Operation Plumbbob

August 31, 1957 – Plumbbob’s “Smoky” Leaves a Troubled Legacy

On August 31, 1957, Operation Plumbob’s “Smoky” test flamed into the sky over busy Yucca Flat, 65 miles north of Las Vegas.  Area 8 of the Nevada Test Site played host that day to the third test of the UCRL TX-41 –  a three-stage, thermonuclear weapon design.  After two previous tests of 3.5 and 5.0 megatons (Redwing Zuni and Tewa), “Smoky” was probably a partial, two-stage test with a decreased yield of 45-50 kilotons.  The MK-41 nuclear device eventually developed from the TX-41 test series became the largest-yield nuclear weapon ever developed or deployed by the United States.  Its yield of 25 megatons was also the highest yield-to-weight ratio for a US nuclear weapon, at about 6 kilotons per kilogram.

Smoky became famous – notorious, even – for its tragic consequences.   Over three thousand servicemen had been in the vicinity of ground zero shortly after the blast, practicing maneuvers as part of the Desert Rock exercise.  Their exposure to radiation from the test eventually became the subject of a Congressional investigation and epidemiological evaluation.  A 1980 study found statistically significant increases in leukemia cases among the 3224 participants.  Instead of the expected four cases, ten were found.

July 19, 1957 – First Genie Nuclear Rocket Test at Yucca Flat

John Operation Plumbbob

On July 19, 1957, the Nevada Testing Site (NTS) hosted the first test-firing of the AIR-2 Genie air-to-air rocket.  Part of Operation Plumbbob, the “John” test over Yucca Flat involved the successful launch and detonation of the nuclear-warhead-tipped rocket from a Northrup F-89J fighter without demolishing the aircraft itself.  The AIR-2 Genie was designed to destroy incoming enemy bombers with its 1.7-kiloton, plutonium core Genie W-25 warhead.  The rocket traveled 4240 meters in 4.2 seconds, achieving about Mach 3, before detonating approximately three miles over five volunteers and a photographer at ground zero in Yucca Flat’s Area 10.  Their presence at the test site was intended to show the apparent safety of battlefield nuclear weapons to personnel on the ground.

Image Credit: U.S. Air Force