Juno II

In the late 1950s, growing interest in space exploration increased the need for launch vehicles able to lift larger scientific payloads, and Juno II was developed by the rocket team at Redstone Arsenal in Huntsville, Alabama, as a modified Jupiter Intermediate Range Ballistic Missile with longer propellant tanks and the same upper stages used on Juno I to increase payload lifting capability. It could place a 100-pound payload in Earth orbit or send a 15-pound payload to the vicinity of the Moon. Its design included clustered small solid-propellant rockets as the second and third stages, housed in a spinning tub above the rocket for balance and stability during launch, while an outer fairing improved aerodynamics and safety. A Rocketdyne first-stage engine burned liquid oxygen and RP-1 kerosene to produce 150,000 pounds of thrust at liftoff. Between December 1958 and April 1961, ten Juno II vehicles were launched from Cape Canaveral, including six from Complex 26 and others from Complex 5. Among its achievements, Juno II launched Pioneer IV on 3 March 1959 and Explorer VII on 13 October 1959; Pioneer IV, a joint project of the Army Ballistic Missile Agency in Huntsville and the Jet Propulsion Laboratory in Pasadena, passed within 37,000 miles of the Moon before entering permanent orbit around the Sun, while Explorer VII, weighing 91.5 pounds, carried instruments to study the space environment near Earth. Juno II also launched a 100-foot inflatable sphere called Beacon. The Juno name was later applied to a next generation of launch vehicles designed by the Army Ballistic Missile Agency, including a proposed Juno V super booster, before the program was transferred to NASA and renamed Saturn.

Florida · United States