Project Artemis

Project Artemis was a project undertaken by the United States Navy in the 1960s, which produced a low-frequency active sonar system that could detect submarines at long range. Robert A. Frosch, in his capacity as Technical Director of Hudson Laboratories (Columbia University), was technical director of the project. The theoretical and experimental studies were conducted by General Atronics Corp., Bala Cynwyd, PA. Dr. Frosch later went on to be the 5th administrator of NASA.

The active array was deployed from a ship, but only as a platform of convenience, since a permanent installation in deep water was extremely costly. The ship's purpose was station-keeping and the ability to orient itself. A World War II tanker, USNS Mission Capistrano was modified to carry the ultra‑high‑powered sonar transducer array. Upon completion of her conversion, she joined Project “Artemis”.

A 500-shaft horsepower, controllable-pitch screw propeller was installed in a transverse tunnel through the forefoot of the USNS Mission Capistrano. The propeller, commonly called a bow thruster, delivered 11,250 pounds of thrust during dock trials. Its use was for the single purpose of controlling the vessel's heading when lying to in the open ocean. Under these conditions, it is reported capable of swinging the ship to any given bearing and maintaining it to within one degree of yaw in sea conditions of 15 knot winds and five foot waves upon six foot swells.

The active portion of the Artemis array was 50 ft (15 m) by 33 ft (10 m) and weighed 400 tons. It consisted of 1440 individual transducers (200 pounds apiece) in a 48 by 30 configuration. The array was developed by Massa Products in Quincy, Massachusetts. The frequency range was 350 to 450 Hz, with a source level of 247 dBm (units? reference 0dB=?) and an acoustic power of 1 megawatt (10 times the sound power of a turbojet engine). The transducer could be raised and lowered like a centerboard through the ship’s bottom. The transducers could be deployed to a depth of 1,200 feet (370 m). The system was not meant to be mobile, and was only used when the ship was in station-keeping mode.

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