Michael Light

A small, tactical thermonuclear weapon expected to yield 50-100 kilotons, Charleston “fizzled” when its fusion second stage failed to ignite.  Had it done so, it would have been the third true thermonuclear test on the continental United States, though the Federal Government and the Atomic Energy Commission denied for decades that any such “H-bomb” devices had ever been detonated in Nevada.

 With Army soldiers in trenches only 2.3 miles from ground zero, Moth vaporizes its tower, creating intense radioactivity 900’ north of the blast. At 445 pounds, it was the lightest nuclear weapon detonated to date. Despite its small size, Moth was seen as an orange flash in the sky as far away as San Francisco.  Its debris cloud spread radioactive fallout across the entire United States and the Atlantic Ocean beyond.

0.0001 seconds after detonation, the blast has not yet vaporized the tower. “Dirty Harry” created the worst fallout contamination of any of the U.S. continental atmospheric nuclear tests. the radioactive debris cloud moved directly over St. George, Utah, 100 miles to the east.  Deadly fallout inundated the entire town of 5000 residents, most of whom would later develop cancer. The Atomic Energy Commission publicly maintained until its dissolution in 1974 that no damage was done from Harry; internal documents declassified thereafter showed this to be a patent lie.

Hornet’s fireball engulfs its tower about 0.0003 seconds after detonation.  At this point the temperature at the fireball’s core is 10 times hotter than the sun’s core and its visible light about 100 times brighter.  Hornet tested what would become the W-30 warhead, an air-defense weapon that was stockpiled from 1959 to 1979 with a yield of 140 tons to 19 kilotons.

0.0008 seconds after detonation, How shows surface mottling and expanding cable fire spikes as it engulfs its tower. How became the Mark-12 bomb, a jet fighter-carried tactical weapon yielding 12 to 14 kilotons that was stockpiled from 1954 to 1962.

Six miles away, the world’s first nuclear explosion expands 0.053 seconds after detonation.  Director J. Robert Oppenheimer quotes the Bhagavad-Gita: “If the radiance of a thousand suns were to burst forth at once in the sky, that would be like the splendor of the Mighty One . . . I am become Death, the shatterer of worlds.” Three weeks later, the U.S. dropped a nuclear bomb on Hiroshima, Japan on August 6, 1945, killing over 200,000 people and wounding 79,000.  Three days after, the U.S. dropped another on the Japanese city of Nagasaki, killing 60-90,000 people and wounding 60,000.

Silhouetted against light which literally illuminated their insides, soldiers try to shield themselves from the expanding fireball.  Closer in, 600 troops observed the blast in trenches only 1.98 miles from ground zero.  Radiation at the blast point measured a lethal 500 roentgens/hour.

Army soldiers are atomically “conditioned” by viewing Stokes’ fireball, now 700 feet wide and more than 50 times brighter than the sun; despite their shut and shielded eyes, many saw the bones of their arms and hands.  Stokes tested the W-30 air-defense and tactical warhead, stockpiled from 1959 to 1979, variably yielding 140 tons to 19 kilotons. 

This tiny 158-pound nuclear device was a prototype for the W-54 air-to-air defense and tactical missile warhead, stockpiled from 1961 to 1972 with a variable yield of 10 tons to 6 kilotons.  Despite being an uncharacteristically small creation from Edward Teller’s University of California Radiation Laboratory (Livermore), known for its massive thermonuclear designs, Wheeler’s radioactive debris cloud rose to 17,000’.

Its fireball having progressed outwards enough to begin rising vertically, Franklin Prime begins to suck up alluvial desert soil to form the classic nuclear “mushroom” cloud.  It tested the W-30 air-defense and tactical atomic warhead, stockpiled from 1959 to 1979, with a variable yield of 140 tons to 19 kilotons.

A test of a tactical nuclear weapon used for low airbursts, Laplace weighed 503 pounds and was probably a prototype neutron bomb.  A neutron bomb is one designed to minimize blast and heat effects, while maximizing deadly radiation.

