Editing UGM-27 Polaris (section)

== History and development ==
The Polaris missile replaced an earlier plan to create a submarine-based missile force based on a derivative of the [[United States Army|U.S. Army]] [[PGM-19 Jupiter|Jupiter]] [[Intermediate-range ballistic missile]]. [[Chief of Naval Operations]] Admiral [[Arleigh Burke]] appointed [[Rear Admiral]] [[William Raborn|W. F. "Red" Raborn]] as head of a Special Project Office to develop Jupiter for the Navy in late 1955. The Jupiter missile's large diameter was a product of the need to keep the length short enough to fit in a reasonably-sized submarine. At the seminal [[Project Nobska]] conference in 1956, with Admiral Burke present, [[Nuclear physics|nuclear physicist]] [[Edward Teller]] stated that a physically small one-megaton warhead could be produced for Polaris within a few years, and this prompted Burke to leave the Jupiter program and concentrate on Polaris in December of that year.<ref>{{cite book
  | last = Teller
  | first = Edward
  | title = Memoirs: A Twentieth Century Journey in Science and Politics
  | publisher = Perseus Publishing
  | year = 2001
  | location = Cambridge, Massachusetts
  | pages = [https://archive.org/details/memoirstwentieth0000tell/page/420 420–421]
  | url = https://archive.org/details/memoirstwentieth0000tell/page/420
  | isbn = 978-0-7382-0532-8
  | url-access = registration
  }}</ref><ref>Friedman, pp. 109–114.</ref> Polaris was spearheaded by the Special Project Office's Missile Branch under Rear Admiral Roderick Osgood Middleton,<ref name="[https://web.archive.org/web/20070715174818/http://www.usslittlerock.org:80/CO%20Data/Little_Rock_Middleton_Bio.html]">{{cite web |url = http://www.usslittlerock.org/CO%20Data/Little_Rock_Middleton_Bio.html |title = Navy Office of Information biography on Roderick Osgood Middleton |archive-url=https://web.archive.org/web/20070715174818/http://www.usslittlerock.org/CO%20Data/Little_Rock_Middleton_Bio.html |archive-date=15 July 2007 |url-status=dead}}</ref> and is still under the Special Project Office.<ref name="heroicrelics.org">{{cite web| url = http://heroicrelics.org/info/jupiter/jupiter-hist.html| title = History of the Jupiter Missile|pages=23–35}}</ref> Admiral Burke later was instrumental in determining the size of the Polaris submarine force, suggesting that 40–45 submarines with 16 missiles each would be sufficient.<ref name=HMIE>[http://www.gwu.edu/~nsarchiv/nukevault/ebb275/index.htm "How Much is Enough?": The U.S. Navy and "Finite Deterrence"], National Security Archive Electronic Briefing Book No. 275</ref> Eventually, the number of Polaris submarines was [[41 for Freedom|fixed at 41]].<ref>Friedman, pp. 196–197.</ref>

The {{USS|George Washington|SSBN-598|6}} was the first submarine capable of deploying U.S. developed [[submarine-launched ballistic missile]]s (SLBM). The responsibility of the development of SLBMs was given to the Navy and the Army. The Air Force was charged with developing a land-based intermediate range ballistic missile (IRBM), while an IRBM which could be launched by land or by sea was tasked to the Navy and Army.<ref name=":2">{{cite journal |last1=Miles |first1=Wyndham D. |title=The Polaris |journal=Technology and Culture |date=1963 |volume=4 |issue=4 |pages=478–489 |doi=10.2307/3101381 |jstor=3101381 |s2cid=260095128 }}</ref> The Navy Special Projects (SP) office was at the head of the project. It was led by Rear Admiral [[William Raborn]].<ref name=":2" />

