Operation Hardtack II explained

Operation Hardtack II
Picture Description:	Hardtack II Sanford, 4.9 kilotons.
Country:	United States
Test Site:	NTS Area 12, Rainier Mesa NTS Areas 5, 11, Frenchman Flat NTS, Areas 1–4, 6–10, Yucca Flat
Period:	1958
Number Of Tests:	37
Test Type:	balloon, dry surface, tower, underground shaft, tunnel
Max Yield:	22ktTNT
Next Series:	Operation Nougat

Operation Hardtack II was a series of 37 nuclear tests conducted by the United States in 1958 at the Nevada Test Site. These tests followed the Operation Argus series and preceded the Operation Nougat series.

With test moratoriums on the horizon, American weapons labs rushed out many new designs. A hard deadline for testing was set at midnight (0000 hrs), October 31, 1958, as negotiations were set to start that day, and the schedule shows it, with 29 tests executed in October, four of them on the last day. One other test was cancelled because weather delays postponed it across the midnight deadline. After the conclusion of Hardtack II, the United States announced a unilateral testing moratorium, which the Soviet Union joined after two last tests on November 1 and 3.^[1] In September 1961, the Soviet Union resumed nuclear testing — including the test of the most powerful nuclear device ever designed, the Tsar Bomba, in October — and the United States followed suit with Operation Nougat.

Nuclear tests

Adams

Adams was planned to be the final test of Hardtack II, but due to unfavorable winds the shot was never fired. The shot was intended to be a balloon test, and had been fully assembled and raised to firing altitude when it was cancelled. After midnight and the start of the moratorium, the device was lowered to the ground and disassembled. The Soviet Union would continue nuclear testing until the 3rd of November.^[2]

A 31st October 1958 meeting of the Atomic Energy Commission following the cancellation resulted in the following note:^[3]

