View source for Operation Crossroads

{{short description|1946 nuclear weapon tests at Bikini Atoll}}
{{Use mdy dates|date=November 2018}}
{{Featured article}}

{{Infobox nuclear weapons test
|name                = Operation Crossroads
|picture             = [[File:CrossroadsAble2.gif|300px]][[File:Crossroads_Baker.gif|300px]]
|picture_description = Operation Crossroads test detonations of Able (top) and Baker (bottom).
|country             = United States
|test_site           = NE Lagoon, Bikini Atoll
|period              = 1946
|number_of_tests     = Two tested and one cancelled.
|test_type           = Free fall air drop, Underwater
|max_yield           = {{convert|22–23|ktTNT|lk=in}}
|previous_series     = [[Trinity (nuclear test)|Trinity]]
|next_series         = [[Operation Sandstone|Sandstone]]
}}

'''Operation Crossroads''' was a pair of [[nuclear weapon]] tests [[nuclear weapons of the United States|conducted by the United States]] at [[Bikini Atoll]] in mid-1946. They were the first [[Nuclear weapons testing|nuclear weapon tests]] since [[Trinity (nuclear test)|Trinity]] on July 16, 1945, and the first [[Detonation|detonations]] of nuclear devices since the [[Atomic bombings of Hiroshima and Nagasaki#Bombing of Nagasaki|atomic bombing of Nagasaki]] on August 9, 1945. The purpose of the tests was to investigate the effect of nuclear weapons on warships.

The Crossroads tests were the first of [[nuclear testing at Bikini Atoll|many nuclear tests]] held in the [[Marshall Islands]] and the first to be publicly announced beforehand and observed by an invited audience, including a large [[news media|press corps]]. They were conducted by Joint Army/Navy Task Force One, headed by [[Vice admiral (United States)|Vice Admiral]] [[William H. P. Blandy]] rather than by the [[Manhattan Project]], which had developed nuclear weapons during [[World War II]]. A fleet of 95 [[target ship]]s was assembled in Bikini Lagoon and hit with two detonations of [[Fat Man]] [[plutonium]] [[implosion-type nuclear weapon]]s of the kind dropped on Nagasaki in 1945, each with a yield of {{convert|23|ktonTNT|lk=on}}.

The first test was ''Able''. The bomb was named ''Gilda'' after [[Rita Hayworth]]'s character in the 1946 film ''[[Gilda]]'' and was dropped from the [[Boeing B-29 Superfortress|B-29 Superfortress]] ''[[Big Stink (B-29)|Dave's Dream]]'' of the [[509th Bombardment Group]] on July 1, 1946. It detonated {{convert|520|ft|0|sigfig=2}} above the target fleet and caused less than the expected amount of ship damage because it missed its [[aim point]] by {{convert|2130|ft|0|sigfig=2}}.

The second test was ''Baker''. The bomb was known as ''Helen of Bikini'' and was detonated {{convert|90|ft}} underwater on July 25, 1946. Radioactive sea spray caused extensive contamination. A third deep-water test named ''Charlie'' was planned for 1947 but was canceled primarily because of the [[United States Navy]]'s inability to decontaminate the target ships after the ''Baker'' test. Ultimately, only nine target ships were able to be scrapped rather than [[Scuttling|scuttled]]. ''Charlie'' was rescheduled as [[Operation Wigwam]], a deep-water shot conducted in 1955 off the coast of Mexico ([[Baja California]]).

Bikini's native residents were evacuated from the island on board the ''LST-861'', with most moving to the [[Rongerik Atoll]]. In the 1950s, a series of large thermonuclear tests rendered Bikini unfit for [[subsistence farming]] and [[fishing]] because of [[radioactive contamination]]. Bikini remains uninhabited {{As of|2017|lc=y}}, though it is occasionally visited by [[sport diver]]s. 

Planners attempted to protect participants in the Operation Crossroads tests against [[radiation sickness]], but one study showed that the life expectancy of participants was reduced by an average of three months. The ''Baker'' test's radioactive contamination of all the target ships was the first case of immediate, concentrated [[radioactive fallout]] from a nuclear explosion. Chemist [[Glenn T. Seaborg]], the longest-serving chairman of the [[United States Atomic Energy Commission|Atomic Energy Commission]], called ''Baker'' "the world's first nuclear disaster."{{sfn|Weisgall|1994|p=ix}}

==Background==
The first proposal to test nuclear weapons against naval warships was made on August 16, 1945, by [[Lewis Strauss]], future chairman of the [[United States Atomic Energy Commission|Atomic Energy Commission]]. In an internal memo to Secretary of the Navy [[James Forrestal]], Strauss argued, "If such a test is not made, there will be loose talk to the effect that the fleet is obsolete in the face of this new weapon and this will militate against appropriations to preserve a postwar Navy of the size now planned."<ref>{{Harvnb|Strauss|1962|pp=208–209}}.</ref> With very few bombs available, he suggested a large number of targets widely dispersed over a large area. A quarter century earlier, in 1921, the Navy had suffered a public relations disaster when [[Brigadier general (United States)|General]] [[Billy Mitchell]]'s bombers sank every target ship the Navy provided for the [[Billy Mitchell#Project B: Anti-ship bombing demonstration|Project B]] ship-versus-bomb tests.<ref>{{Harvnb|Weisgall|1994|pp=19–22}}.</ref> The Strauss test would be designed to demonstrate ship [[survivability]].<ref>{{Harvnb|Weisgall|1994|pp=14–15}}.</ref>

[[File:Crossroads Gathering Pearl.jpg|thumb|300px|right|alt=Aerial photo of target ships anchored in a row at Pearl Harbor, Hawaii.|Prospective Operation Crossroads target ships and support ships at [[Pearl Harbor]] on February 27, 1946. Ships from front to rear: {{USS|Crittenden|APA-77|6}}, {{USS|Catron|APA-71|2}}, {{USS|Bracken|APA-64|2}}, {{USS|Burleson|APA-67|2}}, {{USS|Gilliam|APA-57|2}}, {{USS|Fallon|APA-81|2}}, unknown ship, {{USS|Fillmore|APA-83|2}}, {{USS|Kochab|AKS-6|2}}, {{USS|Luna|AKS-7|2}}, and an unidentified tanker and [[liberty ships|Liberty ship]]. On the right are ''LSM-203'' and ''LSM-465''. Farther in the background are a [[floating drydock]] and a merchant ship hulk.]]
In August 1945, Senator [[Brien McMahon]], who within a year would write the [[Atomic Energy Act of 1946|Atomic Energy Act]] and organize and chair the Congressional [[United States Congress Joint Committee on Atomic Energy|Joint Committee on Atomic Energy]], made the first public proposal for such a test, but one designed to demonstrate the vulnerability rather than survivability of ships. He proposed dropping an atomic bomb on captured Japanese ships and suggested, "The resulting explosion should prove to us just how effective the atomic bomb is when used against the giant naval ships."<ref>{{Harvnb|Shurcliff|1947|p=10}}.</ref> On September 19, the Chief of the [[United States Army Air Forces]] (USAAF), [[General of the Army (United States)|General of the Army]] [[Henry H. Arnold]], asked the Navy to set aside 10 of the 38 captured Japanese ships for use in the test proposed by McMahon.<ref name="Weisgall 1994 16">{{Harvnb|Weisgall|1994|p=16}}.</ref>

Meanwhile, the Navy proceeded with its own plan, which was revealed at a press conference on October 27 by the Commander in Chief, [[United States Fleet]], [[Fleet admiral (United States)|Fleet Admiral]] [[Ernest King]]. It involved between 80 and 100 target ships, most of them surplus U.S. ships.<ref name="Weisgall 1994 16"/> As the Army and the Navy maneuvered for control of the tests, [[United States Assistant Secretary of War|Assistant Secretary of War]] [[Howard C. Petersen|Howard C. Peterson]] observed, "To the public, the test looms as one in which the future of the Navy is at stake&nbsp;... if the Navy withstands [the tests] better than the public imagines it will, in the public mind the Navy will have 'won.{{' "}}<ref>{{Harvnb|Peterson|1946}}, quoted in {{Harvnb|Weisgall|1994|p=17}}.</ref>

The Army's candidate to direct the tests, [[Major general (United States)|Major General]] [[Leslie Groves]], head of the [[Manhattan Project]] which built the bombs, did not get the job. The [[Joint Chiefs of Staff]] decided that because the Navy was contributing the most men and [[materiel]], the test should be headed by a naval officer. [[Commodore (United States)|Commodore]] [[William Sterling Parsons|William S. "Deak" Parsons]] was a naval officer who had worked on the Manhattan Project and participated in the [[bombing of Hiroshima]].{{sfn|Christman|1998|pp=3–5}} He had been promoted to assistant to the [[Deputy Chief of Naval Operations]] for Special Weapons, [[Vice admiral (United States)|Vice Admiral]] [[William H. P. Blandy]],{{sfn|Christman|1998|pp=210–211}} whom Parsons proposed for the role. This recommendation was accepted, and on January 11, 1946, President [[Harry S. Truman]] appointed Blandy as head of Army/Navy Joint Task Force One (JTF-1), which was created to conduct the tests. Parsons became Deputy Task Force Commander for Technical Direction. USAAF Major General [[William Ellsworth Kepner|William E. Kepner]] was Deputy Task Force Commander for Aviation. Blandy codenamed the tests Operation Crossroads.<ref>{{Harvnb|Weisgall|1994|pp=30–31}}.</ref><ref>{{Harvnb|Shurcliff|1946|pp=28–29}}.</ref>

Under pressure from the Army, Blandy agreed to crowd more ships into the immediate target area than the Navy wanted, but he refused USAAF Major General [[Curtis LeMay]]'s demand that "every ship must have a full loading of oil, ammunition, and fuel."<ref>{{Harvnb|Weisgall|1994|p=126}}.</ref> Blandy's argument was that fires and internal explosions might sink ships that would otherwise remain afloat and be available for damage evaluation. When Blandy proposed an all-Navy board to evaluate the results, Senator McMahon complained to Truman that the Navy should not be "solely responsible for conducting operations which might well indeed determine its very existence."<ref>{{Harvnb|Weisgall|1994|p=67}}.</ref> Truman acknowledged that "reports were getting around that these tests were not going to be entirely on the level." He imposed a civilian review panel on Operation Crossroads to "convince the public it was objective."<ref>{{Harvnb|Weisgall|1994|pp=68–69}}.</ref>

==Opposition==

Pressure to cancel Operation Crossroads altogether came from scientists and diplomats. Manhattan Project scientists argued that further testing was unnecessary and environmentally dangerous. A [[Los Alamos National Laboratory|Los Alamos]] study warned "the water near a recent surface explosion will be a witch's brew" of radioactivity.<ref>{{Harvnb|Newson|1945|p=4}}, quoted in {{Harvnb|Weisgall|1994|p=216}}.</ref> When the scientists pointed out that the tests might demonstrate ship survivability while ignoring the effect of radiation on sailors,<ref name="Bulletin Editors">{{Harvnb|Bulletin Editors|1946|p=1}}.</ref> Blandy responded by adding test animals to some of the ships, thereby generating protests from [[animal rights]] advocates.<ref>{{Harvnb|Delgado|1991|loc=Ch 2}}.</ref> [[J. Robert Oppenheimer]] declined an invitation to attend the test and wrote President Truman about his objections to it, arguing that any data obtained from the test could be obtained more accurately and cheaply in a laboratory.<ref>{{cite book |last1=Bird |first1=Kai |author-link=Kai Bird|first2=Martin J. |last2=Sherwin |author-link2=Martin J. Sherwin |title=American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer|location=New York|publisher=Alfred A. Knopf|year=2005|isbn=978-0-375-41202-8 |oclc=56753298 |title-link=American Prometheus | pages=349–350}}</ref>

Secretary of State [[James F. Byrnes]], who a year earlier had told physicist [[Leo Szilard]] that a public demonstration of the bomb might make the [[Soviet Union]] "more manageable" in Europe,<ref>{{Harvnb|Szilard|1978|p=184}}.</ref> now argued the opposite: that further display of U.S. nuclear power could harden the Soviet Union's position against acceptance of the [[Acheson–Lilienthal Report|Acheson–Lilienthal Plan]], which discussed possible methods for the international control of nuclear weapons and the avoidance of future nuclear warfare. At a March 22 cabinet meeting he said, "from the standpoint of international relations it would be very helpful if the test could be postponed or never held at all."<ref>{{Harvnb|Weisgall|1994|p=90}}.</ref> He prevailed on Truman to postpone the first test for six weeks, from May 15 to July 1. For public consumption, the postponement was explained as an opportunity for more Congressional observers to attend during their summer recess.<ref>{{Harvnb|Weisgall|1994|p=94}}. Despite the postponement, only 13 members of Congress witnessed the ''Able'' test, and 7 witnessed the ''Baker'' test. {{Harvnb|Shurcliff|1947|p=185}}.</ref>

When Congressmen complained about the destruction of $450 million worth of target ships, Blandy replied that their true cost was their scrap value at $10 per ton, only $3.7 million.<ref>{{Harvnb|Weisgall|1994|p=79}}.</ref> Veterans and legislators from New York and Pennsylvania requested to keep their namesake battleships as [[museum ship]]s, as Texas had done with {{USS|Texas|BB-35|6}}, but the JTF-1 replied that "it is regretted that such ships as the {{USS|New York|BB-34|6}} cannot be spared."<ref>Letter, Brig. Gen. T. J. Betts, USA, to Peter Brambir, March 21, 1946, filed in Protest Answers, National Archives Record Group 374. Cited in {{Harvnb|Delgado|1991|loc=Ch 2}}.</ref>

==Preparation==

A series of three tests was recommended to study the effects of nuclear weapons on ships, equipment, and materiel. The test site had to be in territory controlled by the United States. The inhabitants would have to be evacuated, so it was best if it was uninhabited, or nearly so, and at least {{convert|300|mi|km|sigfig=1}} from the nearest city. So that a [[Boeing B-29 Superfortress|B-29 Superfortress]] could drop a bomb, there had to be an airbase within {{convert|1000|mi|sigfig=2}}. To contain the target ships, it needed to have a protected anchorage at least {{convert|6|mi|km|sigfig=1}} wide. Ideally, it would have predictable weather patterns and be free of severe cold and violent storms. Predictable winds would avoid having radioactive material blown back on the task force personnel, and predictable ocean currents would allow material to be kept away from shipping lanes, fishing areas, and inhabited shores.<ref>{{Harvnb|Shurcliff|1946|pp=16–17}}.</ref> Timing was critical because Navy manpower required to move the ships was being released from active duty as part of the post-World War II demobilization, and civilian scientists knowledgeable about atomic weapons were leaving federal employment for college teaching positions.<ref name="proceedings">{{Harvnb|Daly|1986|}}. The bomb yields are often reported as 21 kilotons, but the figure of 23 kilotons is used consistently throughout this article per {{Harvnb|Weisgall|1994|p=186}}.</ref>

