Spurred US response
Sputnik crisis → Explorer 1: Spurred US response. The Sputnik crisis was a period of public fear and anxiety in Western nations about the perceived technological gap between the United States and Soviet Union caused by the Soviets' launch of Sputnik 1, the world's first artificial satellite, on October 4, 1957. S. participation in the International Geophysical Year (IGY). The 1958 mission followed the first two satellites, both launched by the Soviet Union during the previous year, Sputnik 1 and Sputnik 2. This began a Space Race during the Cold War between the two nations.