Operation Hardtack - Military Effects Studies Part 4

Operation Hardtack II was a 37-test continental series conducted from September 12 to October 30, 1958, at the Nevada Test Site. Addressing the concerns about fallout from atmospheric tests, more than a third of the Hardtack II tests were conducted underground and had yields that did not exceed 22 kilotons. When the Hardtack series concluded, test ban negotiations between the United States and the Soviet Union were underway in Geneva. These negotiations resulted in a testing moratorium from late 1958 until September 1961. Hardtack II personnel tested nuclear devices for possible inclusion in the nuclear stockpile; evaluated safety features of nuclear devices; and evaluated containment techniques for underground detonations. The safety experiments were designed to determine the stability of nuclear devices during transportation and storage. The tests comprising the 1958 Operation Hardtack II were as follows: OTERO, September 12, shaft, safety experiment, 38 tons BERNALILLO, September 17, shaft, safety experiment, 15 tons EDDY, September 19, balloon, weapons related, 83 tons LUNA, September 21, shaft, safety experiment, 1.5 tons MERCURY, September 23, tunnel, safety experiment, slight yield VALENCIA, September 26, shaft, safety experiment, 2 tons MARS, September 28, tunnel, safety experiment, 13 tons MORA, September 29, balloon, weapons related, 2 kilotons (kt) COLFAX, October 5, shaft, safety experiment, 5.5 tons HIDALGO, October 5, balloon, safety experiment, 77 tons TAMALPAIS, October 8, tunnel, weapons related, 72 tons QUAY, October 10, tower, weapons related, 79 tons LEA, October 13, balloon, weapons related, 1.4 kt NEPTUNE, October 14, tunnel, safety experiment, 115 tons HAMILTON, October 15, tower, weapons related, 1.2 tons LOGAN, October 16, tunnel, weapons related, 5 kt DONA ANA, October 16, balloon, weapons related, 37 tons VESTA, October 17, surface, safety experiment, 24 tons RIO ARRIBA, October 18, tower, weapons related, 90 tons SAN JUAN, October 20, shaft, safety experiment, zero yield SOCORRO, October 22, balloon, weapons related, 6 kt WRANGELL, October 22, balloon, weapons related, 115 tons RUSHMORE, October 22, balloon, weapons related, 188 tons OBERON, October 22, tower, safety experiment, zero yield CATRON, October 24, tower, safety experiment, 21 tons JUNO, October 24, surface, safety experiment, 1.7 tons CERES, October 26, tower, safety experiment, 0.7 tons SANFORD, October 26, balloon, weapons related, 4.9 kt DE BACA, October 26, balloon, weapons related, 2.2 kt CHAVEZ, October 27, tower, safety experiment, 0.6 tons EVANS, October 29, tunnel, weapons related, 55 tons HUMBOLDT, October 29, tower, weapons related, 7.8 tons MAZAMA, October 29, tower, weapons related, zero yield SANTA FE, October 30, balloon, weapons related, 1.3 kt BLANCA, October 30, tunnel, weapons related, 22 kt GANYMEDE, October 30, surface, safety experiment, zero yield TITANIA, October 30, tower, safety experiment, 0.2 tons