Initial construction and early history The keel for SS
George Calvert (build number 2007/MC Hull 20) was laid on 15 August 1941 in the
Bethlehem-Fairfield Shipyard,
Baltimore, Maryland. She was launched 30 December 1941, sponsored by Miss Margaret E. Voss. At 65.4% complete, she was transferred for conversion to a training vessel. She had additional
superstructure added to accommodate more personnel and was renamed TS
American Mariner. The conversion was completed 10 March 1943 and she was delivered to the
War Shipping Administration – Division of Training. She then served the
U.S. Coast Guard as a
cadet training ship, together with SS
American Seaman and SS
American Sailor. After this service to the U.S. Coast Guard she was placed in a standby status on the
Hudson River as she was no longer needed for the war effort. In 1950 she was transferred to the
United States Merchant Marine Academy in
Kings Point, New York for use as a training ship. She was returned to the
Hudson River reserve fleet on 9 December 1953.
Conversion to missile tracking ship On 18 June 1958 she was removed from the
Hudson River, and transferred to the U.S. Army. and outfitted in early 1959 with state-of-the-art C-band-frequency narrow-beam radar tracking equipment for the Army. The ship, re-designated USAS
American Mariner, was then assigned to Mathiesen Tankers Industry, which provided the crew for the ship, and to
RCA Service Company, which provided the necessary
radar and computer equipment and technical personnel, and Barnes Engineering Company, which provided the necessary
optical equipment and technical personnel for the ship's new
DAMP Project assignment.
Atlantic missile test operations During her years on the
DAMP Project USAS
American Mariner operated various types of long-distance, narrow-beam radars to gather data on intercontinental ballistic missiles. This period (1959–1963) represented the infancy of the "space race" and ballistic missiles in particular, and it was necessary, for security reasons, for the U.S. to determine if missiles could be identified in space (from a radar signature, for example) before they re-entered the atmosphere. Her home berth was
Port Canaveral during this period. It was hoped that various types of missiles would provide different radar signatures, something not known at the time. This would be important for distinguishing American missiles from those of other countries. This, if such data could be provided and fed into the computers of that era, would lead to the development of American anti-ballistic-missile defense systems, such as Nike-Zeus, which was a part of
Project Nike. During her Atlantic Ocean operations, USAS
American Mariner gathered radar signature data of ballistic missiles launched by the
Cape Canaveral Air Force Station into the Broad Ocean Area located off of the coast of Florida, as well as intercontinental ballistic missiles launched into the South Atlantic Ocean near
Ascension Island. Collection of signature data of each missile type was important during the in-flight portion of the missile. This was especially true during the missile re-entry as the missile descended through the atmosphere to its designated target point in the ocean, which is where USAS
American Mariner was usually positioned with its narrow-beam radars activated and searching in order to "lock on" to the missile. Tracking of missiles during re-entry was often difficult since, at times, the missile contained decoy pods which would be ejected during re-entry to deceive tracking personnel at the target test location. As a result, it was difficult to ensure that the vessel's radars were tracking the actual vehicle and not one of the decoys. The decoys were intended to deceive the "enemy" and not necessarily the test vessel's radars; however, those who designed the decoys needed to know how effective they actually were. All such data was very important at this critical time in early space and missile development during the early years of the "
Cold War. The primary tracking radars were CBAND radars, which once locked onto their target were accurate within at a distance of . These radars, however, could not search for targets on their own, requiring that they be designated to their target area by computers. There were two designation computers, one was a digital computer named RADAP, for Radar Designation, Acquisition, and Programmer(a militarized version of the commercial RCA 601), and an Analog computer, both used to point the radars to their target vicinity prior to actual lock-on"
Pacific missile test operations In the Pacific Ocean in 1962,
American Mariner gathered radar signature data of missiles launched during
Operation Dominic and
Operation Fishbowl atmospheric nuclear testing. The ship operated in the
Johnston Island area and, during one major test, the nuclear event exploded in the upper atmosphere directly over the vessel in order to determine if the radars on the USAS
American Mariner could track and identify missiles in the nuclear cloud. The cloud itself was "mapped" by the very large ( diameter) L-Band radar system employed. The photo to the right shows the L-Band radar dish straddled by the twin C-Band radar dishes. While investigating reports of foreign missile testing in the North Pacific Ocean in November 1962, USAS
American Mariner became caught up in
Typhoon Karen, which caused significant rolling, and some flooding, of the top heavy ship, which was quickly repaired. After completing test operations in the Pacific Ocean, USAS
American Mariner navigated to the North Pacific where it investigated and tracked Russian missile tests, after which it returned to the
Eastern Test Range in the Atlantic Ocean, by transiting the
Panama Canal in January 1963.
Support of NASA While in the Pacific Ocean, USAS
American Mariner was temporarily assigned in late September 1962 to
NASA in support of NASA's
Project Mercury. During
Wally Schirra's
MA-8 transits over the Pacific Ocean, USAS
American Mariner successfully provided radar track of the capsule. While assigned to this mission, all data provided by the ship's radars was processed by the RADAP computer which produced tape output which was then transmitted via teletype to mission control in accordance with NASA mission principles. The data provided a prediction of splashdown location, enabling the aircraft carrier Kearsarge to sail to that location, facilitating recovery of the capsule.
Vessel support . While performing her missile-tracking operations,
American Mariner was re-provisioned in various ports in both the Atlantic and Pacific Oceans: In the Atlantic Ocean, shore-side support was generally provided at
San Juan, Puerto Rico;
Antigua Island; Chagaramus,
Trinidad;
Recife, Brazil;
Monrovia, Liberia;
Dakar, Senegal; and
Cape Town, South Africa. During Pacific Ocean operations, support, including logistics, mail, embarkation and transfer of technical personnel, occurred at
Pearl Harbor, in Hawaii, at
Midway Island, and at
Johnston Island.
Vessel and equipment overhaul Since
American Mariner remained at sea for approximately four years under U.S. Army service, the ship regularly required shipyard service on her hull and her electronic equipment. Extensive shipyard overhauls and drydocking were conducted in
Brooklyn, New York;
Baltimore, Maryland;
San Juan, Puerto Rico;
Long Beach, California;
Pearl Harbor, Hawaii and
Dakar in Senegal, Africa. Extensive technical enhancements in equipment [ L-band and UHF-band radar dish installation] were conducted in
Cape Town, South Africa with the assistance of local technical personnel. Prior to participating in nuclear testing operations during the Spring and Fall of 1962 under
Operation Dominic, USAS
American Mariner was outfitted at
Pearl Harbor, Hawaii, with protective anti-radiation equipment, including emergency warning lights and a water spraying system that, when turned on during an atomic event, would cover the ship with a fine spray of water intended to remove and wash away nuclear contamination.
Retirement The operations of
American Mariner, a radar-signature data gathering ship, was replaced, in mid-1964, by two U.S. Air Force ships, and , both Advanced Research Instrumentation Ships (ARIS) which gathered and provided metric data to the Air Force. These ships were based in Cape Canaveral. == Fate ==