问题解答：
Space travel bets on a dream. To design and build a spacecraft for space travel, you need to be able to figure out how big to make it, how heavy it can be, how fast it will have to go, how much fuel it needs and so forth. For that, you need a theory of how objects move in space and how to make the calculations. Over a period of nearly three centuries (from 1600 to 1900), three brilliant men - Johannes Kepler, Isaac Newton and Konstantin Tsiolkovsky, who said "the Earth is the cradle of mankind - one cannot remain in the cradle forever", worked out almost all the theories of space flight.
By 1951 space travel plans had become more grandiose. Famed rocket scientist Wernher von Braun predicted that a successful Mars mission could be accomplished with as few as 46 rockets in a round trip that would take three years. In a later interview with TIME, von Braun affirmed, "Man belongs wherever he wants to go - and he'll do plenty well when he gets there."
The space age began in 1957 when the Soviet Union launched Sputnik 1, the world's first man-made satellite. Also in 1957, Sputnik 2 was launched carrying Laika, a dog that was the first animal to orbit the Earth. In 1961, Yuri Gagarin became the first person to pilot a spacecraft. In 1963, the United States and the Soviet Union started a race to see who could put a man on the Moon first. In March of 1965, Alexei Leonov of the Soviet Union left his spacecraft to become the first person to walk in space. On July 20, 1969, the United States won when Neil Armstrong and Buzz Aldrin landed on the Moon's surface. The two superpowers have also put space stations into orbit around the Earth. These space structures serve as both a home and a laboratory for space travelers. The United States created and launched the first reusable manned spacecraft, the Space Shuttle, in 1981.
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