USNS Mizar (MA-48/T-AGOR-11/T-AK-272) was a vessel of the United States Navy. She was named after the star Mizar.
Mizar was built as a small ice-strengthened cargo ship of the Eltanin class on a Maritime Administration type (C1-ME2-13a) hull, by Avondale Marine Ways, Inc. from January 1957. She entered service on March 7, 1958 and served as part of the Military Sea Transportation Service, working around Canada and Greenland, with a single voyage to Antarctica in 1961.
In 1963 she was chosen for a major conversion. On April 15, 1964 she was reclassified AGOR-11, designed for deep oceanographic search and research and fitted with a deepsea probe, equipped with strobe lights, cameras, sonar, and magnetometer. She was then operated by the MSTS under the Naval Research Laboratory, Washington. Her major tasks were ocean floor study and service as a floating base for underwater acoustic, chemical, and biological research.
She was assigned to Military Sealift Command Pacific in 1975 and underwent another major modification in 1980.
Mizar took part in the search operations for USS Thresher (SSN-593), the Palomares Incident in which nuclear weapons were lost off Palomares, Spain, and the extended search for USS Scorpion (SSN-589) - which was found in October, 1968. She has also taken part in searches for foreign wrecks, including Eurydice and Soviet submarines including K-129.
She was withdrawn from active service in the 1990s and reclassified as AK-272. Bay Bridge Enterprizes, LLC, was awarded a contract for the dismantling and recycling of Mizar on 21 July 2005.