On September 13, 1955, [[James R. Killian]], head of a special committee organized by President Eisenhower, recommended that both the Army and Navy come together under a program aimed at developing an [[Intermediate Range Ballistic Missile|intermediate-range ballistic missile]] (IRBM). The missile, later known as Jupiter, would be developed under the Joint Army-Navy Ballistic Missile Committee approved by Secretary of Defense [[Charles Erwin Wilson|Charles E. Wilson]] in early November of that year.<ref>{{Cite book|last1=von Braun|first1=Wernher|last2=I. Ordway III|first2=Frederick|date=1969 |title=History of Rocketry and Space Travel|url=https://archive.org/details/historyofrocketr0000vonb_s2x4|url-access=registration|location=New York|publisher=Thomas Y. Crowell Company|pages=[https://archive.org/details/historyofrocketr0000vonb_s2x4/page/128 128]–133}}</ref> The first IRBM boasted a [[Liquid-propellant rocket|liquid-fueled design]]. Liquid fuel is compatible with aircraft; it was considered less compatible with submarines in the West, even though in the [[Soviet Navy]] liquid-fuelled SLBMs, none of which used cryogenic components, were in overwhelming majority, and [[R-29RMU2]] is still in service with the [[Russian Navy]] {{as of|2021}} (it's expected to be phased out after 2030). Solid fuels, on the other hand, make logistics and storage simpler and are safer.<ref name=":2" /> Not only was the Jupiter a liquid fuel design, it was also very large; even after it was designed for solid fuel, it was still a whopping 160,000 pounds.<ref name="MacKenzie & Spinardi 1988"/>  A smaller, new design would weigh much less, estimated at 30,000 pounds. The Navy would rather develop a smaller, more easily manipulated design. Edward Teller was one of the scientists encouraging the progress of smaller rockets. He argued that the technology needed to be discovered, rather than apply technology that is already created.<ref name=":2" /> Raborn was also convinced he could develop smaller rockets. He sent officers to make independent estimates of size to determine the plausibility of a small missile; while none of the officers could agree on a size, their findings were encouraging nonetheless.<ref name=":2" />

=== Project Nobska ===
{{Main|Project Nobska}}
The U.S. Navy began work on nuclear-powered submarines in 1946. They launched the first one, the [[USS Nautilus (SSN-571)|USS Nautilus]] in 1955. Nuclear powered submarines were the least vulnerable to a first strike from the Soviet Union. The next question that led to further development was what kind of arms the nuclear-powered submarines should be equipped with.<ref>Istvan Hargittai. p. 357. ''Judging Edward Teller: A Closer Look at One of the Most Influential Scientists of the Twentieth Century'' {{ISBN?}}</ref> In the summer of 1956, the navy sponsored a study by the National Academy of Sciences on anti-submarine warfare at Nobska Point in Woods Hole, Massachusetts, known as [[Project Nobska|Project NOBSKA]]. The navy's intention was to have a new missile developed that would be lighter than existing missiles and cover a range up to fifteen hundred miles. A problem that needed to be solved was that this design would not be able to carry the desired one-megaton thermonuclear warhead.

This study brought [[Edward Teller]] from the recently formed nuclear weapons laboratory at Livermore and [[J. Carson Mark]], representing the Los Alamos nuclear weapons laboratory. Teller was already known as a nuclear salesman, but this became the first instance where there was a big betting battle where he outbid his Los Alamos counterpart. The two knew each other well: Mark was named head of the theoretical division of Los Alamos in 1947, a job that was originally offered for Teller. Mark was a cautious physicist and no match for Teller in a bidding war.<ref>Istvan Hargittai. p. 358. ''Judging Edward Teller: A Closer Look at One of the Most Influential Scientists of the Twentieth Century''</ref>

At the NOBSKA summer study, Edward Teller made his famous contribution to the FBM program. Teller offered to develop a lightweight warhead of one-megaton strength within five years. He suggested that nuclear-armed torpedoes could be substituted for conventional ones to provide a new anti-submarine weapon. Livermore received the project. When Teller returned to Livermore, people were astonished by the boldness of Teller's promise. It seemed inconceivable with the current size of nuclear warheads, and Teller was challenged to support his assertion. He pointed out the trend in warhead technology, which indicated reduced weight to yield ratios in each succeeding generation.<ref name="ReferenceA">Graham Spinardi. p. 30. ''From Polaris to Trident: The Development of U.S. Fleet Ballistic Missile Technology'' {{ISBN?}}</ref> When Teller was questioned about the application of this to the FBM program, he asked, ‘Why use a 1958 warhead in a 1965 weapon system?’<ref>William F. Whitmore, Lockheed Missiles and Space Division (Whitemore 1961, p. 263)</ref>

Mark disagreed with Teller's prediction that the desired one-megaton warhead could be made to fit the missile envelope within the timescale envisioned. Instead, Mark suggested that half a megaton would be more realistic and he quoted a higher price and a longer deadline. This simply confirmed the validity of Teller's prediction in the Navy's eyes. Whether the warhead was half or one megaton mattered little so long as it fitted the missile and would be ready by the deadline.<ref name="ReferenceA" /> Almost four decades later, Teller said, referring to Mark's performance, that it was “an occasion when I was happy about the other person being bashful.”<ref name="ReferenceA" />
When the Atomic Energy Commission backed up Teller's estimate in early September, Admiral Burke and the Navy Secretariat decided to support SPO in heavily pushing for the new missile, now named Polaris by Admiral Raborn.

