Following the launch of the Soviet satellite Sputnik 1 on October 4, 1957, there was a frenzied effort by the United States to launch a satellite of its own, beginning the space race. Explorer 1 was designed and built by the Jet Propulsion Laboratory, while the Army Ballistic Missile Agency modified their Jupiter-C rocket to accommodate a satellite payload. Explorer 1 was ready for launch in 84 days. Before work was completed, however, the Soviet Union launched a second satellite, Sputnik 2, on November 3, 1957. Explorer 1 was launched on February 1, 1958, and orbited Earth until March 31, 1970.
Instrumentation on Explorer 1, designed by Dr. James Van Allen of the University of Iowa, consisted of a cosmic-ray detection package, an internal temperature sensor, three external temperature sensors, a nose-cone temperature sensor, a micrometeorite impact microphone, and a ring of micrometeorite erosion gauges. Data from these instruments were transmitted to the ground by a 60 mW transmitter operating on 108.03 MHz and a 10 mW transmitter operating on 108.00 MHz.
This spacecraft model is on loan from Chris Vancil.