Martin Marietta Sprint
The Sprint was a nuclear-armed point defense ABM (Anti-Ballistic Missile), which was developed in the 1960s as one component of an American defense system against Soviet ICBMs. It was operational for a very short time in 1975.
In the late 1950s, the U.S. Army began the development of the XLIM-49A Nike Zeus B exo-atmospheric anti-ballistic missile. While it was definitely desirable to intercept ICBMs at the highest possible altitude to minimize the contamination effects of the interceptor missile's thermonuclear warhead, it was also clear that a terminal defense missile would be needed to catch those reentry vehicles which slipped past the "first line" of defense. After studies in the early 1960s showed that a very-high speed interceptor missile was feasable, Martin Marietta received a development contract for the Sprint missile in March 1963. Component testing began in early 1964, including launches of Squirt experimental missiles. The first Sprint launch occured at WSMR (White Sands Missile Range) in November 1965, and Sprint tests continued at WSMR through 1970.
The cone-shaped Sprint missile was powered by a two-stage solid-propellant rocket motor. The motor ignited after the missile had been ejected from its silo by gas pressure, and accelerated the Sprint with more than 100 g. Within seconds, the missile reached a speed of Mach 10+, and the extreme thermodynamic heating demanded sophisticated ablative shielding (the nose was already glowing red-hot less than a second after launch). The Sprint was guided to the target by radio-commands from the ground control system, which used high-speed phased-array MSRs to track the incoming ICBM reentry vehicles. The command uplink had to be powerful enough to work through the exhaust plume and the plasma sheathe around the missile body. Sprint's first stage used fluid-injection jet vanes for control, and the second stage had four small moving fins. The missile was armed with a 1 kT W-66 enhanced radiation thermonuclear warhead, which was detonated by ground command. It destroyed the target's warhead not only with the nuclear blast, but mainly with the very high neutron flux. The whole flight time for an intercept was expected to be not more than 15 seconds.
Full scale testing of the Sprint and the MSR (Missile Site Radar) began in mid-1970, and the first successful intercept of a reentry vehicle by a Sprint occurred in December 1970. A total of about 50 flight tests, the majority being successful, were conducted between this date and December 1973.
During the 1960s, the initially planned nation-wide ABM system had been reduced in scope for cost reasons (see also article about LIM-49 Spartan). The final plan, introduced in 1969, was called Safeguard, an ABM system to defend only SAC's ICBM bases, and not the cities of the United States. The SALT I treaty of 1972, and a 1974 addendum, limited Safeguard to only one site with 100 ABMs. On 1 October 1975, the U.S.'s one and only Safeguard ABM site became operational with 30 LIM-49A Spartan and 70 Sprint missiles. However, because the very limited defense offered by a single ABM site did not warrant the costs, the site was deactivated by Congress the next day. About 150 Sprint missiles were built for flight tests and operational deployment.
In May 1971, Martin Marietta had received a contract for an improved missile called Sprint II. This variant would have had an improved guidance system, higher agility and improved reliability, but the Sprint II program did apparently not result in any flight tests. Studies of nuclear armed ABMs were finally ended in 1983.
Designation Note: Several sources (including [2]) explicitly say that Sprint never received a formal missile designation (LIM-nnn). However, it is possible that one of the designations XLIM-99A and XLIM-100A, which were reserved in October 1972, was in fact planned for Sprint (but not taken up for unknown reasons).
Specifications
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for Sprint:
Length 8.20 m (26 ft 11 in)
Diameter 1.35 m (4 ft 5 in)
Weight 3500 kg (7700 lb)
Speed Mach 10+
Ceiling 30000 m (100000 ft)
Range 40 km (25 miles)
Propulsion 1st stage: Hercules X-265 solid-fueled rocket; 2900 kN (650000 lb) for 1.2 s
2nd stage: Hercules X-271 solid-fueled rocket
Warhead W-66 thermonuclear (1 kT)
Main Sources
[1] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[2] Bill Gunston: "The Illustrated Encyclopedia of Rockets and Missiles", Salamander Books Ltd, 1979
[3] R.T. Pretty, D.H.R. Archer (eds.): "Jane's Weapon Systems 1972-73", Jane's, 1973
[4] Mark Paine: Nuclear ABMs of the USA
http://www.designation-systems.net/d...p4/sprint.html
Safeguard
On the 14th March 1969, Nixon announced another change in the deployment of the ABM system which was called Safeguard. This consisted of 12 installations of both Spartan and Sprint missiles and provided a limited defence against incoming ballistic missiles and fractional-orbit bombardment missiles (FOBS). Even this reduced ABM system meet stiff political opposition with the US congress approving it by only the deciding vote of Vice-President Spiro Agnew on 6 August 1969. This initial Phase I deployment consisted of two sites for the protection of the Minutemen ICBM missiles. The sites selected for this first phase were Malmstrom AFB in Montana and Grand Forks AFB in North Dakota.
Phase II deployment consisted of construction of a Safeguard site at Whiteman AFB Missouri, and for advanced construction works at Warren AFB Wyoming. This Phase II, which also consisted of missile inventories for the Phase I sites, was approved in December 1970. However, advanced preparation for another four sites was not approved.
