Wednesday, March 13, 2013

Jupiter IRBM

Even as the Cold War was heating up between the superpowers during the mid-1950s, another conflict was brewing in the United States, a bureaucratic battle between different branches of the nation's armed forces. Beset with post-Korea budget cutbacks, the USAF, Army, and Navy were all trying to ensure their future by hopping on the nuclear bandwagon. Nuclear arms promised devastating firepower without the manpower cost of conventional forces, but the rush to nuclearization would lead to a serious flare-up of the roles and missions controversy between the Army and Air Force.

The USAF attempted to claim hegemony over ballistic missiles with the assertion that the new weapons were aerospace vehicles, and as such, evolutionary extensions of the strategic aircraft operated by the Air Force. On the other hand, the Army was of the opinion that it had greater experience with guided missiles, and in any case, missiles were merely very long range artillery. The Army Ballistic Missile Agency, headquartered at Redstone Arsenal and staffed with many of the German A-4/V-2 personnel that had helped develop the Redstone, was established to develop an IRBM with a range of 1,500 miles. By mid-1956 this had coalesced as the Jupiter missile, with Chrysler being contracted to develop the new weapon.

Powered by an S-3D engine, the single stage Jupiter had similar performance to the Air Force's Thor, although a slightly higher-yield warhead would be used. A key technical innovation of Jupiter would be its use of an RV coated with ablative material, which would disperse reentry heat by gradually melting. This would allow weight-savings when compared to heat sink-type RVs, but there was little experience with ablative materials and construction. ABMA tested the concept using the Jupiter-C vehicles, which were in fact Redstones that had been uprated with a longer first stage and three solid propellant upper stages to loft subscale ablative test vehicles on profiles that would encounter heating conditions similar to those that would be encountered by operational Jupiters. A successful recovery of a Jupiter-C RV and the article's subsequent examination helped to confirm that the ablative design was feasible. The Jupiter-A was another Redstone-derived testbed, in this case for proving the guidance system. Flight testing of this version began on March 14, 1956, and a total of twenty-five were launched.

Flight testing of actual Jupiters began on March 1, 1957, and by March of the following year the ablative RV design had been conclusively demonstrated by the launch and recovery of a full-sized test article. Unlike the Thor, Jupiter was housed vertically, sitting on a pedestal.

Army hopes of operating the Jupiter had been dashed in November 1956 when the Secretary of Defense issued an edict that forbade the Army from operating SSMs with ranges beyond 200 miles. Jupiter would have to be operated by the USAF, which was already developing the comparable Thor, putting the Redstone-developed missile's future in jeopardy.

Secretary of Defense Wilson appointed a small committee that was charged with settling the IRBM debate, and many thought that the program would be cut altogether. Combining the technologies of both missiles into a new type was also considered, but both weapons had many similarities in the first place, and starting anew would have of course entailed major delays. The decision kept being pushed back, and in the meantime the Soviets orbited the first artificial satellite, Sputnik 1, in October 1957. Overnight, US missile programs were almost guaranteed a future, and in November of that year it was announced that both IRBM programs were to be continued.

Jupiter's intermediate range dictated basing near the peripheries of the USSR; deployment to several locations in the Pacific was looked at, but in the end, Jupiters were only to be emplaced in NATO countries. In 1958, France turned down a proposal to host the Jupiter system, but in the following year, Italy and Turkey agreed to deploy the missiles.

The Jupiter deployment on NATO's southern flank was one of the factors that provoked the Soviets into deploying missiles to Cuba, and as part of the settlement of the Cuban Missile Crisis, the US agreed to withdraw the Jupiters. This withdrawal was not as significant as it might have seemed to some, as by late 1962 increasing numbers of Polaris A1-armed SSBNs could be assigned to hit targets formerly assigned to the Jupiters, and could do so with far less vulnerability.

Army film showing the first Jupiter test launch
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