The PGM-19 Jupiter was the first nuclear armed, medium-range ballistic missile (MRBM) of the United States Air Force (USAF). It was a liquid-propellant rocket using RP-1 fuel and LOX oxidizer, with a single Rocketdyne LR79-NA (model S-3D) rocket engine producing of thrust. It was armed with the W49 nuclear warhead. The prime contractor was the Chrysler Corporation.
The Jupiter was designed by the US Army, which needed a highly accurate missile designed to strike enemy states such as China and the Soviet Union. The US Navy also expressed an interest in the design as an SLBM but dropped the collaboration to work on their solid-fuel Polaris. Jupiter retained the short, squat shape intended to fit in submarines.
Development history
Initial concept Jupiter traces its history ultimately to the PGM-11 Redstone missile, the US's first nuclear ballistic missile. While it was entering service, Wernher von Braun's Army Ballistic Missile Agency (ABMA) team at Redstone Arsenal began to consider an upgraded version using the LR89 rocket engine being developed by Rocketdyne for the Air Force's Atlas missile project. Using the LR89 and adding a second stage would allow the new design to reach , a dramatic improvement over the Redstone's roughly .
As Rocketdyne continued working on the LR89, it appeared that it could be improved to increase thrust over the promised . In 1954, the Army asked Rocketdyne to provide a similar design with a thrust of . During this same period, the weight of nuclear warheads was rapidly falling, and by combining this engine with a warhead of they could build a single-stage missile able to reach while being significantly less complicated and easier to handle in the field than a two-stage model. This engine was continually upgraded, ultimately reaching . This last model, known to the Army as the NAA-150-200, became much better known by its Rocketdyne model number, S-3.
Navy SLBM interest
Around the same time, the US Navy was looking for ways to join the nuclear club, and had been focusing mostly on cruise missiles and similar systems. Some consideration had been given to the use of ballistic missiles on ships, but Admiral Hyman Rickover, "father" of the nuclear submarine, was skeptical that this could be done, and was worried it would take up funding needed elsewhere. Another skeptic of missiles was the Chief of Naval Operations, Robert B. Carney.
Lower-ranking Navy officials became increasingly interested when the Army and Air Force began serious development of their long-range missiles. In an attempt to bypass high-ranking Navy officials, who remained uninterested in the concept, the Navy liaison to the Killian Committee championed the cause. The Committee took up the concept, and in September 1955 released a report calling for the development of a sea-based missile system.
The Navy's interest in missiles had been greatly increased with the August 1955 appointment of Admiral Arleigh Burke to replace Carney. Burke was convinced the Navy had to get into the missile field as rapidly as possible, and was well aware that the Air Force would oppose any such endeavor. Instead, he approached the Army, and found that the proposed Jupiter fit the range goals needed by the Navy.
Development begins The issue of who would be given the go-ahead to build an IRBM by this time had reached the Joint Chiefs of Staff (JCS), who proved unable to reach a decision. This forced the Secretary of Defense Charles Erwin Wilson to move ahead without an official recommendation from the military. He saw the Navy interest as a reasonable argument to continue the Army project in any event, and on 8 November 1955 approved both programs. The Air Force would develop IRBM No. 1, or SM-75 (for "strategic missile"), the Army would develop their design as IRBM No. 2 or . The Navy would develop systems to launch the Army missile from ships and, later, submarines. BuShips completed a conceptual design that would take a Maritime Administration hull and convert it into a Jupiter missile launch ship, which was given the hull symbols YAG-58 then EAG-155; the conversion would later be canceled.
The requirement for shipboard storage and launching dictated the size and shape of the Jupiter. The original Army design was long and in diameter. The Navy stated they were not interested in anything longer than . The ABMA team responded by increasing the diameter to . This precluded it from being carried aboard contemporary cargo aircraft, limiting it to sea and road. Even with this change, they were unable to reduce its length enough to suit the Navy. They suggested that they begin with a long version and then scale it down as improvements in the engines were worked into the design. This was rejected, and after briefly considering a version, finally settled on the version.
On 2 December 1955, the secretaries of the Army and Navy publicly announced the dual Army–Navy program to create a land- and sea-based MRBM. In April 1956, as part of a widespread effort to assign names to various missile projects, the Army's effort was given the name "Jupiter" and the Air Force's became "Thor".
Accuracy and mission Redstone provided an accuracy of at its maximum range, which, when combined with its large warhead, allowed it to attack hard targets like protected airbases, bridges, command and control sites, as well as other strategic targets like railway marshaling yards and pre-attack concentration areas. This was in keeping with the Army's view of nuclear weapons, which was in effect more powerful artillery. They saw the weapons as part of a large-scale battle in Europe, in which both sides would use nuclear weapons during a limited war that did not include the use of strategic weapons on each other's cities. In that case, "if wars were to be kept limited, such weapons would have to be capable of hitting only tactical targets." This approach saw the support of a number of influential theorists, notably Henry Kissinger, and was seized on as a uniquely Army mission.
