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The U.S. Launches its First Artificial Satellite, Explorer-1 (January 31, 1958)

On January 31, 1968, four months after the Soviets launched Sputnik, the United States launched its first artificial satellite, Explorer-1, officially known as Satellite 1958 Alpha, from Cape Canaveral Missile Annex, Florida. It was built at the Jet Propulsion Laboratory at Caltech, and it ceased transmission on May 23 after less than 4 months.

Explorer I is credited with the most important discovery of the International Geophysical Year: the discovery of one of the belts of radiation surrounding the earth. They were subsequently named the Van Allen Belts after James Van Allen, the scientist who identified them.