Complete details of Soyuz

Soyuz Launch Preparation

Throughout history, more than 1,500 launches have been made with Soyuz launchers to orbit satellites for telecommunications, Earth observation, weather and scientific missions, as well as for human flights. 

Image to right: Expedition Four Flight Engineer Dan Bursch has a window seat in a Soyuz, which is docked to the International Space Station. Credit: NASA

The basic Soyuz vehicle is considered a three-stage launcher in Russian terms and is composed of:

• A lower portion consisting of four boosters in the first stage and a central core in the second stage.
• An upper portion, consisting of the third stage, payload adapter and payload fairing.
• Liquid oxygen and kerosene are used as propellants in all three Soyuz stages.

First Stage Boosters

The four boosters of the first stage are assembled laterally around the second stage central core. The boosters are identical and cylindrical-conic in shape with the oxygen tank located in the cone-shaped portion and the kerosene tank in the cylindrical portion. 

An NPO Energomash RD 107 engine with four main chambers and two gimbaled vernier thrusters is used in each booster. The vernier thrusters provide three-axis flight control. 

Ignition of the first stage boosters and the second stage central core occur simultaneously on the ground. When the boosters have completed their powered flight during ascent, they are separated, and the core second stage continues to function. 

First stage booster separation occurs when the predefined velocity is reached, which is about 118 seconds after liftoff. 

Image to left: This diagram shows the three elements of the Soyuz spacecraft. Credit: NASA
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Second Stage

An NPO Energomash RD 108 engine powers the Soyuz second stage. This engine differs from those of the boosters by the presence of four vernier thrusters, which are necessary for three-axis flight control of the launcher after the first stage boosters have separated. 

An equipment bay located atop the second stage operates during the entire flight of the first and second stages. 

Third Stage

The third stage is linked to the Soyuz second stage by a latticework structure. When the second stage's powered flight is complete, the third stage engine is ignited. Separation of the two stages occurs by the direct ignition forces of the third stage engine. A single-turbopump RD 0110 engine from KB KhA powers the Soyuz third stage. 

The third stage engine is fired for about 240 seconds, and cutoff occurs when the calculated velocity increment is reached. After cutoff and separation, the third stage performs an avoidance maneuver by opening an outgassing valve in the liquid oxygen tank. 

Launcher Telemetry Tracking and Flight Safety Systems

Soyuz launcher tracking and telemetry is provided through systems in the second and third stages. These two stages have their own radar transponders for ground tracking. Individual telemetry transmitters are in each stage. Launcher health status is downlinked to ground stations along the flight path. Telemetry and tracking data are transmitted to the Russian Mission Control Center, where the incoming data flow is recorded. Partial realtime data processing and plotting are performed for flight following an initial performance assessment. All flight data is analyzed and documented within a few hours after launch. 

Image to left: A Soyuz rocket makes its way to the launch site at Baikonur Cosmodrome by rail. Credit: NASA

Baikonur Cosmodrome Launch Operations

Soyuz missions use the Baikonur Cosmodrome's proven infrastructure, and launches are performed by trained personnel with extensive operational experience. 

Baikonur Cosmodrome is located in the Republic of Kazakhstan in Central Asia, between 45 degrees and 46 degrees North latitude and 63 degrees East longitude. Two launch pads are dedicated to Soyuz missions. 

Final Launch Preparations

The assembled launch vehicle is moved to the launch pad on a horizontal railcar. Transfer to the launch zone occurs two days before launch, during which the vehicle is erected and a launch rehearsal is performed that includes activation of all electrical and mechanical equipment. 

On launch day, the vehicle is loaded with propellant and the final countdown sequence is started at three hours before the liftoff time.