Soyuz 7K-OK spacecraft (original) (raw)

Soyuz 7K-OK variant

Compared to its predecessors -- Vostok and Voskhod -- the three-seat Soyuz offered enormous advantages. The most important feature of the new ship would be its rendezvous and docking system.

Previous chapter: Origin of the Soyuz project

External design of the 7K-OK (Soyuz) spacecraft.

An upper composite configuration during the Dec. 14, 1966, attempt to launch the Soyuz 7K-OK No. 1 vehicle.

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The Soyuz (7K-OK) spacecraft at a glance:

Spacecraft design

The capability of spacecraft to link up in orbit promised to overcome the limitations of existing rockets by assembling bigger vehicles out of smaller components. Because the original design of the Soyuz complex envisioned the use of unmanned tankers, the new spacecraft inherited the fully automated Igla (needle) rendezvous system.

The Soyuz spacecraft also sported a newly developed habitation module, which provided most life-support functions for the crew, including a toilet, thus enabling much longer missions than those possible aboard Vostok. In addition, this ball-shaped habitation compartment could also double as an airlock for space walks. To perform the transfer of crew members between docked ships, the Soyuz carried new spacesuits. However, the developers chose not to equip crew members with protective suits inside the spacecraft, because Vostok and Voskhod missions had never experienced loss of pressure.

Internal design of the 7K-OK (Soyuz) spacecraft.

During the transition from Vostok to Soyuz, most of the existing internal systems developed for human space flight were radically reworked. Practically all the hardware was built on the principle that any failed component would have to be backed up by an alternative system, ensuring the safety of the crew.

The flight control system, developed at Department 27 led by Boris Raushenbach, could maintain orientation of the spacecraft in orbital and inertial coordinate systems and it could also place the vehicle in the correct attitude for orbital and deorbiting maneuvering, rendezvous and point its solar arrays toward the Sun.

For the first time in the Soviet space technology, the Descent Control System, SUS, could steer the descent capsule during its return to Earth and maintain the correct attitude to produce aerodynamic lift. As a result, the crew would enjoy a gentler descent, when compared to loads experienced by pilots aboard Vostok. Several groups of small thrusters were using pressure-fed highly concentrated hydrogen peroxide to maneuver the descent module.

Propellant tanks for the descent control thrusters were initially placed inside the crew capsule, but in 1964, Korolev found this arrangement too dangerous and the tanks were moved to a specially designed niche on the exterior of the module.

Instead of the single braking engine on Vostok capable of just one firing, the Soyuz received a brand-new dual-engine propulsion system, designed for multiple firings in space. The KTDU-35 propulsion system was conceived as an integrated unit comprised of propellant tanks, the main rendezvous and correction engine, SKD, and a two-chamber backup correction engine, DKD, which could be used for a braking maneuver in an emergency.

Soyuz also carried two groups of small thrusters with their own autonomous tanks: small engines, DO, which could be used for attitude control in orbit, and a group of larger engines, DPO, which had an additional rendezvous function.

The brand-new power supply system on Soyuz relied on a pair of solar panels feeding multiple rechargeable batteries.

The multi-functional communications system of the Soyuz spacecraft originally conceived for a lunar flyby missions, enabled the transmission of commands, TV signals and telemetry data, as well as voice communications. Radio signals could also be used to measure the orbital parameters of the ship.

By 1970, a total of 17 flight-worthy 7K-OK vehicles had been manufactured and from 1968, the Air Force was pushing for the production of 10 more such vehicles, however, the space directorate of the Soviet military, GUKOS, and the General Staff were skeptical about the role of piloted spacecraft in military operations. The Head of TsKBEM design bureau Vasily Mishin was also not enthusiastic, because the work on Soyuz was siphoning resources from the lunar project. (142) However, after the US won the Moon Race in 1969, the Soviet political priorities quickly shifted to the Earth-orbiting space station, making the Soyuz the best candidate for ferrying the crews to the orbital outposts.

Soyuz 7K-OK development responsibilities at OKB-1/TsKBEM:

*Based on a calculation group of Department 8 from Artillery design bureau TsNII-58, which was absorbed by OKB-1 in 1959. **After August 1963.

Key contractors in the Soyuz 7K-OK project:

Missions of the Soyuz 7K-OK variant:

Next chapter: Origin of the Soyuz 7K-OK variant

The article and illustration by Anatoly Zak; Last update:June 23, 2024

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

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Basic architecture of the 7K-OK spacecraft (in "active" configuration).

Artist depiction of the 7K-OK variant in "passive" configuration.

A demo of the Soyuz spacecraft with a passive docking port. Credit: MAI

Flight control console inside the original version of the Soyuz spacecraft. Click to enlarge Copyright © 2000 Anatoly Zak

Kazbek chair for the Soyuz spacecraft. Copyright © 2011 Anatoly Zak

Front section of the 7K-OK spacecraft with active docking port.

Soyuz 7K-OK spacecraft during pre-launch processing in Tyuratam.

A 7K-OK spacecraft is being fueled for launch.

A payload section with a 7K-OK spacecraft is being integrated with the third stage of the launch vehicle.

An early Soyuz spacecraft during final processing on the launch pad in Tyuratam. Credit: RKK Energia

Footage from the joint mission of Soyuz-4 and Soyuz-5 spacecraft in 1969 likely captured this view of departing Soyuz-4 spacecraft. Credit: Roskosmos

Launch of a Soyuz 7K-OK spacecraft.