Explorer 1 was the first satellite of the United States, launched as part of its participation in the International Geophysical Year. The mission followed the first two Sputnik missions by the Soviet Union.
The satellite was designed and built by a team led by Wernher von Braun at the Jet Propulsion Laboratory (JPL), which had been established for just this purpose 8 years earlier in 1958. The decision to build Explorer 1 was made on October 24, 1957, less than 2 weeks after Sputnik 1’s launch. At that time, the United States had not yet attempted to launch a satellite into orbit. Von Braun and his team put together a plan to do so quickly and cheaply using existing technology and hardware. The team succeeded in launching Explorer 1 on January 31, 1958.
The satellite carried a scientific instrument called a cosmic ray detector built by James Van Allen, which discovered the presence of radiation belts around Earth, now known as the Van Allen radiation belts. This discovery was one of the most important scientific results of the space age and helped pave the way for further exploration of our solar system.
Explorer 1 was also notable for being one of humanity’s first successes in orbital rocketry; it paved the way for future American space exploration programs such as NASA’s Apollo Moon landing program. In addition, data from Explorer 1 provided scientists with their first looks at conditions outside Earth’s atmosphere and laid groundwork for future studies in fields such as astrophysics and cosmology