The first studies to create systems capable of countering ballistic missile strikes in the United States began shortly after the end of World War II. American military analysts were well aware of the danger ballistic missiles equipped with nuclear warheads could pose to the continental United States. In the second half of 1945, representatives of the Air Force initiated the "Wizard" project. The military wanted a high-speed guided missile capable of intercepting ballistic missiles superior in speed and range to the German V-2. Most of the work under the project was carried out by scientists from the University of Michigan. Since 1947, more than $ 1 million has been allocated annually for theoretical research in this direction. At the same time, together with the interceptor missile, radars for target detection and tracking were designed.
As the topic was worked out, experts more and more came to the conclusion that the practical implementation of intercepting ballistic missiles turned out to be a much more difficult task than it seemed at the very beginning of the work. Great difficulties have arisen not only with the creation of anti-missiles, but also with the development of the ground component of the anti-missile defense - early warning radars, automated control and guidance systems. In 1947, after generalizing and working out the obtained material, the development team came to the conclusion that it would take at least 5-7 years to create the necessary computers and control systems.
Work on the Wizard progressed very slowly. In the final design version, the interceptor was a large two-stage liquid-propellant missile about 19 meters long and 1.8 meters in diameter. The rocket was supposed to accelerate to a speed of about 8000 km / h and intercept the target at an altitude of 200 kilometers, with a range of about 900 km. To compensate for errors in guidance, the interceptor had to be equipped with a nuclear warhead, while the probability of hitting an enemy ballistic missile was estimated at 50%.
In 1958, after the division of responsibilities between the Air Force, the Navy and the Army command occurred in the United States, work on the creation of the Wizard interceptor missile, which was operated by the Air Force, ceased. The existing groundwork for the radars of the unrealized anti-missile system was later used to create the AN / FPS-49 missile attack warning radar.
The AN / FPS-49 radar, put on alert in Alaska, Great Britain and Greenland in the early 60s, consisted of three 25-meter parabolic antennas with a mechanical drive weighing 112 tons, protected by radio-transparent fiberglass spherical domes with a diameter of 40 meters.
In the 50s and 70s, the defense of US territory from Soviet long-range bombers was carried out by the MIM-3 Nike Ajax and MIM-14 Nike-Hercules anti-aircraft missile systems, which were operated by the ground forces, as well as by the Air Force's long-range unmanned interceptors, the CIM-10 Bomarc. Most of the anti-aircraft missiles deployed in the United States were equipped with nuclear warheads. This was done in order to increase the likelihood of hitting group air targets in a difficult jamming environment. An aerial explosion of a nuclear charge with a capacity of 2 kt could destroy everything within a radius of several hundred meters, which made it possible to effectively hit even complex, small-sized targets like supersonic cruise missiles.
The MIM-14 Nike-Hercules anti-aircraft missiles with nuclear warheads also had some anti-missile potential, which was confirmed in practice in 1960. Then, with the help of a nuclear warhead, the first successful interception of a ballistic missile, the MGM-5 Corporal, was carried out. However, the US military did not create illusions about the anti-missile capabilities of the Nike-Hercules complexes. In a real combat situation, anti-aircraft systems with missiles equipped with nuclear warheads were able to intercept no more than 10% of ICBM warheads in a very small area (more details here: American MIM-14 Nike-Hercules anti-aircraft missile system).
The three-stage rocket complex "Nike-Zeus" was an improved SAM "Nike-Hercules", on which acceleration characteristics were improved due to the use of an additional stage. According to the project, it was supposed to have a ceiling of up to 160 kilometers. The rocket, about 14.7 meters long and about 0.91 meters in diameter, weighed 10.3 tons in the equipped state. The defeat of intercontinental ballistic missiles outside the atmosphere was to be carried out by a W50 nuclear warhead with a capacity of 400 kt with an increased neutron yield. Weighing about 190 kg, a compact warhead, when detonated, ensured the defeat of an enemy ICBM at a distance of up to two kilometers. When irradiated by a dense neutron flux of an enemy warhead, neutrons would provoke a spontaneous chain reaction inside the fissile material of an atomic charge (the so-called "pop"), which would lead to the loss of the ability to carry out a nuclear explosion or to destruction.
