23/05/1958 NASA contacts Explorer 1 for the last time
Explorer 1: First U.S. Satellite
1958: Explorer 1 (USA)
Explorer 1: America's First Satellite - Classic Documentary
The Launch of Explorer 1
First U. S. satellite stopped to transmit data. It was launched after Russian satellites Sputnik 1 and 2 as a part of American participation in the International Geophysical Year. Explorer 1 was the first spacecraft to detect the Van Allen radiation belt. It remained in orbit until 1970 and has been followed by other probes in Explorer series.