model of Vostok spacecraft with 3rd stage of launcher
|Designed by||Sergei Korolev|
|Maiden flight||May 15, 1960|
|Retired||June 19, 1963|
|Status||Last 7 flights cancelled|
|Primary users||Soviet space program|
|Variants||Voskhod spacecraft, Foton|
The Vostok (Russian: Восток, translated as East) was a type of spacecraft built by the Soviet Union. The first human spaceflight in history was accomplished on this spacecraft on April 12, 1961, by Soviet cosmonaut Yuri Gagarin.
The spacecraft was part of the Vostok programme in which six manned spaceflights were made from 1961 to 1963. Two further manned space flights were made in 1964 and 1965 by Voskhod spacecraft, which were modified Vostok spacecraft. By the late 1960s both were superseded by the Soyuz spacecraft, which are still used as of 2013[update].
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 manned 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 forty years, gradually adapted for a range of other unmanned satellites. The descent module design was reused, in heavily-modified form, by the Voskhod programme.
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 conical 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.
There were several models of the Vostok leading up to the manned version:
Vostok 1K 
Vostok 2K 
Photo-reconnaissance and signals intelligence spacecraft. Later named Zenit spy satellite.
Vostok 3KA 
The Vostok 3KA was the spacecraft used for the first human spaceflights. They were launched from Baikonur Cosmodrome using Vostok 8K72K launch vehicles. The first flight of a Vostok 3KA occurred on March 9, 1961. The first flight with a crew -- Vostok 1 carrying Yuri Gagarin—took place on April 12, 1961. The last flight -- Vostok 6 carrying the first woman in space, Valentina Tereshkova—took place on June 16, 1963.
A total of 8 Vostok 3KA spacecraft were flown, 6 of them with a human crew.
Specifications for this version are:
Reentry Module: Vostok SA. SA stands for Spuskaemiy apparat - descent or reentry system. It was nicknamed Sharik (little sphere).
- Crew Size: 1
- Diameter: 2.3 m sphere
- Mass: 2,460 kg
- Heat Shield Mass: 837 kg
- Recovery equipment: 151 kg
- Parachute deploys at 2.5 km altitude
- Crew seat and provisions: 336 kg
- Crew ejects at 7 km altitude
- Ballistic reentry acceleration: 8 g (78 m/s²)
Equipment Module: Vostok PA. PA stands for Priborniy otsek - instrument section.
- Length: 2.25 m
- Diameter: 2.43 m
- Mass: 2,270 kg
- Equipment in pressurized compartment
- RCS Propellants: Cold gas (nitrogen)
- RCS Propellants: 20 kg
- Main Engine (TDU): 397 kg
- Main Engine Thrust: 15.83 kN
- Main Engine Propellants: RFNA/amine
- Main Engine Propellants: 275 kg
- Main Engine Isp: 266 s (2.61 kN·s/kg)
- Main Engine Burn Time: 1 minute (typical retro burn = 42 seconds)
- Spacecraft delta v: 155 m/s
- Electrical System: Batteries
- Electric System: 0.20 average kW
- Electric System: 24.0 kW·h
- Total Mass:4,730 kg
- Endurance: Supplies for 10 days in orbit
- Launch Vehicle: Vostok 8K72K
- Typical orbit: 177 km x 471 km, 64.9 inclinaton
The Vostok capsule had limited thruster capability. As such, the reentry path and orientation could not be controlled after the capsule had separated from the engine system. This meant that the capsule had to be protected from reentry heat on all sides, thus explaining the spherical design (as opposed to Project Mercury's conical design), which allowed for maximum volume while minimizing the external surface. Some control of the capsule reentry orientation was possible by way of positioning of the heavy equipment to offset the vehicle center of gravity, which also maximized the chance of the cosmonaut surviving g-forces while in a horizontal position. Even then, the cosmonaut experienced 8 to 9g.
See also 
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