science

Kosmos 421

Kosmos 421 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 Kosmos 421 rather than just read about it. In short: Kosmos 421 (Russian: Космос 421 meaning Cosmos 421), known before launch as DS-P1-Yu No.48, was a Soviet satellite which was launched in 1971 as part of the Dnepropetrovsk Sputnik programme. It was a 325-kilogram (717 lb) spacecraft, which was built by the Yuzhnoye Design Bureau, and was used as a radar calibration target for anti-ballistic missile tests.

Key takeaways

Kosmos 421 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kosmos 421 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kosmos 421 from memory before moving on to harder problems.

Reference excerpt

Kosmos 421 (Russian: Космос 421 meaning Cosmos 421), known before launch as DS-P1-Yu No.48, was a Soviet satellite which was launched in 1971 as part of the Dnepropetrovsk Sputnik programme. It was a 325-kilogram (717 lb) spacecraft, which was built by the Yuzhnoye Design Bureau, and was used as a radar calibration target for anti-ballistic missile tests.

Launch Kosmos 421 was successfully launched into low Earth orbit on 19 May 1971, with the rocket lifting-off at 10:20:00 UTC. The launch took place from Site 133/1 at the Plesetsk Cosmodrome, and used a Kosmos-2I 63SM carrier rocket.

Orbit Upon reaching orbit, it was assigned its Kosmos designation, and received the International Designator 1971-044A. Kosmos 421 was the forty-second of seventy nine DS-P1-Yu satellites to be launched, and the thirty-eighth of seventy two to successfully reach orbit. It was operated in an orbit with a perigee of 266 kilometres (165 mi), an apogee of 445 kilometres (277 mi), 70.9 degrees of inclination, and an orbital period of 91.65 minutes. It remained in orbit until it decayed and reentered the atmosphere on 8 November 1971.

Worked examples

Example 1 — a first encounter with Kosmos 421

Start with the simplest possible case. Write down what Kosmos 421 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 Kosmos 421 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 Kosmos 421 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 Kosmos 421

In research: Kosmos 421 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 Kosmos 421 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: Kosmos 421 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1971 in spaceflight, Dnepropetrovsk Sputnik program, Kosmos satellites, so understanding it makes those chapters shorter.
In everyday life: Look for Kosmos 421 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 Kosmos 421 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kosmos 421 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 Kosmos 421 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kosmos 421 in simple terms?

Why does Kosmos 421 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 Kosmos 421?

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 Kosmos 421.