science

USA-206

USA-206 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 USA-206 rather than just read about it. In short: USA-206, also GPS SVN-50, PRN-05 and NAVSTAR 64 and known before launch as GPS IIR-21, GPS IIRM-8 or GPS IIR-21(M), is an American navigation satellite that forms part of the Navstar Global Positioning System. It was the twenty-first and last Block IIR GPS satellite to be launched and the eighth to use the modernized IIRM configuration.

Key takeaways

USA-206 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect USA-206 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of USA-206 from memory before moving on to harder problems.

Reference excerpt

USA-206, also GPS SVN-50, PRN-05 and NAVSTAR 64 and known before launch as GPS IIR-21, GPS IIRM-8 or GPS IIR-21(M), is an American navigation satellite that forms part of the Navstar Global Positioning System. It was the twenty-first and last Block IIR GPS satellite to be launched and the eighth to use the modernized IIRM configuration.

GPS IIR-21 was built by Lockheed Martin, based on the AS-4000 satellite bus, with the navigation payload being built by ITT. It was launched by a United Launch Alliance Delta II rocket, using the 7925-9.5 configuration, on 17 August 2009 at 10:35 GMT. It was the last spacecraft to launch from Space Launch Complex 17A at the Cape Canaveral Air Force Station, a launch pad which was first used in August 1957 for test flights of the PGM-17 Thor missile. It is also the final flight of an AS-4000 bus, the final GPS launch on a Delta II, and the final Delta II launch to be overseen by the US Air Force. Following separation from its carrier rocket, GPS IIR-21 received its USA designation, USA-206. It was deployed into a transfer orbit, from which raised itself to a semi-synchronous medium Earth orbit on 19 August, using an onboard Star 37FM apogee motor. It is a 2,032-kilogram (4,480 lb) satellite, and is expected to operate for at least ten years. Once it had completed on-orbit testing, it began covering Slot 3 of Plane E of the GPS constellation, replacing USA-126, or GPS IIA-26, which was launched in July 1996. It was declared operational on 27 August 2009.

References

Illustrations

Worked examples

Example 1 — a first encounter with USA-206

Start with the simplest possible case. Write down what USA-206 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 USA-206 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 USA-206 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 USA-206

In research: USA-206 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 USA-206 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: USA-206 is common in secondary-school and first-year university syllabi. It links to neighbouring topics GPS satellites, Spacecraft launched by Delta II rockets, Spacecraft launched in 2009, so understanding it makes those chapters shorter.
In everyday life: Look for USA-206 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 USA-206 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what USA-206 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 USA-206 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is USA-206 in simple terms?

Why does USA-206 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 USA-206?

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 USA-206.