On January 24, Blandy named the Bikini Lagoon as the site for the two 1946 detonations, ''Able'' and ''Baker''. The deep underwater test, ''Charlie'', scheduled for early 1947, would take place in the ocean west of Bikini.<ref>{{Harvnb|Weisgall|1994|p=117}}.</ref> Of the possible places given serious consideration, including Ecuador's [[Galápagos Islands]],<ref>Parsons, Rear Admiral. "Subject: site for atomic bomb experiments, May 12, 1948." Appendix to U.S. Commanding Lieutenant General J. E. Hull's memorandum to the U.S. Army Chief of Staff, "Subject: location of proving ground for atomic weapons." Quoted in: ''[https://ieer.org/wp/wp-content/uploads/1991/06/RadioactiveHeavenEarth1991.pdf Radioactive Heaven and Earth:] The health and environmental effects of nuclear weapons testing in, on, and above the earth: A report of the IPPNW International Commission to Investigate the Health and Environmental Effects of Nuclear Weapons Production and the Institute for Energy and Environmental Research'' (1991) p. 70 {{ISBN|0-945257-34-1}}. Accessed February 23, 2019</ref> Bikini offered the most remote location with a large protected anchorage, suitable but not ideal weather,<ref>Bikini failed to meet one of the stipulated weather criteria: "predictable winds directionally uniform from sea level to {{convert|60,000|ft|km}}." {{Harvnb|Daly|1986|p=68}}.</ref> and a small, easily moved population. It had come under exclusive United States control on January 15, when Truman declared the United States to be the sole trustee of all the Pacific islands captured from Japan during the war. The Navy had been studying test sites since October 1945 and was ready to announce its choice of Bikini soon after Truman's declaration.<ref>{{Harvnb|Weisgall|1994|pp=31–33}}.</ref> On February 6, the survey ship [[USS Sumner (AGS-5)|''Sumner'']] began blasting channels through the Bikini [[reef]] into the [[lagoon]]. The local residents were not told why.<ref>{{Harvnb|Weisgall|1994|pp=105, 106}}.</ref>

The 167 Bikini islanders first learned their fate four days later, on Sunday, February 10, when Navy Commodore Ben H. Wyatt, United States military [[governor]] of the [[Marshall Islands]], arrived by seaplane from [[Kwajalein]]. Referring to Biblical stories which they had learned from Protestant missionaries, he compared them to "the children of Israel whom the Lord saved from their enemy and led into the Promised Land." He also claimed it was "for the good of mankind and to end all world wars." There was no signed agreement, but he reported by cable "their local [[chieftain]], referred to as King Juda, arose and said that the natives of Bikini were very proud to be part of this wonderful undertaking."<ref>{{Harvnb|Weisgall|1994|p=107}}.</ref> On March 6, Wyatt attempted to stage a filmed [[Historical reenactment|reenactment]] of the February 10 meeting in which the Bikinians had given away their atoll. Despite repeated promptings and at least seven retakes, Juda confined his on-camera remarks to, "We are willing to go. Everything is in God's hands." The next day, LST-861 moved them and their belongings {{convert|128|mi|0}} east to the uninhabited [[Rongerik Atoll]], to begin a permanent exile.<ref>{{Harvnb|Weisgall|1994|p=113}}.</ref> Three Bikini families returned in 1974 but were evacuated again in 1978 because of radioactivity in their bodies from four years of eating [[Radioactive contamination|contaminated]] food.<ref name=bikiniatoll.com>* {{citation
| last = Niedenthal
| first = Jack
| year = 2013
| title = A Short History of the People of Bikini Atoll
| url = http://www.bikiniatoll.com/history.html
| access-date = May 4, 2013
}}.</ref> As of 2022, the atoll remains unpopulated.<ref name="diving"/>

[[File:Bikini Atoll Operation Crossroads.svg|thumb|left|400 px|alt=Map of Bikini Atoll, with target area highlighted.|Map of Bikini Atoll and the target area for the tests.]]

===Ships===

To make room for the target ships, {{convert|100|ST|sigfig=1}} of [[dynamite]] were used to remove [[coral]] heads from Bikini Lagoon. On the grounds of the [[David Taylor Model Basin]] outside Washington, DC, dress rehearsals for ''Baker'' were conducted with dynamite and model ships in a pond named "Little Bikini."<ref>{{Harvnb|Shurcliff|1946|pp=22–27}}.</ref> A fleet of 93 target vessels was assembled in Bikini Lagoon. At the center of the target cluster, the density was 20 ships per square mile (7.7&nbsp;per&nbsp;km<sup>2</sup>), three to five times greater than [[military doctrine]] would allow. The stated goal was not to duplicate a realistic anchorage but to measure damage as a function of distance from the blast center, at as many distances as possible.<ref name="Shurcliff119">{{Harvnb|Shurcliff|1946|p=119}}.</ref> The arrangement also reflected the outcome of the Army/Navy disagreement about how many ships should be allowed to sink.<ref>{{Harvnb|Weisgall|1994|p=124}}.</ref>

The target fleet included four obsolete U.S. battleships, two [[aircraft carrier]]s, two [[cruiser]]s, thirteen [[destroyer]]s, eight [[submarine]]s, forty landing ships, 18 transports, two oilers, one floating drydock, and three surrendered Axis ships, the Japanese cruiser [[Japanese cruiser Sakawa|''Sakawa'']], the battleship [[Japanese battleship Nagato|''Nagato'']], and the German cruiser [[German cruiser Prinz Eugen|''Prinz Eugen'']].<ref name="proceedings"/> The ships carried sample amounts of fuel and ammunition, plus scientific instruments to measure [[air pressure]], ship movement, and [[radiation]]. The live animals on some of the target ships<ref name="CrossroadsFactSheet">{{Harvnb|Navy History and Heritage Command|2002}}</ref> were supplied by the support ship {{USS|Burleson|APA-67|6}}, which brought 200 pigs, 60 guinea pigs, 204 goats, 5,000 rats, 200 mice, and grains containing insects to be studied for genetic effects by the [[National Cancer Institute]].<ref name="proceedings"/> [[Amphibious craft|Amphibious]] target ships were beached on Bikini Island.<ref>{{Harvnb|Shurcliff|1947|p=106}}.</ref>

A support fleet of more than 150 ships provided quarters, experimental stations, and workshops for most of the 42,000 men (more than 37,000 of whom were Navy personnel) and the 37 female nurses.<ref>{{Harvnb|Shurcliff|1947|p=33}}.</ref> Additional personnel were located on nearby atolls such as [[Eniwetok]] and Kwajalein. Navy personnel were allowed to extend their service obligation for one year if they wanted to participate in the tests and see an atomic bomb explode.<ref name="p2">{{Harvnb|Waters|1986|pp=72–74}}.</ref> The islands of the Bikini Atoll were used as instrumentation sites and, until ''Baker'' contaminated them, as recreation sites.<ref>{{Harvnb|Shurcliff|1947|p=32}}.</ref>

===Cameras===

[[File:CrossroadsAble2.gif|thumb|250px|Crossroads-''Able'', 23-kilotons.]]
Radio-controlled [[autopilot]]s were installed in eight [[Boeing B-17 Flying Fortress|B-17]] bombers, converting them into [[unmanned aerial vehicle|remote-controlled drones]] which were then loaded with automatic cameras, radiation detectors, and air sample collectors. Their pilots operated them from mother planes at a safe distance from the detonations. The drones could fly into radiation environments, such as ''Able's'' [[mushroom cloud]], which would have been lethal to crew members.<ref>{{Harvnb|Shurcliff|1946|p=111}}.</ref> All the land-based detonation-sequence photographs were taken by remote control from tall towers erected on several islands of the atoll. In all, Bikini cameras took 50,000 still pictures and {{convert|1500000|ft|sigfig=2}} of [[motion picture]] film. One of the cameras could shoot 1,000 frames per second.<ref>{{Harvnb|Shurcliff|1946|p=9}}.</ref>

Before the first test, all personnel were evacuated from the target fleet and Bikini Atoll. They boarded ships of the support fleet, which took safe positions at least {{convert|10|nmi|km|sigfig=2}} east of the atoll. Test personnel were issued special dark glasses to protect their eyes, but a decision was made shortly before ''Able'' that the glasses might not be adequate. Personnel were instructed to turn away from the blast, shut their eyes, and cradle their arm across their face for additional protection. A few observers who disregarded the recommended precautions advised the others when the bomb detonated. Most shipboard observers reported feeling a slight [[concussion]] and hearing a disappointing little "poom".<ref name="p2"/>

[[File:Mark III Nuclear Bomb nicknamed 'Gilda'.png|thumb|right|The ''Able'' bomb, a Mark III 'Fat Man'-type nuclear bomb with its nickname 'Gilda' stenciled onto it, along with a photo of [[Rita Hayworth]] in the title role from [[Gilda|the movie]].]]
On July 26, 2016, the [[National Security Archive]] declassified and released the entire stock of footage shot by surveillance aircraft that flew over the nuclear test site just minutes after the bomb detonated.<ref>{{Cite news|url=http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11681565|title=New footage reveals Bikini Atoll atomic bomb test aftermath|last=Network|first=News Corp Australia|date=July 26, 2016|newspaper=New Zealand Herald|language=en-NZ|issn=1170-0777|access-date=July 26, 2016}}</ref><ref>{{Cite web|url=https://twitter.com/NSArchive/status/757655285477572608|title=NatlSecurityArchive on Twitter|access-date=July 26, 2016}}</ref> The footage can be seen on [[YouTube]].<ref>{{Cite web|url=https://www.youtube.com/watch?v=9KgKrHFuhgE| archive-url=https://web.archive.org/web/20160724174220/https://www.youtube.com/watch?v=9KgKrHFuhgE| archive-date=2016-07-24 |title=Video6|website=[[YouTube]]|access-date=March 13, 2019}}</ref>

===Nicknames===

''Able'' and ''Baker'' are the first two letters of the [[Joint Army/Navy Phonetic Alphabet]], used from 1941 until 1956. ''Alfa'' and ''Bravo'' are their counterparts in the current [[ICAO spelling alphabet|NATO phonetic alphabet]]. ''Charlie'' is the third letter in both systems. According to eyewitness accounts, the time of detonation for each test was announced as H or ''How'' hour;<ref>{{Harvnb|Bradley|1948|pp=40, 91}}.</ref> in the official JTF-1 history, the term M or ''Mike'' hour is used instead.<ref>{{Harvnb|Shurcliff|1947|pp=109, 155}}.</ref>

There were only seven nuclear bombs in existence in July 1946.<ref>{{Harvnb|Weisgall|1994|p=286}}.</ref> The two bombs used in the test were [[Fat Man]] plutonium [[implosion-type nuclear weapon]]s of the kind dropped on Nagasaki. The ''Able'' bomb was stenciled with the name ''Gilda'' and decorated with an ''[[Esquire (magazine)|Esquire]]'' magazine photograph of [[Rita Hayworth]], star of the 1946 movie, ''[[Gilda]]''.<ref>{{cite web |url=http://conelrad.blogspot.com/2013/08/atomic-goddess-revisited-rita-hayworths.html |title=Atomic Goddess Revisited: Rita Hayworth's Bomb Image Found |date=August 13, 2013|publisher=CONELRAD Adjacent (blog) |access-date=March 11, 2015}}</ref> The ''Baker'' bomb was ''Helen of Bikini.'' This [[Femme fatale|femme-fatale]] theme for nuclear weapons, combining seduction and destruction, is epitomized by the use in all languages, starting in 1946, of "[[bikini]]" as the name for a woman's two-piece [[bathing suit]].<ref name="Weisgall, pp. 263-265">{{Harvnb|Weisgall|1994|pp=263–265}}.</ref>

{| class="wikitable sortable"
|+ United States' Crossroads series tests and detonations
|-
!style="background:#efdead;" | Name
!style="background:#efefef;" | Date, time ([[Universal Time|UTC]])
!style="background:#efefef;" | Location
!style="background:#efdead;" | Elevation + height
!style="background:#efefef;" | Delivery
!style="background:#efdead;" | Purpose
!style="background:#efefef;" | Device
!style="background:#efdead;" | [[TNT equivalent|Yield]]
!style="background:#efefef;" | References
|-
! ''Able''
| {{dts|1946-06-30}} 21:00:01.0
| NE Lagoon, Bikini Atoll {{coord|11.59|165.50|name=Able|display=inline}}
| {{sort|000158|}}0 + {{convert|158|m|abbr=on}}
| Free fall air drop
| Weapon effect
| [[Mark 3 nuclear bomb|Mk III]] "Gilda"
| style="text-align:center;" | {{sort|000210000|23&nbsp;kt}}
|<ref name=LT_1>{{cite report|publisher=Department of Energy, Nevada Operations Office |date=December 1, 2000 |title=United States Nuclear Tests: July 1945 through September 1992 (DOENV-209 REV15) |location=Las Vegas, NV |url=http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf |access-date=December 18, 2013 |archive-url=https://web.archive.org/web/20061012160826/http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf |archive-date=October 12, 2006 }}</ref><ref name=LT_2>{{cite report|last1=Yang|first1=Xiaoping|first2=Robert|last2=North|first3=Carl|last3=Romney |date=August 2000 |title=CMR Nuclear Explosion Database (Revision 3)|publisher=SMDC Monitoring Research}}</ref><ref name=LT_7>{{cite journal|last1=Norris|first1=Robert Standish|first2=Thomas B.|last2=Cochran|date=February 1, 1994|title=United States nuclear tests, July 1945 to 31 December 1992 (NWD 94-1)|journal=Nuclear Weapons Databook Working Paper|publisher=Natural Resources Defense Council|location=Washington, DC|url=http://docs.nrdc.org/nuclear/files/nuc_02019401a_121.pdf|access-date=October 26, 2013|archive-url=https://web.archive.org/web/20131029194805/http://docs.nrdc.org/nuclear/files/nuc_02019401a_121.pdf|archive-date=October 29, 2013}}</ref><ref name=LT_b>{{cite report|publisher=Defense Nuclear Agency|date=May 1, 1984|title=Operation Crossroads, 1946 (DNA-6032F)|url=http://www.dtra.mil/documents/ntpr/historical/DNA6032F.pdf|access-date=January 6, 2014|archive-url=https://web.archive.org/web/20140201120238/http://www.dtra.mil/documents/ntpr/historical/DNA6032F.pdf|archive-date=February 1, 2014}}</ref><ref name=LT_ca>{{cite web|url=http://www.nuclearweaponarchive.org/Usa/Tests|access-date=January 6, 2014|last=Sublette|first=Carey|title=Nuclear Weapons Archive}}</ref>
|-
! ''Baker''
| {{dts|1946-07-24}} 21:34:59.8
| NE Lagoon, Bikini Atoll {{coord|11.59|165.52|name=Baker|display=inline}}
| {{sort|000000|}}0 – {{convert|27.5|m|abbr=on}}
| Underwater
| Weapon effect
| [[Mark 3 nuclear bomb|Mk III]] "Helen of Bikini"
| style="text-align:center;" | {{sort|000210000|23&nbsp;kt}}
|<ref name=LT_1/><ref name=LT_2/><ref name=LT_ca/>
|-
! ''Charlie''<br />''(canceled)''
| {{dts|1947-03-01}}
| NE Lagoon, Bikini Atoll {{coord|11.57|165.51|name=Charlie|display=inline}}
| {{sort|000000|}}0 – {{convert|50|m|abbr=on}}
| Underwater
| Weapon effect
| [[Mark 3 nuclear bomb|Mk III]]
| style="text-align:center;" | {{sort|000210000|23&nbsp;kt}}
|<ref name=LT_ca/>
|}

The United States' test series summary table is here: [[United States' nuclear testing series]].

