Moving About in SpaceMoving About in SpaceA spacecraft uses most of its energy getting up into space. With no drag to overcome once in orbit, the spacecraft can then "coast" without expending any more energy. But how can you change a spacecraft's course? Move it from one orbit to another? Bring it back to Earth?
This map of the solar system shows the path of the Voyager 2 spacecraft from Earth (blue orbit) to Jupiter and Saturn. Voyager 2 went on to explore Uranus and Neptune as well, using the gravity of each planet it visited to "sling" it on to the next. Without these gravitational boosts, its 12-year journey would have taken 60 years.
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(Rev. 10/01/96)