On November 1, 1952, U.S. military scientists demonstrated the first human hydrogen bomb in the Marshall Islands, a test site about 9,000 kilometers from the United States. Ivy Mike, as the hydrogen bomb was commonly called, was an explosive force of about 10.4 megatons of TNT explosive, about 700 times the explosive power of the atomic bomb dropped on Hiroshima at 8:15 a.m. on August 6, 1945, which exploded and killed about 160,000 people. Ivy Mike set a record for the largest explosion in history, making it the fourth largest nuclear test conducted by the United States in the 20th century.
The Ivy Mike test was designed based on the principles of the thermonuclear device that had first been tested at the George test about a year earlier. Using a Nagasaki-type implosion device, a secondary bomb was detonated from a cylindrical tank about 30 centimeters thick filled with deuterium, a stable isotope of hydrogen, the cooling liquid. The trigger used the principle of nuclear fission, and the secondary energy drew its energy from nuclear fusion. This is the same reaction that provides energy to the sun. Significantly different from the atomic bomb, the new hydrogen bomb is a destructive super-bomb. Not only does it split an atom in two, but it also fuses hydrogen atoms together to form a third atom. Ivy Mike is a sausage-shaped object that weighs about 82 tons, stands about 6 meters tall, and has a diameter of about 2 meters.
The detonation of the hydrogen bomb created a boiling mushroom cloud in the stratosphere that was up to 50 kilometers long and over 100 kilometers wide. Scientists observed the explosion from a boat at a distance of 50 kilometers. They underestimated the explosive power and saw the cloud just above their heads and felt the irradiated coral remnants raining down on them. It produced a fireball of about 150 million degrees, about 4.8 kilometers in diameter and many times stronger than the sun. El Gelab Island, where Ivy Mike was placed, was completely obliterated, with only a crater about 50 meters deep remaining. The fallout was blown into the Pacific Ocean and the neighboring Marshall Islands.
Many other hydrogen bomb tests followed from Ivy Mike. A nuclear weapon capable of detonating the five that were constructed was produced in January 1954. These weaponized versions were tested during Operation Castle, a series of hydrogen-based bomb tests in March of the same year, New Castle Bravo, which unleashed about 15 megatons, about two and a half times as much as Ivy Mike, making it the largest nuclear test in the United States. The radioactive fallout contaminated populated islands and Japan's Daigo Fukuryu Maru, making it the worst radiological incident in the history of American nuclear testing. If the fireball and radioactivity from the hydrogen bomb radiate into the atmosphere, just as the dinosaurs became extinct some 66 million years ago, humanity, with the earth surrounded by radiation, will enjoy a similar fate.
