Following the launch of the Soviet satellite Sputnik I in October 1957, there was a frenzied effort by the US to launch a satellite of its own, beginning the so-called Space Race. Launched in January 1958 as part of the US program for the International Geophysical Year project, Explorer-I was the first Earth satellite of the US. It contributed to the discovery of the Van Allen Belts but stopped transmission of data when its batteries died in 1958. It remained in orbit, however, for how long? Discuss
Source: The Free Dictionary