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, 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

Operation Ranger

Operation Ranger was the fourth American nuclear test series. It was conducted in 1951 and was the first series to be carried out at the Nevada Test Site. All the bombs were exploded in the open air, having been dropped by B-50 bombers....

 and succeeded by Operation Buster-Jangle

Operation Buster-Jangle

Operation Buster-Jangle was a series of seven nuclear weapons tests conducted by the United States in late 1951 at the Nevada Test Site. Buster-Jangle was the first joint test program between the DOD and Los Alamos National Laboratories. 6,500 troops were involved in the Desert Rock I, II, and III...

.

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

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

'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

Torus

In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...

, the "George Device" had a small amount of heavy isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s of liquid hydrogen

Liquid hydrogen

Liquid hydrogen 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 pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...

 (deuterium

Deuterium

Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...

 and tritium

Tritium

Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...

) 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" test was actually that of a "boosted" atomic bomb. The small amount of heavy deuterium and tritium in this test fused, but its role was to generate a strong flurry of fast neutron

Neutron

The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...

s - ones that sparked more fission

Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

s in the uranium

Uranium

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

 nuclei that were present, and which also caused fission in uranium-238

Uranium-238

Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...

 - which does not fission under bombardment with slow neutrons, as does uranium-235

Uranium-235

- References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...

.

However, the "George" test validated the principles which would be used for the first full-scale thermonuclear bomb test, Ivy Mike

Ivy Mike

Ivy Mike was the codename given to the first United States test of a thermonuclear weapon, in which a major part of the explosive yield came from nuclear fusion. It was detonated on November 1, 1952 by the United States at on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy...

, one year later, on 1 November 1952, at Eniwetok Atoll. "Greenhouse Item

Greenhouse Item

Greenhouse Item was an American nuclear test conducted on May 25, 1951, as part of Operation Greenhouse at the Pacific Proving Ground, specifically on the island of Engebi in the Eniwetok Atoll in the Central Pacific Ocean. This test explosion was the first test of a boosted fission weapon...

" was the first boosted fission weapon

Boosted fission weapon

A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. The neutrons released by the fusion reactions add to the neutrons released in the fission, as well as inducing the fission reactions...

, nearly doubling the normal yield of a similar non-boosted weapon.

Greenhouse Test Blasts

Test Name	Date	Location	Yield	Note
Dog	8 April 1951	Pacific Proving Ground	70 kilotons
Easy	21 April 1951	Pacific Proving Ground	47 kilotons
George	9 May 1951	Pacific Proving Ground	225 kilotons	First thermonuclear experiment, deuterium core
Item Greenhouse Item Greenhouse Item was an American nuclear test conducted on May 25, 1951, as part of Operation Greenhouse at the Pacific Proving Ground, specifically on the island of Engebi in the Eniwetok Atoll in the Central Pacific Ocean. This test explosion was the first test of a boosted fission weapon...	25 May 1951	Pacific Proving Ground	45.5 kilotons	First bomb with tritium "boosting"

See also

• Trinity and Beyond
  Trinity and Beyond
  Trinity and Beyond: The Atomic Bomb Movie is a 1995 American documentary film directed by Peter Kuran and narrated by William Shatner. Using restored archive footage, the film traces the development of nuclear weapons and their testing, from America's Trinity test of 1945 to the first Chinese...
  
  
• Nuclear Test Film: Operation Greenhouse (1951)

Literature

• Magdi Ragheb: Nuclear, Plasma and Radiation Science – Inventing the future (Web Text), Part I, Chapter 5 (2009): Race for the Super.