THIS DAY IN HISTORY:
United States Launches Explorer I (1958)
Explorer I was the first American satellite. It was launched four months after the first artificial satellite, Sputnik I, was put into orbit by the Soviet Union, beginning the so-called space race. Although it carried a number of instruments, Explorer I was relatively small, weighing just 30 lbs (13 kg). It stopped transmission of data later in 1958, when its batteries died, but remained in orbit for more than 12 years.