After World War II both the United States and the Soviet Union realized how important rocket research would be to the military. They each recruited the top rocket scientists from Germany to help with their research. Soon both sides were making progress in rocket technology. The Space Race began in 1955 when both countries announced that they would soon be launching satellites into orbit. The Soviets took the US announcement as a challenge and even established a commission whose goal was to beat the US in putting a satellite into space. On October 4, 1957 the Russians placed the first successful satellite into orbit. It was called Sputnik I. The Russians had taken the lead in the Space Race. The Americans successfully launched their first satellite four months later called the Explorer I.