==Test ''Able''==

[[File:CrossroadsAble.gif|thumb|alt=The airburst nuclear explosion of July 1, 1946. Photo taken from a tower on Bikini Island, {{convert|3.5|mi}} away.|''Gilda'', the 23-kiloton air-deployed nuclear weapon detonated on July 1, 1946, during Crossroads ''Able'']]

=== Detonation ===
[[File:USS Nevada (BB-36) Operation Crossroads Target Ship.jpg|thumb|right|''Nevada'' painted in high visibility orange for the atomic tests]]
[[File:View of the target fleet after Crossroads test Able on 1 July 1946.jpg|thumb|The target fleet after test ''Able''. The aircraft carrier ''Saratoga'' is right-center with ''Independence'' burning at left-center. The battleship ''Nagato'' is between them. The ship at left, next to the battleship ''Pennsylvania'', is trying to wash down the radioactivity with water from the lagoon.]]
At 09:00 on July 1, 1946, ''Gilda'' was dropped from the B-29 ''Dave's Dream'' of the [[509th Bombardment Group]]. The plane, formerly known as ''[[Big Stink (B-29)|Big Stink]]'', had been the photographic equipment aircraft on the Nagasaki mission in 1945. It had been renamed in honor of [[Dave Semple]], a [[Bombardier (air force)|bombardier]] who was killed during a practice mission on March 7, 1946.<ref>{{harvnb|Campbell|2005|pp=18, 186–189}}.</ref> ''Gilda'' detonated {{convert|520|ft|0|sigfig=2}} above the target fleet, with a yield of 23 kilotons. Five ships were sunk.<ref name="proceedings"/><ref name="Shurcliff119"/> Two attack transports sank immediately, two destroyers within hours, and [[Japanese cruiser Sakawa|''Sakawa'']] the following day.<ref>{{Harvnb|Shurcliff|1946|pp=130–135}}.</ref>

Some of the 114 press observers expressed disappointment at the effect on ships.<ref>{{Harvnb|Delgado|1991|p=26}}.</ref> ''The New York Times'' reported, prematurely, that "only two were sunk, one capsized, and eighteen damaged."<ref>''New York Times,'' July 1, 1946, p. 1.</ref> The next day, the ''Times'' carried an explanation by Forrestal that "heavily built and heavily armored ships are difficult to sink unless they sustain underwater damage."<ref>''New York Times,'' July 2, 1946, p. 3.</ref>

The main cause of less-than-expected ship damage was that the bomb missed its [[aim point]] by {{convert|710|yd|0|sigfig=2}}.<ref>{{Harvnb|Delgado|1991|p=86}}.</ref> The ship the bomb was aimed at failed to sink. The miss resulted in a government investigation of the flight crew of the B-29 bomber. Various explanations were offered, including the bomb's known poor ballistic characteristics, but none was convincing. Images of the drop were inconclusive. The [[bombsight]] was checked and found error free. [[Pumpkin bomb]] drops were conducted and were accurate. Colonel [[Paul W. Tibbets]] believed that the miss was caused by a miscalculation by the crew. The mystery was never solved.<ref>{{Harvnb|Shurcliff|1946|p=114}}.</ref><ref>{{Harvnb|Weisgall|1994|pp=201–202}}.</ref> 

There were other factors that made ''Able'' less spectacular than expected. Observers were much farther away than at the [[Trinity (nuclear test)|Trinity test]], and the high humidity absorbed much of the light and heat.<ref>{{Harvnb|Weisgall|1994|p=188}}.</ref>

The battleship {{USS|Nevada|BB-36|6}}, the only battleship to get underway at the [[Attack on Pearl Harbor]] in 1941, had been designated as the aim point for ''Able'' and was painted orange, with white gun barrels and [[gunwales]], to make her stand out in the central cluster of target ships. There were eight ships within {{convert|400|yd|0|sigfig=2}} of it. Had the bomb exploded over the ''Nevada ''as planned, at least nine ships, including two battleships and an aircraft carrier, likely would have sunk. The actual detonation point, west-northwest of the target, was closer to the attack transport {{USS|Gilliam|APA-57|6}}, in much less crowded water.<ref>{{Harvnb|Shurcliff|1946|pp=134–135}}.</ref>

===''Able'' Target array===

[[File:Crossroads Able Target Ship Map.png|left|thumb|500px|alt=Map showing ship locations for the nuclear explosion of July 1, 1946. The locations of the 19 ships listed in the accompanying tables are marked with symbols and numbers.|The array of target ships in Bikini lagoon for the ''Able'' shot of Operation Crossroads. Half of the target ships were outside the area of this map. The five red X's mark the five ships that sank. The tables (right) contain the key to ship numbers. The circle, with a radius of {{convert|1000|yd|0}} from the point of detonation, outlines the area of serious ship damage. The intended bullseye for the bomb was ship #32, the battleship {{USS|Nevada|BB-36|6}}, which was painted orange to aid the bombardier. The bomb landed closer to ship #5, the attack transport {{USS|Gilliam|APA-57|6}}. All submarines were on the surface.]]
{| class="wikitable"
|+ Location at which ships sank<ref name=shiparray>Data in the table and the map come from {{Harvnb|Delgado|1991}}. The ''Able'' map is on p. 16, the ''Baker'' map on p. 17, and ship damage and distances on pp. 86–87. The full text of this reference is posted on the Internet (see link in Sources, below).</ref>
|-
! #
! Name
! Type
! Distance from zero
|-
| style="text-align:center;"|5
| style="text-align:center;"|{{USS|Gilliam|APA-57|2}}
| style="text-align:center;"|Transport
| style="text-align:center;"|{{convert|50|yd|m|abbr=on}}
|-
| style="text-align:center;"|9
| style="text-align:center;"|{{ship|Japanese cruiser|Sakawa||2}}
| style="text-align:center;" |Cruiser
| style="text-align:center;"|{{convert|420|yd|m|abbr=on}}
|-
| style="text-align:center;"|4
| style="text-align:center;"|{{USS|Carlisle|APA-69|2}}
| style="text-align:center;"|Transport
| style="text-align:center;"|{{convert|430|yd|m|abbr=on}}
|-
| style="text-align:center;"|1
| style="text-align:center;"|{{USS|Anderson|DD-411|2}}
| style="text-align:center;"|Destroyer
| style="text-align:center;"|{{convert|600|yd|m|abbr=on}}
|-
| style="text-align:center;"|6
| style="text-align:center;"|{{USS|Lamson|DD-367|2}}
| style="text-align:center;"|Destroyer
| style="text-align:center;"|{{convert|760|yd|m|abbr=on}}
|-
|}

{| class="wikitable"
|+ Serious damage
|-
! #
! Name
! Type
! Distance from zero
|-
| style="text-align:center;"|40
| style="text-align:center;"|{{USS|Skate|SS-305|2}}
| style="text-align:center;"|Submarine
| style="text-align:center;"|{{convert|400|yd|m|abbr=on}}
|- style="text-align:center;"
||12
||[[commons:File:Yard Oiler YO-236.jpg|''YO-160'']]
||Yard oiler
||{{convert|520|yd|m|abbr=on}}
|-
| style="text-align:center;"|28
| style="text-align:center;"|{{USS|Independence|CVL-22|2}}
| style="text-align:center;" |Aircraft carrier
| style="text-align:center;"|{{convert|560|yd|m|abbr=on}}
|-
| style="text-align:center;"|22
| style="text-align:center;"|{{USS|Crittenden|APA-77|2}}
| style="text-align:center;"|Transport
| style="text-align:center;"|{{convert|595|yd|m|abbr=on}}
|-
| style="text-align:center;"|32
| style="text-align:center;"|{{USS|Nevada|BB-36|2}}
| style="text-align:center;"|Battleship
| style="text-align:center;"|{{convert|615|yd|m|abbr=on}}
|-
| style="text-align:center;"|3
| style="text-align:center;"|{{USS|Arkansas|BB-33|2}}
| style="text-align:center;"|Battleship
| style="text-align:center;"|{{convert|620|yd|m|abbr=on}}
|-
| style="text-align:center;"|35
| style="text-align:center;"|{{USS|Pensacola|CA-24|2}}
| style="text-align:center;"|Cruiser
| style="text-align:center;"|{{convert|710|yd|m|abbr=on}}
|-
| style="text-align:center;"|11
| style="text-align:center;"|[[Floating drydock|''ARDC-13'']]
| style="text-align:center;"|Drydock
| style="text-align:center;"|{{convert|825|yd|m|abbr=on}}
|-
| style="text-align:center;"|23
| style="text-align:center;"|{{USS|Dawson|APA-79|2}}
| style="text-align:center;"|Transport
| style="text-align:center;"|{{convert|855|yd|m|abbr=on}}
|-
| style="text-align:center;"|38
| style="text-align:center;"|{{USS|Salt Lake City|CA-25|2}}
| style="text-align:center;"|Cruiser
| style="text-align:center;"|{{convert|895|yd|m|abbr=on}}
|-
| style="text-align:center;"|27
| style="text-align:center;"|{{USS|Hughes|DD-410|2}}
| style="text-align:center;"|Destroyer
| style="text-align:center;"|{{convert|920|yd|m|abbr=on}}
|-
| style="text-align:center;"|37
| style="text-align:center;"|{{USS|Rhind|DD-404|2}}
| style="text-align:center;"|Destroyer
| style="text-align:center;"|{{convert|1,012|yd|m|abbr=on}}
|-
| style="text-align:center;"|49
| style="text-align:center;"|[[Landing Ship, Tank|''LST-52'']]
| style="text-align:center;"|LST
| style="text-align:center;"|{{convert|1,530|yd|m|abbr=on}}
|-
| style="text-align:center;"|10
| style="text-align:center;"|{{USS|Saratoga|CV-3|2}}
| style="text-align:center;" |Aircraft carrier
| style="text-align:center;"|{{convert|2,265|yd|m|abbr=on}}
|}
{{Clear}}
In addition to the five ships that sank, fourteen were judged to have serious damage or worse, mostly as a result of the [[shock wave]]. All but three were located within {{convert|1000|yd|0}} of the detonation. Inside that radius, orientation to the bomb was a factor in shock wave impact. For example, ship #6, the destroyer {{USS|Lamson|DD-367|6}}, which sank, was farther away than seven ships that stayed afloat. ''Lamson'' was [[Broadside (naval)|broadside]] to the blast, taking the full impact on her port side, while the seven closer ships were anchored with their [[stern]]s toward the blast, somewhat protecting the most vulnerable part of the hull.<ref>{{Harvnb|Weisgall|1994|p=189}}.</ref>

The only large ship inside the {{convert|1000|yd|0|adj=on}} radius which sustained moderate rather than serious damage was the sturdily built Japanese battleship {{ship|Japanese battleship|Nagato||2}}, ship #7, whose stern-on orientation to the bomb gave her some protection. Unrepaired damage from World War II may have complicated damage analysis. As the ship from which the Pearl Harbor attack had been commanded, ''Nagato'' was positioned near the aim point to guarantee her being sunk. The ''Able'' bomb missed its target, and the symbolic sinking came three weeks later, five days after the ''Baker'' shot.<ref>{{Harvnb|Shurcliff|1946|p=165}}.</ref>

Fire caused serious damage to ship #10, the aircraft carrier {{USS|Saratoga|CV-3|2}}, more than {{convert|1|mi|sigfig=2}} from the blast. For test purposes, all the ships carried sample amounts of fuel and ordnance, plus airplanes. Most warships carried a [[seaplane]] on deck which could be lowered into the water by crane,<ref>{{Harvnb|Shurcliff|1946|pp=165, 166, 168}}.</ref> but ''Saratoga'' carried several airplanes with highly volatile [[aviation fuel]], both on deck and in the [[hangar]]s below. The fire was extinguished, and ''Saratoga'' was kept afloat for use in the ''Baker'' shot.<ref>{{Harvnb|Shurcliff|1946|p=197}}.</ref><ref>{{Harvnb|Weisgall|1994|p=190}}.</ref>