There is a contention that the Navy's "Jupiter" missile program was unrelated to the Army program. The Navy also expressed an interest in Jupiter as an SLBM, but left the collaboration to work on their Polaris. At first, the newly assembled SPO team had the problem of making the large, liquid-fuel Jupiter IRBM work properly. Jupiter retained the short, squat shape intended to fit in naval submarines. Its sheer size and volatility of its fuel made it very unsuited to submarine launching and was only slightly more attractive for deployment on ships. The missile continued to be developed by the Army's German team in collaboration with their main contractor, Chrysler Corporation. SPO's responsibility was to develop a sea-launching platform with necessary fire control and stabilization systems for that very purpose. The original schedule was to have a ship-based IRBM system ready for operation evaluation by January 1, 1960, and a submarine-based one by January 1, 1965.<ref>Graham Spinardi. p. 27. ''From Polaris to Trident: The Development of US Fleet Ballistic Missile Technology'' {{ISBN?}}</ref>
However, the Navy was deeply dissatisfied with the liquid fuel IRBM. The first concern was that the cryogenic liquid fuel was not only extremely dangerous to handle, but launch-preparations were also very time-consuming. Second, an argument was made that liquid-fueled rockets gave relatively low initial acceleration, which is disadvantageous in launching a missile from a moving platform in certain sea states. By mid-July 1956, the Secretary of Defense's Scientific Advisory Committee had recommended that a solid-propellant missile program be fully instigated but not using the unsuitable Jupiter payload and guidance system.
By October 1956, a study group comprising key figures from Navy, industry and academic organizations considered various design parameters of the Polaris system and trade-offs between different sub-sections. The estimate that a 30,000-pound missile could deliver a suitable warhead over 1500 nautical miles was endorsed. With this optimistic assessment, the Navy now decided to scrap the Jupiter program altogether and sought out the Department of Defense to back a separate Navy missile.<ref>Graham Spinardi. p. 28. ''From Polaris to Trident: The Development of US Fleet Ballistic Missile Technology''</ref>
A huge surfaced submarine would carry four "Jupiter" missiles, which would be carried and launched horizontally.<ref>[https://www.usna.com/NetCommunity/SSLPage.aspx?pid=659&srcid=502 1946:1<!-- Bot generated title -->]{{dead link|date=December 2016}}</ref> This was probably the never-built [[SSM-N-2 Triton]] program.<ref>Friedman, p. 183</ref> However, a history of the Army's Jupiter program states that the Navy was involved in the Army program, but withdrew at an early stage.<ref name="heroicrelics.org" />

Originally, the Navy favored cruise missile systems in a strategic role, such as the [[Regulus missile]] deployed on the earlier {{USS|Grayback|SSG-574|6}} and a few other submarines, but a major drawback of these early cruise missile launch systems (and the Jupiter proposals) was the need to surface, and remain surfaced for some time, to launch. Submarines were very vulnerable to attack during launch, and a fully or partially fueled missile on deck was a serious hazard. The difficulty of preparing a launch in rough weather was another major drawback for these designs, but rough sea conditions did not unduly affect Polaris' submerged launches.

It quickly became apparent that solid-fueled ballistic missiles had advantages over cruise missiles in range and accuracy, and could be launched from a submerged submarine, improving submarine survivability.

