Vostok program (Russian: Восто́к, East) Soviet Union's manned space flight program. Mankind went into space for the first time on a Vostok 1 flight. Vostok was a secret word until it was revealed to the press. The Vostok spacecraft was developed from the Zenit spy satellite, and the Vostok rockets based on the R-7 intercontinental ballistic missile by chief engineer Sergey Korolyov and design bureau OKB-1.