The first modification of the Nike-Zeus-A missile, also known as Nike-II, first launched in a two-stage configuration in August 1959. Initially, the rocket had developed aerodynamic surfaces and was designed for atmospheric interception.
Launch of the Nike-Zeus-A anti-missile
In May 1961, the first successful launch of the three-stage version of the rocket, the Nike-Zeus B, took place. Six months later, in December 1961, the first training interception took place, during which the Nike-Zeus-V missile with an inert warhead passed at a distance of 30 meters from the Nike-Hercules missile, which served as a target. In the event that the anti-missile warhead was combat, the conditional target would be guaranteed to be hit.
Launch of the Nike-Zeus-V anti-missile
The first test launches of the Zeus program were carried out from the White Sands test site in New Mexico. However, for a number of reasons, this test site was not suitable for testing anti-missile defense systems. Intercontinental ballistic missiles launched as training targets, due to closely located launch positions, did not have time to gain sufficient altitude, because of this it was impossible to simulate the trajectory of the warhead entering the atmosphere. Another missile range, at Point Mugu, did not meet safety requirements: when intercepting ballistic missiles launched from Canaveral, there was a threat of debris falling into densely populated areas. As a result, Kwajalein Atoll was chosen as the new missile range. The remote Pacific atoll made it possible to accurately simulate the situation of intercepting ICBM warheads entering the atmosphere. In addition, Kwajalein already partially had the necessary infrastructure: port facilities, a capital runway and a radar station (more information about American missile ranges here: US Missile Range).
The ZAR (Zeus Acquisition Radar) radar was created especially for Nike-Zeus. It was intended to detect approaching warheads and issue primary target designation. The station had a very significant energy potential. The high-frequency radiation of the ZAR radar posed a danger to people at a distance of more than 100 meters from the transmitting antenna. In this regard, and in order to block the interference resulting from signal reflection from ground objects, the transmitter was isolated around the perimeter by a double inclined metal fence.
Station ZDR (eng. Zeus Discrimination Radar - radar selection "Zeus") produced target selection, analyzing the difference in the deceleration rate of tracked warheads in the upper atmosphere. Separating real warheads from lighter decoys that decelerate faster.
The real ICBM warheads screened out with the help of ZDR were taken to accompany one of the two TTR radars (Target Tracking Radar - target tracking radar). Data from the TTR radar on the target position in real time was transmitted to the central computing center of the anti-missile complex. After the missile was launched at the estimated time, it was taken to escort the MTR radar (MIssile Tracking Radar - missile tracking radar), and the computer, comparing the data from the escort stations, automatically brought the missile to the calculated interception point. At the moment of the closest approach of the interceptor missile, a command was sent to detonate the nuclear warhead of the interceptor missile.
According to the preliminary calculations of the designers, the ZAR radar was supposed to calculate the target trajectory in 20 seconds and transmit it to the TTR radar tracking. Another 25-30 seconds was needed for the launched anti-missile to destroy the warhead. The anti-missile system could simultaneously attack up to six targets, two interceptor missiles could be guided to each attacked warhead. However, when the enemy used decoys, the number of targets that could be destroyed in a minute was significantly reduced. This was due to the fact that the ZDR radar needed to "filter out" false targets.
According to the project, the Nike-Zeus launch complex consisted of six launch positions, consisting of two MTR radars and one TTR, as well as 16 missiles ready for launch. Information about the missile attack and the selection of false targets was transmitted to all launch positions from the ZAR and ZDR radars common to the entire complex.