The prime contractor for all three versions of Polaris was [[Lockheed Missiles and Space Company]] (now [[Lockheed Martin]]).
[[File:1960-07-21 First Polaris Firing By Submerged U-Boat.ogv|thumb|thumbtime=57|Universal International Newsreel of first Polaris submerged firing on 20 July 1960]]
The Polaris program started development in 1956. {{USS|George Washington|SSBN-598|6}}, the first U.S. missile submarine, successfully launched the first Polaris missile from a submerged submarine on July 20, 1960. The A-2 version of the Polaris missile was essentially an upgraded A-1, and it entered service in late 1961. It was fitted on a total of 13 submarines and served until June 1974. Ongoing problems with the [[W47|W-47 warhead]], especially with its mechanical arming and safing equipment, led to large numbers of the missiles being recalled for modifications, and the U.S. Navy sought a replacement with either a larger yield or equivalent destructive power. The result was the [[W58|W-58 warhead]] used in a "cluster" of three warheads for the Polaris A-3, the final model of the Polaris missile.

One of the initial problems the Navy faced in creating an SLBM was that the sea moves, while a launch platform on land does not. Waves and swells rocking the boat or submarine, as well as possible flexing of the ship's hull, had to be taken into account to properly aim the missile.

The Polaris development was kept on a tight schedule and the only influence that changed this was the USSR's launching of [[Sputnik]] on October 4, 1957.<ref name=":2" /> This caused many working on the project to want to accelerate development. The launch of a second Russian satellite and pressing public and government opinions caused Secretary Wilson to move the project along more quickly.<ref name=":2" />

The Navy favored an underwater launch of an IRBM, although the project began with an above-water launch goal. They decided to continue the development of an underwater launch, and developed two ideas for this launch: wet and dry. Dry launch meant encasing the missile in a shell that would peel away when the missile reached the water's surface.<ref name=":2" />  Wet launch meant shooting the missile through the water without a casing.<ref name=":2" /> While the Navy was in favor of a wet launch, they developed both methods as a failsafe.<ref name=":2" /> They did this with the development of gas and air propulsion of the missile out of the submerged tube as well.

The first Polaris missile tests<ref name=":2" /> were given the names “AX-#” and later renamed “A1X-#”. Testing of the missiles occurred:

*September 24, 1958: AX-1, at Cape Canaveral from a launch pad; the missile was destroyed, after it failed to turn into the correct trajectory following a programming-error.

*October 1958: AX-2, at Cape Canaveral from a launch pad; exploded on the launch pad.

*December 30, 1958: AX-3, at Cape Canaveral from a launch pad; launched correctly, but was destroyed because of the fuel overheating.

*January 19, 1959: AX-4, at Cape Canaveral from launch pad: launched correctly but began to behave erratically and was destroyed.

*February 27, 1959: AX-5, at Cape Canaveral from launch pad: launched correctly but began to behave erratically and was destroyed.

*April 20, 1959: AX-6, at Cape Canaveral from launch pad: this test was a success. The missile launched, separated, and splashed into the Atlantic 300 miles off shore.

It was in between these two tests that the inertial guidance system was developed and implemented for testing.

*July 1, 1959: AX-11 at Cape Canaveral from a launch pad: this launch was successful, but pieces of the missile detached causing failure. It did show that the new guidance systems worked.

=== Guidance ===
At the time that the Polaris project went live, submarine navigation systems accuracy was adequate for existing weapons systems. Initially, developers of Polaris were set to utilize the existing 'Stable Platform' configuration of the inertial guidance system. Created at the MIT Instrumentation Laboratory, this Ships Inertial Navigation System (SINS) was supplied to the Navy in 1954.<ref name="MacKenzie & Spinardi 1988">{{cite journal |last1=MacKenzie |first1=Donald |last2=Spinardi |first2=Graham |title=The Shaping of Nuclear Weapon System Technology: US Fleet Ballistic Missile Guidance and Navigation: I: From Polaris to Poseidon |journal=Social Studies of Science |date=August 1988 |volume=18 |issue=3 |pages=419–463 |doi=10.1177/030631288018003002 |s2cid=108709165 }}</ref> The developers of Polaris encountered many issues from the outset of the project, including the outdated technology of the gyroscopes they would be implementing.

