Vostok-K

The Vostok-K, with the GRAU index 8K72K, was an expendable carrier rocket used by the Soviet Union for thirteen launches between 1960 and 1964, six of them crewed. It carried several changes to the core and strap-ons to make it safe for crews, and its Blok E stage had the improved RD-0109 engine to correct some deficiencies of the RD-0105 used on earlier 8K78 rockets. The Vostok-K flew first on 22 December 1960, when the third stage engine failed and a Korabl-Sputnik spacecraft did not reach orbit. On 12 April 1961 a Vostok-K launched Vostok 1, the first human spaceflight, with Yuri Gagarin aboard, and all six crewed Vostok missions used this rocket. It also launched the first two Zenit reconnaissance satellites and four Elektron scientific satellites in 1964.