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Inside Soyuz launch pad: The Service Cabin
Visitors to the Soyuz launch facility often do not suspect that a multi-floor maze is hidden below the pad's vast concrete surface. However a careful observer would notice that when the Soyuz rocket is erected onto its launch pad, the lower portion of the vehicle ends up deep below the pad. To service the business end of the rocket, a massive movable structure is located under the pad.
An isolated view of the Service Cabin, KO, for the Soyuz launch pad in Vostochny shown in deployed position. Credit: Roskosmos
Side view of the Service Cabin, KO, in retracted (left) and in stowed position. Credit: TsKBTM
The Service Cabin in deployed position during testing at Tyazhmash factory in Syzran.
Personnel works on the top level of the Service Cabin, KO, in Plesetsk circa 1990. Credit: VKS
Access bridges of the Service Cabin, KO. Credit: KBOM
Following the delivery of the Soyuz rocket to the launch pad, the Service Cabin, KO (a Russian abbreviation for "Kabina Obslyzhnivaniya"), moves into position around the wide base of the rocket under the launch pad. A series of access bridges then are deployed and raised vertically to form a three-level scaffolding just inches from the vehicle. The bridges provide access for the launch personnel to the first and second stage of the rocket at three levels, all located below the main concrete surface of the launch pad. The structure is used by fueling personnel to connect kerosene and liquid oxygen supply lines from the launch complex propellant storage to the multiple propellant tanks onboard the rocket.
The service cabin also provides access to the lower support structures of the pad, which hold the fueled rocket at the tail.
First built in 1956, the movable Service Cabin is common for all Soyuz pads in Baikonur, Plesetsk, Kourou and Vostochny. The original structure, designated 8U216, was developed at the TsKBTM design bureau in Moscow and manufactured at the Novokramatorsk Machine-building Plant, NKMZ, in Ukraine.
In the original Service Cabin, all access bridges formed a circular turntable, which could rotate along with other service systems to orient the rocket for a correct ascent azimuth depending on the orbital inclination of the upcoming mission. This feature became unnecessary with the introduction of the Soyuz-2 variant, whose flight control system could perform the necessary roll maneuver in flight to attain the correct azimuth.
Shortly before liftoff, the access bridges of the structure are folded and it moves on rails into a large niche below the pad. A special vertical shield protects the structure from the exhaust of the rocket at launch.
Read much more about history, today and tomorrow of the Russian space program in a richly illustrated, large-format glossy edition:
An engineer demonstrates the Service Cabin during its assembly and checking in June 2015 at the Soyuz launch pad in Vostochny. Click to enlarge. Credit: Roskosmos
The final assembly of the Service Cabin in Vostochny in March 2015. Click to enlarge. Credit: Spetsstroi
The Service Cabin in Vostochny in operational position, with lowered (top) and lifted (bottom) access bridges. Click to enlarge. Credit: Spetsstroi