After its shock wave hits the ground and agitates soil in a broad circle, Stokes begins to draw it up in a central stem, created by atmospheric low-pressure. Stokes tested the W-30 air-defense and tactical warhead, stockpiled from 1959 to 1979, with a variable yield of 140 tons to 19 kilotons.

Red aerial view of the Stokes fireball. Stokes was a test of the W-30 air-defense and tactical atomic warhead, stockpiled from 1959 to 1979, with a variable yield of 140 tons to 19 kilotons.

In a red aerial view photographed with special film, How’s fireball has yet to rise and break away from the ground.  Radiation levels at ground zero reached intense levels of 1500 roentgens/hour, and the fission debris cloud was tracked all the way to Germany.  How would become the Mark-12 bomb, a jet fighter-carried tactical weapon yielding 12 to 14 kilotons stockpiled from 1954 to 1962.

Sugar created especially intense radioactivity, with its crater measuring a deadly 7500 roentgens/hour; four minutes exposure to such energy is lethal. Troops observed the blast from 5.5 miles away. Sugar showed that the greater the distance between the blast and the ground, the less surface radioactivity and radioactive fallout in the debris clouds.  Ever-higher towers, and finally balloons, were used in successive Nevada operations to try to calm an American public increasingly aware of the profound dangers from fallout, while behind closed doors almost half of the A.E.C.’s own commissioners argued for moving all testing to the Pacific.

Zucchini tested the primary stage of a two-stage thermonuclear bomb mockup. 500 roentgens/hour of radiation was measured at ground zero after the blast, and the radioactive debris cloud rose to 40,000’.

950 Army troops observed detonation 3.97 miles from the blast and then maneuvered towards ground zero, a lethal 2000 roentgens/hour at a distance of 400 yards. Shortly before the Fox test the Atomic Energy Commission relented to the military’s ongoing demand to move troops closer to the blast. A.E.C. doctors were furious that their own 7-mile-distant safety guidelines for staff were being sidestepped by the Department of Defense. “Troop-testing” tactical atomic weapons on the battlefield thereafter began in earnest. Fox tested the Mark-5 bomb, stockpiled from 1952 to 1963 and yielding 11 to 47 kilotons.

Hood was the largest atmospheric nuclear test conducted on the continental United States, and the first true two-stage thermonuclear device detonated in Nevada. The flash was seen from Canada. 2500 Marines participated in troop maneuvers, with a number stationed in trenches only 2 miles away from ground zero. Hood broke an understanding between the Federal Government and the Department of Defense that the nuclear weapons labs would never detonate a hydrogen bomb at the Nevada Test Site; the Government strenuously maintained that no thermonuclear weapons were being detonated there until the dissolution of the A.E.C. in 1974.

Soldiers in a trench shield themselves from the detonation. In a moment the ground and air shockwaves will toss them like dolls, then fill their mouths with radioactive dust and render them temporarily blind. 3000 troops witnessed the detonation. Simon’s radioactive debris cloud scattered deadly fallout throughout Southwest Utah, and highly radioactive rain fell in Albany, NY the following day.  Simon tested the early versions of the Mark-17 and Mark-24 thermonuclear bombs, which were stockpiled from 1954 to 1957. Yielding 10 to 15 megatons, they were some of the largest and deadliest weapons ever deployed by the U.S.

Fizeau’s fireball dwarfs the surrounding Nevada landscape.  Probably a prototype test of the W-34 warhead, which was used in anti-submarine warfare and stockpiled from 1958 to 1977, Fizeau’s nuclear device weighed only 131 pounds.

Low-level aerial image, showing the rising stem debris cloud just about to meet the fireball. The cluster of smoke trails at left are from rockets fired just before detonation to help photographically measure the explosion’s invisible air shock wave. Climax tested the Mark-7 bomb, a small, light tactical nuclear weapon ranging in yield from 8 to 61 kilotons stockpiled from 1952 to 1967.

Seen from a distance of 8 miles, Hornet’s cooling fireball and debris cloud still continues to radiate much visible energy in the form of ionized glowing air; in this long photographic exposure it appears as an undifferentiated white mass. Hornet was a test of what would become the W-30 warhead, an air-defense weapon that was stockpiled from 1959 to 1979 with a yield of 140 tons to 19 kilotons.

