Hardtack I-Umbrella, 8-kilotons.Operation Hardtack I was a series of 35 nuclear tests conducted by the United States from April 28 to August 18, 1958, at the Pacific Proving Grounds.
United States LGM-118A Peacekeeper Intercontinental Ballistic Missile (ICBM) system & U.S. Air Force maintenance personnel training to remove and install the Avco MK-21 re-entry vehicles from the bus of a Peacekeeper missile.