===Radiation===
[[File:Operation Crossroads - Able 001.jpg|thumb|right|upright|alt=Aerial view of the mushroom cloud.|Aerial view of the ''Able'' mushroom cloud rising from the lagoon with Bikini Island visible in the background. The cloud carried the radioactive contaminants into the stratosphere.]]
As with [[Little Boy]] (Hiroshima) and Fat Man (Nagasaki), the Crossroads ''Able'' shot was an [[air burst]]. These were purposely detonated high enough in the air to prevent surface materials from being drawn into the fireball. The height-of-burst for the Trinity test was {{convert|100|ft}}; the device was mounted on a tower. It made a crater {{convert|6|ft}} deep and {{convert|500|ft}} wide, and there was some [[Trinity (nuclear test)#Test results|local fallout]]. The test was conducted in secret, and the world at large learned nothing about the radioactive fallout at the time.<ref>{{Harvnb|Hansen|1995|p=154, Vol 8, Table A-1}}. and {{Harvnb|Glasstone|Dolan|1977|pp=409, 622}}.</ref> To be a true air burst with no local fallout, the Trinity height-of-burst needed to be {{convert|580|ft}}.<ref name="Fletcher">{{Harvnb|Fletcher|1977}}.</ref> With an air burst, the radioactive [[fission products]] rise into the [[stratosphere]] and become part of the global, rather than the local, environment. Air bursts were officially described as "self-cleansing."<ref>{{Harvnb|Shurcliff|1946|p=143}}.</ref> There was no significant local fallout from ''Able''.<ref>{{Harvnb|Weisgall|1994|p=193}}.</ref>

There was an intense transitory burst of fireball radiation lasting a few seconds. Many of the closer ships received doses of [[neutron radiation|neutron]] and [[gamma radiation]] that could have been lethal to anyone on the ship, but the ships did not become radioactive. [[Neutron activation]] of materials in the ships was judged to be a minor problem by the standards of the time. One sailor on the support ship {{USS|Haven|AH-12|6}} was found to be "sleeping in a shower of gamma rays" from an illegal metal [[souvenir]] he had taken from a target ship. Fireball [[Neutron|neutrons]] had made it radioactive.<ref>{{Harvnb|Bradley|1948|p=70}}.</ref> Within a day nearly all the surviving target ships had been reboarded. The ship inspections, instrument recoveries, and moving and remooring of ships for the ''Baker'' test proceeded on schedule.<ref>{{Harvnb|Weisgall|1994|pp=218–221}}.</ref>

=== Test animals ===
57 guinea pigs, 109 mice, 146 pigs, 176 goats, and 3,030 white rats had been placed on 22 target ships in stations normally occupied by people.<ref>{{Harvnb|Shurcliff|1946|p=108}}.</ref> 35% of these animals died or were euthanised in the three months following the explosion: 10% were killed by the air blast, 15% were killed by radiation, and 10% were killed by the researchers as part of later study.<ref>{{Harvnb|Shurcliff|1947|p=140}}.</ref> The most famous survivor was Pig #311, which was reportedly found swimming in the lagoon after the blast and was brought back to the [[National Zoological Park (United States)|National Zoo in Washington, DC]].<ref>{{cite web |url=https://www.nlm.nih.gov/exhibition/animals/atomic.html |title=Animals as Cold Warriors |publisher=Online Exhibit at the National Library of Medicine |access-date=May 4, 2013}}</ref> The mysterious survival of Pig #311 caused some consternation at the time and has continued to be reported in error. However, an investigation pointed to the conclusion that it had neither swum in the ocean nor escaped the blast; it had likely been safely aboard an observation vessel during the test, thus "absent without leave" from its post on ''Sakawa'' and showing up about the same time other surviving pigs were captured.<ref name="Lewiston">"[https://news.google.com/newspapers?nid=1928&dat=19460722&id=YrcgAAAAIBAJ&sjid=PGgFAAAAIBAJ&pg=3340,1572517&hl=en Myth of Pig 311 Finally Cleared]," ''Lewiston Daily Sun'', July 22, 1946.</ref>

[[File:Crossroads Able Goats.jpg|thumb|left|alt=Two goats penned on ship deck, within reach of water and food.|Test animals were deliberately confined to the ships of Operation Crossroads. Goat #53, penned like this on {{USS|Nevada|BB-36|2}}{{'}}s deck, died of radiation exposure two days after ''Able''.<ref>{{Harvnb|Life Editors|1947|p=77}}. These two goats, on the attack transport {{USS|Niagara|APA-87|2}}, may have been far enough away to survive. {{Harvnb|Delgado|1991|p=22}}.</ref>]]

The high rate of test animal survival was due in part to the nature of single-pulse radiation. As with the two Los Alamos criticality accidents involving the earlier [[demon core]], victims who were close enough to receive a lethal dose died, while those farther away recovered and survived. Also, all the mice were placed outside the expected lethal zone in order to study possible [[mutation]]s in future generations.<ref>{{Harvnb|Shurcliff|1947|pp=140–144}}.</ref>

Although ''Gilda'' missed its target ''Nevada'' by nearly half a mile (800 m), and it failed to sink or to contaminate the battleship, a crew would not have survived. Goat #119, tethered inside a [[gun turret]] and shielded by [[armor plate]], received enough fireball radiation to die four days later of [[radiation sickness]] having survived two days longer than goat #53, which was on the deck, unshielded.<ref>{{Harvnb|Life Editors|1947|p=76}}.</ref> Had ''Nevada ''been fully manned, she would likely have become a floating coffin, dead in the water for lack of a live crew. Two years later she was finished off by an [[aerial torpedo]] 65 miles southwest of Pearl Harbor on 31 July 1948. In theory, every unprotected location on the ship received 10,000&nbsp;rems (100&nbsp;Sv) of initial nuclear radiation from the fireball.<ref name="Fletcher"/> Therefore, people deep enough inside the ship to experience a 90% radiation reduction would still have received a lethal dose of 1,000&nbsp;rems.<ref>{{Harvnb|Glasstone|Dolan|1977|p=580}}.</ref> In the assessment of the ''[[Bulletin of the Atomic Scientists]]'':<ref name="Bulletin Editors"/>
{{blockquote|"a large ship, about a mile away from the explosion, would escape sinking, but the crew would be killed by the deadly burst of radiations from the bomb, and only a ghost ship would remain, floating unattended in the vast waters of the ocean."}}

[[File:Able Fireball.jpg|thumb|center|500px|Photographic montage of the first few micro-seconds of the ''Able'' detonation, fireball and radiation effects.]]

==Test ''Baker''==

[[File:Crossroads-Baker Slow Motion.gif|thumb|Crossroads-''Baker'' detonation in slow-motion. [[USS LSM-60|''LSM-60'']], which was anchored directly above the device, is completely destroyed.]]

=== Detonation ===
In ''Baker'' on July 25, the weapon was suspended beneath [[landing craft]] [[USS LSM-60|''LSM-60'']] anchored in the midst of the target fleet. ''Baker'' was detonated at 08:35,<ref name="proceedings" /> {{convert|90|ft}} underwater, halfway to the bottom in water {{convert|180|ft}} deep. No identifiable part of ''LSM-60'' was ever found; it was presumably vaporized by the nuclear fireball. Ten ships were sunk,{{sfn|Shurcliff|1947|pp=164–166}} including the [[German cruiser Prinz Eugen|German heavy cruiser ''Prinz Eugen'']], which sank in December, five months after the test, because radioactivity prevented repairs to a leak in the hull.{{sfn|Shurcliff|1947|p=275}}

Photographs of ''Baker'' are unique among nuclear detonation pictures. The searing, blinding flash that usually obscures the target area took place underwater and was barely seen. The clear image of ships in the foreground and background gives a sense of scale. The large [[condensation cloud]] and the vertical water column are distinctive ''Baker'' shot features. One picture shows a mark where the 27,000-ton battleship {{USS|Arkansas|BB-33|6}} was.<ref name=Arkansas>The upending was reported by Operation Crossroads participants and depicted in two contemporary drawings (see [https://web.archive.org/web/20000914072139/http://history.navy.mil/ac/bikini/bikini5.htm Battleship Arkansas Being Tossed in Giant Pillar]), but two authors have suggested that what looks like the silhouette of a vertical battleship hull is actually a gap in the water column, an upside-down rain shadow, caused by the unseen, still-horizontal hull of ''Arkansas'' as it blocks the rise of water in the column. This explanation was described as a possibility in {{Harvnb|Shurcliff|1947|pp=155,156}}. Delgado stated it as a certainty in {{Harvnb|Delgado|1991|pp=55,88}}, and again in {{Harvnb|Delgado|1996|p=75}}.</ref>

As with ''Able'', any ships that remained afloat within {{convert|1000|yd|0|sigfig=1}} of the detonation were seriously damaged, but this time the damage came from below, from water pressure rather than air pressure. The greatest difference between the two shots was the radioactive contamination of all the target ships by ''Baker''. Regardless of the degree of damage, only nine surviving ''Baker'' target ships were eventually decontaminated and sold for scrap. The rest were sunk at sea after decontamination efforts failed.<ref>The fate of 13 small landing craft is unknown; they may have been sold for scrap, rather than scuttled. {{Harvnb|Delgado|1991|p=33}}.</ref>

===''Baker'' Target array===
[[File:Crossroads Baker Target Ship Map.png|thumb|500px|alt=Map showing ship locations for the nuclear explosion of July 25, 1946. The locations of the 10 ships listed in the accompanying table are marked with symbols and numbers.|The array of target ships in Bikini lagoon for the ''Baker'' shot of Operation Crossroads. Half of the target ships were outside the area of this map. The ten red X's mark the ten ships that sank. The table (left) contains the key to ship numbers. The black circle, with a radius of {{convert|1000|yd|0}} from the point of detonation, outlines the area of serious ship damage. The blue circle, {{convert|330|yd|0}} radius, marks the rim of the shallow underwater crater created by the blast, as well as the outer circumference of the hollow water column which enveloped {{USS|Arkansas|BB-33|2}}. The submarines were submerged: {{USS|Pilotfish|SS-386|2}}, ship #8, to a keel depth of {{convert|56|ft|0}}, {{USS|Apogon|SS-308|2}}, ship #2, to a keel depth of {{convert|100|ft|0}}, and {{USS|Skipjack|SS-184|2}}, ship #41, to {{convert|150|ft|0}}.]]

{| class="wikitable"
|+ Ships sunk<ref>{{cite web |url=https://apps.dtic.mil/sti/pdfs/AD0367496.pdf |title=Technical Report of Operation Crossroads |last=Shurcliff |first=William A. |date=November 18, 1946 |website=Defense Technical Information Center |publisher=Joint Task Force One |access-date=2024-07-25 |pages=280-281 |ref=none}}</ref>
|-
! #
! Name
! Type
! Distance from zero to [[Bow (watercraft)|bow]]
|-
| style="text-align:center;"|50
| style="text-align:center;"|{{USS|LSM-60||2}}
| style="text-align:center;"|Amphibious
| style="text-align:center;"|{{convert|0|yd|m|abbr=on}}
|-
| style="text-align:center;"|3
| style="text-align:center;"|{{USS|Arkansas|BB-33|2}}
| style="text-align:center;"|Battleship
| style="text-align:center;"|{{convert|259|yd|m|abbr=on}}
|-
| style="text-align:center;"|8
| style="text-align:center;"|{{USS|Pilotfish|SS-386|2}}
| style="text-align:center;"|Submarine
| style="text-align:center;"|{{convert|363|yd|m|abbr=on}}
|-
| style="text-align:center;"|10
| style="text-align:center;"|{{USS|Saratoga|CV-3|2}}
| style="text-align:center;" |Aircraft carrier
| style="text-align:center;"|{{convert|446|yd|m|abbr=on}}
|- style="text-align:center;"
||12
||''[[YO-160]]''
||Yard oiler
||{{convert|543|yd|m|abbr=on}}
|-
| style="text-align:center;"|41
| style="text-align:center;"|{{USS|Skipjack|SS-184|2}}
| style="text-align:center;"|Submarine
| style="text-align:center;"|{{convert|808|yd|m|abbr=on}}
|-
| style="text-align:center;"|2
| style="text-align:center;"|{{USS|Apogon|SS-308|2}}
| style="text-align:center;"|Submarine
| style="text-align:center;"|{{convert|846|yd|m|abbr=on}}
|-
| style="text-align:center;"|7
| style="text-align:center;"|{{ship|Japanese battleship|Nagato||2}}
| style="text-align:center;"|Battleship
| style="text-align:center;"|{{convert|852|yd|m|abbr=on}}
|-
| style="text-align:center;"|11
| style="text-align:center;"|''[[ARDC-13]]''
| style="text-align:center;"|[[Floating drydock|Drydock]]
| style="text-align:center;"|{{convert|1,276|yd|m|abbr=on}}
|}
{{ship|German cruiser|Prinz Eugen||2}}, ship #36, survived both the ''Able'' and ''Baker'' tests but was too radioactive to have leaks repaired. In September 1946 she was towed to [[Kwajalein Atoll]], where she [[capsizing|capsized]] in shallow water on December 22. She remains there today, with starboard propeller blades in the air.<ref>{{Harvnb|Delgado|1991|pp=60–64}}. In 1978, her port propeller was salvaged and is preserved at the German Naval Memorial at [[Laboe Naval Memorial|Laboe]].</ref>

The submarine {{USS|Skipjack|SS-184|6}} was the only sunken ship successfully raised at Bikini.<ref>{{Harvnb|Delgado|1996|p=83}}.</ref> She was towed to California and sunk again, as a target ship off the coast, two years later.
<ref>{{cite web |url=http://www.history.navy.mil/photos/sh-usn/usnsh-s/ss184.htm |title=USS Skipjack (SS-184) |access-date=April 14, 2013 |publisher=United States Navy |archive-url=https://web.archive.org/web/20130614031250/http://www.history.navy.mil/photos/sh-usn/usnsh-s/ss184.htm |archive-date=June 14, 2013 }}</ref>

Three other ships, all in sinking condition, were towed ashore at Bikini and beached:<ref>{{Harvnb|Delgado|1996|p=87}}.</ref> attack transport {{USS|Fallon|APA-81|6}}, ship #25; destroyer {{USS|Hughes|DD-410|6}}, ship #27; and submarine {{USS|Dentuda|SS-335|6}}, ship #24. ''Dentuda'', with her crew safely away from their submarine, being submerged (thus avoiding the [[base surge]]) and outside the {{convert|1000|yd|0}} circle, escaped serious contamination and hull damage and was successfully decontaminated, repaired, and briefly returned to service.<ref name="Weisgall 1994 229">{{Harvnb|Weisgall|1994|p=229}}.</ref><ref>{{cite web |url=https://www.history.navy.mil/research/histories/ship-histories/danfs/d/dentuda.html |title=Dentuda (SS-335) |author=<!--Not stated--> |date=April 21, 2016 |publisher=Naval History and Heritage Command |access-date=2024-07-23}}</ref><ref>{{cite web |url=https://apps.dtic.mil/sti/pdfs/AD0367471.pdf |title=OPERATION CROSSROADS. U.S.S. DENTUDA (SS335). TEST BAKER |last=Gaasterland |first=C.L. |date=1947 |publisher=JOINT TASK FORCE ONE WASHINGTON DC |page=10 |access-date=2024-07-23}}</ref>

