Nike Zeus
Nike-Zeus was an anti-ballistic missile system developed by the United States Army during the late 1950s and early 1960s that was designed to destroy incoming Soviet intercontinental ballistic missile warheads before they could hit their targets. It was designed by Bell Labs' Nike team, and was initially based on the earlier Nike Hercules anti-aircraft missile. The original, Zeus A, was designed to intercept warheads in the upper atmosphere, mounting a 25 kiloton W31 nuclear warhead. During development, the concept changed to protect a much larger area and intercept the warheads at higher altitudes. This required the missile to be greatly enlarged into the totally new design, Zeus B, given the tri-service identifier XLIM-49, mounting a 400 kiloton W50 warhead. In several successful tests, the B model proved itself able to intercept warheads, and even satellites.
The nature of the strategic threat changed dramatically during the period that Zeus was being developed. Originally expected to face only a few dozen ICBMs, a nationwide defense was feasible, although expensive. When the Soviets claimed to be building hundreds of missiles, the US faced the problem of building enough Zeus missiles to match them. The Air Force argued they close this missile gap by building more ICBMs of their own instead. Adding to the debate, a number of technical problems emerged that suggested Zeus would have little capability against any sort of sophisticated attack.
The system was the topic of intense inter-service rivalry throughout its lifetime. When the ABM role was given to the Army in 1958, the United States Air Force began a long series of critiques on Zeus, both within defense circles and in the press. The Army returned these attacks in kind, taking out full page advertisements in popular mass market news magazines to promote Zeus, as well as spreading development contracts across many states in order to garner the maximum political support. As deployment neared in the early 1960s, the debate became a major political issue. The question ultimately became whether a system with limited effectiveness would be better than nothing at all.
The decision whether to proceed with Zeus eventually fell to President John F. Kennedy, who became fascinated by the debate about the system. In 1963, the United States Secretary of Defense, Robert McNamara, convinced Kennedy to cancel Zeus. McNamara directed its funding toward studies of new ABM concepts being considered by ARPA, selecting the Nike-X concept, which addressed Zeus' various problems by using an extremely high-speed missile, Sprint, along with greatly improved radars and computer systems. The Zeus test site built at Kwajalein was briefly used as an anti-satellite weapon.
History
Early ABM studies
The first known serious study on attacking ballistic missiles with interceptor missiles was carried out by the Army Air Force in 1946, when two contracts were sent out as Project Wizard and Project Thumper to consider the problem of shooting down missiles of the V-2 type. These projects identified the main problem being one of detection; the target could approach from anywhere within hundreds of miles, and reach their targets in only five minutes. Existing radar systems would have difficulty seeing the missile launch at those ranges, and even assuming one had detected the missile, existing command and control arrangements would have serious problems forwarding that information to the battery in time for them to attack. The task appeared impossible at that time.These results also suggested that the system might be able to work against longer-ranged missiles. These flew to a higher altitude which eased the problem of detection, and although they traveled at higher speeds, their total flight time was longer and provided more time to prepare. Both projects were allowed to continue as research efforts. They were transferred to the US Air Force when that force separated from the Army in 1947. The Air Force faced significant budget constraints and canceled Thumper in 1949 in order to use its funds to continue its GAPA surface-to-air missile efforts. The next year, Wizard's funding was also rolled into GAPA to develop a new long-range SAM design, which would emerge a decade later as the CIM-10 Bomarc. ABM research at the Air Force practically, although not officially, ended.
Nike II
By the early 1950s the Army was firmly established in the surface-to-air missile field with their Nike and Nike B missile projects. These projects had been led by Bell Labs, working with Douglas.The Army contacted the Johns Hopkins University Operations Research Office to consider the task of shooting down ballistic missiles using a Nike-like system. The ORO report took three years to complete, and the resulting The Defense of the United States Against Aircraft and Missiles was comprehensive. While this study was still progressing, in February 1955 the Army began initial talks with Bell, and in March they contracted Bell's Nike team to begin a detailed 18-month study of the problem under the name Nike II.
The first section of the Bell study was returned to the Army Ordnance department at the Redstone Arsenal on 2 December 1955. It considered the full range of threats including existing jet aircraft, future ramjet powered aircraft flying at up to, short-range ballistic missiles of the V-2 type flying at about the same speed, and an ICBM reentry vehicle traveling at. They suggested that a missile with a common rocket booster could serve all of these roles by changing between two upper stages; one with fins for use in the atmosphere against aircraft, and another with vestigial fins and thrust vectoring for use above the atmosphere against missiles.