List of nuclear tests

United States' Hardtack II series tests and detonations
- !style="background:#ffdead;"	Name ^[4] !style="background:#efefef;"	Date time (UT) !style="background:#ffdead;"	Local time zone^[5] ^[6] !style="background:#efefef;"	Location^[7] !style="background:#ffdead;"	Elevation + height ^[8] !style="background:#efefef;"	Delivery ^[9] Purpose ^[10] !style="background:#efefef;"	Device^[11] !style="background:#ffdead;"	Yield^[12] !style="background:#efefef;" class="unsortable"	Fallout^[13] !style="background:#ffdead;" class="unsortable"	References !style="background:#efefef;" class="unsortable"	Notes	- ! Otero	20:00:00.2	PST (–8 hrs)	NTS Area U3q 37.0499°N -116.0326°W	1229m (4,032feet)–150m (490feet)	underground shaft, safety experiment	XW-54 ?		Venting detected, 6kCi		1-point test, failed, device similar to HT-I Sequoia.	- ! Bernalillo	19:30:00.2	PST (–8 hrs)	NTS Area U3h (n?) 37.0494°N -116.0335°W	1229m (4,032feet)–150m (490feet)	underground shaft, safety experiment			Venting detected on site		1-point test, repeat of Otero, also failed.	- ! Eddy	14:00:00.2	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 150m (490feet)	balloon, weapons development			Venting detected, 12kCi		test device successful.	- ! Luna	19:00:00.2	PST (–8 hrs)	NTS Area U3m 37.0492°N -116.0345°W	1230m (4,040feet)–150m (490feet)	underground shaft, safety experiment	XW-54 ?		Venting detected on site		1-point test, repeat of Otero/Bernalillo, still unsafe.	- ! Mercury	22:00:00.0	PST (–8 hrs)	NTS Area U12f.01 37.1927°N -116.2002°W	2038m (6,686feet)–55.78m (183.01feet)	tunnel, safety experiment	XW-47 primary ?				1-point test, declared success despite yield, XW-42 test, similar to Pascal-C and San Juan devices.	- ! Valencia	20:00:00.2	PST (–8 hrs)	NTS Area U3r 37.0496°N -116.0306°W	1227m (4,026feet)–150m (490feet)	underground shaft, safety experiment	XW-42 ?		Venting detected on site		1-point test, declared success despite yield, similar to Pascal-C and San Juan devices.	- ! Mars	00:00:00.2	PST (–8 hrs)	NTS Area U12f.02 37.193°N -116.2013°W	2082m (6,831feet)–42.67m (139.99feet)	tunnel, safety experiment			Venting detected on site		1-point test, similar to Tamalpais and Ceres.	- ! Mora	14:05:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 460m (1,510feet)	balloon, weapons development	XW-54 Gnat		Venting detected, 340kCi		Full yield test of device similar to Otero et al., fizzled.	- ! Hidalgo	14:10:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 110m (360feet)	balloon, safety experiment	Moccasin		Venting detected, 11kCi		This 1-point test failed; similar to Coulomb-C.	- ! Colfax	16:15:00.2	PST (–8 hrs)	NTS Area U3k 37.0488°N -116.0349°W	1229m (4,032feet)–107m (351feet)	underground shaft, safety experiment	XW-54 Gnat		Venting detected, 240kCi		1-point test of device similar to Otero et al., failed. Unstemmed shaft.	- ! Tamalpais	22:00:00.13	PST (–8 hrs)	NTS Area U12b.02 37.1953°N -116.2013°W	2152m (7,060feet)–124.05m (406.99feet)	tunnel, weapons development					Full yield test, similar to Mars and Ceres.	- ! Quay	14:30:00.1	PST (–8 hrs)	NTS Area 7c 37.0947°N -116.0245°W	1294m (4,245feet) + 30m (100feet)	tower, weapons development	XW-50 ?		Venting detected, 200Ci		Concept feasibility test, similar to HT-I Linden.	- ! Lea	13:20:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 460m (1,510feet)	balloon, weapons development	XW-54 Gnat ?		Venting detected, 240kCi		Full yield test of device similar to Otero et al., fizzled.	- ! Neptune	18:00:00.2	PST (–8 hrs)	NTS Area U12c.03 37.1938°N -116.2006°W	2080m (6,820feet)–30.02m (98.49feet)	tunnel, safety experiment			Venting detected on site		1-point test, failed, similar to HT-I Hickory and HT-II Titania. First NTS subsidence crater at Rainier despite low yield and depth buried.	- ! Hamilton	16:00:00.2	PST (–8 hrs)	NTS Area 5 36.8022°N -115.9331°W	940m (3,080feet) + 15m (49feet)	tower, weapons development	XW-51 ? Quail		Venting detected, 200Ci		Davy Crockett prototype test, fizzled, extremely small device (16kg (35lb)).	- ! Logan	06:00:00.14	PST (–8 hrs)	NTS Area A12e.02 37.184°N -116.2021°W	2155m (7,070feet)–283.58m (930.38feet)	tunnel, weapons development					ABM warhead test, small (28.6kg (63.1lb), 28cmx29cmcm (11inchesx11inchescm)) kiloton-range device, successful.	- ! Dona Ana	14:20:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 150m (490feet)	balloon, weapons development	XW-54 Gnat		Venting detected, 6kCi		Low yield test, similar to Otero et al.	- ! Vesta	23:00:00.2	PST (–8 hrs)	NTS Area S9e 37.1226°N -116.0347°W	1294m (4,245feet) + 0	dry surface, safety experiment	XW-47 primary		Venting detected, 4kCi		1-point test, failed, similar to Wrangell, Oberon, Sanford.	