===Sequence of blast events===

The ''Baker'' shot produced so many unusual phenomena that a conference was held two months later to standardize nomenclature and define new terms for use in descriptions and analysis.<ref>{{Harvnb|Shurcliff|1947|p=151}}.</ref> The underwater fireball took the form of a rapidly expanding hot gas bubble that pushed against the water, generating a [[supersonic]] hydraulic shock wave which crushed the hulls of nearby ships as it spread out. Eventually it slowed to the speed of sound in water, which is one mile per second (1,600&nbsp;m/s), five times faster than that of sound in air.<ref>{{Harvnb|Glasstone|Dolan|1977|p=244}}.</ref> On the surface, the shock wave was visible as the leading edge of a rapidly expanding ring of dark water, called the "slick" for its resemblance to an oil slick.<ref>{{Harvnb|Glasstone|Dolan|1977|p=48}}.</ref> Close behind the slick was a visually more dramatic but less destructive whitening of the water surface called the "crack".<ref>{{Harvnb|Glasstone|Dolan|1977|p=49}}.</ref>

When the gas bubble's diameter equaled the water depth, {{convert|180|ft|0}}, it hit the sea floor and the sea surface simultaneously. At the bottom, it created a shallow [[explosion crater|crater]] {{convert|30|ft|0}} deep and {{convert|2000|ft|0|sigfig=1}} wide.<ref>{{Harvnb|Glasstone|Dolan|1977|p=251}}.</ref> At the top, it pushed the water above it into a "spray dome", which burst through the surface like a [[geyser]]. Elapsed time since detonation was four milliseconds.<ref>{{Harvnb|Glasstone|Dolan|1977|pp=49, 50}}.</ref>

During the first full second, the expanding bubble removed all the water within a {{convert|500|ft|0|adj=on|sigfig=2}} radius and lifted two million tons<ref>{{Harvnb|Shurcliff|1947|p=156}}.</ref> of spray and seabed sand into the air. As the bubble rose at {{convert|2500|ft/s|0|sigfig=2}},<ref>{{Harvnb|Glasstone|Dolan|1977|p=50}}.</ref> it stretched the spray dome into a hollow cylinder or chimney of spray called the "column", {{convert|6000|ft|0|sigfig=2}} tall and {{convert|2000|ft|0|sigfig=1}} wide, with walls {{convert|300|ft|0|sigfig=1}} thick.<ref name="Shurcliff, pp. 150-156"/>

As soon as the bubble reached the air, it started a supersonic atmospheric shock wave which, like the crack, was more visually dramatic than destructive. Brief low pressure behind the shock wave caused instant fog which shrouded the developing column in a "Wilson cloud", also called a "[[condensation cloud]]", obscuring it from view for two seconds. The Wilson cloud started out hemispherical, expanded into a disk which lifted from the water revealing the fully developed spray column, then expanded into a doughnut shape and vanished. The ''Able'' shot also produced a Wilson cloud, but heat from the fireball dried it out more quickly.<ref name="Shurcliff, pp. 150-156">{{Harvnb|Shurcliff|1947|pp=150–156}}.</ref>

By the time the Wilson cloud vanished, the top of the column had become a "cauliflower", and all the spray in the column and its cauliflower was moving down, back into the lagoon. Although cloudlike in shape, the cauliflower was more like the top of a geyser where water stops moving upward and starts to fall. There was no mushroom cloud; nothing rose into the stratosphere.<ref name="Weisgall, p. 225">{{Harvnb|Weisgall|1994|p=225}}.</ref>

<gallery class="center" widths="220" heights="175" style="font-size:95%;line-height:1.4">
File:Crossroads baker explosion.jpg|alt=Aerial photo of nuclear explosion rising from lagoon. Hemispherical condensation cloud on the surface is 1 mile (1.6&nbsp;km) in diameter. In comparison, Navy ships in the foreground look like bathtub toys.|Crossroads ''Baker'', showing the white surface "crack" under the ships, and the top of the hollow spray column protruding through the hemispherical Wilson cloud. Bikini Island beach is in the background.
File:Operation Crossroads Baker Battleship Arkansas.jpg|alt=The Wilson cloud lifts.|The Wilson cloud lifts, revealing a vertical black object, larger than ships in the foreground. One popular (but discounted) theory claims that this was the upended battleship ''Arkansas'';<ref>Two video frames taken from the 1988 Robert Stone documentary film ''[[Radio Bikini]]'', at times 42:44 and 42:45. Eyewitness reports at {{Harvnb|Weisgall|1994|pp=162–163}}. On August 2, 1946, the Preliminary Statement of the Joint Chiefs of Staff Evaluation Board said, "From some of the photographs, it appears that this column lifted the 26,000-ton battleship ''Arkansas'' for a brief interval before the vessel plunged to the bottom of the lagoon. Confirmation of this must await the analysis of high-speed photographs which are not yet available". {{Harvnb|Shurcliff|1947|p= 196}}. The video frames shown here were first made public in 1988 when Robert Stone got permission to use them in his documentary film. They are viewable on the Internet at sonicbomb.com, 39 seconds into the video, {{cite web|title=Baker|url=http://www.sonicbomb.com/modules.php?name=Content&pa=showpage&pid=47&page=1|access-date=November 3, 2008}}{{Dead link|date=March 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> in reality, the dark area is caused by ''Arkansas'''s hull interfering with the development of the spray column, creating a hole in the plume via its presence.<ref name = gov>{{Cite web|url=https://www.nps.gov/parkhistory/online_books/swcrc/37/chap4.htm|title=National Park Service: The Archeology of the Atomic Bomb (Chapter 4)|website=www.nps.gov|access-date=2019-09-26}}</ref>
File:Operation Crossroads Baker.jpg|alt=The same scene five seconds later, photographed from a camera tower, showing a water column 2,000 feet (600 m) in diameter and 6,000 feet (1,800 m) tall.|The Wilson cloud has evaporated revealing the cauliflower atop the spray column. Two million tons of water spray fall back into the lagoon. The radioactive [[base surge]] is moving toward the ships.
</gallery>

Meanwhile, lagoon water rushing back into the space vacated by the rising gas bubble started a [[tsunami]] which lifted the ships as it passed under them. At 11 seconds after detonation, the first wave was {{convert|1000|ft|0|sigfig=1}} from surface zero and {{convert|94|ft|m}} high.<ref name="Glasstone, Effects, p 52">{{Harvnb|Glasstone|Dolan|1977|p=52}}.</ref> By the time it reached the Bikini Island beach, {{convert|3.5|mi|0}} away, it was a nine-wave set with shore breakers up to {{convert|15|ft|0}} high, which tossed landing craft onto the beach and filled them with sand.<ref>{{Harvnb|Shurcliff|1947|loc=plate 29}}.</ref>

Twelve seconds after detonation, falling water from the column started to create a {{convert|900|ft|0|adj=on|sigfig=2}} tall "base surge" resembling the mist at the bottom of a large [[waterfall]]. Unlike the water wave, the base surge rolled over rather than under the ships. Of all the bomb's effects, the base surge had the greatest consequence for most of the target ships, because it painted them with radioactivity that could not be removed.<ref name="Glasstone, Effects, p 52"/> Tactical nuclear warfare advocates described the base surge as generation of very high sea states (GVHSS) disregarding radiation to emphasize the physical damage capable of disabling communication and radar equipment on warship superstructures.<ref>{{cite journal |last=Brown |first=Peter J. |year=1986 |title=Blue-out and Nuclear Sea States |journal=Proceedings |volume=112 |issue=1 |pages=104&105 |publisher=[[United States Naval Institute]] }}</ref>

===''Arkansas''===

''Arkansas'' was the closest ship to the bomb other than the ship from which it was suspended. The underwater shock wave crushed the starboard side of her hull, which faced the bomb, and rolled the battleship over onto her port side. It also ripped off the two starboard [[propeller]]s and their shafts, along with the [[rudder]] and part of the stern, shortening the hull by {{convert|25|ft|m}}.<ref>{{Harvnb|Shurcliff|1946|p=151}}.</ref>

She was next seen by Navy divers the same year, lying upside down with her bow on the rim of the underwater bomb crater and stern angled toward the center. There was no sign of the [[superstructure]] or the big guns. The first diver to reach ''Arkansas'' sank up to his armpits in radioactive mud. When [[National Park Service]] divers returned in 1989 and 1990, the bottom was again firm-packed with sand, and the mud was gone. They were able to see the barrels of the forward guns, which had not been visible in 1946.<ref>{{Harvnb|Delgado|1996|pp=119, 120}}.</ref>

All battleships are top-heavy and tend to settle upside down when they sink. ''Arkansas'' settled upside down, but a 1989 diver's sketch of the wreck shows hardly any of the starboard side of the hull, making it look like the ship is lying on her side. Most of the starboard side is present but severely compacted.<ref name="Delagado, p. 95">{{Harvnb|Delgado|1991|p=95}}.</ref>

The superstructure has not been found. It either was stripped off and swept away or is lying under the hull, crushed and buried under sand which flowed back into the crater, partially refilling it. The only diver access to the inside is a tight squeeze through the port side [[casemate]], called the "aircastle." The National Park Service divers practiced on the similar casemate of the battleship {{USS|Texas|BB-35|6}}, a museum ship, before entering ''Arkansas'' in 1990.<ref>{{Harvnb|Delgado|1996|p=117}}.</ref>

Contrary to popular belief, ''Arkansas'' was not lifted vertically by the blast of the weapon test. Forensic examination of the wreck during multiple surveys since the test conclusively show that structural failure of hull plating along the starboard side allowed rapid flooding and capsized the ship.<ref name="gov" />

{{Gallery|width=265 |align=center
|File:Battleship Arkansas diver sketch.png|alt1=Line drawing of partially crushed battleship hull lying upside down on the seabed.|Battleship {{USS|Arkansas|BB-33|2}} upside down, {{convert|180|ft|m}} deep in Bikini Lagoon. Diver's sketch from a 1989 National Park Service dive.
|File:Battleship Arkansas aircastle.jpg|alt2=Underwater photograph of a gun protruding from an opening in the side of a sunken ship.|Port casemate of ''Arkansas'' in 1989, upside down against the bottom. The only diver's access into the ship, it was entered in 1946 and again in 1990.
|File:USS Texas BB-35 aircastle.jpg|alt3=A permanently docked museum ship with a red circle on the photograph to highlight a gun protruding from an opening in the ship's port side.|A similar battleship, {{USS|Texas|BB-35|6}}, with casemate circled. At Bikini, everything that was above the lower deck guns of ''Arkansas'' is either missing or is buried in the sand.
}}

===Aircraft carriers===

''Saratoga'', placed close to ''Baker'', sank 7.5 hours after the underwater shock wave opened up leaks in the hull. Immediately after the shock wave passed, the water wave lifted the stern {{convert|43|ft|m}} and the bow {{convert|29|ft|m}}, rocked the ship side to side, and crashed over her, sweeping all five moored airplanes off the [[flight deck]] and knocking the stack over onto the deck. She remained upright and outside the spray column but close enough to be drenched by radioactive water from the collapsing cauliflower head as well as by the base surge.<ref>{{Harvnb|Delgado|1991|p=101}}.</ref> Blandy ordered tugs to tow the carrier to Enyu Island for beaching, but ''Saratoga'' and the surrounding water remained too radioactive for close approach until after she sank.<ref>{{Harvnb|Shurcliff|1946|p=213}}.</ref> She settled upright on the bottom, with the top of her mast {{convert|40|ft|m}} below the surface.<ref>{{Harvnb|Davis|1994|p=}}.</ref>

{{USS|Independence|CVL-22|6}} survived ''Able'' with spectacular damage to the flight deck.<ref>{{Harvnb|Shurcliff|1946|pp=154–157}}.</ref> She was moored far enough away from ''Baker'' to avoid further physical damage but was severely contaminated. She was towed to San Francisco,<ref>{{Harvnb|Weisgall|1994|p=261}}.</ref> where four years of decontamination experiments at the [[San Francisco Naval Shipyard|Hunters Point Naval Shipyard]] failed to produce satisfactory results. On January 29, 1951, she was scuttled near the [[Farallon Islands]].<ref>{{cite web |url=http://www.history.navy.mil/photos/sh-usn/usnsh-i/cvl22.htm |archive-url=https://web.archive.org/web/20000925225034/http://www.history.navy.mil/photos/sh-usn/usnsh-i/cvl22.htm |archive-date=September 25, 2000 |title=USS ''Independence'' (CVL-22) |access-date=April 14, 2013 |publisher=United States Navy}}</ref>

{{Gallery |align=center |width=300 |File:Carrier Saratoga diver sketch.png|Diver's sketch of {{USS|Saratoga|CV-3|6}} on the bottom of Bikini Lagoon. Starboard torpedo blister is crumpled.|alt1=Line drawing of aircraft carrier sitting upright on the seabed.||
|File:USS Independence (CVL-22) burning.png|alt2=Photograph of badly damaged aircraft carrier, afloat with smoke coming from deck.|{{USS|Independence|CVL-22|6}}, ship #28, showing blast damage from ''Able'', before ''Baker'' made her radioactive.|
}}

===Fission-product radioactivity===

''Baker'' was the first nuclear explosion close enough to the surface to keep the radioactive fission products in the local environment. It was not "self-cleansing." The result was radioactive contamination of the lagoon and the target ships. While anticipated, it caused far greater problems than were expected.<ref>Memorandum, Col. A. W. Betts, USACOE, to Brig. Gen. K. D. Nichols, MED, USACOE, August 10, 1946, quoted in {{Harvnb|Delgado|1996|p=87}}.</ref>

The ''Baker'' explosion produced about {{convert|3|lb|kg}} of fission products.<ref>The conversion ratio of fission to energy is {{convert|1|lb|kg|spell=in}} of fission per eight kilotons of energy. The 23-kiloton yield of the ''Baker'' device indicates that just under {{convert|3|lb|kg|spell=in}} of plutonium-239 became fission products.{{Harvnb|Glasstone|1967|p=481}}.</ref><ref>{{Harvnb|Shurcliff|1947|pp=167, 168, & plate 28}}.</ref> These fission products were thoroughly mixed with the two million tons of spray and seabed sand that were lifted into the spray column and its cauliflower head and then dumped back into the lagoon. Most of it stayed in the lagoon and settled to the bottom or was carried out to sea by the lagoon's internal tidal and wind-driven currents.<ref name="Weisgall, p. 225"/>

