science

Progress 21

Progress 21 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 Progress 21 rather than just read about it. In short: Progress 21 (Russian: Прогресс 21) was a Soviet uncrewed Progress cargo spacecraft, which was launched in May 1984 to resupply the Salyut 7 space station. Launch Progress 21 launched on 7 May 1984 from the Baikonur Cosmodrome in the Kazakh SSR.

Key takeaways

Progress 21 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Progress 21 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Progress 21 from memory before moving on to harder problems.

Reference excerpt

Progress 21 (Russian: Прогресс 21) was a Soviet uncrewed Progress cargo spacecraft, which was launched in May 1984 to resupply the Salyut 7 space station.

Launch Progress 21 launched on 7 May 1984 from the Baikonur Cosmodrome in the Kazakh SSR. It used a Soyuz-U rocket.

Docking Progress 21 docked with the aft port of Salyut 7 on 10 May 1984 at 00:10 UTC, and was undocked on 26 May 1984 at 09:41 UTC.

Decay It remained in orbit until 26 May 1984, when it was deorbited. The deorbit burn occurred at 15:00:30 UTC, with the mission ending at around 15:45 UTC.

Illustrations

Worked examples

Example 1 — a first encounter with Progress 21

Start with the simplest possible case. Write down what Progress 21 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 Progress 21 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 Progress 21 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 Progress 21

In research: Progress 21 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 Progress 21 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: Progress 21 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1984 in the Soviet Union, Progress (spacecraft) missions, Soviet spacecraft stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Progress 21 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 Progress 21 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Progress 21 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 Progress 21 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Progress 21 in simple terms?

Progress 21 (Russian: Прогресс 21) was a Soviet uncrewed Progress cargo spacecraft, which was launched in May 1984 to resupply the Salyut 7 space station. Launch Progress 21 launched on 7 May 1984 from the Baikonur Cosmodrome in the Kazakh SSR.

Why does Progress 21 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 Progress 21?

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 Progress 21.