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The Tsar Bomb - 1961
Tsar assembly video
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On October 30, 1961, the most powerful weapon ever constructed by mankind was exploded over the island of Novaya Zemlya in the Arctic Sea. The device (code name Ivan or Vanya) also known by its alphanumerical designation 'AN602', was a multi-stage thermonuclear bomb built in only sixteen weeks by engineers in the USSR at the order of Soviet Premier Nikita Khrushchev.
Soviet physicist Andrei Sakharov oversaw the project at Arzamas-16, while the main work of design was by Sakharov, Viktor Adamsky, Yuri Babayev, Yuri Smirnov and Yuri Trutnev.
Origin and Development
It was intended as a display of Soviet superiority during a period of grave tension between the USSR and the United States. The Russians had erected the Berlin Wall only two months earlier. Before this, the largest explosion the world had seen was the 15 megaton shot Bravo during Operation Castle in February 1954.The Tsar's explosion was over three times more powerful than this, despite the fact that the device was deliberately prevented from operating to its full potential.
A de facto moratorium had existed between the US, USSR and UK since the last US and Soviet test series in 1958, talks regarding limitations of testing had been ongoing for two years. The 1961 test series of which Tsar was a part, was initiated by Premier Nikita Khrushchev, known for his political/nuclear brinkmanship. Khrushchev called a meeting with his atomic scientists on the 10th July 1961 simply declaring that testing would resume in the fall to 'show the imperialists what we could do'.
Facing the tight schedule, bomb assembly began even during design development. The fabrication was rushed, many calculations were skipped, and last minute modifications to the design were made. Since preparation of the original 100 megaton bomb design only began after the 10th of July meeting at which Khrushchev had ordered the test series be held, only 112 days elapsed from initial concept to detonation, and incredibly short period of time. For comparison, in the US a device would often spend up to two years being developed before testing, not 16 weeks.
The extremely short schedule for designing and building the device, in conjunction with typical Soviet price of failure led the scientists to use a conservative design using existing tools, processes, and techniques. It's thought that the tertiary stage of final design utilized an array of multiple thermonuclear fuel capsules instead of just one huge one. Some evidence supports this theory - the bulbous shape of the bomb casing that would be required for a radial arrangement of capsules. The circular cluster of cylinders visible through the rear access panel shown in the assembly video.
The completed weapon weighed 27 metric tons, and though it was technically 'aircraft-deliverable', it was too large to fit inside the bomb bay of the largest Soviet bomber of that era, the Tu-95. Consequently the plane was specially modified, including the removal of the bomb bay doors to allow the bomb to protrude from the plane, and a coating of a special reflective paint to minimize the damage from the massive thermal pulse. It was also retarded by a huge 1,645 square meter parachute to give the bomber crew a fighting chance of escaping to a safe distance.
The bomb was assembled in a dedicated workshop, and taken by train to the airfield where it was loaded directly into the delivery aircraft.
The Test
At 08:33 GMT 30/10/1961, the weapon was dropped by a modified Tu-95V bomber from an altitude of 10,500 meters over the Mityushikha Bay Nuclear Testing Range at Novaya Zemlya. The bomber was piloted by mission commander Major Andrei E. Durnovtsev, who was immediately promoted to lieutenant colonel and made Hero of the Soviet Union. The weapon's on-board barometric sensors detonated the bomb at approximately 3,900 meters.
One second after detonation, the fireball was over 6.5 kilometers wide. Despite the high altitude of the test, the fireball swelled down to the surface almost licking the ground. The mushroom cloud that followed the blast stretched sixty kilometers into the sky, reaching a diameter of about forty kilometers.
Initial fireball video
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Despite the very substantial burst height the vast fireball reached down to the ground, and swelled upward to nearly the height of the release plane. The blast pressure below the burst point was 300 PSI. In clear air, the explosion was capable of inflicting third degree burns at a distance of up to 100 km.
Rather than the fireball engulfing the ground around ground zero, the shock wave reached the ground before the fireball and bounced upward. Striking the bottom of the the fireball, flattening it and driving it upward preventing contact with the ground.
One cameraman recalled:
"The clouds beneath the aircraft and in the distance were lit up by the powerful flash. The sea of light spread under the hatch and even clouds began to glow and became transparent. At that moment, our aircraft emerged from between two cloud layers and down below in the gap a huge bright orange ball was emerging. The ball was powerful and arrogant like Jupiter. Slowly and silently it crept upwards.... Having broken through the thick layer of clouds it kept growing. It seemed to suck the whole earth into it. The spectacle was fantastic, unreal, supernatural..."
Despite cloudy skies, the flash of light was clearly visible 2,500 kilometers away. The shockwave destroyed buildings and tore roofs off of homes hundreds of kilometers from ground zero. Windows in Norway and Finland were shattered. The scientific settlement on the Matochkin Strait called Severney, some 56 kilometers south of the explosion, was devastated. The thermal pulse of the blast was felt 800 kilometers from the epicenter. Radio communications were knocked out for an hour and no word of the safety of the Tu-95 and its crew could be reported for some time. Blast data and footage were recorded by a Soviet Tu-16.
In preparation for estimating of the bomb's yield, a crash program code-named 'Speedlight' was initiated. A US KC-135 Stratotanker had been modified to carry broadband electromagnetic and special optical equipment including a high-speed photometer known as a 'bhangmeter'. Speedlight was able to get close to the detonation point; close enough that the fuselage suffered thermal damage.
The data it captured was analyzed by the Foreign Weapons Evaluation Panel which assigned the yield estimate of 57 Mt rather than 50 Mt. The test was intended to be a spectacular demonstration of awesome might of the Soviet Union, the Soviets had no reason to provide a more accurate, but lower, yield. The higher inaccurate yield of 57 Mt is still seen quoted to this day.
Aftermath
Some time after the explosion, a Soviet team was dispatched to ground zero to take photographs.
One witness reported:
"The ground surface of the island has been levelled, swept and licked so that it looks like a skating rink. The same goes for rocks. The snow has melted and their sides and edges are shiny. There is not a trace of unevenness in the ground. Everything in this area has been swept clean, scoured, melted and blown away."
Analysis of the explosion showed that complete destruction extended to a radius of 25km surrounding the blast, and severe damage as far as 35km away.
This three stage weapon was actually a 100 megaton bomb design, but the uranium tamper of the other stages was replaced with lead. This reduced the yield by 50% by eliminating the fast fissioning of the uranium tamper by high energy neutrons produced by the fusion reactions. This eliminated most of the fallout, yet still proved the full yield design. The result was the 'cleanest' weapon ever tested with 97% of the energy coming from fusion reactions. Even at the decreased yield, it was approximately 4,000 times more powerful than the bomb that destroyed Hiroshima.
The truth was that even at half strength, Tsar was so powerful that it was essentially impractical. Much of the explosion's energy radiated upwards into space, and that which didn't was so excessive that using the device on any populated target world would have resulted in adverse effects on Russian interests. The slow Tu-95 would have made an easy target for Western interceptor aircraft and air defences. The first Soviet intercontinental ballistic missile (ICBM) the R-7 Semyorka became operational three years earlier, making weapons delivered by aircraft obsolete for strategic roles.
Naturally, the United States was outraged, and responded by rattling its nuclear saber in return. The U.S. soon followed suit with an extensive series of nuclear weapons tests during Operation Nougat in September 1961.
Panoramic view of ground zero after the explosion
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