The middle star in the handle of the Great Dipper (Ursa Major).
(AK‑272: dp. 1,850 (lt.); l. 266'; b. 52'; dr. 18'; s. 13 k.; cpl. 42; cl. Eltanin)
The second Mizar (AK‑272) was laid down in January 1957 by Avondale Marine Ways, Inc., Avondale, La.; launched 7 October 1957; sponsored by Mrs. Roland N. Smoot; acquired by the Navy and placed in service 7 March 1958.
Mizar, a small ice‑strengthened cargo ship built for the Military Sea Transportation Service, completed her shakedown in time to join Arctic operations in the summer of 1958, resupplying the Dew line and military bases on Greenland and in the Canadian Arctic. The following year the new Polynya bubbling air system permitted her to close the operating season at Thule, Greenland on 18 October, 40 days later than usual.
In 1961, Mizar forced entry into St. George’s Bay, Newfoundland, in February, breaking through 5‑foot thick ice to deliver needed supplies to Harmon AFB. Later the same year she made her only voyage to Antarctica. With a load of helicopters and provisions she joined TG 43.1 at Littleton, New Zealand, early in November and steamed to McMurdo Bound. Led by icebreakers, Mizar entered the sound 28 November, almost a month earlier than previous arrivals of surface ships.
Two years later she commenced an extensive conversion and 15 April 1964 was reclassified AGOR‑11. The loss of the submarine Thresher had emphasized the need for ships capable of carrying out deep oceanographic search and research. Modified to tow a deepsea probe, equipped in part with strobe lights, cameras, sonar, and magnetometer, she soon found the hull of Thresher. In April 1966 Mizar played a key role in the location and recovery of an H‑bomb lost off Palomares, Spain.
Working primarily under the direction of the Naval Research Laboratory, Washington, D.C., her basic mission remains ocean floor study and service as a floating base for underwater acoustic, chemical, and biological research. Mizar, loaded with sensitive instruments, and with her additional accommodations for scientists frequently occupied, continues to serve science and the Navy. In October 1968, while operating southwest of the Azores, she discovered remnants of the nuclear‑powered submarine Scorpion (SSN‑589) overdue from patrol since 21 May 1968.