The launch complex of Nike-Zeus anti-missile interceptors had six TTR radars, which simultaneously made it possible to intercept no more than six warheads. From the moment the target was detected and taken to accompany the TTR radar, it took about 45 seconds to develop a firing solution, that is, the system was physically unable to intercept more than six attacking warheads at the same time. Given the rapid increase in the number of Soviet ICBMs, it was predicted that the USSR would be able to break through the missile defense system by simply launching more warheads against the protected object at the same time, thereby overloading the capabilities of the tracking radars.
After analyzing the results of test launches of Nike-Zeus anti-missile missiles from Kwajalein Atoll, US Department of Defense experts came to the disappointing conclusion that the combat effectiveness of this anti-missile system was not too high. In addition to frequent technical failures, the noise immunity of the detection and tracking radar left much to be desired. With the help of "Nike-Zeus" it was possible to cover a very limited area from ICBM attacks, and the complex itself required a very serious investment. In addition, the Americans seriously feared that the adoption of an imperfect missile defense system would push the USSR to build up the quantitative and qualitative potential of nuclear weapons and deliver a preemptive strike in the event of an aggravation of the international situation. In early 1963, despite some success, the Nike-Zeus program was finally closed. However, this did not mean abandoning the development of more effective anti-missile systems.
In the early 1960s, both superpowers were exploring options for using orbiting satellites as a preventive means of nuclear attack. A satellite with a nuclear warhead, previously launched into low-earth orbit, could deliver a sudden nuclear strike on enemy territory.
In order to avoid the final curtailment of the program, the developers proposed to use the existing Nike-Zeus interceptor missiles as a weapon of destruction of low-orbit targets. From 1962 to 1963, as part of the development of anti-satellite weapons, a series of launches were carried out at Kwajalein. In May 1963, an anti-missile missile successfully intercepted a low-orbit training target - the upper stage of the Agena launch vehicle. The Nike-Zeus anti-satellite complex was on alert in the Pacific atoll of Kwajalein from 1964 to 1967.
A further development of the Nike-Zeus program was the Nike-X missile defense project. For the implementation of this project, the development of new super-powerful radars with phased array, capable of simultaneously fixing hundreds of targets and new computers with much greater speed and performance, was carried out. That made it possible to simultaneously aim several missiles at several targets. However, a significant obstacle to the consistent shelling of targets was the use of nuclear warheads of interceptor missiles to intercept warheads of ICBMs. During a nuclear explosion in space, a cloud of plasma was formed that was impenetrable for the radiation of detection and guidance radars. Therefore, in order to obtain the possibility of a phased destruction of the attacking warheads, it was decided to increase the range of the missiles and supplement the missile defense system being developed with one more element - a compact atmospheric interceptor missile with a minimum reaction time.
A new promising missile defense system with anti-missile missiles in the far transatmospheric and near atmospheric zones was launched under the designation "Sentinel" (English "Guard" or "Sentinel"). The long-range transatmospheric interceptor missile, created on the basis of Nike, received the designation LIM-49A "Spartan", and the short-range intercept missile - Sprint. Initially, the anti-missile system was supposed to cover not only strategic facilities with nuclear weapons, but also large administrative and industrial centers. However, after analyzing the characteristics and cost of the developed elements of the missile defense system, it turned out that such expenditures on missile defense are excessive even for the American economy.
In the future, the LIM-49A "Spartan" and Sprint interceptor missiles were created as part of the Safeguard anti-missile program. The Safeguard system was supposed to protect the starting positions of the 450 Minuteman ICBMs from a disarming strike.
In addition to interceptor missiles, the most important elements of the American missile defense system created in the 60s and 70s were ground stations for early detection and tracking of targets. American specialists managed to create radars and computing systems that were very advanced at that time. A successful Safeguard program would have been unthinkable without PAR or Perimeter Acquisition Radar. The PAR radar was created on the basis of the AN / FPQ-16 missile attack warning system station.
