[1][4] On commissioning the ship was classified as the "experimental miscellaneous auxiliary" (EAG), USS Observation Island (EAG-154) supporting fleet ballistic missile development.

[4] 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.

However, extensive alterations were accomplished in the superstructure and hold areas so as to accommodate the Fleet Ballistic Missile (FBM) Weapons System.

[1] In March 1959, Observation Island returned to Norfolk Naval Shipyard for installation of additional equipment, including the Ships Inertial Navigation System (SINS).

[1] Following this milestone, Observation Island returned to Norfolk Naval Shipyard for installation of a fire control system to enable her to launch more sophisticated guided versions of new generation Polaris missiles.

She provided optical and electronic data gathering services, and acted as communications relay station between submerged submarines and the supervisor of range operations at the Cape.

The first successful fully guided Polaris missile launching from a submerged submarine took place 20 July 1960 from USS George Washington (SSBN-598).

[1] Following further modifications at Norfolk Naval Shipyard in the fall of 1960, Observation Island returned to Port Canaveral in December to continue fleet ballistic missile support work and systems test and evaluation.

[1] In late 1961, Observation Island served as a survey ship on the Atlantic Missile Range, and in January 1962 she again put in at Norfolk Naval Shipyard, this time for modifications preparatory to launching the new A-3 Polaris.

She commenced an extensive ten month conversion 24 June at Norfolk Naval Shipyard in preparation for support of the Poseidon C-3 missile program.

[3] The ship underwent a number of modifications including the installation of the AN/SPQ-11 Cobra Judy passive electronically scanned array radar which was used for verification of strategic arms treaties.