Nedelin Catastrophe 1960
At Baikonur Cosmodrome in Kazakhisthan SSR on 24 October 1960, the Soviet Union endured one of its worst secret disasters. During launch preparations for a prototype R-16 ICBM, the second-stage engine accidentally ignited before launch under intense schedule pressure, triggering a chain reaction that detonated first-stage fuel tanks below. Marshal Mitrofan Nedelin, commander of the Strategic Rocket Forces, and dozens of engineers and technicians died in the explosion. Official estimates vary-some sources say 54 dead, others between 60 and 150, with Roscosmos later citing about 126.
The Soviet government kept the tragedy secret for nearly three decades, officially misreporting it as a plane crash. It wasn't until 1989 that the disaster was publicly acknowledged.