A small fraction of the contaminated spray was thrown back into the air as the base surge. Unlike the Wilson cloud, a meteorological phenomenon in clean air, the base surge was a heavy fog bank of radioactive mist that rolled across all the target ships, coating their surfaces with fission products.<ref>{{Harvnb|Shurcliff|1947|p=159}}.</ref> When the mist in the base surge evaporated, the base surge became invisible but continued to move away, contaminating ships several miles from the detonation point.<ref>{{Harvnb|Glasstone|Dolan|1977|pp=53–55}}.</ref>

Unmanned boats were the first vessels to enter the lagoon. Onboard instruments allowed remote-controlled radiation measurements to be made. When support ships entered the lagoon for evaluation, decontamination, and salvage activities, they steered clear of lagoon water hot spots detected by the drone boats. The standard for radiation exposure to personnel was the same as that used by the Manhattan Project: 0.1 roentgens per day.<ref>{{Harvnb|Delgado|1996|p=85}}.</ref> Because of this constraint, only the five most distant target ships could be boarded on the first day.<ref>{{Harvnb|Delgado|1991|p=28}}.</ref> The closer-in ships were hosed down by Navy [[fireboat]]s using saltwater and flame retardants. The first hosing reduced radioactivity by half, but subsequent hosings were ineffective.<ref name="Delgado, p 29">{{Harvnb|Delgado|1991|p=29}}.</ref> For most of the ships, reboarding had to wait until the short-lived radioisotopes decayed; ten days elapsed before the last of the targets could be boarded.<ref>{{Harvnb|Shurcliff|1947|p=168}}.</ref>

In the first six days after ''Baker'', when radiation levels were highest, 4,900 men boarded target ships.<ref>{{Harvnb|Delgado|1996|p=175}}.</ref> Sailors tried to scrub off the radioactivity with brushes, water, soap, and lye. Nothing worked, short of [[sandblasting]] to bare metal.<ref name="Delgado, p 29"/>

{{Gallery|width=270 |align=center
|File:Crossroads Baker Base Surge.jpg|alt1=Ships silhouetted against an approaching cloud of mist from falling water in the background.|As the spray column falls, a radioactive "base surge," like mist at the bottom of a waterfall, moves out toward the target ships. Foreground ship (left) is the {{convert|725|ft|0}} long Japanese battleship ''[[Japanese battleship Nagato|Nagato]]''.
|File:USS New York (BB-34) is washed down at Bikini Atoll after Operation Crossroads, circa in July 1946.jpg|alt2=Aerial photo of a fireboat hosing down the stern of a battleship.|In a largely ineffective effort to wash off base surge contamination, a fireboat hoses down the battleship {{USS|New York|BB-34|2}} with radioactive lagoon water. The ship was outside the area of the above map.
|File:Crossroads Baker Scrubdown.jpg|alt3=Sailors scrubbing down a ship deck.|Sailors scrubbing down the German cruiser ''[[German cruiser Prinz Eugen|Prinz Eugen]]'' with brushes, water, soap, and lye. Five months later, the ship was still too radioactive to permit repairs to a leak, and she sank.
}}

===Test animals===

[[File:Crossroads Aftermath4.png|thumb|Aftermath of animal testing during Operation Crossroads]]
Only pigs, goats and rats were used in the ''Baker'' test. All the pigs and most of the rats died. Several days elapsed before sailors were able to board the target ships where test animals were located; during that time the accumulated doses from the gamma rays produced by fission products became lethal for the animals.{{sfn|Shurcliff|1947|pp=166–167}} Since much of the public interest in Operation Crossroads had focused on the fate of the test animals, in September Blandy asserted that radiation death is not painful: "The animal merely languishes and recovers or dies a painless death. Suffering among the animals as a whole was negligible."{{sfn|Shurcliff|1947|p=167}} This was clearly not true. While the well-documented suffering of [[Harry Daghlian]] and [[Louis Slotin]] as they died of radiation injury at Los Alamos was still secret, the widely reported radiation deaths at Hiroshima and Nagasaki had not been painless. In 1908, Dr. Charles Allen Porter had stated in an academic paper, "the agony of inflamed X-ray lesions is almost unequalled in any other disease."<ref name="Weisgall 1994 229"/>

===Induced radioactivity===

The ''Baker'' explosion ejected into the environment about twice as many free neutrons as there were fission events. A plutonium fission event produces, on average, 2.9 neutrons, most of which are consumed in the production of more fission, until fission falls off and the remaining uncaptured neutrons escape.<ref>{{Harvnb|Glasstone|1967|p=486}}.</ref> In an air burst, most of these environmental neutrons are absorbed by superheated air which rises into the stratosphere, along with the fission products and unfissioned plutonium. In the underwater ''Baker'' detonation, the neutrons were captured by seawater in the lagoon.<ref name="Delgado, Ghost Fleet, p 86"/>

Of the four major elements in seawater – [[hydrogen]], [[oxygen]], [[sodium]], and [[chlorine]] – only sodium takes on intense, short-term radioactivity with the addition of a single neutron to its nucleus: common sodium-23 becomes radioactive [[sodium-24]], with a 15-hour half-life. In six days, its intensity drops a thousandfold, but the corollary of short half-life is high initial intensity. Other isotopes were produced from seawater: [[tritium|hydrogen-3]] (half-life 12 years) from [[deuterium|hydrogen-2]], [[oxygen-17]] (stable) from [[oxygen-16]], and [[chlorine-36]] (half-life about 300,000 years) from chlorine-35, and some trace elements, but scarcity or low short-term intensity (long half-life) rendered them insignificant compared with sodium-24.<ref name="Delgado, Ghost Fleet, p 86"/>

Less than one pound of radioactive sodium was produced. If all the neutrons released by the fission of {{convert|2|lb}} of plutonium-239 were captured by sodium-23, {{convert|0.4|lb}} of sodium-24 would result, but sodium did not capture all the neutrons. Unlike fission products, which are heavy and eventually sank to the bottom of the lagoon, the sodium stayed in solution. It contaminated the hulls and onboard salt water systems of support ships that entered the lagoon, as well as the water used in decontamination.<ref name="Delgado, Ghost Fleet, p 86">{{Harvnb|Delgado|1996|p=86}}.</ref>

===Unfissioned plutonium===

The {{convert|10.6|lb}} of plutonium which did not undergo fission and the {{convert|3|lb}} of fission products were scattered.<ref>The total amount of plutonium in the core, later called the pit, was {{convert|13.6|lb}}, {{convert|3|lb}} of which fissioned. {{Harvnb|Coster-Mullen|2003|p=45}}.</ref> Plutonium is not a biological hazard unless ingested or inhaled, and its alpha radiation cannot penetrate skin. Once inside the body it is significantly toxic both radiologically and chemically, having a [[heavy metal toxicity]] on a par with that of [[Arsenic poisoning|arsenic]].<ref>{{cite web |url=http://www.world-nuclear.org/info/inf15.html |title=Plutonium |publisher=[[World Nuclear Association]] |access-date=May 4, 2013 |archive-date=March 30, 2010 |archive-url=https://web.archive.org/web/20100330221426/http://www.world-nuclear.org/info/inf15.html}}</ref> Estimates based on the Manhattan Project's "tolerance dose" of one microgram of plutonium per worker put 10.6 pounds at the equivalent of about five billion tolerable doses.<ref>On December 17, 1945, Henry Newson, in a memo to Los Alamos director Norris Bradbury, had estimated that for ''Baker'', "there will probably be enough plutonium near the surface to poison the combined forces of the United States at their highest wartime strength. The fission products will be worse." {{Harvnb|Weisgall|1994|p=216}}.</ref>

Plutonium alpha rays could not be detected by the film badges and [[Geiger counter|Geiger counters]] used by people who boarded the target ships because alpha particles have very low penetrating power, insufficient to enter the glass detection tube. It was assumed to be present in the environment wherever fission product radiation was detected. The decontamination plan was to scrub the target ships free of fission products and assume the plutonium would be washed away in the process. To see if this plan was working, samples of paint, rust, and other target ship surface materials were taken back to a laboratory on the support ship ''Haven'' and examined for plutonium.<ref name="Weisgall 1994 241">{{Harvnb|Weisgall|1994|p=241}}.</ref> The tests showed that the plan was not working. The results of these plutonium detection tests, and of tests performed on fish caught in the lagoon, caused all decontamination work to be abruptly terminated on August 10, effectively shutting down Operation Crossroads for safety reasons.<ref name="Weisgall 1994 242">{{Harvnb|Weisgall|1994|p=242}}.</ref> Tests conducted on the support ship {{USS|Rockbridge|APA-228|6}} in November indicated the presence of {{convert|2|mg}} of plutonium,<ref>{{Harvnb|Weisgall|1994|p=272}}.</ref> which represented 2,000 tolerable doses.<ref>{{Harvnb|Weisgall|1994|p=238}}.</ref>

==Failed ''Baker'' cleanup and program termination==

The program termination on August 10, sixteen days after ''Baker'', was the result of a showdown between Dr. [[Stafford Warren]], the Army colonel in charge of radiation safety for Operation Crossroads, and Deputy Chief of Naval Operations for Special Weapons, Vice Admiral William H. P. Blandy. A radiation safety monitor under Warren's command later described him as "the only Army colonel who ever sank a Navy flotilla."<ref name="Weisgall 1994 236">{{Harvnb|Weisgall|1994|p=236}}.</ref>

Warren had been chief of the medical section of the Manhattan Project<ref>{{Harvnb|Compton|1956|p=179}}.</ref> and was in charge of radiation safety at the ''Trinity'' test,<ref>{{Harvnb|Groves|1962|p=298}}.</ref> as well as of the on-ground inspections at Hiroshima and Nagasaki after the bombings.<ref>{{Harvnb|Weisgall|1994|pp=209–210}}.</ref> At Operation Crossroads, it was his job to keep the sailors safe during the cleanup.<ref>{{Harvnb|Weisgall|1994|pp=211–213}}.</ref>

===Radiation monitoring===

[[File:Crossroads Aftermath1.png|thumb|Extensive structural damage and clean-up attempts on ships]]
A total of 18,875 [[film badge dosimeter]]s were issued to personnel during the operation. About 6,596 dosimeters were given to personnel who were based on the nearby islands or support ships that had no potential for radiation exposure. The rest were issued to all of the individuals thought to be at the greatest risk for radiological contamination along with a percentage of each group who were working in less contaminated areas. Personnel were removed for one or more days from areas and activities of possible exposure if their badges showed more than 0.1 [[roentgen (unit)|roentgen]] (R) per day exposure. Experts believed at the time that this radiation dose could be tolerated by individuals for long periods without any harmful effects. The maximum accumulated dose of 3.72 R was received by a radiation safety monitor.<ref>{{cite web|title=Operation Crossroads: Fact Sheet|url=http://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/o/operation-crossroads/fact-sheet.html|publisher=U.S. Defense Nuclear Agency, Defense Nuclear Agency|access-date=May 4, 2015|date=1984}}</ref>

===Cleanup issues===

The cleanup was hampered by two significant factors: the unexpected base surge and the lack of a viable cleanup plan. It was understood that if the water column fell back into the lagoon, which it did, any ships that were drenched by falling water might be contaminated beyond redemption. Nobody expected that to happen to almost the entire target fleet.<ref>According to a Navy report, the base surge spread contamination {{convert|7|mi|km|spell=in}} downwind and severely contaminated all but nine of the ninety-five target vessels.{{Harvnb|Weisgall|1994|pp=223, 224}}.</ref> No decontamination procedures had been tested to see if they would work and to measure the potential risk to personnel. In the absence of a decontamination protocol, the ships were cleaned using traditional deck-scrubbing methods: hoses, mops, and brushes, with water, soap, and lye.<ref>{{Harvnb|Weisgall|1994|p=230}}.</ref> The sailors had no protective clothing.<ref>{{Harvnb|Weisgall|1994|p=231}}.</ref>

===Secondary contamination===

[[File:Crossroads Aftermath2.png|thumb|left|Aftermath of Operation Crossroads from the air, with extensive ongoing fires on affected vessels]]
By August 3, Colonel Warren concluded the entire effort was futile and dangerous.<ref name="Weisgall 1994 239">{{Harvnb|Weisgall|1994|p=239}}.</ref> The unprotected sailors were stirring up radioactive material and contaminating their skin, clothing, and, presumably, their lungs. When they returned to their support ship living quarters, they contaminated the shower stalls, laundry facilities, and everything they touched. Warren demanded an immediate halt to the entire cleanup operation. He was especially concerned about plutonium, which was undetectable on site.<ref>{{Harvnb|Weisgall|1994|pp=238–242}}.</ref>

Warren also observed that the [[radiation safety]] procedures were not being followed correctly.<ref name="Weisgall 1994 232">{{Harvnb|Weisgall|1994|p=232}}.</ref> Fire boats got too close to the target ships they were hosing and drenched their crews with radioactive spray. One fire boat had to be taken out of service.<ref name="Weisgall 1994 232"/> Film badges showed 67 overdoses between August 6 and 9.<ref name="Weisgall 1994 236"/> More than half of the 320 Geiger counters available shorted out and became unavailable.<ref>{{Harvnb|Weisgall|1994|p=213}}.</ref> The crews of two target ships, {{USS|Wainwright|DD-419|6}} and {{USS|Carteret|APA-70|6}}, moored far from the detonation site, had moved back on board and become overexposed. They were immediately evacuated back to the United States.<ref>{{Harvnb|Weisgall|1994|p=237}}.</ref>

Captain L. H. Bibby, commanding officer of the apparently undamaged battleship ''New York'', accused Warren's radsafe monitors of holding their Geiger counters too close to the deck.<ref name="Weisgall 1994 236"/> He wanted to reboard his ship and sail it home. The steadily dropping radiation counts on the target ships gave an illusion that the cleanup was working, but Warren explained that although fission products were losing some of their gamma ray potency through radioactive decay, the ships were still contaminated. The danger of ingesting microscopic particles remained.<ref name="Weisgall 1994 239"/>
{{Clear}}