Troops shield themselves from the light of the detonation several miles away. Smoky was the second instance of thermonuclear detonation on the continental U.S., after Hood, and tested what would become the Mark-41 bomb.

Troops watch as the cooling fireball churns upwards surrounded by a halo of ionized, glowing air.  Smoky tested a prototype of the Mark-41 bomb, which was stockpiled from 1960 to 1976, and at 25 megatons yield was the most destructive weapon the U.S. ever produced.  A single 25 megaton bomb carries the equivalent explosive power of 1,666 Hiroshima bombs.

Towering over the desert floor, Diablo’s debris cloud glows with ionized air. Diablo was a test of the primary stage of a two-stage thermonuclear device.

Seen from the ground, Whitney’s debris cloud glows with ionized air. Whitney was a test of the W-27 warhead, stockpiled from 1958 to 1965, yielding 2 megatons.

Shasta’s ionization corona glows as its fireball cools. Shasta was a test of the primary stage of a two-stage thermonuclear device, much like Diablo, and exhibited similar characteristics.

Its fireball having cooled and now surrounded by a corona of ionized air, the Hood debris cloud moves upwards on its way to a final height of 43,770. Hood was the largest atmospheric nuclear test ever conducted on the continental United States, and the first true two-stage thermonuclear device detonated in Nevada. Total weight of the device was 393 pounds; it was a prototype missile warhead.

Soldiers huddle in a trench less than two miles from ground zero at detonation, while the photographer shoots by fission light.  Visible are the cluster of smoke trails from rockets set off just before detonation to help measure the explosion’s invisible air shock wave.

Made from a hill just above the media bleachers of “News Nob,” Turk’s fireball expands outwards thirteen miles away with such brightness that it solarizes the photographic negative. Turk was a test of what would become the W-27 thermonuclear ballistic missile warhead, stockpiled from 1958 to 1965 and yielding 2 megatons

This long-duration photographic exposure shows a truck backing out of the image frame while the debris cloud moves upward in the distance thirteen miles away. Apple-1 was a test of a thermonuclear bomb mockup.

Creating a second dawn, Priscilla’s fireball rises upwards in a rare, double-tiered cloud surrounded by a halo of fire. Priscilla tested various bomb shelter designs; it used the primary fission stage of the two-stage Mark-39 thermonuclear bomb, stockpiled from 1957 to 1966 and yielding 3 to 4 megatons.

Priscilla's moment of detonation is documented by members of the Lookout Mountain Air Force Station with still and motion picture cameras.  From 1947 to 1969, the Hollywood-based photographers and cinematographers of the Station were charged with visually recording all aspects of U.S. nuclear tests at the Nevada Test Site, as well as offshore tests in the Pacific Proving Grounds.

Priscilla’s distinctive double-tiered cloud is documented by members of the Lookout Mountain Air Force Station with still and motion picture cameras.  From 1947 to 1969, the Hollywood-based photographers and cinematographers of the Station were charged with visually recording all aspects of U.S. nuclear tests at the Nevada Test Site, as well as offshore tests in the Pacific Proving Grounds.

In a blue aerial image made with special film, Priscilla’s double-tiered cloud and fire-halo rise upwards amongst the basins and ranges of Nevada’s geology, visible to the horizon.

Grable tested the new artillery-fired Mark-9 nuclear weapon, stockpiled from 1952 to 1957. Launched at a target 6 miles away from an 85-ton, 280mm cannon, Grable so inspired American politicians that members of Congress clamored for the use of the Mark-9 during the Korean War.

Members of the Canadian and British military observe detonation thirteen miles away.   Zucchini was a test of the fission primary stage of a two-stage thermonuclear bomb mockup.

MET was a “Military Effects Test” that investigated, among other things, radiation effects on the winter and summer uniforms of Soviet and Chinese troops.

