Nike-X was an
The Nike-X system was developed in response to limitations of the earlier
The key concept that led to Nike-X was that the rapidly thickening atmosphere below 60 kilometers (37 mi) altitude disrupted the reflectors and explosions. Nike-X intended to wait until the enemy warheads descended below this altitude and then attack them using a very fast missile known as
Building a complete deployment would have been extremely expensive, on the order of the total yearly budget of the
In 1955 the
Zeus was similar to the two Nike SAM designs that preceded it. It used a long range search radar to pick up targets, separate radars to track the target and interceptor missiles in flight, and a computer to calculate intercept points. The missile itself was much larger than earlier designs, with a range of up to 200 miles (320 km), compared to Hercules' 75 miles (121 km). To ensure a kill at 100,000 feet (30 km) altitude, where there was little atmosphere to carry a
The Zeus missile began testing in 1959 at
Zeus had initially been proposed in an era when ICBMs were extremely expensive and the US believed that the Soviet fleet contained a few dozen missiles. At a time when the US
Technological improvements in warheads and missiles in the late 1950s greatly reduced the cost of ICBMs. After the launch of Sputnik,
Additionally, technical problems arose that appeared to make the Zeus almost trivially easy to defeat. One problem, discovered in
It was also possible to deploy radar decoys to confuse the defense. Decoys are made of lightweight materials, often
The Advanced Research Projects Agency (ARPA, today known as
Meanwhile, one improvement to Zeus was already being studied: a new
By late 1962 a decision on whether or not to deploy Zeus was looming. Bell began considering a replacement for the Zeus missile that would operate at much shorter ranges, and in October sent out study contracts to three contractors to be returned in February. Even before these were returned, in January 1963 McNamara announced that the construction funds allocated for Zeus would not be released, and the funding would instead be used for development of a new system using the latest technologies. The name Nike-X was apparently an ad hoc suggestion by
Decoys are lighter than the RV,[b] and therefore suffer higher atmospheric
Low-altitude intercepts would also have the advantage of reducing the problem with nuclear blackout. The lower edge of an extended fireball used to induce nuclear blackout extended down to about 60 km, the same as the altitude at which decluttering became effective. Hence, low-altitude intercepts meant that deliberate attempts to create a blackout would not affect the tracking and guidance of the
The centerpiece of the Nike-X system was MAR, using the then-new
Because the Sprint was designed to operate at short range, a single base could not provide protection to a typical US city, given
When the system was first being proposed it was not clear whether the phased-array systems could provide the accuracy needed to guide the missiles to a successful interception at very long ranges. Early concepts retained Zeus Missile Tracking Radars and Target Tracking Radars (MTRs and TTRs) for this purpose. In the end, the MAR proved more than capable of the required resolution, and the additional radars were dropped.
Nike-X had been defined in the early 1960s as a system to defend US cities and industrial centers against a heavy Soviet attack during the 1970s. By 1965 the growing fleets of ICBMs in the inventories of both the US and USSR were making the cost of such a system very expensive. NIE 11-8-63, published 18 October 1963, estimated the Soviets would have 400–700 ICBMs deployed by 1969, and their deployment eventually reached 1,601 launchers, limited by the
While Nike-X could be expected to attack these with a reasonable 1 to 1 exchange ratio, compared to Zeus' 20 to 1, it could only do so over a limited area. Most nationwide deployment scenarios contained thousands of Sprint missiles protecting only the largest US cities. Such a system would cost an estimated $40 billion to build ($320 billion in 2018, about half the annual military budget).
This led to further studies of the system to try to determine whether an ABM would be the proper way to save lives, or if there was some other plan that would do the same for less money. In the case of Zeus, for instance, it was clear that building more
This led to a series of increasingly sophisticated models to better predict the effectiveness of an ABM system and what the opposition would do to improve their performance against it. A key development was the
Prim-Read theory, which provided an entirely mathematical solution to generating the ideal defensive layout. Using a Prim-Read layout for Nike-X, Air Force Brigadier General
Glenn Kent began considering Soviet responses. His 1964 report produced a cost-exchange ratio that required $2 of defense for every $1 of offence if one wanted to limit US casualties to 30 percent of the population. The cost increased to 6-to-1 if the US wished to limit casualties to 10 percent. ABMs would only be cheaper than ICBMs if the US was willing to allow over half its population to die in the exchange. When he realized he was using outdated exchange rates for the
As the cost of defeating Nike-X by building more ICBMs was less than the cost of building Nike-X to counter them, reviewers concluded that the construction of an ABM system would simply prompt the Soviets to build more ICBMs. This led to serious concerns about a new
[He] observed that this was a race that we probably would not win and should avoid. He noted that it would be difficult indeed to stay the course with a strategy that aimed to limit the damage. The detractors would proclaim that, with 70 percent surviving, there would be upwards of 60 million dead.
