Saturday, October 14, 2006

The Tsar Bomb

Tsar Bomba (Russian: Царь-бомба, literally "Emperor-bomb") is the Western name for the largest, most powerful nuclear explosive ever detonated. Developed by the Soviet Union, the ~50 megaton bomb was codenamed Ivan (Russian: Иван) by its developers.

The bomb was tested on October 30, 1961 in Novaya Zemlya, an island in the Arctic Sea. The device was scaled down from its original design of 100 megatons to minimize nuclear fallout.

Codenamed "Ivan" during its development, the Tsar Bomba was not intended for use in warfare, but should be seen as an instance of the Cold War-era saber-rattling indulged in by the USSR and the USA.

The Tsar Bomba was a multi-stage hydrogen bomb with a yield of about 50 megatons (Mt). The initial three-stage (fission-fusion-fission) design was capable of approximately 100 Mt, but at a cost of much radioactive fallout. To limit fallout, the third stage, consisting of a uranium 238 fission tamper (which greatly amplifies the reaction by fissioning uranium atoms with fast neutrons from the fusion reaction), was replaced with one made of lead. This eliminated fast fission by the fusion-stage neutrons, so that approximately 97% of the total energy resulted from the fusion stage alone (as such, it was ironically one of the "cleanest" bombs ever created, generating a very low amount of fallout in respect to its yield). There was a strong incentive for this feature regression, as most of the fallout from a test of the bomb would fall on Soviet territory.

The components were designed by a team of physicists, headed by Academician Julii Borisovich Khariton, which included Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev. Shortly after the Tsar Bomba was detonated, Sakharov began speaking out against nuclear weapons, which culminated in him becoming a full-blown dissident (see his Memoirs).

The Tsar Bomba was flown to its test site by a specially modified Tu-95 release plane which took off from an airfield in the Kola peninsula, flown by Major Andrei E. Durnotsev. The release plane was accompanied by a Tu-16 observer plane which took air samples and filmed the test; hence the movie stills that illustrate this and other articles about the test. Both aircraft were painted with a special reflective white paint to limit the heat damage from the test.

The bomb, weighing 27 tonnes, was so large (8 metres long by 2 metres in diameter) that the Tu-95 had to have its bomb bay doors and wing fuel tanks removed. The bomb was attached to an 800 kg fall retardation parachute, which gave the release and observer planes time to fly about 45 km from ground zero. Failing such retardation, the bomb would have either reached its planned detonation altitude soon enough to turn the test into a suicide mission, or crashed into the ground at high speed, with unpredictable results. The USA has fitted a few of its nuclear bombs with parachute retardation for the same reason. An apocryphal story has it that the fabrication of this parachute required so much raw nylon that the small Soviet nylon hosiery industry was noticeably disrupted.

The Tsar Bomba detonated at 11:32 a.m., located approximately at 73.85° N 54.50° E , over the Mityushikha Bay nuclear testing range (Sukhoy Nos Zone C), north of the Arctic Circle on Novaya Zemlya Island in the Arctic Sea. The bomb was dropped from an altitude of 10,500 metres, and designed to detonate at a height of 4,000 m over the land surface (4,200 m over sea level) by barometric sensors.

The original USA estimate of the yield was 57 Mt, but since 1991 all Russian sources have stated its yield as "only" 50 Mt. Nonetheless, Khrushchev warned in a filmed speech to the Communist parliament of the existence of a 100 Mt bomb. The fireball touched the ground, reached nearly as high as the altitude of the release plane, and was seen 1,000 km away. The heat could have caused third degree burns at a distance of 100 km. The subsequent mushroom cloud was about 60 km high and 30–40 km wide. The explosion could be seen and felt in Finland, even breaking windows there.[citation needed] Atmospheric focusing caused blast damage up to 1,000 km away. The seismic shock created by the detonation was measurable even on its third passage around the earth.

Since 50 Mt is 2.1×1017 joules, the average power produced during the entire fission-fusion process, lasting around 3.9×10-8 seconds or 39 nanoseconds, was a power of about 5.3×1024 watts or 5.3 yottawatts. This is equivalent to approximately 1% of the energy output of the Sun during the same fraction of a second. The detonation of Tsar Bomba therefore qualifies, even to this day, as being the single most powerful device ever utilized throughout the history of humanity. By contrast, the largest weapon ever produced by the United States, the now-decommissioned B41, had a predicted maximum yield of 25 Mt, and the largest nuclear device ever tested by the USA (Castle Bravo) yielded 15 Mt. Note the recent comparison with asteroid impacts which may have formed the Chicxulub Crater and the Wilkes Land crater, both larger events by some six orders of magnitude.

Although powerful, the Tsar Bomba was too powerful to be used in wartimes. The weight of the weapon is also too heavy for any of the Soviet bomber to flew it to its destination without getting shot down. As the footage suggested, the bomb is nearly one quarter the length of the carrier. So, in te end, the bomb was deemed too impractical to be used against any nation. Here, a clip showing nuclear weapon tests.


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