Seen left to right, Army soldiers Schmidt, Wilson, Zerfas, Roth, Moore and Schleuter observe the Dog fireball after detonation. Dog was the first “troop-test” deployment by the Department of Defense, which placed soldiers 6.8 miles away from the blast point. The Army wanted them much closer, but the Atomic Energy Commission refused, citing the seven-mile-distance safety guidelines it required for its own personnel.  Later tests would dangerously place troops less than 2 miles from ground zero at detonation and allow maneuvers to ground zero shortly thereafter.

Soldiers watch the Dog debris cloud rise 6.8 miles away.  2796 troops observed the detonation; 883 troops then “attacked” an objective 500 yards from ground zero in the world’s first “atomic warfare maneuver”; sixty of these troops went even closer. Dog used the Mark-4 bomb, stockpiled from 1949 to 1953, with a variable yield of 1 to 31 kilotons.

Red filter aerial view; the cluster of smoke trails visible to the left of the fireball is from rockets launched just before detonation to help photographically measure the explosion’s invisible air shock wave. Sugar was a weapons-effects test that investigated the nature of a surface burst.

Aerial photograph showing a clearly visible shockwave effect on the alluvial desert soil.  Easy tested a prototype of the Mark-7 bomb, stockpiled from 1952 to 1967 and yielding 8 to 61 kilotons.

Army soldiers turn away and shield themselves from the MET detonation blast 6 miles away. MET was a “Military Effects Test” that investigated, among other things, radiation effects on the winter and summer uniforms of Soviet and Chinese troops.

Army soldiers watch MET's rising debris cloud 6 miles away. It tested a Mark-7 bomb, stockpiled from 1952 to 1967, with a variable yield of 8 to 61 kilotons.

Released into the air just after detonation to test its response to the force of an atomic air shock wave, an unmanned Navy ZSG-3 airship ruptures lodges on the desert floor.  The debris cloud rises in the distance. Stokes was a test of the W-30 air-defense and tactical atomic warhead, stockpiled from 1959 to 1979, with a variable yield of 140 tons to 19 kilotons.

Its debris cloud rising about 40 seconds after detonation, Little Feller I was the last atmospheric nuclear test at the Nevada Test Site, and used the tiny W-54 air defense and tactical warhead to test the one-man-operated “Davy Crockett” nuclear rocket launcher. The W-54 was stockpiled from 1961 to 1972, with a variable yield of 10 tons to 6 kilotons, and weighed only 50 pounds.

Seen in a long-exposure photograph, a portion of Wilson’s detonation cloud, five miles distant, drifts in the early morning wind. Wilson tested a prototype of the single-stage, 150-pound W-45 warhead, stockpiled from 1961 to 1989, with a yield of 500 tons to 15 kilotons.

Within an hour of detonation, U.S. Marine helicopters fly north and east around Hood’s dispersing debris cloud, helping to coordinate a ground-troop “invasion” of ground zero. Hood was the largest atmospheric nuclear test conducted on the continental United States, and the first true two-stage thermonuclear device exploded there. it was a prototype for eventual use on a missile warhead.

In this north-looking image, John explodes high in the early morning sky; shadows from the actual sun can be seen amongst the sagebrush. John proof-tested the W-25 warhead, demonstrating the capability of an air-to-air nuclear missile designed to destroy incoming Soviet strategic bombers.  The 218-pound W-25 was stockpiled from 1956 to 1984 and yielded 1 to 2 kilotons.

Viewed aerially looking directly down over ground zero at left and from about 2000’ at right, X-Ray explodes in the Pacific Ocean.  X-Ray and Operation Sandstone were approved by President Harry Truman in 1947 to develop an entirely new generation of atomic weapons than those used on Japan in 1945. The atoll’s 142 natives were relocated to Ujelang, 143 miles distant. A total of 43 nuclear weapons tests were conducted by the United States at Enewetak over the next decade, most of them thermonuclear and of massive destructive capacity.

Obliterating Engebi Island, X-Ray’s fireball roars upwards in this aerial view seen from about 2000’.

Photographed from a neighboring island, Yoke’s fireball rises amidst cloud cover in the humid Pacific morning. Like X-Ray, it was a prototype of the Mark-4 bomb design, the first mass-produced nuclear weapon. It was stockpiled from 1949 to 1953, with a variable yield of 1 to 31 kilotons.

