| 1958 was a banner year for nuclear weapons testing by the U.S., with a total of 77 U.S. tests, more than the three previous record setting years combined. This burst of testing activity was partly due to building pressure for an imminent test moratorium, leading the weapons labs to rush as many device types to the test range as possible, and partly due to the accelerating momentum of the arms race of the 1950s hitting full stride. 1958 was exceeded only by the 96 tests in 1962, sandwiched as it was between a testing moratorium followed by a surprise moratorium breakout by the Soviet Union in 1961, and the imminent prospect of a permanent atmospheric testing ban.
Hardtack II included 37 tests, the largest test series so far, exceeding the 35 tests of the just completed Hardtack I. Hardtack I had focused primarily on high yield proof or developemental tests of complete thermonuclear weapons, which necessitated it be conducted in the distant Pacific (a total of 35.6 Mt being fired). In contrast, Hardtack II consisted exclusively of low yield tests, many of them attempted zero-yield one-point safety tests, which could be conducted in relative safety in Nevada (some were underground). Only 45.8 kt total was fired in Hardtack II, and of this only 18.5 kt was fired above ground. This was a dramatic turnaround from the previous Nevada test series, Plumbbob, in which the above ground Hood shot by itself was 74 kt. Concern about the effects of fallout on the U.S. was certainly making itself felt.
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The world's first underground nuclear test had been fired in the previous NTS series (Plumbbob Ranier), and this series introduced underground testing as a routine procedure. The intention was to reduce the fallout effects of the testing, which were raising great concern, but the "underground" testing procedures were still relatively primitive. Many of these shots were conducted in "unstemmed" holes, that is, holes not back-filled and sealed prior to testing. These shots were called "roman candles" since the incandescent gas from the fireball was ejected as a jet from the mouth of the shaft. Obviously fallout containment was much less than perfect, but most of the fission product was nonetheless deposited in the shaft instead of escaping, and the radiation that did escape was not lofted so that it could travel far downwind.
Hardtack Phase II still released some 3,140 kilocuries of radioiodine (I-131) into the atmosphere (about equal to the Trinity test), only ~5% as much as the previous test series (Plumbbob). This radiation also did not nearly spread as far, only about one-millionth as much radiation exposure occurred to civilians. The total civilian radiation exposures was a mere 160 person-rads of thyroid tissue exposure. The odds are about 20-1 against this producing even one additional cancer case. Chart of fallout exposures from "Hardtack Phase II" (51 K, 539x577). From National Cancer Institute Study Estimating Thyroid Doses of I-131 Received by Americans From Nevada Atmospheric Nuclear Bomb Test, 1997. To go to the National Cancer Institute and get the full report, click here.
| Test: | Lea |
|---|---|
| Time: | 13:20 13 October 1958 (GMT) |
| Location: | NTS, Area 7b |
| Test Height and Type: | Balloon, 1500 Feet |
| Yield: | 1.4 kt |
This was a fizzled attempt to fire the LASL designed XW-54 primary at full yield. One of many (at least ten) shots that attempted to verify safety and effectiveness of this device in several variants (not even counting at least two safety shots - Pascal A and B - attempted in Plumbbob). This was probably a version of the Gnat device, and was similar to devices fired in Hardtack II Otero, Bernalillo, Luna, Mora, Colfax, etc.
Device dimensions: 11.7 inches in diameter, 15 inches long, weight 63 lb.
In the picture below, spikes can be seen propagating down the mooring cables of the balloon. These were termed "rope tricks" by Dr. John Malik, and are caused by thermal energy from the fireball surface vaporizing the cables.
Click here for a larger picture (34 K)
| Test: | Socorro |
|---|---|
| Time: | 13:30 22 October 1958 (GMT) |
| Location: | NTS, Area 7b |
| Test Height and Type: | Balloon, 1450 Feet |
| Yield: | 6 kt |
Finally a successful full yield test of the XW-54 primary! Predicted yield was 5-9 kt. Similar to the Lea device. Device dimensions: 11.7 inches in diameter, 15 inches long, weight 58.1 lb.
| Test: | De Baca |
|---|---|
| Time: | 16:00 26 October 1958 (GMT) |
| Location: | NTS, Area 7b |
| Test Height and Type: | Balloon, 1500 Feet |
| Yield: | 2.2 kt |
Another attempt at firing a full yield version of the XW-54/Gnat system puts in a disappointing showing. Similar to the Catron and Mora devices the 2.2 kt yield was below predictions. Device dimensions: 11.3 inches in diameter, 15 inches long, weight 66 lb.
| Test: | Santa Fe |
|---|---|
| Time: | 3:00 30 October 1958 (GMT) |
| Location: | NTS, Area 7b |
| Test Height and Type: | Balloon, 1,500 Feet |
| Yield: | 1.3 kt |
Similar to devices fired in many of the preceding Hardtack II shots. Based on device characteristics - 11.3 inches in diameter, 15 inches long, weight 57.3 lb. - it was probably another XW-54/Gnat attempt. Yield below predictions.
| Test: | Blanca |
|---|---|
| Time: | 15:00.00.0 30 October 1958 (GMT) |
| Location: | NTS, Area 12e |
| Test Height and Type: | Tunnel, -987 Feet |
| Yield: | 22 kt |
UCRL test of an alternate W-47 primary in a thermonuclear system mockup. This shot was successful, the predicted yield was 20 kt. Similar to Hardtack II Evans. The device was 18 inches in diameter, 45.5 inches long, and weighed 717.6 lb.
