On Nov. 27, after the launch of the Soyuz 2.1a rocket with the Soyuz MS-28 crew and spacecraft, an accident occurred on the launch pad at Site 31/6 at the Baikonur Cosmodrome. The launch itself was successful, and the crew — consisting of Roscosmos cosmonauts Sergey Kud-Sverchkov and Sergei Mikayev, and NASA astronaut Christopher Williams — arrived safely at the Station a few hours after launch.
However, a drone flying around the launch complex showed Site 31/6’s mobile maintenance cabin lying upside down in the flame trench.
The main issue with the structure collapse is that it puts Site 31/6 — the only Russian launch site capable of launching crew and cargo to the International Space Station (ISS) — out of service until the structure is fixed. There are other Soyuz 2 rocket launch pads, but they are either located at an unsuitable latitude, like Plesetsk, or not certified for crewed flights, like Vostochny, or decommissioned and transferred to a museum, like Gagarin’s Start at Baikonur.
According to unconfirmed rumors, after today's #SoyuzMS28 launch, an emergency occurred at Pad 31: part of the launch facility, the maintenance cabin, located under the rocket, was damaged. Roscosmos has not yet commented on these rumors, I also have no additional information. pic.twitter.com/LQ0uPL5Kk1
— Katya Pavlushchenko (@katlinegrey) November 27, 2025
As a result, Russia is temporarily unable to launch Soyuz crewed spacecraft and Progress cargo ships to the ISS, whose nearest launch (Progress MS-33) was scheduled for Dec. 21. Site 31/6’s return now depends on the availability of spare parts and the speed of repairs.
The 8U216 maintenance cabin is a mobile metal platform that is 19.06 m x 16.92 m in size and 144 tons weight, on which two lifting platforms are located. When a rocket is being prepared for launch, the maintenance cabin is brought under the rocket, with the platforms lifted on, providing access to the engines of the first and second stages of the Soyuz rocket. From here, the launch team conducts all pre-launch operations with the lower part of the rocket, including removing protective covers and installing pyrotechnic devices (the famous “matches”) on the rocket engines.
When the pre-launch preparation is completed, the lifting platforms are lowered, and the maintenance cabin is moved along special rails into a special nook under the launch pad, freeing the way to the flame trench. The opening of the cabin’s nook is then closed with a special metal curtain attached to the maintenance cabin. There it is fixed with two locks.
The maintenance cabin at Site 31/6. (Credit: TyazhMash)
On Nov. 27, all preparations for the launch of the Soyuz 2.1a rocket with the Soyuz MS-28 spacecraft went smoothly, and 44 minutes before launch, the maintenance cabin, according to the launch crew report, was moved to its nook. However, further inspection following launch showed that either it was not properly fixed in the nook, or the locks holding it in the retracted position could not withstand the load.
When the rocket launched, a pressure difference was created between the space under the rocket, where gases from running engines are discharged, and the nook where the maintenance cabin was located. The resulting pressure difference pulled the service cabin out of the nook and threw it into the flame trench, where it fell upside down from a height of 20 m.
Photos of the accident showed significant damage to the maintenance cabin, which, according to experts, is too extensive to allow for repairs. The only way to resume launches from Site 31/6 is to install a spare maintenance cabin or construct a new one.
Image of the collapse maintenance cabin at Site 31/6. (Credit: Kosmonavtiki Novosti)
Despite the fact that the fallen structure was manufactured in the 1960s, two similar service cabins were manufactured recently at the Tyazhmash heavy-engineering plant in Syzran for other Soyuz launch complexes at the Guiana Space Center and Vostochny Cosmodrome. The production of each cabin took around two years to complete, however, it was not for an emergency situation.
According to the first official press release from Roscosmos, all the necessary spare parts are available for the restoration of the launch complex, and it will be repaired in the near future. Sources in the Russian space industry have confirmed that a spare set of elements for the maintenance cabin does exist in Roscosmos warehouses.
Theoretically, it is also possible to dismantle a suitable maintenance cabin from one of the currently unused Soyuz launch pads, the closest of which is Pad 1, also known as Gagarin’s Start, from which the first human space flight was carried out. Unfortunately, however, Gagarin’s Start was recently converted into an open-air museum, which will make part allocation difficult. Fortunately, there are unused launch pads at the Plesetsk cosmodrome too.
Various experts gave different possible estimates of the recovery time of the Site 31 launch complex: from several months to three years. The latest estimates are clearly based on the assumption that a new maintenance cabin will be required. But even if there are enough spare parts available, a comprehensive inspection of the launch complex must first take place to determine if the current maintenance cabin damaged other elements of the launch pad during its collapse. All of these inspections will surely take more than a few months, even if Roscosmos throws all its forces into eliminating the consequences of the accident.
Soyuz MS-28 at Site 31/6 ahead of launch and the maintenance cabin collapse. (Credit: NASA/Bill Ingalls)
At minimum, the launch of the Progress MS-33 cargo ship, scheduled for December 21, 2025, will definitely be postponed, and the cosmonauts are unlikely to receive their New Year’s gifts. If everything goes according to plan, Roscosmos has a chance to restore Site 31 before the launch of the next crewed Soyuz MS-29, which is scheduled to fly to the ISS on July 14, 2026, although the chance of postponing this mission is also high. After all, before the first crewed launch from the repaired site takes place, the rules require to perform at least one launch of an uncrewed payload. So far, neither Roscosmos nor NASA has published any changes to the flight schedule to the ISS.
However, if there are other launch pads for Soyuz rockets, is it possible to transfer missions to the ISS to one of them?
Unfortunately, this is an unlikely scenario. In addition to the Soyuz spacecraft and rocket, the launch pad must also be certified for crewed launches. Such a process takes extended amounts of time to complete.
Site 31/6 at Baikonur. (Credit: Roscosmos)
Furthermore, as mentioned, the Plesetsk cosmodrome is located too far north for a Soyuz rocket to launch spacecraft to the ISS’s orbit.
Theoretically, the possibility of launching Progress cargo ships from the Vostochny cosmodrome exists, although a lot of work and logistical changes will be required. But launching crewed Soyuz spacecraft from there is problematic: first, the emergency landing areas when launching from Vostochny will be located in mountainous and wooded areas, as well as over the ocean, while the Soyuz capsule is designed for landing on land. Secondly, the SAS — or the emergency rescue system — would not fit in the mobile maintenance tower used for pre-launch operations at Vostochny. The launch pad at the Kourou cosmodrome is not only intended for another version of the Soyuz rocket, but also cannot be used due to sanctions that arise from Russia’s invasion of Ukraine.
This is not the first time a launch site has been heavily damaged in the history of the R7 rocket family, which includes the Soyuz 2.1a. The most recent incident occurred on April 28, 2016, at the Vostochny cosmodrome, when the protective curtain of the maintenance cabin was torn out and fell into the flame trench. Fortunately, the maintenance cabin itself wasn’t damaged. It isn’t known for sure how long took the repair itself, since the 1C site at the Vostochny cosmodrome is rarely used at all, but the next launch from this site was carried out only 1.5 years later, in November 2017.
Without future information from Roscosmos, or, only estimates can inform how long the restoration of the Pad 31 will take.
(Lead image: Site 31/6 at the Baikonur Cosmodrome. Credit: P. Katin)
The post Russia left without access to ISS following structure collapse at Baikonur launch site appeared first on NASASpaceFlight.com.
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