UGM-73 Poseidon

Infobox Weapon
is_missile=yes
name = UGM-73A Poseidon C3


type = Strategic SLBM
vehicle_range = With MIRV: 2,500 nm, With RV: 3,200 nm
filling = 10 or 14 W-68 warheads of approx 50 kt yield in Mark 3 MIRVed RVs. 500 kt total |yield.
engine = Two-stage solid-propellant rocket, each single nozzle with thrust-vectoring
guidance = Inertial
cep = 0.3 nm (550 m)
speed = 8000 mph (12900 km/h) (terminal phase)
length = 34 feet 1.2 inches (10.39 m)
diameter = 74 inches (1.88 m)
weight = 64400 pounds
payload_capacity =
manufacturer = Lockheed Martin Space Systems
unit_cost =
service = 31 March, 1971 to September 1992 (Trident I phased in from October 1979)
used_by = United States

The Poseidon missile was the second US Navy ballistic missile system, powered by a two-stage solid fuel rocket. It succeeded the Polaris missile beginning in 1972, bringing major advances in warheads and accuracy. It was followed by Trident I in 1979, and Trident II in 1990.

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 which had their fiberglass liners and locating rings removed.

The project was given the title Polaris B3 in November, but the missile was eventually named Poseidon C3 to emphasis 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. [ [http://www.spaceline.org/rocketsum/poseidon-c3.html Poseidon C3 at Spaceline.com] ]

Poseidon, although slightly longer and considerably wider and heavier than Polaris A3, had the same 4600 km (2500 nautical mile) range, although with increased payload weight. It also had improved accuracy and up to fourteen W68 thermonuclear warheads [ [http://www.missilethreat.com/missilesoftheworld/id.92/missile_detail.asp] ] contained in Mk.3 reentry vehicles that were of a new MIRVed high-re-entry-speed design intended to counter sprint-type terminal ABM defenses. See Atmospheric re-entry for blunt body theory.

The low-yield warheads were apparently selected to make the weapon unsuitable as a first-strike weapon against hardened targets in the Soviet Union, [ [http://www.designation-systems.net/dusrm/m-73.html] ] but could be used in a retaliatory strike against soft targets, or in a pre-emptive strike against unhardened surface targets such as airfields, SAM sites, radar sites and other similar targets, opening a pathway for heavy bombers. In later years this targeting technique has been demonstrated by the use of cruise missiles to neutralize airfields, SAM sites etc in the opening phases of the Gulf War. Similarly a new more accurate celestial/intertial guidance system was not developed because it was feltFact|date=February 2007 a highly accurate invulnerable weapon might destabilize the nuclear deterrence balance with the Soviet Union. [ [http://www.designation-systems.net/dusrm/m-73.html Designation-Systems.Net] ]

As with Polaris, starting a rocket motor when the missile was still in the submarine was considered very dangerous. The missile was ejected from its launch tube using high pressure steam produced by a solid-fueled boiler.

The first test launch took place on 16 August, 1968 whilst the first test launch from a submarine took place on the USS "James Madison" on 3 August 1970. The weapon officially entered service on 31 March 1971. It eventually equipped all 10 "Lafayette"-class submarines, the submarines' original Polaris outfit being replaced with Poseidon during refits.

About 620 UGM-73A missiles were built between 1970 and 1978. [ [http://www.designation-systems.net/dusrm/m-73.html Designation-Systems.Net] ]

Operators

*USA
**United States Navy

References

ee also

* List of missiles