Atomic Photographers Marshall Islands

Operation Crossroads, Bikini Atoll 1946

Operation Crossroads was a series of nuclear tests conducted by the United States at Bikini Atoll in the Pacific Ocean in 1946. It aimed to assess the effects of atomic weapons on naval forces, infrastructure, and the environment. The operation consisted of two main tests, Able and Baker, collectively known as Operation Crossroads.

Operation Crossroads served multiple purposes. It provided crucial data on the impact of nuclear weapons on naval forces and infrastructure, influencing subsequent developments in nuclear arms technology. The tests also raised awareness about the destructive capabilities and potential long-term consequences of nuclear weapons, leading to public concern and calls for increased safety measures.

Furthermore, Operation Crossroads played a role in shaping international discussions on nuclear arms control and disarmament. It contributed to the establishment of the United Nations Atomic Energy Commission, which aimed to promote peaceful uses of atomic energy while preventing its destructive utilization.

Although Operation Crossroads achieved some of its objectives, the tests also revealed challenges in decontamination efforts and the unpredictable behavior of nuclear weapons. The operation highlighted the need for further research, safety precautions, and international cooperation in the development, testing, and use of nuclear weapons.

Operation Crossroads had significant and lasting effects on both local residents and military personnel involved in the tests. For the local residents of Bikini Atoll, the testing resulted in forced displacement and the loss of their ancestral homeland. They were relocated to other islands, disrupting their traditional way of life and causing cultural and social upheaval. The promise of a temporary displacement turned into long-term displacement as Bikini Atoll remained contaminated, rendering it unsafe for the residents to return. This displacement had profound and lasting impacts on their communities and cultural identity.

For military personnel involved in Operation Crossroads, the effects were both physical and psychological. Many personnel were exposed to radiation during the tests, resulting in acute radiation sickness and long-term health consequences such as an increased risk of cancer and other radiation-related illnesses.

Able June 30, 1946

The Able test, conducted on July 1, 1946, involved the detonation of a plutonium-based atomic bomb above a fleet of decommissioned warships. While it demonstrated the destructive power of nuclear weapons, the test yielded less conclusive results than expected in terms of the long-term effects on the ships and the behavior of different materials.

Aerial view of the Able test, a 23 kt (96 TJ) device detonated on July 1, 1946 at an altitude of 520 ft (160 m). USAAF

The atomic cloud during the "Able" nuclear test at the Bikini atoll. 1 July 1946 U.S. Navy (photo 80-G-396226)

Baker July 24, 1946

The Baker test, conducted on July 25, 1946, was an underwater explosion that assessed the effects of an atomic bomb detonated beneath the surface. This test revealed the devastating effects of a nuclear detonation on ships, causing significant damage and contamination.

The "Baker" explosion, part of Operation Crossroads, a nuclear weapon test by the United States military at Bikini Atoll, Micronesia, on 25 July 1946. The wider, exterior cloud is actually just a condensation cloud caused by the Wilson chamber effect, and was very brief. The actual mushroom cloud is inside the condensation cloud (compare with this image, a photo taken slightly later, after the condensation cloud had cleared). The water released by the explosion was highly radioactive and contaminated many of the ships that were set up near it. Some were otherwise undamaged and sent to Hunter's Point in San Francisco, California, United States for decontamination. Those which could not be decontaminated were sunk a number of miles off the coast of San Francisco. 25 July 1946 United States Department of Defense (either the U.S. Army or the U.S. Navy)

Seventy years ago, at Operation Crossroads, nuclear weapons briefly became a form of consumer entertainment.Photograph Courtesy Library of Congress

Operation Sandstone, Enewetak Atoll, 1948

Three tests were conducted by the Atomic Energy Commission in April and May 1948 with the armed forces having only a supporting role by the Joint Task Force 7, with a work force of 10,366 personnel, of whom 9,890 were military.Operation Sandstone were primarily tests of new bomb designs rather than of the effects of nuclear weapons. The three tests conducted were X-ray on April 14, 1948, Yoke on April 30, 1948 and Zebra on May 14, 1948.

140 people lived on Enewetak when it was chosen as a test site. They were moved to Ujelang Atoll, which had been uninhabited since the last nineteenth century when a typhoon swept over the atoll. The U.S. Navy constructed cisterns, water catchments, latrines, tent frames, and other buildings on Ujelang in November 1947. Enewetak was official closed off on December 2, 1947. By December 20th, all natives of the atoll were moved.

X-Ray April 14, 1948

Sandstone X-Ray, 37-kilotons. U.S. Air Force 1352nd Photographic Group, Lookout Mountain Station - Former Defenses Nuclear Agency (DNA) A-bomb-test Operation Sandstone, Event X-Ray detonation, April 15, 1948, Engebi, Eniwetok-Atoll

Yoke April 30, 1948

Yoke explosion Federal government of the United States - http://sonicbomb.com/albums/nuke_us/yoke.jpg Sandstone Yoke nuclear test.

Zebra May 14, 1948

Operation Castle

Bravo, March 1, 1954

Castle Bravo was the code name for the first test conducted during Operation Castle, a series of nuclear tests conducted by the United States in 1954 at Bikini Atoll in the Pacific Ocean. It is infamous for being the largest and most powerful nuclear test ever conducted by the United States.