In the world’s first thermonuclear explosion, and the largest nuclear detonation to date, the George fireball is shrouded by the Wilson cloud effect, caused by a low-pressure zone just behind the blast’s rapidly advancing shock wave that makes water vapor temporarily condense from the tropical air.  The shock wave itself appears clearly as a white disk on the water. George measured for its designer, Edward Teller, some of the reaction processes that would be critical to the success of the massive thermonuclear detonation Mike -- 46 times larger -- that would occur a year later.

Personnel shield themselves from Erie’s detonation flash. Erie tested a prototype of the primary stage of the Mark-28 thermonuclear bomb, stockpiled from 1958 to 1991 with a variable yield of 70 kilotons to 1.45 megatons.

In the first nuclear detonation after WWII, Able’s airdrop flash is seen aerially at left. Bikini Atoll in the Marshall Islands was selected as the location for tests Able and Baker; 162 Bikinians were relocated to Rongerik Atoll 128 miles to the East. A total of 23 nuclear weapons tests were conducted by the U.S. at Bikini over the next 12 years, most of them thermonuclear and of massive destructive capacity. The Atoll remains uninhabitable. Able used a bomb of the same design and yield as that used to destroy the Japanese city of Nagasaki on August 9, 1945.

Seen from ground level, Able’s debris cloud rises to an altitude of 26,400’. Operation Crossroads assembled a fleet of more than 71 decommissioned WWII U.S., German and Japanese vessels as a nuclear “target armada” in Bikini Lagoon. Able used a bomb of the same design and yield as that used to destroy the Japanese city of Nagasaki on August 9, 1945; the device was produced as the Mark 3 bomb and stockpiled from 1947 to 1950, yielding 21 kilotons.

To left, Baker throws two million gallons of water 10 seconds after detonation over a mile high in a column 2000’ wide, now just beginning to fall and further devastate the decommissioned ghost fleet below. To right, an aerial image shows Baker shrouded by its Wilson condensation cloud, caused by low-pressure behind the blast’s shock wave making water vapor temporarily condense from the humid air. Baker was the first underwater nuclear detonation, and created intense radioactivity.

To right, seen in an aerial image, Baker is shrouded by its Wilson condensation cloud, caused by low-pressure behind the blast’s shock wave making water vapor temporarily condense from the humid air.  The shock wave appears as a white disk on the water surrounding the cloud.

Baker’s Wilson condensation cloud has dissipated closer to the surface of the water, revealing a 2000’-wide water column and the decommissioned armada surrounding it. In an instant more than two million gallons of water will begin to fall. Baker used a bomb of the same design and yield as that used to destroy the Japanese city of Nagasaki on August 9, 1945; the device was mass-produced as the Mark 3 bomb and stockpiled from 1947 to 1950, with a yield of 21 kilotons.

Its Wilson condensation cloud advancing just behind the white disk of its shock wave, Seminole tested the cratering effects of a high-yield thermonuclear device, the Mark-28, under controlled conditions. The Mark-28 was stockpiled from 1958 to 1991, with a variable yield of 70 kilotons to 1.45 megatons.

Seen from about 8000’, Huron’s glowing Wilson cloud and advancing air shockwave illuminate more natural Pacific weather. Huron probably tested a prototype of the W-50 warhead. The W-50 was stockpiled from 1963 to 1991, yielded 60 to 400 kilotons, and was used on the Pershing surface-to-surface tactical missile deployed in Europe.

Personnel watch as Sequoia’s Wilson cloud lights the humid Pacific morning.  Sequoia likely tested a prototype that led to the tiny W-54 air defense and tactical nuclear warhead (see Little Feller I). The W-54 was stockpiled from 1961 to 1972, with a variable yield of 10 tons to 6 kilotons, and weighed only 50 pounds.

The largest fission-only device ever detonated, King disproved the theory of “criticality” -- wherein only so much fissionable material could be brought together in one weapon before it would self-detonate – surpassing supposed 250 kiloton fission limits. At the time, a large fission-only bomb was coveted by the U.S. military, due to the uncertainty of thermonuclear investigations; the spectacular thermonuclear success of Mike, King’s test companion in Operation Ivy, was far from guaranteed.

