The Soviet Union made history when it launched Sputnik I, the world's first artificial satellite. Now, more than half a century later, there are about 5,000 satellites in orbit around Earth. These marvels of modern technology perform many important tasks, from reconnaissance and navigation to communications and predicting the weather. Scientists have also sent satellites to orbit moons and other planets of our solar system. This volume examines the technology behind satellites, including how they are launched from Earth and remain in orbit. Key STEM concepts are highlighted through full-color photographs and age-appropriate text. Diagrams and fact boxes provide supporting information.