This very large locator with a peak power of over 15 megawatts was the eyes of the Safeguard program. It was intended to detect warheads at distant approaches to the protected object and issue target designation. Each anti-missile system had one radar of this type. At a distance of up to 3200 kilometers, the PAR radar could see a radio-contrast object with a diameter of 0.25 meters. The missile defense system detection radar was installed on a massive reinforced concrete base, at an angle to the vertical in a given sector. The station, coupled with a computing complex, could simultaneously track and track dozens of targets in space. Due to the huge range of action, it was possible to timely detect approaching warheads and provide a margin of time for developing a firing solution and intercepting. It is currently the only active element of the Safeguard system. After the modernization of the radar station in North Dakota, it continued to serve as part of the missile attack warning system.
Satellite image of Google Earth: AN / FPQ-16 radar in North Dakota
Radar MSR or Missile Site Radar (eng. Radar missile position) - was designed to track detected targets and anti-missiles launched at them. The MSR station was located at the central position of the missile defense complex. The primary target designation of the MSR radar was carried out from the PAR radar. After capturing to accompany the approaching warheads using the MSR radar, both targets and launching interceptor missiles were tracked, after which the data was transmitted for processing to computers of the control system.
The radar of the missile position was a tetrahedral truncated pyramid, on the inclined walls of which phased antenna arrays were located. Thus, all-round visibility was provided and it was possible to continuously track approaching targets and interceptor missiles that took off. Directly at the base of the pyramid was placed the control center of the anti-missile defense complex.
The LIM-49A "Spartan" three-stage solid-propellant anti-missile missile was equipped with a 5 Mt W71 thermonuclear warhead weighing 1290 kg. The W71 warhead was unique in a number of technical solutions and deserves to be described in more detail. It was developed at the Lawrence Laboratory specifically for the destruction of targets in space. Since a shock wave is not formed in the vacuum of outer space, a powerful neutron flux should have become the main damaging factor of a thermonuclear explosion. It was assumed that under the influence of powerful neutron radiation in the warhead of an enemy ICBM, a chain reaction would begin in the nuclear material, and it would collapse without reaching a critical mass.
However, in the course of laboratory research and nuclear tests, it turned out that for the 5-megaton warhead of the Spartan anti-missile missile, a powerful X-ray flash is a much more effective damaging factor. In an airless space, the X-ray beam could travel great distances without attenuation. When meeting an enemy warhead, powerful X-rays instantly heated the surface of the warhead body material to a very high temperature, which led to explosive evaporation and complete destruction of the warhead. To increase the X-ray output, the inner shell of the W71 warhead was made of gold.
Loading a W71 warhead into a test well on Amchitka Island
According to laboratory data, when a thermonuclear warhead of the "Spartan" missile exploded, the target could be destroyed at a distance of 46 kilometers from the point of explosion. However, it was considered optimal to destroy the warhead of an enemy ICBM at a distance of no more than 19 kilometers from the epicenter. In addition to destroying the ICBM warheads directly, a powerful explosion was guaranteed to vaporize light false warheads, thus facilitating further interceptor actions. After the Spartan interceptor missiles were decommissioned, one of the literally "golden" warheads was used in the most powerful American underground nuclear tests, which took place on November 6, 1971, on Amchitka island in the Aleutian Islands archipelago.
Thanks to the increase in the range of the "Spartan" interceptor missiles to 750 km and the ceiling of 560 km, the problem of the masking effect, opaque to radar radiation of plasma clouds formed as a result of high-altitude nuclear explosions, was partially solved. In its layout, the LIM-49A "Spartan", being the largest, in many respects repeated the LIM-49 "Nike Zeus" interceptor missile. With a curb weight of 13 tons, it had a length of 16.8 meters with a diameter of 1.09 meters.
Launch of the LIM-49A "Spartan" anti-missile
The two-stage solid-propellant anti-missile "Sprint" was intended to intercept the warheads of ICBMs that broke past the "Spartan" missiles after they entered the atmosphere. The advantage of intercepting on the atmospheric part of the trajectory was that the lighter decoys after entering the atmosphere lagged behind real warheads. Because of this, anti-missiles in the near intra-atmospheric zone did not have problems with filtering false targets. At the same time, the speed of the guidance systems and the acceleration characteristics of the interceptor missiles should be very high, since several tens of seconds passed from the moment the warhead entered the atmosphere until its explosion. In this regard, the placement of the Sprint interceptor missiles was supposed to be in the immediate vicinity of the covered objects. The target was to be defeated when the W66 low-power nuclear warhead exploded. For reasons unknown to the author, the Sprint anti-missile missile was not assigned the standard three-letter designation adopted by the US Armed Forces.