V.I.P.s wearing protective goggles watch Dog light the Pacific morning from Adirondack chairs in this image made on the “Officer’s Beach Club Patio.” The explosion lifted 250,000 tons of radioactive reef material to a height of 35,000’. Dog tested the Mark-6 bomb, stockpiled from 1951 to 1962 and yielding 8 to 160 kilotons.  Over a thousand were eventually produced.

Captured by an automatic ultra-high speed camera, the world’s first man-made sun instantly grows to a diameter of 3.5 miles and creates its own electrical storm. Mike was comprised of a huge, 82-ton refrigerator of super-cooled heavy hydrogen isotopes – liquid deuterium and tritium – which a fission atomic bomb trigger fused into helium, releasing the full thermonuclear power of the stars.

Seen in a telephoto aerial view made from about 30,000’, the 3.5 mile-wide Mike fireball rushes upwards. Mike was the first test of a large-scale, “true” thermonuclear device, one based on the Teller-Ulam principles of staged radiation implosion. The explosion was the 4th largest nuclear test the United States ever detonated, equivalent to 10.4 million tons of TNT, greater in a single moment than all of the ordnance detonated in both the First and Second World Wars combined.

Mike’s fireball seen in a wider aerial view made from about 30,000’, showing three ring cloud condensation structures.

Aerial photograph made at about 30,000’ of Mike’s debris cloud and stem. Within 1.5 minutes after detonation Mike’s cloud had climbed to 57,000’; half an hour later it measured 60 miles in diameter. The cloud would eventually reach an altitude of 142,000’ and a maximum diameter of 100 miles. Eugelab Island was vaporized, leaving a crater more than a mile across and 164 feet deep. About 80 million tons of the island was thrown into the sky.

The Mike debris cloud and stem about 10 minutes after detonation, seen from a ship. Personnel and all ships were kept 40 miles distant from the deadly blast.

Seen in an aerial photograph made at 12,000’ from a distance of about 50 miles, the Mike cloud would eventually reach an altitude of 142,000’ and a width of 100 miles.  Mike was as crucial to U.S. nuclear weapons development as Trinity, the world’s first atomic explosion, had been only seven years before, and was 500 times as powerful.  Yields of atomic weapons could now be described not only in kilotons of TNT-equivalent force, but in megatons, and the world instantly became a vastly more dangerous place.

Personnel watch as Oak’s condensation cloud grows.  Oak produced an underwater crater 204’ deep and 5740’ in diameter, and its  yield was 20% higher than the predicted 7.5 megatons.

Personnel watch as Oak’s debris cloud towers 10 miles in height.  The test was an early prototype of the W-53 Titan II missile warhead and B-53 strategic bomb, stockpiled from 1962 to 1997 and yielding 9 megatons.  It is not clear at this time if this oldest and highest-yielding weapon still in the U. S. nuclear arsenal is being kept in the reserve stockpile, or has been slated for actual dismantlement.

Personnel observe Magnolia’s glowing Wilson cloud, lit by the fireball within.  Magnolia was a proof-test of the experimental “Cougar” device.

Seen from 15,000’, Yeso’s fireball rises upwards, illuminating Christmas Island 20 miles away. Two ring-like condensation cloud formations are visible. Yeso was a test of the experimental “16-M” thermonuclear device, dropped in a Mark-39 bomb casing. The Mark-39 was stockpiled from 1959 to 1960 and yielded 3 megatons.

Telephoto image of the Yeso fireball rising shortly after detonation, seen from an altitude of 8000’.

Caught just past its apex, Wahoo’s water blast begins to fall back to the surface.  Wahoo was a test of the Mark-7 bomb in water 3200 feet deep; the Mark-7 was stockpiled from 1952 to 1967 and had a variable yield of 8 to 61 kilotons.