In spite of its technical capabilities, Nike-X still shared one seemingly intractable problem that had first been noticed with Zeus. Facing an ABM system, the Soviets would change their targeting priorities to maximize damage, by attacking smaller, undefended cities for instance. Another solution was to drop their warheads just outside the range of the defensive missiles, upwind of the target. Ground bursts would throw enormous amounts of radioactive dust into the air, causing
It is estimated that a shelter system at a cost of $2 billion would save 48.5 million lives. The cost per life saved would be about $40.00. An active ballistic missile defense system would cost about $18 billion and would save an estimated 27.8 million lives. The cost per life saved in this case would be about $700. ... I personally will never recommend an anti-ICBM program unless a fallout program does accompany it. I believe that even if we do not have an anti-ICBM program, we nonetheless should proceed with the fallout shelter program.
Under any reasonable set of assumptions, even an advanced system like Nike-X offered only marginal protection and did so for huge costs. Around 1965, the ABM became what one historian calls a "technology in search of a mission". In early 1965, the Army launched a series of studies to find a mission concept that would lead to deployment.
One of the original deployment plans for Zeus had been a defensive system for
Things changed in the early 1960s when McNamara placed limits on the Air Force fleet of 1,000
A fresh look at this concept started at ARPA around 1963–64 under the name Hardpoint. This led to the construction of the Hardpoint Demonstration Array Radar, and an even faster missile concept known as HiBEX. This proved interesting enough for the Army and Air Force to collaborate on a follow-up study, Hardsite. The first Hardsite concept, HSD-I, considered the defending of bases within urban areas that would have Nike-X protection anyway. An example might be a SAC command and control center or an airfield on the outskirts of a city. The second study, HSD-II, considered the protection of isolated bases like missile fields. Most follow-up work focused on the HSD-II concept.
HSD-II proposed building small Sprint bases close to Minuteman fields. Incoming warheads would be tracked until the last possible moment, decluttering them completely and generating highly accurate tracks. Since the warheads had to land within a short distance of a
Although initially supportive of the Hardsite concept, by 1966 the Air Force came to oppose it largely for the same reasons it had opposed Zeus in the same role. If money was to be spent on protecting Minuteman, they felt that money would be better spent by the Air Force than the Army. As
In part this was a reflex reaction, a desire not to have Air Force missiles protected by "Army" ABMs. ... The Air Force clearly preferred that the funds for missile defense be used by the Air Force to develop new hard rock silos or mobile systems.
During the project's development phase, the siting and size of the Nike-X bases became a major complaint of smaller cities. Originally intended to protect only the largest urban areas, Nike-X was designed to be built at a very large size with many missiles controlled by an expensive computer and radar network. Smaller sites were to be left undefended in the original Nike-X concept since the system was simply too expensive to build with only a few interceptors. These cities complained that they were not only being left open to attack, but that their lack of defenses might make them primary targets. This led to a series of studies on the Small City Defense (SCD) concept. By 1964 SCD had become part of the baseline Nike-X deployment plans, with every major city being provided some level of defensive system.
SCD would consist primarily of a single autonomous battery centered on a cut-down MAR called TACMAR (TACtical MAR), along with a simplified data processing system known as the Local Data Processor (LDP). This was essentially the DCDP with fewer modules installed, reducing the number of tracks it could compile and the amount of decluttering it could handle. To further reduce costs, Bell later replaced the cut-down MAR with an upgraded MSR, the "Autonomous MSR". They studied a wide variety of potential deployments, starting with systems like the original Nike-X proposal with no SCDs, to deployments offering complete continental US protection with many SCD modules of various types and sizes. The deployments were arranged so that they could be built in phases, working up to complete coverage.