Considering the ICBM problem, the study went on to suggest that the system would have to be effective between 95 and 100% of the time in order to be worthwhile. They considered attacks against the RV while the missile was in the midcourse, just as it reached the highest point in its trajectory and was traveling at its slowest speed. Practical limitations eliminated this possibility, as it required the ABM to be launched at about the same time as the ICBM in order to meet in the middle, and they could not imagine a way to arrange this. Working at much shorter ranges, during the terminal phase, seemed the only possible solution.
Bell returned a further study, delivered on 4 January 1956, that demonstrated the need to intercept the incoming warheads at altitude, and suggested that this was within the abilities of an upgraded version of the Nike B missile. Given a terminal speed up to 5 miles per second, combined with the time it would take an interceptor missile to climb to the RV's altitude, the system required that the RV be initially detected at about range. Due to the RV's relatively small size and limited radar signature, this would demand extremely powerful radars.
To ensure the destruction of the RV, or at least render the warhead within it unusable, the W31 would have to be fired when it was within a few hundred feet of the RV. Given the angular resolution of existing radars, this limited the maximum effective range significantly. Bell considered an active radar seeker, which improved accuracy as it flew toward the RV, but these proved too large to be practical. A command guidance system like the early Nike systems seemed to be the only solution.
The interceptor would lose maneuverability as it climbed out of the atmosphere and its aerodynamic surfaces became less effective, so it would have to be directed onto the target as rapidly as possible, leaving only minor fine-tuning later in the engagement. This required that accurate tracks be developed for both the warhead and outgoing missile very quickly in comparison to a system like Nike B where the guidance could be updated throughout the engagement. This, in turn, demanded new computers and tracking radars with much higher processing rates than the systems used on earlier Nikes. Bell suggested that the recently introduced transistor offered the solution to the data processing problem.
After running 50,000 simulated intercepts on analog computers, Bell returned a final report on the concept in October 1956, indicating that the system was within the state of the art. A 13 November 1956 memo gave new names to the entire Nike series; the original Nike became Nike Ajax, Nike B became Nike Hercules, and Nike II became Nike Zeus.
Army vs. Air Force
The Army and Air Force had been involved in interservice fighting over missile systems since they split in 1947. The Army considered surface-to-surface missiles an extension of conventional artillery, and surface-to-air designs as the modern replacement for their anti-aircraft artillery. The Air Force considered the nuclear SSM to be an extension of their strategic bombing role, and any sort of long-range anti-aircraft system to be their domain as it would integrate with their fighter fleet. Both forces were developing missiles for both roles, leading to considerable duplication of effort which was widely seen as wasteful.For a period the capabilities of the systems being developed were different enough to provide some separation between the forces. For instance, the Army's Ajax was much shorter ranged than the Air Force's Bomarc, and the Army's Redstone much shorter in range than the Air Force's ICBM programs. But by the mid-1950s the Army's programs were rapidly improving and the fighting grew more intense. When the Army's longer-ranged Hercules began deployment, the Air Force complained that it was inferior to Bomarc and that the Army was "unfit to guard the nation". When the Army started its Jupiter missile efforts, the Air Force worried it would trump their Atlas ICBM and responded by rapidly starting its own IRBM, Thor. So when the Army announced Nike II, the Air Force immediately reactivated Wizard, this time as a long-range anti-ICBM system of much greater performance than Zeus.
In a 26 November 1956 memorandum, US Secretary of Defense Charles Erwin Wilson attempted to end the fighting between the forces and prevent duplication of effort. 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 result was another round of fighting between the two forces. Jupiter had been designed to be a highly accurate weapon able to attack Soviet military bases in Europe, as compared to Thor, which was intended to attack Soviet cities and had accuracy on the order of several miles. Losing Jupiter, the Army was eliminated from any offensive strategic role. In return, the Air Force complained that Zeus was too long-ranged and the ABM effort should center on Wizard. But the Jupiter handover meant that Zeus was now the only strategic program being carried out by the Army, and its cancellation would mean "virtually the surrender of the defense of America to the U.S.A.F at some future date."