NationMaster - Encyclopedia: Operation Crossroads

A 23 kiloton dropped nuclear weapon, known as Operation Crossroads (Event Able)

A 21 kiloton underwater nuclear weapons effects test, known as Operation Crossroads (Event Baker), conducted at Bikini Atoll (1946).

Event Baker explosion a few seconds later

Prospective Operation Crossroads target ships and support ships at Pearl Harbor in a photo released on 27 February 1946. Ships present from front to rear include USS Crittenden (APA-77), Catron (APA-71), Bracken (APA-64), Burleson (APA-67), Gilliam (APA-57), Fallon (APA-81), one unidentified ship, USS Fillmore (APA-83), Kochab (AKS-6), Luna (AKS-7) and an unidentified tanker and liberty ship. Identifiable on the right are LSM-203 and LSM-465. Further in the background are a floating drydock and a merchant ship hulk with unidentified fittings forward of the bridge.

Operation Crossroads was a series of nuclear weapon tests conducted by the United States in the summer of 1946. The series consisted of two detonations, each with a yield of 21 kilotons: ABLE detonated at an altitude of 520 feet (158 m) on 1 July 1946; BAKER detonated 90 feet (27 m) underwater on 25 July 1946. A third planned burst, CHARLIE, was scrubbed after BAKER presented more radiological contamination than had been expected. The Crossroads tests were the fourth and fifth nuclear explosions (following the Trinity test and the bombings of Hiroshima and Nagasaki). It was the first nuclear test held in the Marshall Islands and the first to be publicly announced beforehand. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Download high resolution version (800x629, 70 KB)A 21 kiloton underwater nuclear weapons effects test, known as Operation CROSSROADS (Event Baker), conducted at Bikini Atoll (1946). ... Download high resolution version (800x629, 70 KB)A 21 kiloton underwater nuclear weapons effects test, known as Operation CROSSROADS (Event Baker), conducted at Bikini Atoll (1946). ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Size of this preview: 716 Ã— 600 pixelsFull resolution (740 Ã— 620 pixel, file size: 121 KB, MIME type: image/jpeg) Operation Crossroads, 1946 Prospective target ships and support ships at Pearl Harbor in a photo released on 27 February 1946. ... Image File history File links Size of this preview: 716 Ã— 600 pixelsFull resolution (740 Ã— 620 pixel, file size: 121 KB, MIME type: image/jpeg) Operation Crossroads, 1946 Prospective target ships and support ships at Pearl Harbor in a photo released on 27 February 1946. ... This article is about the harbor in Hawaii. ... USS Catron (APA-71) was a Gilliam-class attack transport serving in the United States Navy during World War II, named for Catron County, New Mexico. ... USS Gilliam (APA-57), named for a county in Oregon, was the lead ship in the Gilliam class of attack transports serving in the United States Navy during World War II. She was launched 28 March 1944 under a Maritime Commission contract by the Consolidated Steel Corporation, Wilmington, California; sponsored... SS is one of only two surviving Liberty ships. ... U.S. Navy submarine USS Greeneville in dry dock following collision with a fishing boat. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ... Year 1946 (MCMXLVI) was a common year starting on Tuesday (link will display full 1946 calendar) of the Gregorian calendar. ... is the 182nd day of the year (183rd in leap years) in the Gregorian calendar. ... is the 206th day of the year (207th in leap years) in the Gregorian calendar. ... An early stage in the Trinity fireball. ... The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (11 mi, 60,000 ft) into the air from the hypocenter. ...

General information

The series was to study the effects of nuclear weapons on ships, equipment, and material. A fleet of more than 90 vessels was assembled in Bikini Lagoon as a target. This target fleet consisted of older U.S. capital ships, three surrendered German and Japanese ships, surplus U.S. cruisers, destroyers and submarines, and a large number of auxiliary and amphibious vessels. Military equipment was arrayed on some of the ships as well as amphibious craft that were berthed on Bikini Island. Technical experiments were also conducted to study nuclear weapon explosion phenomena. Some experiments included the use of live animals. Bikini is the eastnorthernmost and biggest island of Bikini Atoll in the Oceanian island nation of the Marshall Islands. ...

The 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) of Joint Task Force 1 (JTF 1), the organization that conducted the tests. Additional personnel were located on nearby atolls such as Eniwetok and Kwajalein. The islands of the Bikini Atoll were used primarily as recreation and instrumentation sites. Enewetak (or Eniwetok) is an atoll in the Marshall Islands of the central Pacific Ocean. ... Kwajalein Atoll - NASA NLT Landsat 7 (Visible Color) Satellite Image Kwajalein Atoll (Marshallese: Kuwajleen) is part of the Republic of the Marshall Islands (RMI). ... This article or section does not cite its references or sources. ...