Loading an anti-missile "Sprint" into silos
The Sprint anti-missile missile had a streamlined conical shape and, thanks to a very powerful engine of the first stage, accelerated to a speed of 10 m during the first 5 seconds of flight. At the same time, the overload was about 100g. The warhead of the anti-missile from friction against the air a second after launch warmed up to redness. To protect the rocket casing from overheating, it was covered with a layer of evaporating ablative material. Rocket guidance to the target was carried out using radio commands. It was quite compact, its weight did not exceed 3500 kg, and its length was 8.2 meters, with a maximum diameter of 1.35 meters. The maximum launch range was 40 km, and the ceiling was 30 km. The Sprint interceptor missile was launched from a silo launcher using a mortar launch.
Launch position of anti-missile "Sprint"
For a number of military-political and economic reasons, the age of the LIM-49A "Spartan" and "Sprint" anti-missile missiles was short-lived in combat service. On May 26, 1972, the Treaty on the Limitation of Anti-Ballistic Missile Systems was signed between the USSR and the United States. As part of the agreement, the parties committed themselves to abandoning the creation, testing and deployment of sea, air, space or mobile-ground-based missile defense systems or components to combat strategic ballistic missiles, and also not to create missile defense systems on the territory of the country.
Sprint launch
Initially, each country could have no more than two missile defense systems (around the capital and in the area of concentration of ICBM launchers), where no more than 100 fixed anti-missile launchers could be deployed within a radius of 150 kilometers. In July 1974, after additional negotiations, an agreement was concluded, according to which each of the parties was allowed to have only one such system: either around the capital or in the area of ICBM launchers.
After the conclusion of the treaty, the Spartan anti-missile missiles, which had been on alert for only a few months, were decommissioned in early 1976. Sprint interceptors as part of the Safeguard missile defense system were on alert in the vicinity of the Grand Forks airbase in North Dakota, where the Minuteman ICBM silo launchers were located. In total, the Grand Forks missile defense was provided by seventy atmospheric intercept missiles. Of these, twelve units covered the radar and anti-missile guidance station. In 1976 they were also taken out of service and mothballed. In the 1980s, Sprint interceptors without nuclear warheads were used in experiments under the SDI program.
The main reason for the abandonment of interceptor missiles by the Americans in the mid-70s was their dubious combat effectiveness at very significant operating costs. In addition, the protection of the deployment areas of ballistic missiles by that time no longer made much sense, since about half of the American nuclear potential was accounted for by ballistic missiles of nuclear submarines that were on combat patrols in the ocean.
Nuclear-powered missile submarines, dispersed under water at a considerable distance from the borders of the USSR, were better protected from surprise attacks than stationary ballistic missile silos. The time of putting into service of the Safeguard system coincided with the beginning of the rearmament of American SSBNs on the UGM-73 Poseidon SLBM with MIRVed IN. In the future, it was expected that the Trident SLBMs with an intercontinental range, which could be launched from any point in the oceans, were expected to be adopted. Given these circumstances, the missile defense of one ICBM deployment area, provided by the Safeguard system, seemed too expensive.
Nevertheless, it is worth recognizing that by the beginning of the 70s the Americans managed to achieve significant success in the field of creating both the missile defense system as a whole and its individual components. In the United States, solid-propellant missiles were created with very high acceleration characteristics and acceptable performance. Developments in the field of creating powerful radars with a long detection range and high-performance computers have become the starting point for the creation of other radar stations and automated weapons systems.
