Air leak in the PrK chamber


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The Zvezda Service Module's troubled start

Originally intended for the Soviet Mir-2 space station, the Zvezda Service Module closely resembled the core component of the original Mir launched in 1986. The overall design of the 20-ton spacecraft traced back to the Salyut and Almaz space stations. After the Mir-2 project had stalled by the collapse of the USSR, its yet-to-be completed first element was re-purposed to be the cornerstone of the International Space Station, ISS.


The integrated simulator, KS, of the Zvezda Service Module, SM, at RKK Energia's checkout facility.


In the Fall of 1993, RKK Energia, the chief developer of the Mir-2 space station, proposed its core module as the first element of the ISS to be launched; however, political considerations prompted NASA to accept a proposal from Moscow-based Khrunichev enterprise to initiate the assembly of the international outpost with a Russian-built and the US-funded FGB Control Module. According to the approved plan, the former core of the Mir-2, renamed the Service Module, SM, would become the third component of the ISS to be launched.

During its adaptation from the Mir-2 project to the ISS, the service module "lost" two out four docking ports located on the sides of its front spherical compartment.

The active construction of the service module coincided with the most difficult period of economic transition in post-Soviet Russia. Deprived of tax revenues, the Kremlin struggled to pay for various federal programs, including defense and space. Because it was the costliest Russian contribution into the ISS program, the Zvezda Service Module remained chronically underfunded during much of the 1990s.

In the Fall of 1996, Russia officially informed NASA that the service module would not be ready for launch in April 1998 due to lack of funding. In response, by the end of 1996, NASA initiated the development of the Interim Control Module, ICM, as a potential American replacement to the Service Module.

In May 1997, anticipating further problems with the construction of the Service Module, the partners in the ISS program officially postponed the launch of the station's first element -- the FGB Control Module -- from November 1997 to June 1998. In turn, the launch of the Service Module was rescheduled from April to November 1998.

In October 1998, the ISS partners agreed to go ahead with the launch of the first element in November 1998, hoping that the continuing problems with the funding of the Service Module would finally be resolved. At the time, the launch of the spacecraft was scheduled in April 1999, but it was expected to be delayed until at least June 1999.

By the time Russia successfully launched the FGB Control Module on November 20, 1998, the subsequent launch of the Service Module was expected no earlier than July 1999.

In April 1999, NASA and the Russian space agency, Rosaviakosmos, agreed to re-schedule the launch of the Service Module to a period between September 20 and November 20, 1999. In May 1999, the Service Module was finally shipped from RKK Energia's checkout facility in Korolev near Moscow to the Baikonur Cosmodrome. The pre-launch processing of the Zvezda officially began at Site 254 in Baikonur on May 19, 1999. The launch was then reported slipping to the end of December 1999 or beginning of January 2000.

On October 13, 1999, RKK Energia's spokesman Sergei Gromov said that it had been agreed during negotiations with NASA that due to ongoing problems with the Space Shuttle fleet, the realistic date for the Zvezda launch would be February 2000.

Russian officials still insisted that Zvezda would technically be ready for launch in November 1999, however, Shuttle delays prompted them to delay the Zvezda launch. According to Gromov, the launch of a Progress cargo ship to the International Space Station, originally planned for the end of November 1999, would be delayed as well.

Hardly two weeks after the latest delay announcement, on October 27, 1999, a Proton rocket, carrying the Ekspress-A1 communications satellite, failed during the firing of its second stage. As in a previous accident in the Summer of 1999, the booster's RD-0210 engine was blamed for the mishap, requiring a thorough investigation. As a result, all the Proton launches, including the mission to deliver the Zvezda Service Module, had to be put on hold until corrective measures could be implemented.

To complicate matters ever further, the cash strapped Rosaviakosmos was under heavy domestic pressure to keep the Mir space station in orbit, while NASA demanded the immediate re-focus of the Russian space budget and attention to the ISS. By the end of 1999, RKK Energia made a controversial decision to re-activate Mir with the help of private funds, while there were reports about the need to delay the launch of the Service Module until as late as August 2000. Obviously, this did not sit well with NASA.