Before the first test, all personnel were evacuated from the target fleet and Bikini Atoll. These men were placed on units of the support fleet, which sortied from Bikini Lagoon and took safe positions at least 10 nautical miles (18.5 km) east of the atoll.

In the ABLE test, the weapon was dropped from the B-29 Superfortress Dave's Dream (formerly Big Stink of the 509th Composite Group) and burst over the target fleet. In BAKER, the weapon was suspended beneath landing craft LSM-60 anchored in the midst of the target fleet. BAKER was detonated 90 feet (27 m) underwater. The Boeing B-29 Superfortress was a four-engine heavy bomber propeller aircraft flown by the United States Army Air Forces in World War II and other military organizations afterwards. ... Big Stink was the name of a B-29 Superfortress (B-29-40-MO 44-27354, victor number 90) participating in the atomic bomb attack on Nagasaki on August 9, 1945. ... The 509th Composite Group was an air combat unit of the United States Army Air Forces during the Second World War and as the 509th Operations Group, is a current unit of the United States Air Force. ... LSM-60 with modifications for the Baker Test, Bikini Atoll LSM-60 was a World War II era landing ship, medium (LSM) amphibious assault ship of the US Navy. ...

ABLE operations went smoothly except that the test weapon was dropped between 1,500 and 2,000 feet (450 and 600 m) off target. The miss resulted in a government investigation of the flight crew of the B-29 bomber. Eventually, it was generally agreed that the bomb itself had a flaw in the tail stabilizer, causing the miss, and the flight crew was cleared of any suspicion.

The radioactivity created by the burst had only a transient effect, and within a day nearly all the surviving target ships had been safely reboarded. The ship inspections, instrument recoveries, and remooring necessary for the BAKER test proceeded on schedule. Five ships were sunk as a result of the test.

The crews of the target ships that had been remanned following ABLE were evacuated before BAKER to the support fleet east of the atoll. BAKER sank eight ships and damaged more ships than ABLE. The detonation caused most of the target fleet to be bathed in radioactive water spray and radioactive debris from the lagoon bottom. With the exception of 12 target vessels anchored in the array and the landing craft beached on Bikini Island, the target fleet remained too radiologically contaminated for several weeks for more than brief on-board activities. The radiation warning symbol (trefoil). ...

CHARLIE was to explode deep under the surface, and indeed the test intended for CHARLIE was later carried out in Operation Wigwam. CHARLIE would have tested the effects of using nuclear weapons as depth charges. However, after the problems with contamination from BAKER, the CHARLIE shot was subsequently cancelled. Wigwam underwater burst Operation Wigwam involved a single test of the Mk-90 Betty nuclear depth bomb. ...

The inability to complete inspections on much of the target fleet threatened the success of the operation after BAKER. A program of target vessel decontamination was begun in earnest about 1 August. This involved washing the ships' exteriors using work crews drawn from the target ships' companies under radiological supervision of monitors equipped with radiation detection and measurement devices. Initially, decontamination was slow as the safe time aboard the target ships was measured only in minutes. As time progressed, the support fleet itself had become contaminated by the low-level radioactivity in marine growth on the ships' hulls and seawater piping systems. is the 213th day of the year (214th in leap years) in the Gregorian calendar. ...

By 10 August, a decision was made to stop work in Bikini and tow the surviving target fleet to Kwajalein Atoll where the work could be done in uncontaminated water. The move was accomplished during the remainder of August and September. A major task at Kwajalein was to offload ammunition stored aboard the target ships. This work continued into the fall of 1946. Personnel continued to work on target ships at Kwajalein into 1947. is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ... Year 1946 (MCMXLVI) was a common year starting on Tuesday (link will display full 1946 calendar) of the Gregorian calendar. ... 1947 (MCMXLVII) was a common year starting on Wednesday (the link is to a full 1947 calendar). ...

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. The remaining target ships were destroyed by sinking off Bikini Atoll, off Kwajalein Atoll, or near the Hawaiian Islands during 1946-1948.

The support ships were decontaminated as necessary and received a radiological clearance before they could return to the fleet. This decontamination and clearance process required a great deal of experimentation and learning at Navy shipyards in the United States, primarily at San Francisco, California. Nickname: Location of the City and County of San Francisco, California Coordinates: , Country United States of America State California City-County San Francisco Government - Mayor Gavin Newsom Area - City 47 sq mi (122 kmÂ²) - Land 46. ...

