1963 October 24 - Launch Vehicle: R-9. Silo explosion kills 7 at Baikonur On 24 October 1963 an R-9 was being prepared for launch in a silo at LC-70. Unknown to the 11 man launch crew, an oxygen leak in the fuelling system had raised the oxygen partial pressure in the silo from the 21% maximum allowed to 32%. Whie the crew was descending in a lift to the 8th level of the silo, a spark from an electrical panel created a fire in the explosive atmosphere, killing seven and destroying the silo. This happened on the same day as the Nedelin disaster three years earlier, and became the cosmodrome's 'Black Day'. Forever after no launches were attempted from Baikonur on October 24.