One issue that emerged from these studies was the problem of providing early warning to the SCD sites. The SCD's MSR radars provided detection at perhaps 100 miles (160 km), which meant targets would appear on their radars only seconds before launches would have to be carried out. In a sneak attack scenario, there would not be enough time to receive command authority for the release of nuclear weapons. This meant the bases would require
This led to proposals for a new radar dedicated solely to the early warning role, determining only which MAR or SCD would ultimately have to deal with the threat. Used primarily in the first minutes of the attack, and not responsible for the engagements, the system could be considered disposable and did not need anything like the sophistication or hardening of the MAR. This led to the Perimeter Acquisition Radar (PAR), which would operate cheaper electronics at
The high-altitude explosions that had caused so much concern for Nike Zeus due to blackout had been further studied in the early 1960s and led to a new possibility for missile defense. When a nuclear warhead explodes in a dense atmosphere, its initial high-energy
In late 1964 Bell was considering the role of an X-ray-armed Zeus missile in the Nike-X system. A January 1965 report[f] outlines this possibility, noting that it would have to have a much larger warhead dedicated to the production of X-rays, and would have to operate at higher altitudes to maximize the effect. A major advantage was that accuracy needs were much reduced, from a minimum of about 800 feet (240 m) for the original Zeus' neutron-based attack, to something on the order of a few miles. This meant that the range limits of the original Zeus, which were defined by the accuracy of the radars to about 75 miles (121 km), were greatly eased. This, in turn, meant that a less sophisticated radar could be used, one with accuracy on the order of a mile rather than feet, which could be built much less expensively using
This Extended Range Nike Zeus, or Zeus EX for short, would be able to provide protection over a wider area, reducing the number of bases needed to provide full-country defense. Work on this concept continued throughout the 1960s, eventually becoming the primary weapon in the following Sentinel system, and in the modified Sentinel system that was later renamed
In February 1965 the Army asked Bell to consider different deployment concepts under the Nth Country study. This examined what sort of system would be needed to provide protection against an unsophisticated attack with a limited number of warheads. Using Zeus EX, a few bases could provide coverage for the entire US. The system would be unable to deal with large numbers of warheads, but that was not a concern for a system that would only be tasked with beating off small attacks.
With only small numbers of targets, the full MAR was not needed and Bell initially proposed TACMAR to fill this need. This would have a shorter detection range, so a long range radar like PAR would be needed for early detection. The missile sites would consist of a single TACMAR along with about 20 Zeus EX missiles. In October 1965 the TACMAR was replaced by the upgraded MSR from the SCD studies. Since this radar had an even shorter range than TACMAR, it could not be expected to generate tracking information in time for a Zeus EX launch. PAR would thus have to be upgraded to have higher accuracy and the processing power to generate tracks that would be handed off to the MSRs. During this same time, Bell had noted problems with long wavelength radars in the presence of radar blackout. Both of these issues argued for a change from VHF to
Further work along these lines led to the Nike-X Deployment Study, or DEPEX. DEPEX outlined a deployment that started out very similar to Nth Country, with a few bases primarily using Nike EX to provide lightweight cover, but which also included design features that allowed more bases to be added as the nature of the threat changed. The study described a four-phase deployment sequence that added more and more terminal defenses as the sophistication of the Nth Country missiles increased over time.
In December 1966, the Army asked Bell to prepare a detailed deployment concept combining the light defense of Nth Country with the point defense of Hardsite. On 17 January 1967, this became the I-67 project, which delivered its results on 5 July. I-67 was essentially Nth Country but with more bases near Minuteman fields, armed primarily with Sprint. The wide-area Zeus and short-range Sprint bases would both be supported by the PAR network.
The basic outlines of these various studies were becoming clear by 1966. The heavy defense from the original Nike-X proposals would cost about $40 billion ($302 billion in 2018) and offer limited protection and damage prevention in an all-out attack, but would be expected to blunt or completely defeat any smaller attack. The thin defense of Nth Country would be much less expensive, around $5 billion ($38 billion in 2018), but would only have any effect at all under certain limited scenarios. Finally, the Hardsite concepts would cost about the same as the thin defense, and provide some protection against a certain class of counterforce attacks.
None of these concepts appeared to be worth deploying, but there was considerable pressure from Congressional groups dominated by
McNamara attempted to short-circuit deployment in early 1966 by stating that the only program that had any reasonable cost-effectiveness was the thin defense against the Chinese, and then noted there was no rush to build such a system as it would be some time before they had an ICBM. Overruling him, Congress provided $167.9 million ($1 billion in 2018) for immediate production of the original Nike-X concept. McNamara and Johnson met on the issue on 3 November 1966, and McNamara once again convinced Johnson that the system could not justify the cost of deployment. McNamara headed off the expected counterattack from Romney by calling a press conference on the topic of Soviet ABMs and stating that the new Minuteman III and
Another meeting on the issue was called on 6 December 1966, attended by Johnson, McNamara, the deputy Secretary of Defense
By 1967 the debate over ABM systems had become a major public policy issue, with almost continual debate on the topic in newspapers and magazines. It was in the midst of these debates, on 17 June 1967, that the Chinese tested their first