science

USA-309

USA-309 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-309 rather than just read about it. In short: USA-309, also known as GPS-III SV04, NAVSTAR 80 or Sacagawea, is a United States navigation satellite which forms part of the Global Positioning System. It was the fourth GPS Block III satellite to be launched.

Key takeaways

USA-309 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-309 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of USA-309 from memory before moving on to harder problems.

Reference excerpt

USA-309, also known as GPS-III SV04, NAVSTAR 80 or Sacagawea, is a United States navigation satellite which forms part of the Global Positioning System. It was the fourth GPS Block III satellite to be launched.

Satellite SV04 is the fourth GPS Block III satellite to be launched. Launch was pushed back several times due to delays with the earlier satellites. The spacecraft is built on the Lockheed Martin A2100 satellite bus, and weighs in at 4,331 kg (9,548 lb).

Launch USA-309 was launched by SpaceX on 5th of November 2020 at 23:24 UTC atop Falcon 9 booster B1062. The launch took place from SLC-40 of the Cape Canaveral Air Force Station, and placed USA-309 directly into semi-synchronous orbit. About eight minutes after launch, Falcon 9 B1062 successfully landed on the droneship Of Course I Still Love You.

Orbit As of 2021, USA-309 was in a 54.9 degree inclination orbit with a perigee of 20,181 kilometers (12,540 mi) and an apogee of 20,198 km (12,550 mi).

References

Illustrations

Worked examples

Example 1 — a first encounter with USA-309

Start with the simplest possible case. Write down what USA-309 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-309 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-309 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-309

In research: USA-309 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-309 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-309 is common in secondary-school and first-year university syllabi. It links to neighbouring topics GPS satellites, SpaceX military payloads, Spacecraft launched in 2020, so understanding it makes those chapters shorter.
In everyday life: Look for USA-309 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-309 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what USA-309 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-309 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is USA-309 in simple terms?

Why does USA-309 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-309?

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-309.