- ! Rio Arriba	14:25:00.1	PST (–8 hrs)	NTS Area 3s 37.0411°N -116.0267°W	1224m (4,016feet) + 20m (70feet)	tower, weapons development			Venting detected, 120kCi		Low yield Mk-7, successful, fired on wooden tower.	- ! San Juan	14:30:00.2	PST (–8 hrs)	NTS Area U3p 37.0498°N -116.0333°W	1229m (4,032feet)–71m (233feet)	underground shaft, safety experiment	XW-42 ?				1-point test, successful, safe design extrapolated from Pascal-C and HT-II Valencia. Unstemmed shaft.	- ! Socorro	13:30:00.2	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 440m (1,440feet)	balloon, weapons development	XW-54 Gnat ?		Venting detected, 1000kCi		Full yield test of XW-54 primary, successful, similar to Otero et al.	- ! Wrangell	16:50:00.1	PST (–8 hrs)	NTS Area 5 36.798°N -115.9298°W	940m (3,080feet) + 460m (1,510feet)	balloon, weapons development	XW-47 Canary ?		Venting detected, 17kCi		Full yield test fizzle, similar to Vesta, Oberon, Sanford.	- ! Oberon	20:30:??	PST (–8 hrs)	NTS Area 8a 37.1829°N -116.0691°W	1355m (4,446feet) + 8m (26feet)	tower, safety experiment	XW-47 primary Canary ?		Venting detected, 17kCi		1-point test, successful, similar to Vesta, Wrangell, Sanford.	- ! Rushmore	23:40:00.1	PST (–8 hrs)	NTS Area B9a ~ 37.1347°N -116.0417°W	1285m (4,216feet) + 150m (490feet)	balloon, weapons development	XW-47 primary Canary ?				Low yield test, fizzled, similar to Mercury, Neptune, Titania.	- ! Catron	15:00:00.2	PST (–8 hrs)	NTS Area 3t 37.0427°N -116.0277°W	1225m (4,019feet) + 20m (70feet)	tower, safety experiment	XW-54 Gnat		Venting detected, 4kCi		1-point test, similar to Mora, failed, fired on wooden tower.	- ! Juno	16:01:00.2	PST (–8 hrs)	NTS Area S9f 37.1236°N -116.0378°W	1287m (4,222feet) + 0	dry surface, safety experiment	Logan				1-point test to determine safety limits.	- ! Ceres	04:00:00.2	PST (–8 hrs)	NTS Area 8b 37.1814°N -116.0691°W	1350m (4,430feet) + 10m (30feet)	tower, safety experiment	XW-48 AFAP				1-point test of atomic artillery shell, similar to Tamalpais and Mars.	- ! Sanford	10:20:00.1	PST (–8 hrs)	NTS Area 5 36.798°N -115.9298°W	940m (3,080feet) + 460m (1,510feet)	balloon, weapons development	XW-47 primary Canary ?		Venting detected, 750kCi		Full yield test, successful, similar to Vesta, Oberon, Wrangell.	- ! De Baca	16:00:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 460m (1,510feet)	balloon, weapons development	XW-54 Gnat		Venting detected, 380kCi		Full yield test, disappointing yield, similar to Catron and Mora.	- ! Chavez	14:30:??	PST (–8 hrs)	NTS Area 3u 37.0443°N -116.0305°W	1225m (4,019feet) + 16m (52feet)	tower, safety experiment	XW-54 Gnat		Venting detected, 100Ci		1-point test of device similar to De Baca, failed, fired on wooden tower.	- ! Evans	00:00:00.15	PST (–8 hrs)	NTS Area U12b.04 37.1948°N -116.2056°W	2282m (7,487feet)–256.03m (839.99feet)	tunnel, weapons development	XW-47 primary Canary ?		Venting detected on site		Full yield test fizzle, similar to Blanca.	- ! Mazama	11:20:??	PST (–8 hrs)	NTS Area 9 37.1265°N -116.042°W	1282m (4,206feet) + 15m (49feet)	tower, weapons development					Fizzle.	- ! Humboldt	14:45:00.1	PST (–8 hrs)	NTS Area 3v 37.0477°N -116.0256°W	1228m (4,029feet) + 10m (30feet)	tower, weapons development	XW-51 ?		Venting detected, 1kCi		Repeat of Hamilton with higher yield, extremely small device (16 kg).	- ! Santa Fe	03:00:00.1	PST (–8 hrs)	NTS Area B7b ~ 37.0866°N -116.0245°W	1282m (4,206feet) + 460m (1,510feet)	balloon, weapons development	XW-54 Gnat		Venting detected, 220kCi		Similar to devices fired in many preceding shots, yield below predictions.	- ! Ganymede	11:00:??	PST (–8 hrs)	NTS Area S9g 37.123°N -116.035°W	1294m (4,245feet) + 0	dry surface, safety experiment					1-point test of W-45/Swan variant, successful.	- ! Blanca	15:00:00.15	PST (–8 hrs)	NTS Area U12e.05 37.1859°N -116.2029°W	2168m (7,113feet)–254.51m (835.01feet)	tunnel, weapons development	XW-47 primary Canary		Venting detected, 510Ci		Test of alternate W-47 primary in TN mockup, successful, similar to Evans, shot vented to atmosphere through the side of the mesa.	- ! Titania	20:34:00.2	PST (–8 hrs)	NTS Area 8c 37.1773°N -116.0699°W	1343m (4,406feet) + 10m (30feet)	tower, safety experiment	XW-47 primary Canary				1-point test of original XW-47 primary, declared safe despite yield, similar to HT-I Hickory and HT-II Neptune.	- ! Adams (canceled)		PST (–8 hrs)	NTS ~ 37.044°N -116.068°W	1220m (4,000feet) + ???	Balloon, weapons development					Test planned for Hardtack II, but held up by atmospherics that would have shattered windows in Las Vegas, and could not be completed in time before start of moratorium negotiations.

