science

Soyuz T-15

Soyuz T-15 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 T-15 rather than just read about it. In short: Soyuz T-15 (Russian: Союз T-15, Union T-15) was a crewed mission to the Mir and Salyut 7 space stations and was part of the Soyuz programme. It marked the final flight of the Soyuz-T spacecraft, the third generation Soyuz spacecraft, which had been in service for seven years from 1979 to 1986.

Key takeaways

Soyuz T-15 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 T-15 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Soyuz T-15 from memory before moving on to harder problems.

Reference excerpt

Soyuz T-15 (Russian: Союз T-15, Union T-15) was a crewed mission to the Mir and Salyut 7 space stations and was part of the Soyuz programme. It marked the final flight of the Soyuz-T spacecraft, the third generation Soyuz spacecraft, which had been in service for seven years from 1979 to 1986. This mission marked the first time that a spacecraft visited, and docked with, two space stations in the same mission.

Crew

Backup crew

Mission parameters Mass: 6,850 kg (15,100 lb) Perigee: 331 km (206 mi) Apogee: 366 km (227 mi) Inclination: 51.6° Period: 91.5 minutes

Mission highlights Soyuz T-15 was both the first expedition to Mir and the last to Salyut 7.

Flight to Mir Due to the pressure of launching Mir in time for the 27th Communist Party Congress, mission planners were left without the newer Soyuz-TM spacecraft or any of the planned modules to launch to the station at first. It was decided to launch an older Soyuz-T as Soyuz T-15 on a dual mission to both Mir and Salyut 7. Leonid Kizim and Vladimir Solovyov first docked with the Mir space station on 15 March 1986 after their launch on 13 March. Plans for Mir intended that only the newer Soyuz-TM would dock with Mir's forward port, leaving the aft port free for arriving Progress spacecraft. However, the older Soyuz-T was not equipped with the Kurs approach system used on Mir's front port, but only with the older Igla approach system used for Mir's aft port. Therefore, Soyuz T-15 had to approach Mir's aft port, and then manually maneuver around the station to dock manually at the forward port. At 20 km Soyuz T-15's Igla system acquired its counterpart on Mir's aft port. At 200 meters, the Igla system was shut off, and the crew manually maneuvered around the station to dock at the front port. For this manual approach, the same laser range finder was used as for the Soyuz T-13 docking with the uncooperative Salyut 7 station in 1985. During their nearly 55-day stay on Mir, the crew unloaded two Progress spacecraft, launched after their arrival. The mission was mostly designed to test out the new space station's systems since it had been launched with little scientific equipment, most of which would have to wait for the launch of add-on modules. Despite Mir's name literally meaning "Peace", US officials during this time accused the Soviet Union of performing military experiments on their supposedly civilian space stations. After the cosmonauts' return to Earth, Leonid Kizim in an official press conference stated that Mir was not being used for any military purposes and that "The US is accusing us of this sort of action in order to justify their own plans to extend the arms race into space." The Reagan Administration did not however reiterate these claims so as not to negatively impact the planned 1987 summit meeting between President Ronald Reagan and Soviet leader Mikhail Gorbachev.

The crew transfers to Salyut 7 In preparation for the trip to Salyut 7, the crew loaded Soyuz T-15 with their personal belongings, plants grown on Mir, and other items. At that time Salyut 7 was still 4000 km ahead of Mir in a lower orbit in the same inclination. Therefore, on 4 May, Mir was lowered by 13 km in order to expedite the approach to Salyut 7 and conserve Soyuz T-15's limited fuel supply for the transfer. On 5 May 1986 12:12:09 UTC they undocked from Mir for their journey to Salyut 7 – at this time, the distance between the two space stations had been reduced to 2500 km due to Mir's maneuver. After a crossing of 29 hours, Soyuz T-15 docked with Salyut 7 on 6 May 16:57:52 UTC.

Experiments on Salyut 7 The previous crew on Salyut 7, Salyut 7 EO-4, had been assigned to conduct experiments with TKS-4 (Kosmos 1686). However, commander Vladimir Vasyutin had fallen ill and the crew had to return prematurely to Earth. Therefore, they were unable to perform EVAs, which would have had implications for the Mir program. After arriving at Salyut 7, the crew of Soyuz T-15 conducted two EVAs and collected experiment results, experimental apparatuses, and samples of materials to finish the work of the previous crew. The first EVA was on 28 May, when the crewmembers climbed outside to retrieve space exposure experiments and test the Ferma-Postroital ("girder-constructor") device. A deployment canister converted a folded girder cartridge into a 15-meter girder in only a few minutes. The girder was retracted by reversing the process at the end of the EVA. This first EVA lasted 3 hours and 50 minutes. The second EVA consisted of girder and welding experiments. On 31 May, Kizim and Solovyov attached measurement devices to the top of the retracted girder, then re-extended it with an aim toward studying its rigidity. They then used an electron gun to weld several of the girder's joints. This second EVA lasted five hours.

Ferry flight back to Mir The crew removed 20 instruments with a total mass of 350 to 400 kg from Salyut 7 before returning to Mir. Mir maneuvered twice again between 24–25 June, raising its orbit slightly and moving closer to Salyut 7. On 25 June, Soyuz T-15 undocked from Salyut 7 to begin their 29-hour journey back to Mir, to which they returned on 25–26 June. On 3 July, Kizim surpassed Valeri Ryumin's record for time spent in space. On 6 July, he became the first human to have spent a full year in space. The crew spent their last 20 days on Mir conducting Earth observations. Meanwhile, between 19 and 22 August, engines on Kosmos 1686 boosted Salyut 7 to a record-high mean orbital altitude of 475 km to forestall reentry. Atmospheric drag took its toll, however, and the station reentered over South America 55 months later. Pieces of Salyut 7 and Kosmos 1686 were found in Argentina. Soyuz T-15 was the last mission to use the Soyuz-T spacecraft, due to its replacement by the Soyuz-TM.

Illustrations

Worked examples

Example 1 — a first encounter with Soyuz T-15

Start with the simplest possible case. Write down what Soyuz T-15 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 T-15 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 T-15 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 T-15

In research: Soyuz T-15 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 T-15 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 T-15 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1986 in spaceflight, 1986 in the Soviet Union, Crewed Soyuz missions, so understanding it makes those chapters shorter.
In everyday life: Look for Soyuz T-15 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 T-15 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Soyuz T-15 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 T-15 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Soyuz T-15 in simple terms?

Why does Soyuz T-15 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 T-15?

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 T-15.