Chelomei's LK spacecraft




Birth of the Soyuz 7K-OK project

Despite its roots in the Soviet lunar exploration effort, the first Soyuz spacecraft to reach space was intended for missions in the Earth's orbit. Designated 7K-OK, its main goal was the rehearsal of orbital rendezvous, which would be crucial for a lunar expedition. Missions of Soyuz 7K-OK also had the political goal of shortening the hiatus in the Soviet human space flight program during the difficult transition from the first Vostok and Voskhod spacecraft to the lunar program.



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In 1963, in parallel with the work on the Voskhod missions at the OKB-1 design bureau, its chief designer Sergei Korolev ordered a detailed study of a three-seat vehicle for missions in the Earth's orbit. The basis for this work was the 7K spacecraft, a part of a multi-ship Soyuz complex for a mission around the Moon. The Soyuz complex designed to carry two cosmonauts, was itself largely on the drawing board at the time. By the beginning of 1964, Department 11 at OKB-1 prepared proposals for a possible configuration of the Earth-orbiting three-seater and, in the spring of the same year, built a mockup of a potential vehicle.

However in 1964, the original Soyuz project had to be virtually put on hold for almost six months, as the OKB-1 design bureau was urgently re-tailoring its plans for the lunar landing effort. The threatening advance in the American effort to put a man on the Moon had finally dawned on Soviet officials and required an urgent response.

After consultations with Korolev in July 1964, on August 3, the Kremlin officially dropped the cumbersome multi-launch scenario for a flight behind the Moon with the help of the Soyuz complex. Instead, the now secondary task of the lunar flyby was delegated to Vladimir Chelomei's own spacecraft launched by the newly developed Proton rocket. At the same time Korolev could now focus on the much more difficult but prestigious task of beating the Americans to the Moon with his L3 lunar landing system.

During this period, all the development work on Soyuz was dropped into the lap of Department 29, led by Evgeny Ryazanov, who reported to Korolev's deputy Pavel Tsybin. At the same time, Korolev directed a group of engineers, including Boris Chertok, Yuri Semenov and Konstantin Shustin, to determine the fate of the original Soyuz design after the latest change of plans.

At the end of 1964, after several conferences with his "Soyuz task force," Korolev approved the idea to dock a pair of the 7K spacecraft in the Earth's orbit as a rehearsal of future operations during lunar expeditions. The Soyuz variant proposed for this purpose was designated 7K-OK, where the "7K" designation was inherited from the original manned vehicle in the lunar fly-by project, while "OK" stood for "near-Earth-orbital."

Obviously, a considerable part of the engineering experience gained during the development of the 7K-OK variant could later be applied to the design of the lunar expeditionary vehicle within the L3 project.

At the beginning of 1965, Korolev presented the new plan for Soyuz 7K-OK missions to the Scientific and Technical Council of the State Committee for Defense Technology, GKOT, which oversaw the rocket industry at the time. On February 6, Korolev sent a proposal on the Soyuz docking mission to Sergei Zverev, the head GKOT. On April 2, Korolev sent similar letters to Leonid Smirnov and Mstislav Keldysh and, a day later, the same proposal went to the newly appointed Minister of General Machine Building Sergei Afanasiev. (84)

Although the 7K-OK variant was far from being a centerpiece of the lunar landing effort, and could, in fact, slow it down, the Kremlin approved its development in order to avoid a long break in high-profile manned missions, which still had a considerable propaganda value for the USSR.

1965: Starting the development


Early Soyuz prototypes during the development: the descent module is on the foreground near the center of the photo. An instrument module is at the center on the background, and the propulsion section is on the right. The habitation module is on the background to the left. Kazbek cosmonaut chairs can be partially seen at the bottom of the image.

As of the beginning of 1965, development work on Soyuz was centered at Department 93, led by I.S. Prudnikov, and some of the original authors of the Soyuz lunar flyby project had now returned to their tasks after the re-start of the project. Beginning in May, the department issued an experimental design with all the data necessary for the production of the working documentation for the 7K-OK spacecraft.

At the management level, Aleksei Topol was appointed the leading designer of the 7K-OK spacecraft, with Yuri Semenov as his deputy. As before with Vostok, Konstantin Feoktistov served as the chief architect behind the project.

On May 28, Korolev and his deputy Vasily Mishin signed a package of documents on the 7K-OK spacecraft, including an assignment for the ship's new propulsion system to the design bureau led by Aleksei Isaev. (774)

In parallel with the work on the spacecraft, the existing Vostok rocket, the only launch vehicle certified for manned missions, needed a considerable upgrade to increase its payload mass from 4.8 to 5.8 tons and, later, to 6.5 tons in order to lift the Soyuz into orbit. (52)

By August 1965, OKB-1 issued updated tactical and technical specifications for the 7K-OK spacecraft. The overall project retained the name "Soyuz," while in the engineering documentation, the spacecraft was designated as 11F615.

On August 17, Korolev already received a letter from the Head of Cosmonaut Training Center, Nikolai Kamanin, with a list of candidates for missions on Soyuz -- Kamanin's usual obsession. (84)

The Oct. 25, 1965, government decree formally approved the development of the 7K-OK Earth-orbiting spacecraft, in parallel with the work on the 7K-L1 variant, which aimed to fly behind the Moon before the Apollo.


Next chapter: Development of the Soyuz 7K-OK spacecraft



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The article and illustration by Anatoly Zak; Last update: January 20, 2023

Page editor: Alain Chabot; Last edit: November 27, 2016

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Original design of the 7K-OK spacecraft. Credit: RKK Energia