Operation Hardtack I - 1958 Poplar - 12/07/1958 Hardtack I included 35 tests, the largest test series so far. 1958 in fact saw a total of 77 U.S. tests, more than the three previous record setting years combined. Partly this burst of test activity was due to an imminent test moratorium, leading the weapons labs to rush as many device types to the test range as possible. A total of 35.6 megatons were shot during this series. Three of the 35 test shots, Yellowwood, Sycamore and Quince fizzled, several others produced significantly less than the predicted yield. The development of nuclear weapons up to this time had been primarily of large-yield. strategic weapons that fit with the established U.S. policy of “massive retaliation.” In 1958, some weapon designers felt that with more testing, smaller and more efflclent and radiologically “clean” weapons could be developed. This development would enhance flexlblllty in the military support of U.S. foreign policy. and the “cleanness” of the test explosions would also make testing operations themselves less contaminating and thus more acceptable to world opinion. The extensive test schedule required the use not only of both atolls (Bikini and Enewetak) but Johnston Island also. This series was the last to conduct atmospheric testing at Bikini and Enewetak atolls. Test names were taken from North American trees and shrubs. The lab tests centered on ICBM and SLBM missile warheads and high yield strategic bombs. The DOD conducted high altitude multi-megaton tests to study the usefulness of nuclear weapons as an anti-ballistic missile defense, and as a means to defeat satellites and manned orbiting vehicles in space. - Video of chorioretinal testing At least 14 mark-designated warheads were tested, plus additional developmental designs not yet awarded a serial number. These included the Mk/TX/XW - 7, 25, 31, 34, 35, 39, 41, 43, 46/53, 47, 49, 50, and 51. This series fired the largest tests since Ivy and Castle (and never equalled since in later U.S. tests) and led to the development and deployment of the largest U.S. weapon ever fielded, the 25 Mt Mk-41 bomb; and the largest U.S. missile warhead ever fielded, the W-53 9 Mt Titan-II warhead. Orange - 12/08/1958 An air dropped bomb variant of the W-53 was the largest (and oldest) weapon in the U.S. inventory up until its retirement in early 1997. The UCRL test of the W-47 Polaris warhead prototype was a major technological breakthrough that led to high yields in small light packages charcteristic of all U.S. missile warheads today. Two underwater effects tests were conducted by the DOD during shots Wahoo and Umbrella. The first in the open ocean and the second within the lagoon at Enewetak. The purpose of the tests was to improve the understanding of the effects of underwater explosions on Navy ships and material. These tests could be considered as a continuation of Baker test of the Crossroad series at Bikini in 1946, and Wigwam in 1955. Three high-altitude shots pertaining to ballistic missile defense were also conducted. The first two ,Teak and Orange, were carried aloft by the US Army Redstone Rocket at Johnston Island. The third, Yucca, was carried aloft by a balloon over the ocean between Enewetak and Bikini. Teak, the second high altitude of Hardtack I produced powerfull EMP (electro magnetic pulse) effects. The effects of this pulse were experienced at Apia Observatory in Samoa, and caused damage to land based electronics as far as 1500 km away. The detonation spread a layer of fission debris in the upper atmosphere, destroying the ability of the normal ionized layers of the upper atmosphere to bend radio waves back