Seen from an airplane, the Starfish blast creates an artificial aurora that lasted seven minutes and knocked out electricity in Oahu, Hawaii, 800 miles away. Starfish Prime was a high-altitude test using the W-49 warhead to explore electromagnetic pulse (EMP) effects. The W-49 was stockpiled from 1958 to 1975, yielded 1.4 to 5 megatons, and was deployed on Thor, Atlas, Jupiter and Titan inter-continental and intermediate-range ballistic missiles.

Seen in a black and white aerial photograph, Checkmate created a green and blue circular formation surrounded by a vivid red ring. Since it detonated above the atmosphere, it did not make a fireball.  Checkmate was a high-altitude test using a prototype of the W-50 warhead, which was stockpiled from 1963 to 1991, yielded 60 to 400 kilotons, and was deployed on Pershing missiles throughout Europe.

Seen about a minute after detonation, Orange exhibits the unusual shapes and colors typical of very high-altitude detonations.  Unexpectedly, the blast curtailed radio communications across the Pacific, blacking out Hawaii for two hours and Australia for nine as well as creating a giant electromagnetic pulse (EMP) that wreaked havoc with electronic systems below. The W-39 was stockpiled from 1959 to 1965, yielded 3 to 4 megatons, and was a ground-launched cruise missile and surface-to-surface warhead.

Silhouetting palm trees, Bluestone’s fireball rises.  Bluestone was a test of the W-56 warhead, stockpiled from 1963 to 1993 and yielding 1 to 2 megatons. About a thousand warheads were produced, with 450 remaining in service until 1993; they were deployed on the Minuteman intercontinental ballistic missile.

Truckee’s debris cloud catches the first rays of dawn. Thermonuclear detonations in the humid Pacific created their own localized weather systems. Truckee was a test of the W-58 warhead on a Polaris A-2 missile. The W-58 was stockpiled from 1964 to 1982, yielded 200 kilotons, and was deployed on submarine-launched ballistic missiles.

Its Wilson cloud seen silhouetting weather monitoring instruments, Harlem’s fireball rushes upward.  Harlem tested the W-47 warhead, stockpiled from 1960 to 1974; the W-47 yielded 600 kilotons to 1.2 megatons, and was deployed on the submarine-launched Polaris ballistic missile.

Cactus’ crater was 37 feet deep and 346 feet wide; in 1979 the U. S. used it to bury 110,000 cubic yards of radioactive soil from other islands in Enewetak, topping it with concrete. Cactus was a test of the primary fission stage of a Mark-43 thermonuclear bomb, which was stockpiled from 1961 to 1991 and yielded 70 kilotons to 1 megaton.

Yellowwood was a prototype of the W-53 Titan II missile warhead and B-53 strategic bomb, stockpiled from 1962 to 1997 and yielding 9 megatons. It is not clear at this time if this oldest and highest-yielding weapon in the U. S. nuclear arsenal is being kept in the reserve stockpile or has been slated for dismantlement.

Photographed from a submarine, Frigate Bird’s debris cloud rises thirty miles away. The only U.S. test of a ballistic missile with a live nuclear warhead, Frigate Bird was launched from another submarine and flew 1174 miles in space before re-entry and detonation. It tested the W-47 warhead, stockpiled from 1960 to 1974 and yielding 600 kilotons to 1.2 megatons.

Personnel observe Mohawk’s fireball and ring-like condensation cloud structure from Japtan Island. Mohawk was a test of a two-stage thermonuclear device; its crater was 8 feet deep and 1340’ wide.

Seen from a nearby island, Mohawk’s fireball and coral-filled stem roil upwards. Mohawk was a test of a two-stage thermonuclear device.

Aerial image of the Zuni fireball obscured by cloud cover.  Zuni was a prototype of the Mark-41 bomb, which was stockpiled from 1960 to 1976, and at a yield of 25 megatons was the most destructive weapon the United States ever produced, about 65% larger than 15-megaton Bravo, its largest test. The Soviet Union airdropped a 58 megaton nuclear bomb over the Arctic in 1961, detuned from its full capacity of 100 megatons. A single 100 megaton bomb carries the explosive power of 6666 Hiroshima bombs.

Aerial image of the Aztec fireball rising through morning clouds. Aztec tested the W-50 thermonuclear warhead, stockpiled from 1963 to 1991, yielding 60-400 kilotons, and deployed on Pershing missiles throughout Europe.

