NASA HISTORY: Explorer 3 Launched On Juno I Rocket From Cape Canaveral In 1958
By Space Coast Daily // March 26, 2016
(NASA) – On this day in 1958, Explorer 3 was launched on a Juno I rocket from Cape Canaveral Air Force Station.
Explorer 3, nearly identical to Explorer 1, was the second successful launch in the Explorer program. The first successful launch was of Explorer 1, the first American satellite.
Following the successful launch of the first satellite, Sputnik, by the Soviet Union, the Explorer program was given the go-ahead. 120 days after the Sputnik launch, Explorer 1 was successfully launched into orbit.
Less than 2 months later, Explorer 3 launched.
The Explorer program confirmed the existence of the Van Allen Belt – a layer of energetic charged particles that are held around Earth due to its magnetic field.