In November 1971, funding was provided for system studies for the installation of a site to protect Washington DC so that the National Command Authority could be protected. Beyond these studies, no further work was ever done for a site to protect the US national capital.
It was early in the 1970s that diplomatic efforts between the USA and the Soviet Union started to pave the way for limited disarmament and arms control. The first of these was the SALT I agreement which limited each country to two 100 ABM missile sites. As a result, in May 1972 all construction work at Montana was suspended as it was some 19 months behind the construction work at Grand Forks. The SALT agreement was further amended on 3 July 1974 to a single ABM site which could either protect the nations capital or an ICBM site.
The installation at Grand Forks reached initial operational condition in April 1975 with 28 Sprint and 8 Spartan missiles. It was declared fully operational on 1 October 1975 with 70 Sprint and 30 Spartan missiles.
On 2 October 1975, the US Congress voted to shut down the system. A final bill was passed in November 1975 that allowed the PAR to continue to function, but the MSR was to be turned off, and the missiles disarmed and removed. Starting in February 1976, the US Army shut down the MSR and started to remove the warheads from the missiles as well as removing the missiles from their launching cells. The site had barely operated for 5 months.
It seems strange that the US Congress voted to shut the system down after it had been operational for barely 24 hours. The were many reasons why it was done. Many were political, and some were technological. It had been known for many years, that the system could be overwhelmed by the Soviets if they used multiple warheads on their missiles - the Soviets were arming their missiles with MIRVs. It was also felt that the huge radars were very vulnerable to attack and represented a critical failure point of the system, even though they had been designed with highly redundant systems and hardened against nuclear attack. Although these were well known problems with the Safeguard system, and all other systems before that, Congress just lost the ability to continue to support it.
Stanley R. Mickelson Complex
The Grand Forks installation was known as the Stanley R. Mickelson complex and was located approximately 160km (100 miles) northwest of Grand Forks. It was designed to protect the 150 Minuteman missiles located in that area as well as provide some defence to the civilian population of that area.
Only one PAR was constructed and was located near Cavalier in North Dakota some 40km (25 miles) north east of the missile site, while the MSR was located near the town of Nekoma, North Dakota.
Testing of the PAR at North Dakota began in August 1972 with it successfully tracking a satellite some 12 months later. It was not until another year later that the PAR Operational Acceptance test had been completed. Meanwhile the MSR started its tests in January 1973 with it successfully tracking a satellite in December of that year. Autonomous tests of the MSR were completed in June 1974 which when combined with the PAR tests permitted the entire installation to be handed over to the US Army in October 1974 on schedule.
Safeguard Developments
An active program during 1969 until 1972 was called Safesam which involved combining Safeguard sites and SAM-D (which later became Patriot) together to protect American cities. Another program which involved a bit more money was the Site Defence of Minuteman (SDM). This was basically the Sprint II missile program and was active during 1971-1974. SDM was developed into the Low Altitude Defence (LoAD) in 1979 for the protection of the MX missile. LoADS then became the Sentry system in June 1982. It was during 1983 that the connection to the nuclear ABM missiles was finally broken as a non-nuclear ABM system became more important in the area of politics and the Department of Defence.
http://www.nuclearabms.info/HSafeguard.html
Sentinel
Defence Secretary McNamara announced on 18th September 1967 plans for the Sentinel ABM defence system. This replaced the Nike X system and changed its focus from a general US defence to one of protecting against Chinese missile attack. At the time the Chinese were exploding nuclear devices and it was felt that they would have an ICBM capability around 1970.
There were a number of reasons for the US to switch to a Chinese threat. It allowed them to continue talks with the Soviets about arms reduction, handling a Chinese threat also presented a fewer number of targets that the ABM system was required to intercept when compared to a Soviet attack and also, it provided defence against a rogue missile launching either from the Soviets or Chinese or anyone else who decided to launch a missile to the US. It was essentially a system designed to be non-threatening to the Soviets.
Sentinel was a wide ranging system which consisted of a number of PARs across the northern boundary of the US as well as Alaska. MSRs were also located in at 13 locations in the US as well as in Alaska and Hawaii, with both Spartan (which was the name given to the Nike-EX missile) and Sprint missiles. The Hawaiian installation was the only site that did not have any Spartan missiles. The entire system had an estimated price tag of $5 billion which did not include R&D or operation and maintenance costs.
Opposition for the ABM was gradually increasing within the US. Vietnam was in full swing and was diverting a lot of funds from other projects and also increasing public opinion away from military projects. Late in 1968 (just as Nixon was elected President), public demonstrations in Seattle, Chicago and Boston about the deployment of nuclear missiles in their back yards started with earnest. An Army community relations meeting was held in Boston on January 29, 1969, where opponents to Sentinel were able to voice their concerns. As a result, Senator Edward Kennedy wrote a letter to the Defence Secretary Melvin Laird questioning the value of Sentinel. As a result of these demonstrations and meetings, construction at the Sharpner's Road site near Boston was halted.
In February 1969 President Nixon suspended Sentinel and ordered a review of the program. Barely a month later, it's deployment was redesigned and after being alive for only 18 months, Sentinel was declared dead and it was replaced with a new deployment which was called Safeguard.
http://www.nuclearabms.info/HSentinel.html
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