USNS Observation Island

USNS Observation Island (T-AGM-23) was built as the Mariner-class merchant ship Empire State Mariner for the United States Maritime Commission, launched 15 August 1953, and operated by United States Lines upon delivery on 24 February 1954, making voyages for the Military Sea Transportation Service (MSTS) until going into reserve at Mobile, Alabama on 9 November 1954.

Title was transferred to the United States Navy on 10 September 1956 and, after conversion, the ship was renamed Observation Island. On commissioning the ship was classified as the "experimental miscellaneous auxiliary" (EAG), USS Observation Island (EAG-154) supporting fleet ballistic missile development. Observation Island was the platform for the first at-sea firing of the Polaris missile in 1959. On 1 April 1968, Observation Island was redesignated as a miscellaneous auxiliary USS Observation Island (AG-154). She was the platform for the first at-sea firing of the Poseidon missile in 1969.

Observation Island was decommissioned and placed in reserve from 1972 until 1977 in the Suisun Bay Reserve Fleet until withdrawn and then returned in 1978. The ship was permanently withdrawn April 1979 and placed in service with MSTS successor, the Military Sealift Command (MSC).

The ship was classified in 1979 as the missile range instrumentation ship USNS Observation Island (T-AGM-23). Observation Island operated worldwide and monitored compliance with strategic arms treaties and supported U.S. military weapons test programs. Observation Island carried the United States Air Force AN/SPQ-11 Cobra Judy passive electronically scanned array radar system for collecting data on missile tests. The ship was operated by MSC for the Air Force Technical Applications Center at Patrick Air Force Base.

The ship served the MSC until her inactivation 25 March 2014 after her mission was taken over by USNS Howard O. Lorenzen.