Jupiter missile (PGM-19)

Development and inter-service rivalry

The Jupiter was conceived in 1954 by Wernher von Braun's Army Ballistic Missile Agency (ABMA) as a follow-on to the short-range PGM-11 Redstone. On 8 November 1955 the Secretary of Defense overrode the range restrictions on the Army and approved both programs: the Army would build IRBM No. 2, the SM-78, while the Air Force would build IRBM No. 1, the SM-75 Thor. The Navy had joined the project intending to launch the missile from ships, but withdrew in December 1956 over the hazards of cryogenic propellants and the promise of solid-fuel rockets, developing Polaris instead. In November 1956 Defense Secretary Charles Wilson's memorandum limited the Army to weapons of under 320 km range and forced it to hand the Jupiter over to the Air Force. Jupiter test flights began with the launch of AM-1A from LC-5 on 1 March 1957, after the first static firing on 12 February 1957; in spite of several launch failures, the missile was declared operational on 15 January 1958.

Propulsion, guidance and specifications

The Jupiter used a single Rocketdyne LR79-series engine, the S-3D, burning RP-1 kerosene with liquid oxygen, producing 150,000 lbf (667 kN) of thrust. Range was 2,400 km, launch weight 49,353 kg, the reentry payload 750 kg, and the circular error probable was 1,500 m. Guidance was the Ford ST-90 inertial system and the warhead was the W49 thermonuclear device. About three minutes of powered flight carried it to a target some sixteen minutes later. The Army planned mobile launchers organized in batteries supported by about 20 vehicles, but after the 1956 transfer to the Air Force the missile was switched to fixed launch sites; some sources list launch weight as 49,885 kg.

Deployment and the Cuban Missile Crisis

When the planned French basing collapsed after Charles de Gaulle refused in 1958, the United States turned to Italy and Turkey. From 1961, 30 missiles (two squadrons) were based around Gioia del Colle Air Base in Italy and 15 missiles (one squadron) around Çiğli Air Base near İzmir in Turkey. The sites came under NATO command arrangements, but U.S. personnel controlled and armed the nuclear warheads, with three missiles at each site turned over to the Italian and Turkish air forces in late October 1962. The Turkish Jupiters brought Moscow within range, and the Soviet Union responded by deploying medium-range missiles to Cuba. Under the secret agreement that ended the Cuban Missile Crisis in October 1962, the Jupiters in Italy and Turkey were all withdrawn by April 1963.

Assessment

The Jupiter was the first U.S. medium-range ballistic missile to be forward-based across Western Europe, but its liquid-fueling and fixed launch sites left it vulnerable to a Soviet first strike. Operational units were formed from late 1958 and actual basing followed in the early 1960s, so its service life as a deployed weapon was short; the United States settled on submarine-launched ballistic missiles as its successor. The Turkish missiles, meanwhile, became a central issue of the Cuban Missile Crisis: the United States removed the Jupiters in exchange for the Soviet withdrawal of missiles from Cuba. The Jupiter's political life thus outlasted its technical service life.