science

Soyuz 25

Soyuz 25 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 25 rather than just read about it. In short: Soyuz 25 (Russian: Союз 25, Union 25) was an October 1977 Soviet crewed space flight, the first to the new Salyut 6 space station, which had been launched 10 days earlier. However, the mission was aborted when cosmonauts Vladimir Kovalyonok and Valery Ryumin failed to engage the docking latches of the station despite five attempts.

Key takeaways

Soyuz 25 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 25 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Soyuz 25 from memory before moving on to harder problems.

Reference excerpt

Soyuz 25 (Russian: Союз 25, Union 25) was an October 1977 Soviet crewed space flight, the first to the new Salyut 6 space station, which had been launched 10 days earlier. However, the mission was aborted when cosmonauts Vladimir Kovalyonok and Valery Ryumin failed to engage the docking latches of the station despite five attempts. Lacking sufficient fuel to attempt a dock at the other end of the station and with battery power for only two days, they returned to Earth. The failure led to a new rule whereby every crew had to have at least one person aboard who had previously flown in space.

Crew

Backup crew

Mission highlights Soyuz 25 was launched on 9 October 1977 with a crew of two cosmonauts to dock with the orbiting Salyut 6 space station, which had been launched 10 days earlier, on 29 September. The crew were to stay on board for about 90 days, which would break the Soviet space endurance record, and possibly the all-time record of 84 days held by the crew of Skylab 4. The station was a new version of a Salyut with modifications including a second docking port which allowed supply ships and other crews to visit during the duration of a mission. The vehicle approached the station the next day, and it contacted the forward port, but the Soyuz craft failed to make a hard dock with the station. The cosmonauts told the ground crew that they had attempted to dock four times, but that the contact light failed to come on. While the crew waited in soft dock – the docking system probe was latched onto the Salyut docking drogue, but the probe had failed to retract and bring the craft together – the ground crew studied the problem. On the 20th orbit, Kovalenko undocked the Soyuz, and attempted to dock for the fifth time during the 23rd orbit, but failed again. The decision was made to return to Earth, as the Soyuz was equipped with batteries designed to last about two days, and the craft lacked fuel to attempt to dock with the port on the opposite side of the station. A news release was issued: "At 07.09 Moscow time today (10 October) the automatic rendezvous of the Soyuz 25 ship and the Salyut 6 station was begun. From a distance of 120 metres, the vehicles performed a docking manoeuvre. Due to deviations from the planned procedure for docking, the link-up was called off. The crew has begun making preparations for a return to Earth." The crew thus had to make an early reentry and landed 185 km (115 mi) northwest of Tselinograd, Kazakhstan on 11 October. The failure was a serious blow to the Soviets, as their media had given the flight a high profile, noting that the flight had come from the same launchpad as Sputnik 1 and Vostok 1, and coincided with the 60th anniversary of the October Revolution. The problem was traced later to a faulty mechanism on the Soyuz; this was not discovered until after the Soyuz 26 flight performed an EVA to inspect the second docking port on Salyut 6. The mission failure resulted in a rule stating that future crews would include at least one cosmonaut who had already flown a space mission. This resulted in the all-rookie backup crew of Aleksandr Ivanchenkov and Yuri Romanenko being paired with veteran cosmonauts for future missions. The rule was not relaxed until 1994 and Soyuz TM-19.

Mission parameters Mass: 6,860 kg (15,120 lb) Perigee: 198.5 km (123.3 mi) Apogee: 258.1 km (160.4 mi) Inclination: 51.66° Period: 88.66 minutes

References

Worked examples

Example 1 — a first encounter with Soyuz 25

Start with the simplest possible case. Write down what Soyuz 25 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 25 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 25 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 25

In research: Soyuz 25 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 25 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 25 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1977 in the Soviet Union, Crewed Soyuz missions, Human spaceflights to Salyut space stations, so understanding it makes those chapters shorter.
In everyday life: Look for Soyuz 25 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 25 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Soyuz 25 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Soyuz 25 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Soyuz 25 in simple terms?

Why does Soyuz 25 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 25?

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 25.