science

USA-242

USA-242 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-242 rather than just read about it. In short: USA-242, also known as GPS IIF-4, GPS IIF SV-5, Navstar-68 and Vega, is an American navigation satellite which was launched on 15 May 2013 and became operational on 21 June 2013. The fourth Block IIF GPS satellite, it forms part of the Global Positioning System.

Key takeaways

USA-242 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-242 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of USA-242 from memory before moving on to harder problems.

Reference excerpt

USA-242, also known as GPS IIF-4, GPS IIF SV-5, Navstar-68 and Vega, is an American navigation satellite which was launched on 15 May 2013 and became operational on 21 June 2013. The fourth Block IIF GPS satellite, it forms part of the Global Positioning System. USA-242 is a 1,630-kilogram (3,590 lb) spacecraft, built by Boeing with a design life of 15 years. It operates from a semi-synchronous medium Earth orbit, at an altitude of 20,459 kilometers (12,713 mi) an inclination of 55 degrees, in slot 5 of plane C of the GPS constellation. The new satellite was originally intended to replace the seventeen-year-old USA-117 satellite, but currently both USA-117 (SVN-33) and USA-242 (SVN-66) are in active use. USA-242 broadcasts its navigation signals using the PRN-27 signal modulation. United Launch Alliance conducted the launch of GPS IIF-4, using an Atlas V 401 carrier rocket. Launch took place from Space Launch Complex 41 at the Cape Canaveral Air Force Station, with liftoff occurring at 21:38 UTC on 15 May 2013, the beginning of an 18-minute launch window. The launch marked the first time since 1985 that a GPS satellite had launched on an Atlas rocket, or indeed any rocket other than a Delta.

References

Illustrations

Worked examples

Example 1 — a first encounter with USA-242

Start with the simplest possible case. Write down what USA-242 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-242 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-242 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-242

In research: USA-242 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-242 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-242 is common in secondary-school and first-year university syllabi. It links to neighbouring topics American spacecraft stubs, GPS satellites, Spacecraft launched by Atlas rockets, so understanding it makes those chapters shorter.
In everyday life: Look for USA-242 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-242 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what USA-242 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-242 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is USA-242 in simple terms?

Why does USA-242 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-242?

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-242.