USNS Observation Island monitors ballistic missile operations

Naval ship was instrumental in developing Polaris, Poseidon missiles

<?xml:namespace prefix = st1 ns = “urn:schemas-microsoft-com:office:smarttags” />USNS Observation Island monitors ballistic missile operations

By Edward Lundquist

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It seemed like a very ordinary cargo ship, one of many C4-S-A1 hulls built by the Maritime Administration at the start of the Cold War.  Launched in 1953, the Empire State Mariner made three voyages carrying general and military cargo for the Military Sea Transportation Service (today known as the Military Sealift Command or MSC), but was laid up in National Defense Reserve Fleet the following year.  The Navy acquired the ship in 1956, and it was converted for naval service, joining the fleet as USS Observation Island in 1958.


Observation Island was classified as EAG-152, for “Auxiliary, General.”  Her mission was to evaluate a new strategic weapon, the Polaris Fleet Ballistic Missile System.  The Polaris was to be test fired from Observation Island as the sea-going launch platform.  She served as an active commissioned ship until 1972 when she was transferred to the Military Sealift Command as T-AGM 23, assigned to the Special Mission Ships Program (PM2), with a civilian crew.


As an EAG, the 564-foot Observation Island displaced about 16,000 tons fully loaded and had a crew of 35 officers and 400 Sailors homeported at Cape Canaveral, Florida.  The ship was fitted with roll stabilization fins and an extensive suite of instrumentation, cameras and data-acquisition gear to monitor the Polaris tests.  The first test of a Polaris from a ship at sea was conducted on August 27, 1959.


“Though strictly a ‘test ship, the Observation Island will perform several most important missions,” said William M. Holaday, director of guided missiles for the Department of Defense during the ship’s commissioning ceremony at Norfolk Naval Shipyard in 1958.  “It will put together for the first time all elements of the Polaris Fleet Ballistic Missile (FBM) system in a sea-going ship and then test them in an ocean environment.  In doing so, it will perform a major service.”


The Polaris missile (the A1 model, designated the UGM-27) was first launched from a submerged submarine, the USS George Washington (SSBN 598), on July 18, 1960, 30 miles east of Cape Canaveral.  Observation Islandwas positioned nearby to observe and monitor the test firing.


Observation Island carried the Ship’s Inertial Navigation System (SINS) (developed aboard a sister ship, USS Compass Island (EAG 153)) as well as the Navigational Data Assimilation Center (NAVDAC), a “supercomputer” at the time, which used navigational data from SINS to create a ballistic fire control solution for the missile.  SINS permitted accurate position fixing without shore-based or celestial aids.  The value of this system was evident when USS Nautilus  (SSN 571) made a submerged transit of the North Pole, under the polar ice in August of 1958.



Observation Island was the test ship for the follow on A2 and A3 versions of the Polaris missile.  In June of 1963 she conducted the first successful at-sea launches of the A-3 Polaris.  President John F. Kennedy came on board Observation Island Nov. 16th  to observe a Polaris launch.


The Navyredesignated Observation Island an AG-154 on April 1, 1968, after undergoing a ten-month conversion at Norfolk Naval Shipyard to prepare her to support the Poseidon C-3 missile program. She returned to Port Canaveral, and resumed her duties of monitoring experimental missile launchings, training FBM submarine crews, and supporting FBM submarine shakedown operations.


Observation Island transferred to Military Sealift Command on Aug. 18, 1977 and reclassified as U.S. Naval Ship (USNS) Observation Island (T-AGM 23).


Between 1977 and 1981 Observation Island was converted to the Missile Range Instrumentation role (AGM) and fitted with the Cobra Judy AN/SPQ-11/G shipboard phased array radar and, during the mid-80s, fitted with the AN/TPQ-31A X-Band parabolic dish radar.  Still “active” after all these years, her current mission is treaty monitoring and verification of foreign strategic ballistic missile tests over the Pacific Ocean. 


The large octagonal structure aft contains the AN/SPQ-11/G S-Band phased array radar to detect and track Intercontinental Ballistic Missiles (ICBMs) for data collection and international treaty verification. The Cobra Judy octagonal S-Band phased array, comprising 12,288 antenna elements, is integrated into a mechanically rotating steel turret. The entire system weighs about 250 tons, stands more than 40 feet high.  The X-Band parabolic dish radar, located forward and above the S-Band phased array radar, collects more detailed track data.


Observation Island – more than 50 years old – is the oldest auxiliary in the Navy’s fleet and is not expected to serve beyond 2012.  To replace Observation Island, a new Missile Range Instrumentation Ship, designated T-AGM (R), will serve as the platform for the Cobra Judy Replacement (CJR) program.  Studies have indicated that a ship-based radar replacement is the most timely and cost-effective solution to the “problem” of treaty verification and monitoring and support to U.S. Navy FBM programs.  The CJR program will provide worldwide, high-quality, high-resolution, multi-wavelength radar data for monitoring missile launches and collecting data to improve missile efficiency and accuracy.  This program will fund the development of a single ship-based radar suite for worldwide technical data collection against ballistic missiles in flight. Prior funding provided instrumentation of quality radar data and imaging, detailing threat assessment of ballistic missile development, testing and range augmentation and monitored or verified specific aspects of U.S. treaties with other countries.  Like it’s predecessor, T-AGM (R) ship will also monitor compliance with strategic arms treaties and support U.S. military weapons test programs.


Observation Island continues her mission of monitoring missile shots.  Originally they were U.S. missiles, and today they are those fired by other countries.  Although the Navy considered launching ballistic missiles from battleships and cruisers, the only U.S. surface ship to ever fire a Polaris missile was USS Observation Island.




Edward Lundquist is a naval analyst and strategic communicator.  He is a retired U.S. Navy captain and is currently the director of corporate communications for the Center for Security Strategies and Operations, Anteon Corporation, Washington, D.C.



Photo with SSBN


Photo in white with domes

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