The UGM-73 Poseidon missile was the second
US Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
nuclear-armed submarine-launched ballistic missile (SLBM) system, powered by a
two-stage solid-fuel rocket. It succeeded the
UGM-27 Polaris
The UGM-27 Polaris missile was a two-stage solid-fueled nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980.
In the mid-1950s the Navy was involved in the Jupiter missi ...
beginning in 1972, bringing major advances in warheads and accuracy. It was followed by
Trident I in 1979, and
Trident II in 1990.
Development
A development study for a longer range version of the Polaris missile—achieved by enlarging it to the maximum possible size allowed by existing launch tubes—started in 1963. Tests had already shown that Polaris missiles could be operated without problems in launch tubes that had their
fiberglass
Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...
liners and locating rings removed.
The project was given the title Polaris B3 in November, but the missile was eventually named Poseidon C3 to emphasize the technical advances over its predecessor. The C3 was the only version of the missile produced, and it was also given the designation UGM-73A.
Slightly longer and considerably wider and heavier than Polaris A3, Poseidon had the same range, greater payload capacity, improved accuracy, and
multiple independently targetable reentry vehicle (MIRV) capability. MIRV capacity has been given as up to either ten
or fourteen
W68
The W68 warhead was the warhead used on the UGM-73 Poseidon SLBM missile. It was developed in the late 1960s at Lawrence Livermore National Laboratory.
Specifications
The W68 weighed and had an official design yield of .
The design was revol ...
thermonuclear warheads
[Poseidon C3 at MissileThreat.com](_blank)
contained in Mark 3 reentry vehicles to multiple targets.
As with Polaris, starting a rocket motor when the missile was still in the submarine was considered very dangerous. Therefore, the missile was ejected from its launch tube using high pressure steam produced by a solid-fueled boiler. The main rocket motor ignited automatically when the missile had risen approximately above the submarine.
The first test launch took place on 16 August 1968, the first successful at-sea launch was from a surface ship, the (from July 1 to December 16, 1969), earning the ship the
Meritorious Unit Commendation, and the first test launch from a submarine took place on the on 3 August 1970. The weapon officially entered service on 31 March 1971. It eventually equipped 31 -, -, and -class submarines.
The Royal Navy also considered adopting Poseidon in the 1970s as an upgrade to its Polaris A3T boats, and like the US this would have kept the existing hulls. Although the Navy's favoured option, the British government instead adopted
Chevaline, a two warhead MRV system with decoys, on the existing Polaris airframes and later moved to the Trident D5 in new boats.
Beginning in 1979, 12 Poseidon-equipped
SSBNs were refitted with
Trident I. By 1992, the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
had collapsed, 12
Ohio-class submarine
The ''Ohio'' class of nuclear-powered submarines includes the United States Navy's 14 ballistic missile submarines (SSBNs) and its four cruise missile submarines (SSGNs). Each displacing 18,750 tons submerged, the ''Ohio''-class boats are the ...
s had been commissioned, and the
START I treaty had gone into effect, so the 31 older Poseidon- and Trident I-armed SSBNs were disarmed, withdrawing Poseidon from service.
Operators
*
**
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
Gallery
See also
*
List of missiles
Below is a list of missiles, sorted alphabetically into large categories and subcategories by name and purpose.
Other missile lists
Types of missiles:
* Conventional guided missiles
** Air-to-air missile
** Air-to-surface missile
** Anti-rad ...
References
{{Authority control
Cold War weapons of the United States
Nuclear weapons of the United States
Cold War submarine-launched ballistic missiles of the United States
Lockheed Corporation
UGM-073
Military equipment introduced in the 1970s