On March 1, 1954, the Castle Bravo test involved the detonation of a hydrogen bomb with an anticipated yield of 6 megatons. However, due to an unexpected and significant increase in the efficiency of the fusion reaction, the bomb yielded around 15 megatons, making it more than two times more powerful than predicted.

The immense power of Castle Bravo caused widespread devastation and had lasting effects. The explosion created a fireball that reached a temperature of several million degrees Celsius, vaporizing everything within its immediate vicinity. The blast generated a mushroom cloud that rose to a height of 15 miles and spread radioactive debris over a vast area.

The fallout from Castle Bravo spread far beyond the test site, affecting nearby islands, including Rongelap and Utirik, and even reaching inhabited atolls hundreds of miles away. The fallout exposed the local populations and U.S. military personnel to high levels of radiation. The crew of a Japanese fishing boat, the Lucky Dragon, also encountered the fallout and suffered from radiation sickness, with one crew member later dying from the exposure.

The long-term effects of the Castle Bravo test were devastating. The radioactive contamination caused severe health issues, including radiation sickness, burns, and increased risks of cancer and other radiation-related illnesses. Many islanders were forced to evacuate their homes due to the hazardous levels of radiation.

The Castle Bravo test served as a stark wake-up call, highlighting the dangers and potential humanitarian consequences of nuclear weapons. It led to increased international awareness about the need for nuclear arms control and spurred discussions on the impact of nuclear testing on the environment and human health. The incident influenced subsequent efforts to establish regulations and treaties to limit the testing and proliferation of nuclear weapons, such as the Partial Nuclear Test Ban Treaty of 1963.

Nuclear weapon test Bravo (yield 15 Mt) on Bikini Atoll. The test was part of the Operation Castle. The Bravo event was an experimental thermonuclear device surface event. United States Department of Energy - US gov

The Castle Bravo nuclear test, the detonation of the most powerful thermonuclear device ever tested by the United States. United States Department of Energy - National Oceanic and Atmosphere Administration

Castle Bravo nuclear test. ENERGY.GOV - HD.10.290

Shrimp device tested in Castle Bravo being unloaded from a truck. United States Atomic Energy Agency

Shot-cab installation of SHRIMP device, with humans for scale. USDE - Trinity & Beyond: The Atomic Bomb Movie Castle Bravo SHRIMP device shot-cab installation, with humans for scale.

Castle Bravo nuclear test. The Shrimp device in its shot cab. DTRIAC photo ID: IM-4: D-92-1 Federal government of the United States

Castle Union, April 25, 1954

The objective of Castle Union was to evaluate the feasibility of a deliverable thermonuclear device, also known as a hydrogen bomb or H-bomb.

The test involved detonating a device codenamed “Runt” on a tower in the Bikini Atoll. The Runt device utilized a fusion reaction to release an immense amount of energy. The yield of Castle Union was approximately 6.9 megatons, making it one of the largest nuclear tests ever conducted by the United States.

The Castle Union test yielded valuable data for the development of more powerful thermonuclear weapons. However, it also raised concerns about the destructive potential and environmental impact of such weapons. The Castle series of tests, including Castle Union, contributed to increased international awareness and discussions about the dangers of nuclear weapons.

Nuclear weapon test Union (yield 6.9 Mt) on Bikini Atoll. United States Department of Energy

Romeo, March 26, 1954

Castle Romeo was the code name given to one of the tests in the Operation Castle series of U.S. nuclear tests. It was the first test of the TX-17 thermonuclear weapon, the first deployed thermonuclear bomb.

It was detonated on March 26, 1954, at Bikini Atoll of the Marshall Islands, on a barge moored in the middle of the crater from the Castle Bravo test. It was the first such barge-based test, a necessity that had come about because the powerful thermonuclear devices obliterated the small islands following detonation.

Nuclear weapon test Romeo (yield 11 Mt) on Bikini atoll. The test was part of the Operation Castle. Romeo was the first nuclear test conducted on a barge. The barge was located in the Bravo crater. United States Department of Energy - US gov

Castle Romeo nuclear test (yield 11 Mt) on Bikini Atoll. It was the first nuclear test conducted on a barge. The barge was located in the Castle Bravo crater.

The Runt I nuclear explosive device used in the Castle Romeo nuclear test. Federal government of the United States

Castle Romeo (March 26, 1954): This test focused on the development of tactical nuclear weapons. A 11-megaton hydrogen bomb was detonated, validating its design for potential military applications.

Castle Yankee, May 4, 1954

Castle Yankee was the code name given to one of the tests in the Operation Castle series of American tests of thermonuclear bombs. It was originally intended as a test of a TX-16/EC-16 Jughead bomb, but the design became obsolete after the Castle Bravo test was successful. The test device was replaced with a TX-24/EC-24 Runt II bomb which was detonated on May 5, 1954, at Bikini Atoll. It released energy equivalent to 13.5 megatons of TNT, the second-largest yield ever in a U.S. fusion weapon test.

Castle Nectar (May 13, 1954)

This test explored the use of nuclear weapons for generating electricity. It involved the detonation of a 1.69-megaton bomb.

Castle-Koon (May 21, 1954)

The final test of Operation Castle was conducted to study the behavior of large-yield nuclear devices in an underground setting. A 110-kiloton bomb was detonated inside a deep borehole.