Vostok (spacecraft)

Vostok (Восток, translated as "East") was a class of single-pilot crewed spacecraft built by the Soviet Union. The first human spaceflight was accomplished with Vostok 1 on April 12, 1961, by Soviet cosmonaut Yuri Gagarin. The Vostok programme made six crewed spaceflights from 1961 through 1963. This was followed in 1964 and 1965 by two flights of Vostok spacecraft modified for up to three pilots, identified as Voskhod. By the late 1960s, these were replaced with Soyuz spacecraft, which are still used . The Vostok spacecraft was originally designed for use both as a camera platform (for the Soviet Union's first spy satellite program, Zenit) and as a crewed spacecraft. This dual-use design was crucial in gaining Communist Party support for the program. The basic Vostok design has remained in use for some 40 years, gradually adapted for a range of other uncrewed satellites. The descent module design was reused, in heavily modified form, by the Voskhod program. The craft consisted of a spherical descent module (mass 2.46 tonnes, diameter 2.3 meters), which housed the cosmonaut, instruments and escape system, and a biconical instrument module (mass 2.27 tonnes, 2.25 m long, 2.43 m wide), which contained propellant and the engine system. On reentry, the cosmonaut would eject from the craft at about 7,000 m (23,000 ft) and descend via parachute, while the capsule would land separately. The reason for this was that the Vostok descent module made an extremely rough landing that could have left a cosmonaut seriously injured. The ejector seat also served as an escape mechanism in the event of a launch vehicle failure, which at this early phase of the space program was a common occurrence. If an accident occurred in the first 40 seconds after liftoff, the cosmonaut would eject from the spacecraft and parachute to Earth. From 40 to 150 seconds into launch, ground controllers could issue a manual shutdown command to the booster. When the launch vehicle fell to a low enough altitude, the cosmonaut would eject.