Although it was fired in an underground tunnel, the shot still vented radioactive material into the atmosphere (visible in the picture below).
Legend:WD=Weapons Development, ST=Safety Test, TN= Thermonuclear, LASL=Los Alamos Scientific Laboratory, UCRL=University of California Radiation Laboratory (later Lawrence Livermore), sim.=similar, HT=Hardtack
| Test Name | Time and Date (GMT) | Location | Test Type | Height (Ft) | Yield - Actual (Predicted) kt | Sponsor | Purpose | Comments |
|---|---|---|---|---|---|---|---|---|
| Otero | 20:00 12-Sep-58 | NTS, Area 3q | Unstemmed Shaft | -480 | 0.038 (0-0.040) | LASL | ST | 1-point test, failed, probable XW-54 (Gnat device) test, similar to HT-I Sequoia |
| Bernalillo | 19:30 17-Sep-58 | NTS, Area 3h | Unstemmed Shaft | -456 | 0.015 (0-0.040) | LASL | ST | 1-point test, repeat of Otero, still unsafe |
| Eddy | 14:00 19-Sep-58 | NTS, Area 7b | Balloon | 500 | 0.083 (0.075-0.15) | LASL | WD | 146 lb, 17.4 device test successful |
| Luna | 19:00 21-Sep-58 | NTS, Area 3m | Unstemmed Shaft | -484 | 0.0015 (0-0.040) | LASL | ST | 1-point test, repeat of Otero/Bernalillo, still unsafe |
| Mercury | 22:00 23-Sep-58 | NTS, Area 12f | Tunnel | -183 | Slight (0-0.010) | UCRL | ST | 1-point test, declared success, XW-47 primary, similar to HT-I Juniper device |
| Valencia | 20:00 26-Sep-58 | NTS, Area 3r | Unstemmed Shaft | -484 | 0.002 (0-0.040) | LASL | ST | 1-point test, declared success despite yield, XW-42 test, sim. to Pascal-C and San Juan devices |
| Mars | 0:00 28-Sep-58 | NTS, Area 12f | Tunnel | -140 | 0.013 (0-0.010) | UCRL | ST | 1-point test for XW-48, similar to Tamalpais and Ceres |
| Mora | 14:05 29-Sep-58 | NTS, Area 7b | Balloon | 1500 | 2 (9-15) | LASL | WD | Full yield test of device sim. to Otero et al, probable XW-54 (Gnat device), fizzled |
| Hidalgo | 14:10 5-Oct-58 | NTS, Area 7b | Balloon | 377 | 0.077 (0-0.040) | LASL | ST | 1-point test of Moccasin, failed, similar to Coulomb-C |
| Colfax | 16:15 5-Oct-58 | NTS, Area 3k | Unstemmed Shaft | -350 | 0.0055 (0-0.040) | LASL | ST | 1-point test of device sim. to Otero et al, probable XW-54 (Gnat device), failed |
| Tamalpais | 22:00.00.1 8-Oct-58 | NTS, Area 12b | Tunnel | -407 | 0.072 (0.100-0.300) | UCRL | WD | Full yield test of XW-48, sim. to Mars and Ceres |
| Quay | 14:30 10-Oct-58 | NTS, Area 7c | Tower | 100 | 0.079 (0.075-0.150) | LASL | WD | Concept feasibility test, sim. to HT-I Linden, possible XW-50 primary |
| Lea | 13:20 13-Oct-58 | NTS, Area 7b | Balloon | 1500 | 1.4 (9-15) | LASL | WD | Full yield test of device sim. to Otero et al, probable XW-54 (Gnat device), fizzled |
| Neptune | 18:00 14-Oct-58 | NTS, Area 12c | Tunnel | -110 | 0.115 (0-0.010) | UCRL | ST | 1-point test of XW-47 primary, failed, sim. to HT-I Hickory and HT-II Titania |
| Hamilton | 16:00 15-Oct-58 | NTS, Area 5 | Tower | 50 | 0.0012 (0.020-0.050) | UCRL | WD | XW-51 Davy Crockett (Quail device) prototype test, fizzled, extremely small device (16 kg) |
| Logan | 06:00.00.1 16-Oct-58 | NTS, Area 12e | Tunnel | -932 | 5 (3-7) | UCRL | WD | ABM warhead test, small (28.6 kg, 28cm x 29cm) kiloton-range device, successful |
| Dona Ana | 14:20 16-Oct-58 | NTS, Area 7b | Balloon | 450 | 0.037 (0.050-0.080) | LASL | WD | Low yield Gnat device test, similar to Otero et al |
