Date of Milestone: 1958
Spacecraft: Explorer 1
Operated by: NASA Jet Propulsion Laboratory
Spacecraft Location: Smithsonian Institution, National Air and Space Museum, Boeing Milestones of Flight Hall
Explorer 1 became America's first satellite on January 31, 1958. Following the Soviet success with Sputnik and the embarrassing failure in December 1957 of the first American attempt to launch a satellite, the U.S. Army launched a scientific satellite using a rocket that had been developed to test guided missile components.
Explorer 1 carried an instrument package developed by a team at the State University of Iowa under the direction of Professor James A. Van Allen. Data returned by Explorer 1 and Explorer 3 (launched in March 1958) provided evidence that the Earth is surrounded by intense bands of radiation, now called the Van Allen radiation belts. This was the first major scientific discovery of the space age
Design Features (in comparison to Sputnik 1):
Three key Explorer 1 team members triumphantly display a full-scale model of the satellite after its successful launch. William H. Pickering, director of the Jet Propulsion Laboratory, which designed and built Explorer.
James A. Van Allen, University of Iowa physicist who directed the design and creation of Explorer's instruments.
Wernher von Braun, head of the U.S. Army Ballistic Missile Agency team that designed and built the Jupiter-C rocket.
Identical backup for the original satellite
This satellite was built as a backup-an identical unit for the original Explorer 1. It could have been launched if the first one had failed. The striped portion contains the instruments, radios, and batteries. It is attached to a single solid-propellant rocket motor, which served as the launch vehicle's fourth stage.
Length: 203 cm (80 in), including rocket motor
Diameter: 15 cm (6 in)
Weight: 13.9 kg (30.7 lb)
Launch Vehicle: Jupiter-C (Juno I)
Transferred from the Jet Propulsion Laboratory and NASA