This 'Stable Platform' configuration did not account for the change in gravitational fields that the submarine would experience while it was in motion, nor did it account for the ever-altering position of the Earth. This problem raised many concerns, as this would make it nearly impossible for navigational readouts to remain accurate and reliable.  A submarine equipped with ballistic missiles was of little to no use if operators had no way to direct them.  The Polaris developers then turned to a guidance system that had been abandoned by the U.S. Air Force, the XN6 Autonavigator. Developed by the [[Autonetics]] Division of North American Aviation for the U.S. Air Force [[SM-64 Navaho|Navaho]], the XN6 was a system designed for air-breathing [[cruise missiles]], but by 1958 had proved useful for installment on submarines.<ref name="MacKenzie & Spinardi 1988"/>

A predecessor to the [[Global Positioning System|GPS]] satellite navigation system, the [[Transit (satellite)|Transit system]] (later called NAVSAT), was developed because the submarines needed to know their position at launch in order for the missiles to hit their targets. Two American physicists at [[Johns Hopkins University|Johns Hopkins]]'s [[Applied Physics Laboratory]] (APL), William Guier and George Weiffenbach, began this work in 1958. A computer small enough to fit through a submarine hatch was developed in 1958, the [[AN/UYK-1]]. It was used to interpret the Transit satellite data and send guidance information to the Polaris, which had its own guidance computer made with ultra miniaturized electronics, very advanced for its time, because there wasn't much room in a Polaris—there were 16 on each submarine. The Ship's [[Inertial Navigation System]] (SINS) was developed earlier to provide a continuous [[dead reckoning]] update of the submarine's position between position fixes via other methods, such as [[LORAN]]. This was especially important in the first few years of Polaris, because Transit was not operational until 1964.<ref>{{cite web| url = http://techdigest.jhuapl.edu/td/td1901/danchik.pdf| title = Danchik, Robert J., "An Overview of Transit Development", pp. 18–26| access-date = 2014-10-22| archive-date = 2017-08-21| archive-url = https://web.archive.org/web/20170821140444/http://techdigest.jhuapl.edu/td/td1901/danchik.pdf| url-status = dead}}</ref> By 1965 microchips similar to the [[Texas Instruments]] units made for the [[Minuteman II]] were being purchased by the Navy for the Polaris. The Minuteman guidance systems each required 2000 of these, so the Polaris guidance system may have used a similar number. To keep the price under control, the design was standardized and shared with [[Westinghouse Electric Company]] and [[RCA]].  In 1962, the price for each Minuteman chip was $50. The price dropped to $2 in 1968.<ref>{{cite book
| title=The Innovators: How a Group of Inventors, Hackers, Geniuses, and Geeks Created the Digital Revolution
| publisher=Simon & Schuster
| year=2014
| pages=181–182| title-link=The Innovators: How a Group of Inventors, Hackers, Geniuses, and Geeks Created the Digital Revolution
}}</ref>

=== Polaris A-3 ===
[[File:Polaris-Poseidon family of SLBMs.jpg|thumb|Polaris A-1 to A-3, Poseidon]]
[[File:DominicFrigateBirdPolaris.gif|thumb|Polaris A-3 [[Operation Dominic]]. Only full-scale US test of a strategic missile system.]]
This missile replaced the earlier A-1 and A-2 models in the [[U.S. Navy]], and also equipped the British Polaris force. The A-3 had a range extended to {{convert|2500|nmi|km|abbr=off}} and a new weapon bay housing three Mk 2 re-entry vehicles (ReB or Re-Entry Body in U.S. Navy and British usage); and the new W-58 warhead of 200&nbsp;[[kiloton|kt]] yield. This arrangement was originally described as a "cluster warhead" but was replaced with the term Multiple Re-Entry Vehicle (MRV). The three warheads, also known as "bomblets", were spread out in a "shotgun" like pattern above a single target and were not independently targetable (such as a [[MIRV]] missile is). The three warheads were stated to be equivalent in destructive power to a single one-megaton warhead due to their spread out pattern on the target. The first Polaris submarine outfitted with MRV A-3's was the [[USS Daniel Webster (SSBN-626)|USS ''Daniel Webster'']] in 1964.<ref>{{Cite book|title=The U.S. nuclear arsenal : a history of weapons and delivery systems since 1945|last=Polmar, Norman.|date=2009|publisher=Naval Institute Press|others=Norris, Robert S. (Robert Stan)|isbn=978-1557506818|location=Annapolis, Md.|oclc=262888426}}</ref> Later the Polaris A-3 missiles (but not the ReBs) were also given limited hardening to protect the missile electronics against [[nuclear electromagnetic pulse]] effects while in the [[boost phase]]. This was known as the A-3T ("Topsy") and was the final production model.