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 January 31, 1958, from Cape Canaveral Missile Annex, Florida, 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.

Length:
7ft
Inclination:
33
Perigee:
222miles
Gross Weight:
31lbs

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 January 31, 1958, from Cape Canaveral Missile Annex, Florida, 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.

Length:
7ft
Inclination:
33
Perigee:
222miles
Gross Weight:
31lbs