to earth, thus cutting many trans-pacific high frequency communication circuits. The blackout lasted 9 hours in Australia, and 2 hours in honolulu. These effects were further investigated in 1958 during Operation Argus. A Honolulu resident described the Teak shot in the Honolulu Star-Bulletin: I stepped out on the lanai and saw what must have been the reflection of the fireball. It turned from light yellow to dark yellow and from orange to red. The red spread In a semi-circular manner until It seemed to engulf a large part of the horizon. A cloud rose In the center of the circle. It was quite large and clearly visible. It remained visible for about a half hour. The crater from the 18 kiloton Cactus shot was used in 1979 as a burial pit to intern 85,000 cubic meters of radioactive soil and debris scraped from the various contaminated Enewetak Atoll islands. The 105 meter wide pit was capped with thick concrete forming a structure know as the Runit Dome. - More information about the Runit Dome - Click on a thumbnail for a larger version Test Shots Video Name Yield Date |UTC| Type Warhead Location LONG/LAT Yucca 1.7 Kt 02:40 28/04/1958 Airburst @26210m W-25 85 nm NE of Enewetak 12.61670 168.02500 Cactus 18 Mt 18:15 05/05/1958 Surface MK-43 Runit Isl. -Enewetak 11.55640 162.35420 - Fir 1360 Kt 17:50 11/05/1958 Barge - Bikini 11.69080 165.27360 - Butternut 81 Kt 18:15 11/05/1958 Barge TX-46 Enewetak 11.54110 162.35060 Koa 1370 Kt 18:30 12/05/1958 Surface XW-35 Enewetak 11.67500 162.20560 Wahoo 9 Kt 12:35 18/04/1953 Sub-surface @-150m MK-7 Enewetak 11.34470 162.17890 - Holly 5.9 Kt 18:30 20/05/1958 Barge XW-31Y3 Enewetak 11.54390 162.35610 Nutmeg 25 Kt 21:20 21/05/1958 Barge XW-47 Bikini 11.54390 162.35610 - Yellowwood 330 Kt 02:00 26/05/1958 Barge TX-46 Enewetak 11.66030 162.22530 - Magnolia 57 Kt 18:00 26/05/1958 Barge - Enewetak 11.54280 162.35390 - Tobacco 11.6 Kt 02:15 30/05/1958 Barge XW-50 Enewetak 11.66330 162.23000 Sycamore 92 Kt 03:00 31/05/1958 Barge TX-41 Bikini 11.69080 165.27360 - Rose 15 Kt 18:45 05/06/1958 Barge XW-49 Enewetak 11.54110 162.35170 Umbrella 8 Kt 23:15 08/06/1958 Sub-surface @-30m MK-7 Enewetak 11.38080 162.21920 - Maple 213 Kt 17:30 10/06/1958 Barge - Bikini 11.68720 165.41500 - Aspen 319 Kt 17:30 14/06/1958 Barge XW-47 Bikini 11.69080 165.27330 - Walnut 1.45 Kt 18:30 14/06/1958 Barge - Enewetak 11.66030 162.22530 - Linden 11 Kt 03:00 18/06/1958 Barge XW-50 Enewetak 11.54420 162.35640 - Redwood 412 Kt 17:30 27/06/1958 Barge XW-47 Bikini 11.68720 165.41500 - Elder 880 Kt 18:30 27/06/1958 Barge XW-43 Enewetak 11.66330 162.23000 Oak 8.9 Mt 19:30 28/06/1958 Barge TX-46/53 Enewetak 11.60780 162.10780 Hickory 14 Kt 00:00 30/06/1958 Barge XW-47 Bikini 11.49610 162.37080 - Sequoia 5.2 Kt 18:35 01/07/1958 Barge - Enewetak 11.54420 162.35640 - Cedar 220 Kt 17:30 02/07/1958 Barge - Bikini 11.69080 165.27360 - Dogwood 397 Kt 18:30 05/07/1958 Barge XW-47 Enewetak 11.66330 162.23000 Poplar 9.3 Mt 03:30 07/07/1958 Barge TX-41 Bikini 11.68810 165.26440 - Scaevola 0 Kt 04:00 14/07/1958 Barge XW-34 Enewetak 11.55000 162.36000 - Pisonia 255 Kt 23:00 17/07/1958 Barge XW-50 Enewetak 11.55000 162.31000 Juniper 65 Kt 04:20 22/07/1958 Barge XW-47 Bikini 11.49610 165.37080 Olive 202 Kt 20:30 22/07/1958 Barge - Enewetak 11.66330 162.23000 - Pine 2 Mt 20:30 26/07/1958 Barge TX-41 Enewetak 11.65610 162.21970 Teak 3.8 Mt 10:50 01/08/1958 Rocket @76800m W-39 Johnston Isl. 16.74390 -169.53330 - Quince 0 Kt 02:15 06/08/1958 Surface XW-51 Enewetak 11.55000 162.36000 Orange 3.8 Mt 10:30 12/08/1958 Rocket @43000m W-39 Johnston Isl. 16.35830 -169.53560 Fig 0.02 Kt 04:00 18/08/1958 Surface XW-51 Enewetak 11.55000 162.36000