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 The Pacific Proving Grounds was the name given by the United States government to a number of sites in the Marshall Islands and a few other sites in the Pacific Ocean at which it conducted nuclear testing between 1946 and 1962. The U.S. tested ...

, on islands of the

Enewetak Atoll Enewetak Atoll (; also spelled Eniwetok Atoll or sometimes Eniewetok; mh, Ānewetak, , or , ; known to the Japanese as Brown Atoll or Brown Island; ja, ブラウン環礁) is a large coral atoll of 40 islands in the Pacific Ocean and with it ...

, all of the devices were mounted in large steel towers, to simulate air bursts. This series of nuclear weapons tests was preceded by Operation Ranger and succeeded by Operation Buster-Jangle. Operation Greenhouse showcased 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, houses 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 In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanar with the circle. If the axis of revolution does not ...

, the ''George'' device had a small amount of heavy

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass number ...

s of

liquid hydrogen Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully l ...

(

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...

and

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus ...

) 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" nuclear 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

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behav ...

s - ones that sparked more fissions in the

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly ...

nuclei that were present, and which also caused fission in

uranium-238 Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However ...

- which does not fission under bombardment with slow neutrons, as does

uranium-235 Uranium-235 (235U or U-235) is an Isotopes of uranium, isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile ...

. 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 Klaus Emil Julius Fuchs (29 December 1911 – 28 January 1988) was a German theoretical physicist and atomic spy who supplied information from the American, British and Canadian Manhattan Project to the Soviet Union during and shortly a ...

and von Neumann in 1946. Its success played a vital role in the history of the Teller–Ulam design. The George Test had a perfect “bell” Wilson cloud formed near the top of the mushroom cloud. The ''George'' test validated the principles which would be used for the first full-scale thermonuclear bomb test, ''

Ivy Mike Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab ...

'', one year later, on November 1, 1952, at

Item

Conducted on May 25, 1951, '' Item'' was the first test of an actual boosted fission weapon, nearly doubling the normal yield of a similar non-boosted weapon. In this test, deuterium-tritium (D-T) gas was injected into the enriched uranium core of a nuclear fission bomb. The extreme heat of the fissioning bomb produced thermonuclear fusion reactions within the D-T gas. While not enough to be considered a full nuclear fusion bomb, the large number of high-energy neutrons released nearly doubled the efficiency of the nuclear fission reaction.

Dog

The ''Dog'' explosion is more 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. 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. Cynthia Miller claims that her father, Van Dine, is the first man on the left in the photo. The

blast wave In fluid dynamics, a blast wave is the increased pressure and flow resulting from the deposition of a large amount of energy in a small, very localised volume. The flow field can be approximated as a lead shock wave, followed by a self-similar sub ...

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.

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* * {{Authority control Explosions in 1951

Greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...

1951 in military history 1950s in the Marshall Islands 1951 in the Trust Territory of the Pacific Islands 1951 in the environment 1951 in science April 1951 events in Oceania May 1951 events in Oceania Articles containing video clips

Item

Dog

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