science

Strela (satellite)

Strela (satellite) 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 Strela (satellite) rather than just read about it. In short: Strela (Russian: Стрела, for Arrow) is a Russian (previously Soviet) military communications satellite constellation operating in low Earth orbit. These satellites operate as mailboxes ("store-and-forward"): they remember the received messages and then resend them after the scheduled time, or by a command from the Earth.

Key takeaways

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

Reference excerpt

Strela (Russian: Стрела, for Arrow) is a Russian (previously Soviet) military communications satellite constellation operating in low Earth orbit. These satellites operate as mailboxes ("store-and-forward"): they remember the received messages and then resend them after the scheduled time, or by a command from the Earth. Some sources state the satellites are capable of only three months of active operation, but through coordination with others they can serve for about five years. The satellites are used for transmission of encrypted messages and images.

History The first three satellites, Kosmos 38 (reentered 8 November 1964), Kosmos 39 (reentered 17 November 1964) and Kosmos 40 (reentered 17 November 1964), were launched on 18 August 1964. Five different types of Strela satellites (six if one counts the Rodnik aka Strela-3M satellites) have been launched, designated Strela-1 (1964–1965), Strela-1M (1970–1992), Strela-2 (1965–1968), Strela-2M (1970–1994), and Strela-3 (1985–2010). Strela satellites are also used for the civilian Gonets program. The current version of Strela, Strela-3M is also known as Rodnik (2005–present). In 2018 Austrian counterintelligence authorities identified an officer of the Bundesheer, Martin M. as a Russian spy. During the investigation, Austrian counterintelligence found a small suitcase. It had radio-communication equipment built into it so that Martin M. was able to connect to Strela-3 satellites and receive and send encrypted messages. The authorities also found a list of times when the satellite was positioned over Austria.

Technology The following observations were published in 2011: On 244.512 MHz a Strela-satellite generates a 0.5s long 'trigger pulse' every 60 seconds; the purpose is to activate ground based transmitters waiting to send a message. Satellites were identified by measuring the time of closest approach using a Doppler curve. Received messages are then re-transmitted on the second known frequency at 261.035 MHz.

Accidents and incidents At 16:56 UTC on 10 February 2009, Kosmos 2251, a retired Strela-2M, collided with the operational Iridium 33 satellite.

References

External links Encyclopedia Astronautica - Strela

Illustrations

Worked examples

Example 1 — a first encounter with Strela (satellite)

Start with the simplest possible case. Write down what Strela (satellite) 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 Strela (satellite) 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 Strela (satellite) 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 Strela (satellite)

In research: Strela (satellite) 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 Strela (satellite) 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: Strela (satellite) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Communications satellites, Communications satellites of Russia, Communications satellites of the Soviet Union, so understanding it makes those chapters shorter.
In everyday life: Look for Strela (satellite) 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 Strela (satellite) in 20 minutes

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

Frequently asked questions

What is Strela (satellite) in simple terms?

Why does Strela (satellite) 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 Strela (satellite)?

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 Strela (satellite).