Developments in 2000


A full-scale prototype of the Zvezda Service Module used for spacewalk training inside the neutral buoyancy facility at the Gagarin Cosmonaut Training Center.

On February 3, 2000, NASA Administrator Daniel Goldin, in the strongest words yet, accused Russia of "dragging its feet" on the ISS project and hinted that the country could face expulsion from the program. Goldin put forward an ultimatum of sorts to Russia to launch Zvezda module by the end of August 2000. NASA also announced a decision to launch its own Interim Control Module, ICM, which could serve as a partial substitution to Zvezda. The ICM launch date depended on the Russian ability to orbit Zvezda, NASA said.

In the face of the criticism, Russian space officials said on February 4, 2000, that they were working to launch the Service Module in June 2000, almost two months earlier than previously planned.

Anatoly Kiselev, the director general of the Khrunichev enterprise, said that his company hoped to have the Proton rocket for the Zvezda ready for launch around June 20, 2000. Rosaviakosmos soon confirmed the fact that plans have been made to launch the Zvezda in June 2000. Vechaslav Mikhailechenko, Rosaviakosmos spokesman, said that the Zvezda launch date had been discussed in a telephone conversation between the agency's director, Yuri Koptev, and NASA administrator Daniel Goldin on February 1, 2000. According to the transcript of the conversation, which Mikhailechenko reviewed, Goldin raised doubts about Russia's ability to provide the Progress cargo ships and Soyuz crew vehicles for the ISS, while simultaneously supporting the Mir space station.

Officially, the Russian decision to move the Zvezda's launch date to June was dictated by unfavorable lighting conditions for docking operations between the service module and the rest of the ISS in July and August 2000. Russian ground controllers reportedly wanted the docking to take place in daylight, so that TV cameras could be effectively used to monitor the final maneuvers between the unpiloted vehicles.

Mikhailechenko also said that despite its political undercurrent, NASA's decision to launch the ICM had a technical sense anyway, especially in case Zvezda was lost in an accident, such as a launch failure. In the past, Rosaviakosmos' director Yuri Koptev had warned that Russian defiance in the face of the US pressure to deorbit Mir could worsen the already soured relationship between the two space agencies. Ironically, NASA's pressure to scrap Mir, combined with the noisy anti-Mir campaign in the US media, only strengthened the determination of Russian lawmakers to find money specifically for Mir operations. "There is an unhealthy attitude toward Mir in the US," the head of mission control in Korolev Victor Blagov said a week before NASA Administrator's attack.

NASA itself was long criticized mostly by the Republican members of Congress for allowing Russian participation in the ISS project. Ironically, NASA invited Russia in the ISS project only after almost a decade-long delay, cost overruns and numerous budget cuts imposed by Congress, which left the space station project bankrupt by 1993. In comparison, Russia was only two years behind schedule with the delivery of its Service Module. Goldin admitted on February 3 that US components of the ISS were behind schedule as well. He also said that NASA could offer no advice to Russia in overcoming its rocket problems, since its own launch vehicles had been plagued with failures in the past...


A frame from the video footage showing the installation of the doughnut-shaped aggregate compartment on the aft bulkhead of the working compartment and around the PrK chamber (center) of the Zvezda Service Module.



Article and photography by Anatoly Zak; Last update: November 24, 2020

Page editor: Alain Chabot; Last edit: July 10, 2020


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Initial assembly of the Service Module. Click to enlarge. Credit: Roskosmos


Early assembly of the Service Module at Khrunichev enterprise in Moscow.


The Zvezda Service Module likely photographed during vacuum tests at GKNPTs Khrunichev.




The Zvezda Service Module is being integrated with its payload fairing in preparation for shipment from RKK Energia to Baikonur in April 1999.


A front section on the development prototype of the service module. Click to enlarge. Note a deployable docking target and the absence of side docking ports. Copyright © 2000 Anatoly Zak


A passive docking port on the development prototype, KS, of the Zvezda service module. Copyright © 2000 Anatoly Zak



The training mockup of the service module of the International Space Station in Star City. Copyright © 2000 Anatoly Zak