===Warren persuades Blandy===

[[File:Crossroads Radioactive Puffy Surgeon Fish.jpg|thumb|alt=Radioactive parts of a fish show as white against a black background.|A radioactive [[surgeonfish]] makes its own x-ray. The bright area is a meal of fresh algae. The rest of the body has absorbed and distributed enough plutonium to make the scales radioactive. The fish was alive and apparently healthy when captured.]]
Blandy ordered Warren to explain his position to 1,400 skeptical officers and sailors.<ref name="Weisgall 1994 236"/> Some found him persuasive, but it was August 9 before he convinced Blandy. That was the date when Blandy realized, for the first time, that Geiger counters could not detect plutonium.<ref name="Weisgall 1994 241"/> Blandy was aware of the health problems of [[radium girls|radium dial painters]] who ingested microscopic amounts of radium in the 1920s, and the fact that plutonium was assumed to have a similar biological effect. When plutonium was discovered in the captain's quarters of ''Prinz Eugen'', unaccompanied by fission products, Blandy realized that plutonium could be anywhere.<ref>{{Harvnb|Weisgall|1994|pp=235–236}}.</ref>

The following day, August 10, Warren showed Blandy an [[autoradiograph]] of a fish, an x-ray picture made by radiation coming from the fish. The outline of the fish was made by alpha radiation from the fish scales, evidence that plutonium, mimicking calcium, had been distributed throughout the fish, out to the scales. Blandy announced his decision, "then we call it all to a halt." He ordered that all further decontamination work be discontinued.<ref name="Weisgall 1994 242"/> Warren wrote home, "A self x ray of a fish&nbsp;... did the trick."<ref name="Weisgall 1994 242"/>

The decontamination failure ended plans to outfit some of the target ships for the 1947 ''Charlie'' shot and to sail the rest home in triumph. The immediate public relations problem was to avoid any perception that the entire target fleet had been destroyed. On August 6, in anticipation of this development, Blandy had told his staff that ships sunk or destroyed more than 30 days after the ''Baker'' shot "will not be considered as sunk by the bomb."<ref>{{Harvnb|Weisgall|1994|p=240}}.</ref> By then, public interest in Operation Crossroads was waning, and the reporters had gone home. The failure of decontamination did not make news until the final reports came out a year later.<ref>{{Harvnb|Life Editors|1947|p=88}}.</ref>

==Test ''Charlie''==

[[File:Admiral Blandy Mushroom Cloud Cake.jpg|thumb|right|alt=A man in naval uniform and a woman wearing a hat cut into a cake labeled Operation Crossroads, and shaped like a mushroom cloud, while another naval officer looks on.|Blandy and his wife slice into an Operation Crossroads cake shaped like Baker's radioactive geyser, while Rear Admiral [[Frank J. Lowry]] looks on, November 7, 1946]]
Testing program staff originally set test ''Charlie'' for early 1947. They wanted to explode it deep under the surface in the lee of the atoll to test the effect of nuclear weapons as depth charges on unmoored ships.<ref name="p2"/> The unanticipated delays in decontaminating the target ships after test ''Baker''<ref name="proceedings"/> prevented the required technical support personnel from assisting with ''Charlie'' and also meant that there were no uncontaminated target ships available for use in ''Charlie''. The naval weapons program staff decided the test was less pressing given that the entire U.S. arsenal had only a handful of nuclear weapons and canceled the test. The official reason given for canceling ''Charlie'' was that the program staff felt it was unnecessary because of the success of the ''Able'' and ''Baker'' tests.<ref>{{Harvnb|Weisgall|1994|pp=259–261}}.</ref> The deep ocean effects testing that ''Charlie'' was to have performed were fulfilled nine years later with ''[[Operation Wigwam]]''.<ref>{{cite web |url=http://www.dtra.mil/documents/ntpr/factsheets/Wigwam.pdf |title=Operation Wigwam |access-date=April 14, 2013 |publisher=[[Defense Threat Reduction Agency]] |archive-url=https://web.archive.org/web/20130218012550/http://www.dtra.mil/documents/ntpr/factsheets/Wigwam.pdf |archive-date=February 18, 2013 }}</ref>

==Aftermath==

All ships leak and require the regular operation of [[bilge pump]]s to stay afloat.<ref>{{Harvnb|Oertling|1996|p=xv}}.</ref> If their bilge pumps could not be operated, the target ships would eventually sink. Only one suffered this fate: ''Prinz Eugen'', which sank in the Kwajalein lagoon on December 22. The rest were kept afloat long enough to be deliberately sunk or dismantled. After the August 10 decision to stop decontamination work at Bikini, the surviving target fleet was towed to Kwajalein Atoll where the live ammunition and fuel could be offloaded in uncontaminated water. The move was accomplished during the remainder of August and September.<ref>{{Harvnb|Delgado|1991|p=31}}.</ref>

Eight of the major ships and two submarines were towed back to the United States and Hawaii for radiological inspection. Twelve target ships were so lightly contaminated that they were remanned and sailed back to the United States by their crews. Ultimately, only nine target ships were able to be scrapped rather than scuttled. The remaining target ships were scuttled off Bikini or Kwajalein Atolls, or near the Hawaiian Islands or the California coast during 1946–1948.<ref>{{Harvnb|Delgado|1991|pp=32, 33}}.</ref> The remains of {{USS|Independence|CVL-22|2}} were retained at [[San Francisco Naval Shipyard|Hunters Point Shipyard]] until 1951 to test decontamination methods.<ref name=HRA-2/>{{rp|6–24}}

The support ships were decontaminated as necessary and received a radiological clearance before they could return to the fleet. This required a great deal of experimentation at Navy shipyards in the United States, primarily in San Francisco at Hunters Point.<ref name=HRA-2>{{cite report |url=https://bracpmo.navy.mil/content/dam/bracpmo/california/former_naval_shipyard_hunters_point/pdfs/all_documents/environmental_documents/radiological/hps_200408_hra.pdf |title=Historical Radiological Assessment, Volume II, Use of General Radioactive Materials, 1939–2003, Hunters Point Shipyard |publisher=United States Department of the Navy |date=2004 |access-date=January 2, 2018 |archive-date=October 22, 2021 |archive-url=https://web.archive.org/web/20211022172649/https://www.bracpmo.navy.mil/content/dam/bracpmo/california/former_naval_shipyard_hunters_point/pdfs/all_documents/environmental_documents/radiological/hps_200408_hra.pdf}}</ref>{{rp|6–15}} The destroyer {{USS|Laffey|DD-724|6}} required "sandblasting and painting of all underwater surfaces, and acid washing and partial replacement of salt-water piping and evaporators."<ref>{{Harvnb|Delgado|1991|p=33}}.</ref>

A survey was conducted in mid-1947 to study long-term effects of the Operation Crossroads tests. According to the official report, decontamination efforts "revealed conclusively that removal of radioactive contamination of the type encountered in the target vessels in test ''Baker'' cannot be accomplished successfully."<ref>Director of Ship Material, JTF-1, "Technical Inspection Report, Radiological Inspection of Target and Non-Target Vessels", Armed Forces Special Weapons Project, 1947, National Archives, quoted in {{Harvnb|Delgado|1996|p=86}}.</ref>

On August 11, 1947, [[Life (magazine)|''Life'']] summarized the report in a 14-page article with 33 pictures.{{sfn|Warren|1947|pp=86–88}} The article states, "If all the ships at Bikini had been fully manned, the Baker Day bomb would have killed 35,000 crewmen. If such a bomb were dropped below New York's Battery in a stiff south wind, 2 million people would die."<ref>{{Harvnb|Life Editors|1947|p=75}}.</ref>

The contamination problem was not widely appreciated by the general public until 1948, when ''[[No Place to Hide (Bradley book)|No Place to Hide]]'', a best-selling book by [[David J. Bradley, M.D. (author, skier)|David Bradley]], was serialized in the ''[[Atlantic Monthly]]'', condensed by the ''[[Reader's Digest]]'', and selected by the [[Book of the Month Club]].<ref>{{Harvnb|Delgado|1996|p=173}}.</ref> In his preface, Bradley, a key member of the Radiological Safety Section at Bikini known as the "Geiger men", asserted that "the accounts of the actual explosions, however well intended, were liberally seasoned with fantasy and superstition, and the results of the tests have remained buried in the vaults of military security."<ref>{{Harvnb|Bradley|1948|p=xii}}.</ref> His description of the ''Baker'' test and its aftermath brought to world attention the problem of radioactive fallout from nuclear weapons.<ref>{{cite web |last= Fox |first= Margalit |title= David Bradley, 92, Author, Antinuclear Advocate, Champion Skier and State Legislator, Is Dead |work= The New York Times |date= January 30, 2009 |url= https://www.nytimes.com/2008/01/30/arts/30bradley.html}}</ref>

=== Personnel exposure ===
[[File:Operation Crossroads Joint Task Force One ID Card.jpg|thumb|right|Operation Crossroads ID Card]]
All Operation Crossroads operations were designed to keep personnel from being exposed to more than 0.1 [[roentgen (unit)|roentgen]] (R) per day. At the time, this was considered to be an amount of radiation that could be tolerated for long periods without any harmful effects on health. Since there was no special clothing or radiation shielding available, the protection plan relied on managing who went where, when, and for how long.<ref name="CrossroadsFactSheet"/>

Radioactively "hot" areas were predicted and then checked with Geiger counters, sometimes by remote control, to see if they were safe. The level of measured gamma radiation determined how long personnel could operate in them without exceeding the allowable daily dose.<ref name="CrossroadsFactSheet"/> Instant gamma readings were taken by radiation safety specialists, but film-badge dosimeters, which could be read at the end of the day, were issued to all personnel believed to be at the greatest radiological risk. Anyone whose badge showed more than 0.1 R per day exposure was removed for one or more days from areas and activities of possible exposure. The maximum accumulated exposure recorded was 3.72&nbsp;R, received by a radiation safety specialist.<ref name="CrossroadsFactSheet"/>

A percentage of each group working in less contaminated areas was badged. Eventually, 18,875 film-badge [[dosimeter]]s were issued to about 15% of the total work force. On the basis of this sampling, a theoretical total exposure was calculated for each person who did not have a personal badge.<ref name="CrossroadsFactSheet"/> As expected, exposures for target ship crewmen who boarded their ships after ''Baker'' were higher than those for support ship crews. The hulls of support ships that entered the lagoon after ''Baker'' became so radioactive that sleeping quarters were moved toward the center of each ship.<ref>Interview with Rear Admiral Robert Conard, MC, USNR (Ret.) in Setauket, NY, November 9, 1993, conducted by Jan K. Herman, Historian, Bureau of Medicine and Surgery {{cite web |title= Interview |publisher= Department of the Navy – Naval Historical Center |date= August 11, 2002 |url= http://www.history.navy.mil/faqs/faq87-6b.htm |access-date= September 27, 2009 |archive-url= https://web.archive.org/web/20090618162850/http://www.history.navy.mil/faqs/faq87-6b.htm |archive-date= June 18, 2009 }}</ref> Of the total mass of [[hot particle|radioactive particles]] scattered by each explosion, 85% was unfissioned plutonium which produces [[alpha radiation]] not detected by film badges or Geiger counters. There was no method of detecting plutonium in a timely fashion, and participants were not monitored for ingestion of it.<ref name="Delgado, Ghost Fleet, p 86"/>

A summary of film badge readings (in roentgens) for July and August, when the largest number of personnel was involved, is listed below:

{| class="wikitable"
|+ Actual film badge readings (+R gamma)
|-
! width=90|Readings<ref name="CrossroadsFactSheet"/>
! width=90|Total
! width=90|0
! width=90|0.001–0.1
! width=90|0.101–1.0
! width=90|1.001–10.0
|-
! July
| style="text-align:right;"|3,767 (100%)
| style="text-align:right;"|2,843 (75%)
| style="text-align:right;"|689 (18%)
| style="text-align:right;"|232 (6%)
| style="text-align:right;"|3 (&lt;0.1%)
|-
! August
| style="text-align:right;"|6,664 (100%)
| style="text-align:right;"|3,947 (59%)
| style="text-align:right;"|2,139 (32%)
| style="text-align:right;"|570 (9%)
| style="text-align:right;"|8 (0.1%)
|}

Service members who participated in the cleanup of contaminated ships were exposed to unknown amounts of radiation. In 1996, a government-sponsored mortality study of Operation Crossroads veterans<ref name=NAS_Study>{{Harvnb|Institute of Medicine|1996}}</ref> showed that, by 1992, 46&nbsp;years after the tests, veterans had experienced a 4.6% higher mortality than a control group of non-veterans. There were 200 more deaths among Operation Crossroads veterans than in the similar control group (12,520 vs. 12,320), implying a life-span reduction of about three months for Operation Crossroads veterans.<ref>The study did not publish life-span figures, but actuarial tables predict about 800 deaths per year for a group that size as they approach 70&nbsp;years in age. Two hundred extra deaths would put the Operation Crossroads veterans about three months ahead of their peers on the mortality curve. Social Security Online, Actuarial Publications, Period Life Table {{cite web|title= Table|publisher= www.socialsecurity.gov|date= April 22, 2009|url= http://www.ssa.gov/OACT/STATS/table4c6.html|access-date= November 10, 2009}}</ref> [[Atomic veteran|Veterans who were exposed to radiation]] formed the non-profit National Association of Atomic Veterans association in 1978 to lobby for veterans benefits covering illnesses they believed were caused by their exposure.<ref name=NAS_Study/>

Legislation was passed in 1988 that removed the need for veterans to prove a causal link between certain forms of [[cancer]] and radiation exposure due to nuclear tests.{{sfn|Weisgall|1994|p=278}} Incidence of the main expected causes of this increased mortality, [[leukemia]] and other cancers, was not significantly higher than normal. Death by those diseases was tabulated on the assumption that if radiation exposure had a life-shortening effect it would likely show up there, but it did not. Not enough data were gathered on other causes of death to determine the reason for this increase in all-cause mortality, and it remains a mystery. The mortality increase was higher, 5.7%, for those who boarded target ships after the tests than for those who did not, whose mortality increase was 4.3%.<ref name=NAS_Study/>

=== Bikini Atoll ===
{{Main|Bikini Atoll}}
[[File:USS Nevada Post Operation Crossroads.png|thumb|USS ''Nevada'' post-Operation Crossroads with extensive damage]]
The 167 Bikini residents who were moved to the Rongerik Atoll prior to the Crossroads tests were unable to gather sufficient food or catch enough fish and shellfish to feed themselves in their new environment. The Navy left food and water for a few weeks and then failed to return in a timely manner. By January 1947, visitors to Rongerik reported the islanders were suffering [[malnutrition]], facing potential [[starvation]] by July, and were [[emaciated]] by January 1948. In March 1948 they were evacuated to Kwajalein, and then settled onto another uninhabited island, [[Kili Island|Kili]], in November. With only one third of a square mile, Kili has one sixth the land area of Bikini and, more importantly, has no lagoon and no protected harbor. Unable to practice their native culture of lagoon fishing, they became dependent on food shipments. Their 4,000 descendants today are living on several islands and in foreign countries.<ref name="bikiniatoll.com"/>