Item tested the feasibility of using deuterium-tritium gas in the core of a weapon to enhance fission, a principle known as “fusion boosting” that increased efficiency of the explosion; predicted yield without boosting was 50% less. The technique led to “dial-a-yield” capability in later weapons, where the power of the explosion could be controlled by the amount of gas added.

Aerial view of Apache’s glowing Wilson condensation cloud. Its radioactive debris rose to a height of 85,000 feet, and produced exceptionally heavy fallout in the northern islands of Enewetak. Apache was a test of the W-27 thermonuclear warhead, stockpiled from 1958 to 1965 and yielding 2 megatons.

The first U.S. airdrop of a thermonuclear weapon, Cherokee tested the new Mark-39 thermonuclear bomb, stockpiled from 1957 to 1966 with a variable yield of 3-4 megatons. It pointedly demonstrated to the Soviet Union that the U.S. now possessed deliverable hydrogen bombs of massive destructive capacity. Seven minutes after detonation the interior of the cloud was measured at 20,000 roentgens per hour – a cumulative dose of just 500 roentgens immediately kills half those exposed to it.

The largest U.S. nuclear device exploded, Bravo’s fireball expands to almost four miles width within a second of detonation and was seen 2,600 miles away. The blast crater was 1.25 miles wide and 250’ deep. Bravo was 2.5 times more powerful than predicted, and became the worst radiological disaster in U.S. testing history. 28 Americans and 236 Marshallese were badly sickened. All the islands of Bikini Atoll were uninhabitable for the rest of Operation Castle, and remain so to this day. Bravo advanced work on the Mark-21 bomb, stockpiled from 1955 to 1957 and yielding 4 to 5 megatons.

Sunset’s fireball rises upwards, surrounded by multiple ring condensation clouds, into the humid morning air. Sunset tested the W-59 warhead, stockpiled from 1962 to 1969 with a yield of 1 megaton, and was deployed on intercontinental and ballistic missiles.

Romeo’s fireball pushes upwards, capped by a ring-like condensation cloud. It would eventually rise to a height of 110,000’. Romeo was a test of the Mark-17/24 bomb, stockpiled from 1954 to 1957 and yielding 10 to 15 megatons.

Aerial telephoto image of the Romeo fireball. The second U.S. solid-fueled thermonuclear device, Romeo’s yield was three times larger than predicted and used plentiful, unprocessed natural lithium as its fusion fuel.

Dakota’s fireball, encircled by Wilson condensation strata, rises through a layer of early morning cloud cover in this aerial view.  Dakota tested the W-28 warhead, stockpiled from 1958 to 1991, and variably yielding from 70 kilotons to 1.45 megatons. The most versatile and widely-used of any U.S. thermonuclear weapon, it was manufactured in five models and had 20 different variants.

Partially obscured by weather of its own making and morning cloud cover, Apache’s glowing fireball rises skywards, followed by a large debris stem. Its cloud would eventually rise to a height of 85,000’, and produce exceptionally heavy fallout in the northern islands of the Atoll. Military landing craft fill the foreground in this surface view. Apache tested the Mark-27 thermonuclear warhead, stockpiled from 1958 to 1965, with a yield of 2 megatons.

Aerial image from 40,000’ a few minutes after detonation. Bravo was the largest U.S. nuclear test, and was about 2.5 times more powerful than predicted. 85 miles northeast of the detonation, the Japanese fishing vessel Fifth Lucky Dragon was blanketed with such strong fallout radiation that all 23 crewmembers were sickened; radioman Aikichi Kuboyama would die. The remaining crewmembers would leave hospital eight months later. Bravo showed that a high-yield surface detonation could create lethal radiological contamination 120 miles downwind of the blast point, and dangerous contamination to 250 miles downwind.

The second-largest test detonated by the U.S., Yankee’s fireball roils upwards surrounded by three condensation ring cloud structures. Yankee tested the Mark-17/24 bomb, stockpiled from 1954 to 1957 and yielding 10 to 15 megatons.