In 1957, the Mark 17 hydrogen bomb was accidentally dropped by a B-36 nuclear bomber landing at Kirtland Air Force Base near Albuquerque NM. This bomb was part of a research to develop thermonuclear weapons, which rely on nuclear fusion rather than fission. Physicists previously thought that fusion was unattainable, but the Ulam-Teller design made it possible. The Mark 17, the most powerful American nuclear bomb at the time, weighed 21 tons and required specially modified bombers for delivery. The accidental drop resulted in a non-nuclear explosion. The incident remained classified until 1986, and small radioactive remains of the bomb are still found in the area.
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