Their desire to return to Bikini was thwarted indefinitely by the U.S. decision to resume nuclear testing at Bikini in 1954. During 1954, 1956, and 1958, 21 more nuclear bombs were detonated at Bikini, yielding a total of {{convert|75|MtonTNT|lk=on}}, equivalent to more than 3,000 ''Baker'' bombs. Only one was an air burst, the 3.8 megaton [[Operation Redwing|Redwing ''Cherokee'']] test. Air bursts distribute fallout in a large area, but surface bursts produce intense local fallout.{{sfn|Hansen|1995|p=154, Vol VII, Table A-1}} The first after Crossroads was the dirtiest: the 15 megaton [[Castle Bravo|''Bravo'']] shot of [[Operation Castle]] on March 1, 1954, which was the largest-ever U.S. test. Fallout from ''Bravo'' caused [[radiation injury]] to Bikini islanders who were living on [[Rongelap Atoll]].{{sfn|Delgado|1996|p=176}}

The brief attempt to resettle Bikini from 1972 until 1978 was aborted when health problems from radioactivity in the food supply caused the atoll to be evacuated again. [[Sport diver]]s who visit Bikini to dive on the shipwrecks must eat imported food. The local government elected to close the [[fly-in fly-out]] sports diving operation in Bikini lagoon in 2008,<ref>{{cite web |url=http://www.bikiniatoll.com/divetour.html |title=Bikini Atoll Dive Tourism Information |publisher=Kili/Bikini/Ejit Local Government Council |access-date=April 14, 2013}}</ref> and the 2009 diving season was canceled due to fuel costs, unreliable airline service to the island, and a decline in the Bikini Islanders' trust fund which subsidized the operation.<ref name=bikiniatoll.com/> After a successful trial in October 2010, the local government licensed a sole provider of dive expeditions on the nuclear ghost fleet at Bikini Atoll starting in 2011. The aircraft carrier {{USS|Saratoga|CV-3|2}} is the primary attraction of a struggling, high-end sport diving industry.<ref name="diving">{{cite web |url=http://www.indiestrader.com/destinations/marshall-islands/bikini-atoll-diving/ |title=Bikini Atoll Diving Charter |publisher=Indies Trader Marine Adventures |access-date=April 14, 2013}}</ref>

==Legacy==

Following test ''Baker'' decontamination problems, the United States Navy equipped newly constructed ships with a Countermeasure Wash Down System of piping and nozzles to cover exterior surfaces of the ship with a spray of salt water from the [[firefighting]] system when [[nuclear attack]] appeared imminent. The film of flowing water would theoretically prevent contaminants from settling into cracks and crevices.<ref>{{cite web|url=http://www.navy.mil/view_image.asp?id=39201|title=United States Navy CMWDS|access-date=May 4, 2013}}</ref>

==In popular culture==

The juxtaposition of half-naked islanders with nuclear weapons that had the power to reduce everyone to a primitive state provided some with an inspirational motif. During Operation Crossroads, Paris swimwear designer [[Louis Réard]] adopted the name ''Bikini'' for his [[bikini|minimalist swimsuit]] design which, revolutionary for the time, exposed the wearer's navel. He explained that "like the bomb, the bikini is small and devastating".<ref name="The Very First Bikini">
{{cite web
|last=Rosebush
|first=Judson
|title=1945–1950: The Very First Bikini
|publisher=Bikini Science
|url=http://www.bikiniscience.com/chronology/1945-1950_SS/1945-1950.html
|archive-url=https://web.archive.org/web/20120627214541/http://bikiniscience.com/chronology/1945-1950_SS/1945-1950.html
|archive-date=June 27, 2012
|access-date=November 25, 2012
}}</ref> Fashion writer [[Diana Vreeland]] described the bikini as the "atom bomb of fashion".<ref name="The Very First Bikini"/> While two-piece swimsuits have been used since antiquity, it was Réard's name of the ''Bikini'' that stuck for all of its modern incarnations.<ref>{{cite web |url=http://www.smithsonianmag.com/smart-news/the-bikinis-inventor-guessed-how-much-it-would-horrify-the-public-6914887/ |first=Rose |last=Eveleth |author-link=Rose Eveleth |title=The Bikini's Inventor Guessed How Much It Would Horrify the Public |date=July 5, 2013 |website=Smithsonian.com |access-date=January 22, 2017}}</ref>

Artist [[Bruce Conner]] made ''[[Crossroads (1976 film)|Crossroads]]'', a 1976 video assembled from the official films, with an audio collage fashioned by [[Patrick Gleeson]] on a Moog synthesizer and a drone composition performed on an electric organ by [[Terry Riley]]. A commentator at ''[[The New York Review of Books]]'' called the experience of watching the video the "nuclear sublime."<ref>[https://www.nybooks.com/daily/2016/07/15/creepy-world-of-bruce-conner/ The Creepy World of Bruce Conner], ''New York Review of Books'', July 15, 2016. Includes link to the video.</ref>

Films and TV shows have used archive footage of the test ''Baker'' explosion in a fictitious capacity. In the animated comedy series ''[[SpongeBob SquarePants]]'', the footage is used three times; in the season 2 episode "Dying for Pie", in the season 5 episode "The Krusty Plate", and in the season 8 episode "Frozen Face-Off". One film example, [[TriStar Pictures|TriStar Pictures']] ''[[Godzilla (1998 film)|Godzilla]]'' from 1998, uses the ''Baker'' test footage in the film's opening to depict the atomic bomb responsible for the creation of the titular monster. In ''[[Godzilla Minus One]]'', Operation Crossroads ended up being directly responsible for mutating Godzilla in the first place. The test ''Baker'' explosion archival footage is also used in the [[Stanley Kubrick]] film ''[[Dr. Strangelove]]''.<ref>{{Cite web |last=Peacock |first=Timothy Noël |date=2021-07-22 |title=From Crossroads to Godzilla: the cinematic legacies of the first postwar nuclear tests |url=http://theconversation.com/from-crossroads-to-godzilla-the-cinematic-legacies-of-the-first-postwar-nuclear-tests-163280 |access-date=2024-02-03 |website=The Conversation |language=en-US}}</ref> The footage plays during the ending montage of the movie accompanied by [[Vera Lynn]] singing "[[We'll Meet Again]]".<ref>{{Cite news |date=2020-06-18 |title=We'll Meet Again: The story of Dame Vera Lynn's wartime classic |url=https://www.bbc.com/news/entertainment-arts-53079190 |access-date=2024-02-03 |language=en-GB}}</ref>

==See also==

* [[Wōdejebato]] – a nearby seamount explored and mapped during these tests.

==Notes==

{{Reflist|30em}}

==References==

{{Refbegin|30em}}
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}}
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|location=Washington, DC
|url=http://www.history.navy.mil/faqs/faq76-1.htm
|access-date=January 1, 2008
|archive-url=https://web.archive.org/web/20121024121304/http://www.history.navy.mil/faqs/faq76-1.htm
|archive-date=October 24, 2012
}}
* {{citation
| last = Newson
| first = Henry W.
| title = Memorandum to Norris Bradbury, December 17, 1945, Possible Difficulties in Naval Tests
| year = 1945
| location = Los Alamos, New Mexico
| publisher = Los Alamos National Laboratory, DOE/CIC 120851
}}
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* {{citation
| last = Niedenthal
| first = Jack
| year = 2009
| title = The world's debt to Bikini
| periodical = [[Bulletin of the Atomic Scientists]] Web Edition
| location = Chicago
| issue = March 11, 2009
| url = http://www.thebulletin.org/web-edition/op-eds/the-worlds-debt-to-bikini
| access-date = December 5, 2009
}} -->
* {{citation
| last = Oertling
| first = Thomas James
| year = 1996
| title = Ships' Bilge Pumps: a History of their Development, 1500–1900
| url = https://books.google.com/books?id=WU7mG9K5A40C&q=Thomas+James+Oertling
| location = Vancouver, BC
| publisher = Texas A&M University Press
| isbn = 978-0-89096-722-5
}}
* {{citation
| last = Peterson
| first = Howard C.
| title = Memorandum to General J. Lawton Collins, February 12, 1946
| year = 1946
| location = Washington, DC
| publisher = Records of the Office of the Secretary of War, RG 107 (Atomic Energy Folder), National Archives
}}
* {{citation
| last = Shurcliff
| first = William A.
| year = 1946
| title = Operation Crossroads: The Official Pictorial Record
| url = https://archive.org/details/operationcrossro00unit
| location = New York
| publisher = William H. Wise and Co.
| access-date = December 14, 2009
| oclc = 1223420
}}
* {{citation
| last = Shurcliff
| first = William A.
| year = 1947
| title = Bombs at Bikini: The Official Report of Operation Crossroads
| url = https://archive.org/details/bombsatbikinioff00unit
| location = New York
| publisher = William H. Wise and Co.
| access-date = December 14, 2009
| oclc = 1492066
}}
* {{citation
| last = Strauss
| first = Lewis
| author-link = Lewis Strauss
| year = 1962
| title = Men and Decisions
| location = Garden City, New York
| publisher = Doubleday
| oclc = 456825
}}
* {{citation
| last = Szilard
| first = Leo
| author-link = Leo Szilard
| editor-last = Weart
| editor-first = Spencer R.
| editor-link = Spencer R. Weart
| editor2-last = Szilard
| editor2-first = Gertrude Weiss
| year = 1978
| title = Leo Szilard: his Version of the Facts: Selected Recollections and Correspondence
| location = Cambridge, Massachusetts
| publisher = MIT Press
| isbn = 978-0-262-69070-6
| bibcode = 1979lshv.book.....W
}}
* {{citation
| last = Warren
| first = Stafford L.
| year = 1947
| title = Conclusions: Tests Proved Irresistible Spread of Radioactivity
| magazine = [[Life (magazine)|Life]]
| location = New York
| volume = 23| issue = 16, August 11, 1947
| url = https://books.google.com/books?id=V04EAAAAMBAJ&pg=PA86
| pages = 86, 88
}}
* {{citation
| last = Waters
| first = Odale D. Jr.
| year = 1986
| title = Crossroads: A Tin Can Perspective
| periodical = Proceedings of the U.S. Naval Institute
| location = Annapolis, Maryland
| volume = 112| issue = 7, July 1986
| pages = 72–74
| issn = 0041-798X
}}
* {{citation
| last = Weisgall
| first = Jonathan
| year = 1994
| title = Operation Crossroads: The Atomic Tests at Bikini Atoll
| location = Annapolis, Maryland
| publisher = Naval Institute Press
| isbn = 978-1-55750-919-2
| url-access = registration
| url = https://archive.org/details/operationcrossro0000weis
}}
{{Refend}}

==External links==

{{Commons|Operation Crossroads}}
* [https://ia801302.us.archive.org/32/items/bombsatbikinioff00unit/bombsatbikinioff00unit_bw.pdf  Bombs at Bikini] The Official Report of Operation Crossroads, Joint Task Force One
* [http://content.lib.washington.edu/donaldsonweb/index.html Lauren R. Donaldson Collection, served as a radiation monitor for Operation Crossroads] – University of Washington Digital Collection
* [https://web.archive.org/web/20000521071018/http://history.navy.mil/ac/bikini/bikini1.htm A series of watercolour paintings], made by U.S. Military combat artists, as a report of the tests.
* [https://web.archive.org/web/19970206084507/http://www.history.navy.mil/faqs/faq4-1.htm US Navy and Nuclear Weapons Testing]
* {{Internet Archive film|id=gov.ntis.ava13712vnb1|title=Operations Crossroads (1949)}}
* {{Internet Archive film|id=1946-06-13_Atom_Test_Nears|title=Atom Test Nears, 1946/06/13 (1946)}}
* {{Internet Archive film|id=1946-07-01_Operations_Crossroads_Underway|title=Operations Crossroads Underway, 1946/07/01 (1946)}}
* {{Internet Archive film|id=1946-07-08_First_Pictures_Atomic_Blast|title=First Pictures Atomic Blast!, 1946/07/08 (1946)}}
* {{Internet Archive film|id=gov.doe.0800002|title=Nuclear Test Film – Project Crossroads}} (42m32s)
* {{Internet Archive film|id=AtomBomb1946|title=Atom Bomb (Joe Bonica's Movie of the Month) (ca. 1955)}}
* [https://web.archive.org/web/20130218065013/http://www.dtra.mil/documents/ntpr/relatedpub/DNATR8205V1.pdf Analysis of Radiation Exposure for Naval Units of Operation Crossroads – Volume I-Basic Report]
* [https://web.archive.org/web/20130218065343/http://www.dtra.mil/documents/ntpr/relatedpub/DNATR8205V2.pdf Analysis of Radiation Exposure for Naval Units of Operation Crossroads – Volume II-(Appendix A) Target Ships]
* [https://web.archive.org/web/20130218065519/http://www.dtra.mil/documents/ntpr/relatedpub/DNATR8205V3.pdf Analysis of Radiation Exposure for Naval Units of Operation Crossroads – Volume II-(Appendix B) Support Ships]
* [https://web.archive.org/web/20130218141446/http://www.dtra.mil/documents/ntpr/relatedpub/DNATR84119.pdf Internal Dose Assessment – Operation Crossroads]
* [https://commons.wikimedia.org/wiki/File:The_Archeology_of_the_Atomic_Bomb,_National_Park_Service,_Santa_Fe,_New_Mexico,_1991_by_Delgado,_James_P.,_et_al._-_NNPS_903_D160_-38840-pg0000.pdf The Archeology of the Atomic Bomb, National Park Service.]

{{Nuclear weapons tests of the United States}}
{{Manhattan Project}}
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[[Category:Explosions in 1946]]
[[Category:Articles containing video clips]]
[[Category:Nuclear testing at Bikini Atoll]]
[[Category:Code names|Crossroads]]
[[Category:Forced migration]]
[[Category:History of the Manhattan Project]]
[[Category:Military projects of the United States]]
[[Category:1946 disasters in the United States]]
[[Category:1946 in military history]]
[[Category:1946 in science]]
[[Category:1946 in the environment]]
[[Category:1946 in the Marshall Islands]]
[[Category:June 1946 events in the United States]]
[[Category:July 1946 events in the United States]]