The original goal for the new longer-range design was to match Redstone's accuracy at the Jupiter's much-extended range. That is, if Redstone could reach at , the new design would provide a circular error probable on the order of . As development continued, it became clear the ABMA team, under the direction of Fritz Mueller, could improve on that. This led to a period in which "The Army would lay down a particular accuracy, and wait for our arguments whether it was possible. We had to promise a lot, but were fortunate."
This process ultimately delivered a superior design intended to provide accuracy at the full range, an order of magnitude better than Redstone and four times better than the best INS designs being used by the Air Force. The system was so accurate that a number of observers expressed their skepticism about the Army's goals, with the WSEG suggesting they were hopelessly optimistic.
The Air Force was dead set against Jupiter. They argued that nuclear weapons were not simply new artillery, and that their employment would immediately trigger a response that might result in a strategic exchange. This would especially be true if the Army launched a long-range weapon like Jupiter, which could reach cities in the Soviet Union and could not immediately be distinguished as attacking a military or civilian target. They suggested that any such launch would trigger a strategic response, and as such, the Army should not be given any long-range weapons.
However, as von Braun's team went from success to success, and with Atlas still years from operational deployment, it was clear that Jupiter represented a threat to the Air Force's desired hegemony over strategic forces. This led to them starting their own MRBM program Thor, in spite of having repeatedly dismissed the medium-range role in the past. The fighting between the Army and Air Force grew through 1955 and 1956 until practically every missile system the Army was involved in was being attacked in the press.
Navy exit
The Navy was concerned from the start about Jupiter's cryogenic propellants, but at the time there was no other option. Given the size and weight of contemporary nuclear weapons, only a large liquid-fuel rocket engine provided the energy needed to meet the Navy's range goal of launching from safe areas in the Atlantic Ocean. They justified the risk thus:
All of this changed radically in the summer of 1956, when Project Nobska brought together leading scientists to consider antisubmarine warfare. As part of this workshop, Edward Teller stated that by 1963 a 1 megaton warhead would be reduced to only . Rocketry experts at the same meeting suggested that an intermediate-range weapon carrying one of these weapons could be built using solid propellant. Even in this case, the missile would be much smaller than Jupiter; Jupiter was expected to weigh , while estimates of a solid-fuel missile with similar range were closer to , along with a similar reduction in size which was of paramount importance to a submarine design.
The Navy announced their desire to develop their own missile that summer, initially under the name Jupiter-S. After intensive follow-up studies, the Navy withdrew from the Jupiter program in December 1956. This was officially announced by the Army in January 1957. In its place, the Navy began development of what was then known as the Fleet Ballistic Missile Program, and the missile was later renamed Polaris, their first submarine-launched ballistic missile (SLBM). Rickover, one of the few remaining skeptics, was won over by pointing out that a properly designed submarine was needed specifically for this role, and he would be called upon to produce it. Rickover was from that point on a staunch ally of the program.
Saved from cancellation
On 4 October 1957, the Soviets successfully launched Sputnik I from their R-7 Semyorka ICBM. The US was aware of these efforts and had already talked to the press about it, suggesting that if the Soviets launched a satellite first it would be no big deal. To their surprise, the press exploded in rage over the affair. Having spent over a decade working on similar missiles, like Atlas, the fact that the Soviets could beat them was a serious blow, and prompted a deep review of the ongoing programs.
One problem noted from the start was that the internecine fighting between the Army and Air Force was leading to significant duplication of effort, with little to show for it. The Department of Defense responded by creating the Advanced Research Projects Agency (ARPA), whose initial mission was to look over all of the ongoing projects and select ones based solely on their technical merits.
At the same time, the fighting had begun to have negative political effects. In a 26 November 1956 memorandum, recently appointed US Secretary of Defense Charles Erwin Wilson attempted to end the fighting. His solution was to limit the Army to weapons with range, and those involved in surface-to-air defense to only . The memo also placed limits on Army air operations, severely limiting the weight of the aircraft it was allowed to operate. To some degree this simply formalized what had largely already been the case in practice, but Jupiter fell outside the range limits and the Army was forced to hand them to the Air Force.
The Air Force, of course, had no interest in taking over a weapon system they had long argued was not needed. However, ARPA's studies clearly showed it was an excellent system, and as it was ready to enter production, any Air Force thoughts about canceling it were immediately quashed. New orders for 32 prototypes and 62 operational missiles were soon placed, bringing the total number of Jupiters to be built to 94. The first, hand-built at ABMA, would be delivered by the end of FY57, and the first production models from Chrysler's Michigan Ordinance Missile Plant near Warren, Michigan between FY58 and FY61.
Lingering complaints