Notes and References

Web site: Gallery of U.S. Nuclear Tests .
Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Meade. Roger Allen. Hardtack II. 2024-01-23. 2022-09-12.
US Department of Energy (USDOE), Nevada Operations Office.. William E Ogle. An Account of the Return to Nuclear Weapons Testing by the United States After the Test Moratorium 1958-1961. 2021-07-16. October 1985. 107-108.
The US, France and Great Britain have code-named their test events, while the USSR and China did not, and therefore have only test numbers (with some exceptions – Soviet peaceful explosions were named). Word translations into English in parentheses unless the name is a proper noun. A dash followed by a number indicates a member of a salvo event. The US also sometimes named the individual explosions in such a salvo test, which results in "name1 – 1(with name2)". If test is canceled or aborted, then the row data like date and location discloses the intended plans, where known.
To convert the UT time into standard local, add the number of hours in parentheses to the UT time; for local daylight saving time, add one additional hour. If the result is earlier than 00:00, add 24 hours and subtract 1 from the day; if it is 24:00 or later, subtract 24 hours and add 1 to the day. Historical time zone data obtained from the IANA time zone database.
Web site: Time Zone Historical Database. iana.com. March 8, 2014.
Rough place name and a latitude/longitude reference; for rocket-carried tests, the launch location is specified before the detonation location, if known. Some locations are extremely accurate; others (like airdrops and space blasts) may be quite inaccurate. "~" indicates a likely pro-forma rough location, shared with other tests in that same area.
Elevation is the ground level at the point directly below the explosion relative to sea level; height is the additional distance added or subtracted by tower, balloon, shaft, tunnel, air drop or other contrivance. For rocket bursts the ground level is "N/A". In some cases it is not clear if the height is absolute or relative to ground, for example, Plumbbob/John. No number or units indicates the value is unknown, while "0" means zero. Sorting on this column is by elevation and height added together.
Atmospheric, airdrop, balloon, gun, cruise missile, rocket, surface, tower, and barge are all disallowed by the Partial Nuclear Test Ban Treaty. Sealed shaft and tunnel are underground, and remained useful under the PTBT. Intentional cratering tests are borderline; they occurred under the treaty, were sometimes protested, and generally overlooked if the test was declared to be a peaceful use.
Include weapons development, weapon effects, safety test, transport safety test, war, science, joint verification and industrial/peaceful, which may be further broken down.
Designations for test items where known, "?" indicates some uncertainty about the preceding value, nicknames for particular devices in quotes. This category of information is often not officially disclosed.
Estimated energy yield in tons, kilotons, and megatons. A ton of TNT equivalent is defined as 4.184 gigajoules (1 gigacalorie).
Radioactive emission to the atmosphere aside from prompt neutrons, where known. The measured species is only iodine-131 if mentioned, otherwise it is all species. No entry means unknown, probably none if underground and "all" if not; otherwise notation for whether measured on the site only or off the site, where known, and the measured amount of radioactivity released.