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Soyuz 7K-OK

Soyuz 7K-OK is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Soyuz 7K-OK rather than just read about it. In short: Soyuz 7K-OK was the first generation of Soyuz spacecraft and was flown between 1967 and 1971. The 7K-OK was used for the first ferry flights to the Salyut space station program, beginning a long history of space station service that continues with the International Space Station (ISS).

Soyuz 7K-OK — main illustration
Soyuz 7K-OK — illustration

Key takeaways

  • Soyuz 7K-OK belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Soyuz 7K-OK to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Soyuz 7K-OK from memory before moving on to harder problems.

Reference excerpt

Soyuz 7K-OK was the first generation of Soyuz spacecraft and was flown between 1967 and 1971. The 7K-OK was used for the first ferry flights to the Salyut space station program, beginning a long history of space station service that continues with the International Space Station (ISS). As of 2026, the 7K-OK was responsible for the only fatalities of the Soyuz programme, with Soyuz 1 in 1967 (sole crew-member killed by parachute failure) and Soyuz 11 in 1971 (three crew killed by depressurisation during reentry). The first uncrewed automated docking in the history of spaceflight was achieved between 7K-OK spacecraft Kosmos 186 and Kosmos 188 in 1967. Additional firsts include the first docking between two crewed spacecraft (Soyuz 4 and Soyuz 5), the longest crewed flight involving only one spacecraft (the 18-day flight of Soyuz 9 in 1970), and the first successful transfer of crew to the first space station in the history of space flight (Soyuz 11 and Salyut 1 in 1971).

Description The Soyuz 7K-OK vehicles carried a crew of up to three without space suits. The craft can be distinguished from those following by their bent solar panels and their use of the Igla automatic docking navigation system, which required special radar antennas. The 7K-OK was primarily intended as a variant of the 7K-LOK (the lunar mission Soyuz) for Earth orbital testing. Mostly the same vehicle, it lacked the larger antenna needed to communicate at lunar distance. The early Soyuz models also sported an external toroidal fuel tank surrounding the engines and meant to store extra propellant for lunar flights, but it was left empty on the first nine flights. After the spacecraft's purpose was changed to space station ferry duties, the tank was removed. Soyuz 7K-OK spacecraft had a "probe and drogue" docking mechanism to connect with other spacecraft in orbit, in order to gather engineering data as a preparation for the Soviet space station program. There were two variants of Soyuz 7K-OK: Soyuz 7K-OK (active) featuring an active "probe" docking port, and Soyuz 7K-OK (passive) featuring a passive "drogue" docking target. The docking mechanisms of 7K-OK and 7K-LOK did not allow internal transfer (this feature was added on the Soyuz 7K-OKS version), thus cosmonauts had to spacewalk between docked modules. This procedure was conducted successfully on the joint Soyuz 4 and Soyuz 5 missions, where Aleksei Yeliseyev and Yevgeny Khrunov transferred from their Soyuz 5 to the Soyuz 4 craft. The first uncrewed test of this version was Kosmos 133, launched on 28 November 1966.

Soyuz 7K-OKS

The last two Soyuz space craft of this series were of the designation Soyuz 7K-OKS. The main modification was the addition of the new SSVP docking system that allowed internal crew transfer, which was performed for the first time on the Salyut 1 space station by Soyuz 11. The SSVP docking adapter is still in use today on the International Space Station (ISS).

Uncrewed and test missions Kosmos 133 Soyuz 7K-OK No.1 Kosmos 140 Kosmos 186 and Kosmos 188, the first uncrewed automated docking in the history of spaceflight. Kosmos 212 and Kosmos 213, uncrewed automated docking mission. Kosmos 238 Soyuz 2, intended docking target for the crewed Soyuz 3.

Crewed missions Soyuz 1, the first crewed Soyuz flight, commander and sole crew-member killed on re-entry. Soyuz 3 Soyuz 4 and Soyuz 5, the first crewed docking and first crew transfer in the history of spaceflight. Soyuz 6 Soyuz 7 and Soyuz 8: Intended docking, to be filmed by Soyuz 6 crew – docking failed due to malfunction. Soyuz 9 Soyuz 10 (Soyuz 7K-OKS), Salyut 1 ferry, the first docking attempt to a space station in the history of spaceflight. Soyuz 11 (Soyuz 7K-OKS), Salyut 1 ferry, the first crewing of a space station in the history of spaceflight – crew killed on re-entry.

References

External links RSC Energia: Concept Of Russian Manned Space Navigation Development Mir Hardware Heritage David S.F. Portree, Mir Hardware Heritage, NASA RP-1357, 1995 Mir Hardware Heritage (wikisource) Information on Soyuz spacecraft OMWorld's ASTP Docking Trainer Page NASA - Russian Soyuz TMA Spacecraft Details Space Adventures circum-lunar mission - details

Illustrations

Soyuz 7K-OK illustration
Soyuz 7K-OK: Soyuz family tree: Proposed Soyuz models in white, models that flew in blue and lunar models in green.[citation needed]
Soyuz family tree: Proposed Soyuz models in white, models that flew in blue and lunar models in green.[citation needed]

Worked examples

Example 1 — a first encounter with Soyuz 7K-OK

Start with the simplest possible case. Write down what Soyuz 7K-OK claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Soyuz 7K-OK before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Soyuz 7K-OK ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Soyuz 7K-OK

In research
Soyuz 7K-OK appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Soyuz 7K-OK in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Soyuz 7K-OK is common in secondary-school and first-year university syllabi. It links to neighbouring topics Crewed spacecraft, Soyuz programme, Vehicles introduced in 1966, so understanding it makes those chapters shorter.
In everyday life
Look for Soyuz 7K-OK outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Soyuz 7K-OK in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Soyuz 7K-OK means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Soyuz 7K-OK out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Soyuz 7K-OK in simple terms?

Soyuz 7K-OK was the first generation of Soyuz spacecraft and was flown between 1967 and 1971. The 7K-OK was used for the first ferry flights to the Salyut space station program, beginning a long history of space station service that continues with the International Space Station (ISS).

Why does Soyuz 7K-OK matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Soyuz 7K-OK?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Soyuz 7K-OK.

Tags

  • Crewed spacecraft
  • Soyuz programme
  • Vehicles introduced in 1966

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