Finally, a formal resurvey of Bikini Atoll was conducted in the summer of 1947 to study long-term effects of the CROSSROADS tests. 1947 (MCMXLVII) was a common year starting on Wednesday (the link is to a full 1947 calendar). ...

All CROSSROADS operations were undertaken under radiological supervision intended to keep personnel from being exposed to more than 0.1 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. The röntgen or roentgen (symbol R) is a unit of exposure to ionising radiation (X or gamma rays), and is named after the physicist Wilhelm Röntgen. ...

Radiological supervision included predicting areas of possible danger, providing trained personnel equipped with radiation survey instruments to act as guides during operations involving potential exposure, and elaboration of rules and regulations governing conduct in these operations. Personnel were removed for one or more days from areas and activities of possible exposure if their badges showed more than 0.1 R / day exposure.

About 15 percent of the JTF 1 personnel was issued at least one of the 18,875 film-badge dosimeters during CROSSROADS. Approximately 6,596 personnel were on the islands or ships that had no potential for radiation exposure. Personnel anticipated to be at the greatest radiological risk were badged, and a percentage of each group working in less contaminated areas was badged. The maximum accumulated exposure recorded was 3.72 R, received by a radiation safety monitor.

Lacking complete radiation exposure data, reconstructions have been made of all personnel exposures for unbadged crewmembers of the ships involved. These calculations have considered the several sources of radiation at work in Bikini, such as the low-level contamination in the lagoon water, living aboard support ships, and boarding the contaminated target ships. The calculations relied upon radiation measurements recorded by radiation safety personnel in 1946. This data was used in a computer model that includes such factors as the radiation-shielding properties of ships' hulls and realistic patterns of daily personnel activity on weather decks and below. The actual movements of each ship were then used to reconstruct a dose for the crew. Calculated exposures range from 0 to 2.5 rem (25 mSv) (gamma) for support ships. Exposures for target ship crews that reboarded their ships after BAKER were higher than those for support ship crews. A summary of film badge readings (in roentgens) for July and August, when the largest number of personnel was involved, is listed below: The Röntgen equivalent man or rem (symbol rem) is an obsolete unit of radiation dose. ... The röntgen or roentgen (symbol R) is a unit of exposure to ionising radiation (X or gamma rays), and is named after the physicist Wilhelm Röntgen. ...

Actual film badge readings (R gamma)

Ships sunk during test Able, 1 July 1946

Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Sakawa was an Agano class light cruiser that served with the Imperial Japanese Navy during World War II. Because it never entered combat, the Sagawa is most often remembered as a target ship during Operation Crossroads, the American nuclear weapon tests of 1946. ... The Imperial Japanese Navy (IJN) (: å¤§æ—¥æœ¬å¸åœ‹æµ·è» Shinjitai: å¤§æ—¥æœ¬å¸å›½æµ·è» or æ—¥æœ¬æµ·è» Nippon Kaigun), officially Navy of Empire of Greater Japan, also known as the Japanese Navy or Combined Fleet was the Navy of Empire of Japan from 1869 until 1947, when it was dissolved following Japans constitutional renunciation of the use of force... USS Port Royal (CG-73), a Ticonderoga-class guided missile cruiser (really an uprated guided missile destroyer), launched in 1992. ... USS Anderson (DD-411) was a Sims-class destroyer in the United States Navy. ... The third USS Lamson (DD-367) was a Mahan-class destroyer in the United States Navy during World War II. She was named for Roswell Hawkes Lamson. ... USS Carlisle (APA-69) was US Navy ship that served during World War II and was sunk as a target during Operation Crossroads in 1 July 1946. ... USS Gilliam (APA-57), named for a county in Oregon, was the lead ship in the Gilliam class of attack transports serving in the United States Navy during World War II. She was launched 28 March 1944 under a Maritime Commission contract by the Consolidated Steel Corporation, Wilmington, California; sponsored...

