Operation Greenhouse

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Operation Greenhouse
Greenhouse George.jpg
Greenhouse George
Country United States
Test site Ebiriru (Ruby), Enewetak Atoll; Enjebi (Janet), Enewetak Atoll; Runit (Yvonne), Enewetak Atoll
Period 1951
Number of tests 4
Test type tower
Max. yield 225 kilotonnes of TNT (940 TJ)
Previous test series Operation Ranger
Next test series Operation Buster–Jangle

Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons (hydrogen bombs). Conducted at the new Pacific Proving Ground, specifically on islands of the Enewetak Atoll, all of the devices were mounted in large steel towers, to simulate air bursts. This series of nuclear weapons tests were preceded by Operation Ranger and succeeded by Operation Buster-Jangle.

Operation Greenhouse represented new and aggressive designs for nuclear weapons. The main idea was to reduce the size, weight, and most importantly, reduce the amount of fissile material necessary for nuclear weapons, while increasing the destructive power. With the Soviet Union's first nuclear test a year and half earlier, the United States had begun stockpiling the new designs before they were actually proven. Thus the success of Operation Greenhouse was vital before the development of thermonuclear weapons could continue.

A number of target buildings, including bunkers, homes and factories were built on Mujinkarikku Islet to test nuclear weapon effects.


The George explosion was the world's first thermonuclear burn, though it was just a test design, unsuitable for weaponization. Shaped like a torus, the George device had a small amount of heavy isotopes of liquid hydrogen (deuterium and tritium) placed at its center. The vast majority of its yield derived from fission. The energy output from the thermonuclear fusion in this test was insignificant in comparison. The "George" device was more like a "boosted" atomic bomb than a thermonuclear one. The small amount of heavy deuterium and tritium in this test fused, but its role was to generate a strong flurry of fast neutrons - ones that sparked more fissions in the uranium nuclei that were present, and which also caused fission in uranium-238 - which does not fission under bombardment with slow neutrons, as does uranium-235.

The George design was a 'Classical Super' prototype with a binary triggering device using radiation implosion upon a cylinder. The design of the triggering system in this test was based on the one patented by Klaus Fuchs and von Neumann in 1946.[1] Its success played a vital role in the History of the Teller–Ulam design.

The George test validated the principles which would be used for the first full-scale thermonuclear bomb test, Ivy Mike, one year later, on 1 November 1952, at Enewetak Atoll. Item was the first boosted fission weapon, nearly doubling the normal yield of a similar non-boosted weapon.


The Dog explosion is most popularly known for an image taken of those viewing it than the actual explosion itself, the photograph depicts numerous VIPs wearing safety goggles sitting on Adirondack chairs while being illuminated by the flash of the detonation.[2] This photograph takes up the bottom portion of the cover of the 1995 documentary Trinity and beyond by Peter Kuran. The safety goggles worn by all those viewing the test in the picture have become somewhat of a museum collectors item, with a possibility that Norman F. Ramsey may have been present.[3] Cynthia Miller claims that her father, Van Dine, is the first man on the left in the photo.[4] The blast wave safely arrived at the location of the VIPs some 45 seconds after the initially silent flash of the detonation as observed from their position on Parry island.[5]


United States' Greenhouse series tests and detonations
Name [note 1] Date time (UT) Local time zone [note 2][6] Location [note 3] Elevation + height [note 4] Delivery,[note 5]
Purpose [note 6]
Device [note 7] Yield [note 8] Fallout [note 9] References Notes
Dog 7 April 1951 17:33:57.8 MHT (11 hrs)
Runit (Yvonne), Enewetak Atoll 11°33′08″N 162°20′47″E / 11.55234°N 162.34648°E / 11.55234; 162.34648 (Dog) 2 m (6 ft 7 in) + 91 m (299 ft) tower,
weapons development
Mk-6D 81 kt [7][8][9][10][11] Proof test of Mark 6, 60 point implosion. Hansen says "north end of Runit".
Easy 20 April 1951 17:27:00.1 MHT (11 hrs)
Enjebi (Janet), Enewetak Atoll 11°39′56″N 162°14′02″E / 11.66543°N 162.23379°E / 11.66543; 162.23379 (Easy) 2 m (6 ft 7 in) + 91 m (299 ft) tower,
weapon development and effects
TX-5D 47 kt [7][8][9][10][11] Proof test of Mark 5, 92 point lense implosion system, used as the primary for Ivy Mike. Mock buildings (homes, bunkers, factories) were assembled on Enjebi and Mujinkarikku Island. Hansen: "west end of Engebi".
George 8 May 1951 20:30:00.7 MHT (11 hrs)
Ebiriru (Ruby), Enewetak Atoll 11°37′37″N 162°17′47″E / 11.62703°N 162.29626°E / 11.62703; 162.29626 (George) 2 m (6 ft 7 in) + 62 m (203 ft) tower,
weapons development
"Cylinder" 225 kt [7][8][9][10][11] Deuterium core, first thermonuke using cylinder/disk design, but most yield from boosted fission.
Item 24 May 1951 17:16:59.3 MHT (11 hrs)
Enjebi (Janet), Enewetak Atoll 11°39′58″N 162°14′33″E / 11.66604°N 162.24254°E / 11.66604; 162.24254 (Item) 2 m (6 ft 7 in) + 62 m (203 ft) tower,
weapons development
45.5 kt [7][8][10][11] First tritium boosted test.

See also[edit]


  1. ^ "FROM THE HISTORY OF PHYSICS Physics ± Uspekhi 39 (10) 1033 ± 1044 (1996) American and Soviet H-bomb development programmes: historical background. G A Goncharov". 
  2. ^ "VIP observers sitting on the patio of the Officer's Beach Club on Parry Island are illuminated by the 81 kiloton Dog test, part of Operation Greenhouse, at Enewetak Atoll, April 8, 1951.". 
  3. ^ "Atomic Goggles ca. 1950". 
  4. ^ "Operation Greenhouse, Bombs Part 7". 
  5. ^ "GREENHOUSE Defense Technical Information Center". 
  6. ^ "Timezone Historical Database". iana.com. Retrieved 2014-03-08. 
  7. ^ a b c d - DNA 6034F - Operation GREENHOUSE 1951.pdf Operation Greenhouse (DNA-6043F), Washington, DC: Department of Defense, 1951, retrieved 2013-10-26 
  8. ^ a b c d Sublette, Carey, Nuclear Weapons Archive, retrieved 2014-01-06 
  9. ^ a b c Hansen, Chuck (1995), The Swords of Armageddon, Vol. 8, Sunnyvale, CA: Chukelea Publications, ISBN 978-0-9791915-1-0 
  10. ^ a b c d United States Nuclear Tests: July 1945 through September 1992 (DOE/NV-209 REV15), Las Vegas, NV: Department of Energy, Nevada Operations Office, 2000-12-01, retrieved 2013-12-18 
  11. ^ a b c d Yang, Xiaoping; North, Robert; Romney, Carl (August 2000), CMR Nuclear Explosion Database (Revision 3), SMDC Monitoring Research 

External links[edit]