Simultaneously with the development of anti-missile systems in the 50-70s, work was carried out on the creation of new radars for warning of a missile attack. One of the first was the AN / FPS-17 over-the-horizon radar with a detection range of 1600 km. Stations of this type were built in the first half of the 60s in Alaska, Texas and Turkey. If radars located in the United States were erected to alert about a missile attack, then the AN / FPS-17 radar in Diyarbakir in southeastern Turkey was intended to track missile test launches at the Soviet Kapustin Yar range.
Radar AN / FPS-17 in Turkey
In 1962, in Alaska, near the Clear airbase, the AN / FPS-50 early warning missile warning system began operating, and in 1965 the AN / FPS-92 escort radar was added to it. The AN / FPS-50 detection radar consists of three antennas and associated equipment that monitors three sectors. Each of the three antennas monitors a 40-degree sector and can detect objects in space at a distance of up to 5000 km. One antenna of the AN / FPS-50 radar covers an area equal to a football field. The AN / FPS-92 radar parabolic antenna is a 26-meter dish hidden in a radio-transparent dome 43 meters high.
Radar AN / FPS-50 and AN / FPS-92
The radar complex at the Clear airbase as part of the AN / FPS-50 and AN / FPS-92 radars was in operation until February 2002. After that, it was replaced in Alaska with a radar with AN / FPS-120 HEADLIGHTS. Despite the fact that the old radar complex has not officially functioned for 14 years, its antennas and infrastructure have not yet been dismantled.
In the late 60s, after the appearance of strategic submarine missile carriers in the USSR Navy along the Atlantic and Pacific coasts of the United States, the construction of a radar station for fixing missile launches from the ocean surface began. The detection system entered service in 1971. It included 8 AN / FSS-7 radars with a detection range of more than 1,500 km.
Radar AN / FSS - 7
The AN / FSS-7 missile attack warning station was based on the AN / FPS-26 air surveillance radar. Despite its venerable age, several modernized AN / FSS-7 radars in the United States are still in operation.
Satellite image of Google Earth: radar AN / FSS-7
In 1971, the AN / FPS-95 Cobra Mist over-the-horizon station was built at Cape Orfordness in Great Britain with a design detection range of up to 5000 km. Initially, the construction of the AN / FPS-95 radar was supposed to be on the territory of Turkey. But after the Cuban missile crisis, the Turks did not want to be among the priority targets for a Soviet nuclear strike. Trial operation of the AN / FPS-95 Cobra Mist radar in the UK continued until 1973. Due to unsatisfactory noise immunity, it was decommissioned, and the construction of a radar of this type was subsequently abandoned. Currently, the buildings and structures of the failed American radar station are used by the British Broadcasting Corporation BBC to host a radio transmission center.
More viable was a family of long-range over-the-horizon radars with phased array, the first of which was the AN / FPS-108. A station of this type was built on Shemiya Island, near Alaska.
Radar AN / FPS-108 on Shemiya Island
Shemiya Island in the Aleutian Islands was not chosen as the site for the construction of the over-the-horizon radar station. From here it was very convenient to collect intelligence information about the tests of Soviet ICBMs, and track the warheads of tested missiles falling on the target field of the Kura test site in Kamchatka. Since its commissioning, the station on Shemiya Island has been modernized several times. It is currently being used in the interests of the United States Missile Defense Agency.
In 1980, the first AN / FPS-115 radar was deployed. This station with an active phased antenna array is designed to detect land-based and sea-based ballistic missiles and calculate their trajectories at a distance of more than 5000 km. The height of the station is 32 meters. Emitting antennas are placed on two 30-meter planes with an inclination of 20 degrees upward, which makes it possible to scan the beam within the range from 3 to 85 degrees above the horizon.
Radar AN / FPS-115
In the future, the AN / FPS-115 missile attack warning radars became the base on which more advanced stations were created: AN / FPS-120, AN / FPS-123, AN / FPS-126, AN / FPS-132, which are currently the basis of the American missile attack warning system and a key element of the national missile defense system under construction.