Sunk during test Baker, 25 July 1946

The ex-German heavy cruiser Prinz Eugen 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 capsized on 22 December 1946. Nagato (Japanese: é•·é–€, named after Nagato province) was a battleship of the Imperial Japanese Navy, the lead ship of her class. ... The firepower of a battleship demonstrated by USS Iowa A battleship is a large, heavily-armored warship with a main battery consisting of the largest caliber of guns. ... USS Arkansas (BB-33), a Wyoming-class battleship was the third ship of the United States Navy named in honor of the 25th state. ... The fifth USS Saratoga (CV-3) was the second aircraft carrier of the United States Navy. ... USS Apogon (SS-308), a Balao-class submarine, was a ship of the United States Navy named for the apogon, a group of large-headed salt water fishes with oblong compressed bodies found in tropical or subtropical waters. ... USS Pilotfish (SS-386), a Balao-class submarine, was a ship of the United States Navy named for the pilotfish, a carangoid fish, often seen in warm latitudes in company with sharks. ... LSM-60 with modifications for the Baker Test, Bikini Atoll LSM-60 was a World War II era landing ship, medium (LSM) amphibious assault ship of the US Navy. ... The term heavy cruiser is used to refer to large cruisers, a form of warship. ... The German cruiser Prinz Eugen (pron. ... Infantry inspect a hole in the devasted Kwajalein Atoll Kwajalein Atoll is part of the Republic of the Marshall Islands (RMI), 2,100 nautical miles (3900 km) southwest of Honolulu, Hawaii, at 8. ... December 22 is the 356th day of the year (357th in leap years) in the Gregorian calendar. ... Year 1946 (MCMXLVI) was a common year starting on Tuesday (link will display full 1946 calendar) of the Gregorian calendar. ...

Crossroads Baker in Popular Culture

The name "Bikini" was adopted for bikini swimwear on the theory that both caused a burst of excitement. bikini briefs, from Roman London. ...

The 1987 film "Radio Bikini" was nominated for the Best Documentary Oscar. Directed by Robert Stone (no relation to Oliver Stone), it recounts the story of Operation Crossroads, concentrating on how it affected the Bikini islanders (they were deported en masse to Rongerik Atoll) and the servicemen who took part in the operation. The film almost exclusively uses archival footage, much of it in colour. Rongerik Atoll - NASA NLT Landsat 7 (Visible Color) Satellite Image Map of Rongerik Atoll, taken from the 1893 map Schutzgebiet der Marshall Inseln, published in 1897. ...

Video of the Crossroads Baker explosion is among the most often shown video of a nuclear explosion, and exists in many sources. Bruce Conner compiled footage of the explosions to create his film Crossroads (1976). The front angle of the explosion, which generally shows the rising condensation layer before exposing the stem of the mushroom cloud, was used in the music video for Michael Jackson's song "Man in the Mirror". The aerial shot was among many in the final montage in the 1964 film Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb, and was also used in an episode of the American TV sitcom Family Matters where Steve Urkel accidentally blew up Chicago with an atomic bomb in a dream sequence. It was also featured in the 1999 film Deterrence, even though it is supposed to depict a nuclear explosion over Baghdad, Iraq. In addition, it featured alongside footage of the Nagasaki detonation in the video game Metal Gear Solid, during a cut scene that dealt with the Manhattan Project and the history of nuclear weaponry. Also in the cartoon SpongeBob SquarePants episode Dying for Pie when the exploding pie hits Squidward caused an explosion which showed a clip of Operation Crossroads. Bruce Conner is a key experimental filmmaker and assemblage artist. ... Michael Joseph Jackson (August 29, 1958), commonly known as MJ as well as the King of Pop, is an American musician, entertainer, and pop icon whose successful career and controversial personal life have been a part of pop culture for the last three decades. ... Man in the Mirror was a number-one hit for singer Michael Jackson when released as a single in the spring of 1988. ... 1964 (MCMLXIV) was a leap year starting on Wednesday (the link is to a full 1964 calendar). ... For the hit 1987 single by Depeche Mode, see the album Music for the Masses Film poster for Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb is a 1964 satirical film directed by Stanley Kubrick. ... Family Matters is an American sitcom about a middle-class, African-American family living in Chicago. ... Steven Quincy Urkel (born 1976), better known as Steve Urkel (portrayed by Jaleel White) was the breakout character on the 1990s sitcom Family Matters. ... Nickname: Motto: Urbs In Horto (Latin: City in a Garden), I Will Location in the Chicago metro area and Illinois Coordinates: , Country United States State Illinois County Cook & DuPage Settled 1770s Incorporated March 4, 1837 Government - Mayor Richard M. Daley (D) Area - City 234. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... Deterrence is a low-budget 1999 movie by director Rod Lurie depicting fictional events about nuclear brinksmanship. ... Baghdad (Arabic: ) is the capital of Iraq and of Baghdad Governorate. ... This article is about the original Metal Gear Solid released for the PlayStation. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... Production Order Dying for Pie is a SpongeBob SquarePants episode from season two. ... Squidward Tentacles Squidward Johannsen Tentacles is a fictional character in the animated cartoon television show SpongeBob SquarePants. ...

Contents

General information

Actual film badge readings (R gamma)

Ships sunk during test Able, 1 July 1946

Sunk during test Baker, 25 July 1946

Crossroads Baker in Popular Culture

See also

External links