How nuclear weapons tests were named

From Trinity in 1945 to Divider in 1992

November 1, 2022

@theBradbury November Opt
A hat with the Divider test logo, from the Bradbury Science Museum’s collection. The logo for Divider features a caricature of the draftsman Larry Smith holding a divider — a common drawing tool.

By Julie Miller, National Security Research Center librarian

Editor’s note: The United States’ last full-scale nuclear weapons test was conducted 30 years ago on Sept. 23, 1992. Divider was a Los Alamos test and took place in Nevada. Over a 47-year period, it was the nation’s 1,054th nuclear test.

What do Galileo, Husky Pup, Turquoise and Barracuda have in common? They’re names of nuclear weapons tests conducted at what is now called the Nevada National Security Site. More than 1,000 U.S. nuclear tests were conducted at various sites between 1945 and 1992, and each of the tests was inaugurated with a name, as documented in Los Alamos National Laboratory’s vast weapons test collections housed in the National Security Research Center

According to publications from the Departments of Defense and Energy and their predecessor organizations, they sponsored weapons tests for 46 years. The purpose of the tests was to advance weapon design, determine weapons effects or to verify weapon safety. Though the overall weapons testing program was collaborative it was ultimately overseen by the president of the United States.

To protect the classified information about nuclear weapons and maintain security, nuclear weapons tests were assigned names. This has been true since Trinity, the first atomic bomb test in 1945. Lab Director J. Robert Oppenheimer later said the test name may have been inspired by his love of poetry. 

Test names

Weapons tests were named differently depending on which government organization sponsored the test. Following World War II, U.S. weapons tests were named in alphabetical order for each operations series, beginning with the Crossroads Able test on July 1, 1946, at Bikini Atoll in the Pacific.

After about 1952, the Able Baker alphabet was no longer used in order to avoid duplicating test names. New names from a variety of inspirations were picked each year, including:

  • famous scientists’ names: Newton, Galileo, Pascal
  • colors: Purple, Chartreuse, Sienna
  • sailing terms: Jib, Mast, Keel
  • birds: Wagtail, Merlin, Tern

Since about 1975, the Department of Defense named its co-sponsored tests using the Code Word, Nickname and Exercise Term system called NICKA, which resulted in names like Diamond Ace and Husky Pup. 

Meanwhile, the Department of Energy did not have a formal naming system — the national laboratories chose names instead. Names within a test series were often categorically related, like New Mexico counties (Socorro, Rio Arriba, De Baca) and fish species (Tuna, Bonefish, Pike).

Logos featuring test names began appearing as stickers, patches and artwork on test towers as early as 1969, although most tests did not have a patch or logo until about 1981. The logo for Divider, for example, features a caricature of the draftsman Larry Smith holding a divider — a common drawing tool.

Looking for more? 

To mark Divider’s 30th anniversary and the Lab’s 47 years of incredible scientific achievement, read “Of Clouds and Craters: The Incredible Story of U.S. Nuclear Weapons Testing,” by Alan Carr, senior historian, National Security Research Center.

Also in this issue: How a moratorium on nuclear testing launched a supercomputing revolution. Read on, and visit the Bradbury Science Museum for more on nuclear weapons, supercomputing and other exciting research happening at the Lab.