| Vesta | 23:00 15-Oct-58 | NTS, Area 9e | Surface | 0 | 0.024 (0-0.010) | UCRL | ST | 1-point test of XW-47 primary, failed, sim. to Wrangell, Oberon, Sanford |
| Rio Arriba | 14:25 18-Oct-58 | NTS, Area 3s | Tower | 72.5 | 0.090 (0.100-0.150) | LASL | WD | Low yield Mk-7, successful, fired on wooden tower |
| San Juan | 14:30 20-Oct-58 | NTS, Area 3p | Unstemmed Shaft | -234 | 0 (0-0.040) | LASL | ST | 1-point test, successful, safe design extrapolated from Pascal-C and HT-II Valencia |
| Socorro | 13:30 22-Oct-58 | NTS, Area 7b | Balloon | 1450 | 6 (5-9) | LASL | WD | Full yield test of XW-54, successful, sim. to Otero et al |
| Wrangell | 16:50 22-Oct-58 | NTS, Area 5 | Balloon | 1500 | 0.115 (5-10) | UCRL | WD | Full yield test fizzle, XW-47 primary, sim. to Vesta, Oberon, Sanford |
| Oberon | 20:30 22-Oct-58 | NTS, Area 8a | Tower | 25 | 0 (0-0.010) | UCRL | ST | 1-point test, successful, XW-47 primary, sim. to Vesta, Wrangell, Sanford |
| Rushmore | 23:40 22-Oct-58 | NTS, Area 9a | Balloon | 500 | 0.188 (1-1.5) | UCRL | WD | Low yield test of XW-47 primary (Canary device), fizzled, sim. to Mercury, Neptune, Titania |
| Catron | 15:00 24-Oct-58 | NTS, Area 3t | Tower | 72.5 | 0.021 (-) | LASL | ST | 1-point test of Gnat, sim. to Mora, failed, fired on wooden tower |
| Juno | 16:01 24-Oct-58 | NTS, Area 9f | Surface | 0 | 0.0017 (-) | UCRL | ST | 1-point test to determine safety limits of Logan |
| Ceres | 4:00 26-Oct-58 | NTS, Area 8b | Tower | 25 | 0.0007 (-) | UCRL | ST | 1-point test of XW-48 atomic artillery shell, sim. to Tamalpais and Mars |
| Sanford | 10:20 26-Oct-58 | NTS, Area 5 | Balloon | 1500 | 4.9 (-) | UCRL | WD | Full yield test of XW-47 primary, successful, sim. to Vesta, Oberon, Wrangell |
| De Baca | 16:00 26-Oct-58 | NTS, Area 7b | Balloon | 1500 | 2.2 (>2.2) | LASL | WD | Full yield Gnat device test, similar to Catron and Mora |
| Chavez | 14:30 27-Oct-58 | NTS, Area 3u | Tower | 52.5 | 0.0006 (0) | LASL | ST | 1-point test of device sim. to De Baca (Gnat), failed, fired on wooden tower |
| Evans | 00:00.00.2 29-Oct-58 | NTS, Area 12b | Tunnel | -852 | 0.055 (2-8) | UCRL | WD | Full yield test fizzle, XW-47 primary in TN mockup, sim. to Blanca |
| Mazama | 11:20 29-Oct-58 | NTS, Area 9 | Tower | 50 | 0 (>0) | LASL | WD | Fizzle |
| Humbodt | 14:45 29-Oct-58 | NTS, Area 3v | Tower | 25 | 0.0078 (-) | UCRL | WD | Repeat of Hamilton with higher yield, XW-51 Davy Crockett (Quail device) prototype, extremely small device (16 kg) |
| Santa Fe | 3:00 30-Oct-58 | NTS, Area 7b | Balloon | 1,500 | 1.3 (>1.3) | LASL | WD | Similar to devices fired in many preceding shots, yield below predictions |
| Ganymede | 11:00 30-Oct-58 | NTS, Area 9g | Surface | 0 | 0 (0) | UCRL | ST | 1-point test of W-45/Swan variant, successful |
| Blanca | 15:00.00.0 30-Oct-58 | NTS, Area 12e | Tunnel | -987 | 22 (20) | UCRL | WD | Test of alternate W-47 primary in TN mockup, successful, sim. to Evans |
| Titania | 20:34 30-Oct-58 | NTS, Area 8c | Tower | 25 | 0.0002 (0) | UCRL | ST | 1-point test of original XW-47 primary, declared safe despite yield, sim. to HT-I Hickory and HT-II Neptune |
Hardtack II Lea (14 K)
Hardtack II Socorro (25 K)
Hardtack II De Baca (63 K)
Hardtack II Santa Fe (15 K)
Hardtack II Blanca (59 K)
