Rockets used for space launches are usually made up of two or three separate sections, known as stages, to help provide enough power to reach orbit. Each stage fires in turn and then falls away after a few minutes when it runs out of fuel. In this way the rocket gets progresively lighter, allowing it to reach great speed as it approaches the borders of space. The three-stage Saturn V was the largest rocket ever built and was designed for the Apollo Moon misions. It flew from 1967-1973, and the 5 engines of its first stage generated 7.5 million pounds of thrust.
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