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USA-168

USA-168 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-168 rather than just read about it. In short: USA-168, also known as GPS IIR-9 and GPS SVN-45, is an American navigation satellite which forms part of the Global Positioning System. It was the ninth Block IIR GPS satellite to be launched, out of thirteen in the original configuration, and twenty one overall.

USA-168 — main illustration
USA-168 — illustration

Key takeaways

  • USA-168 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-168 to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of USA-168 from memory before moving on to harder problems.

Reference excerpt

USA-168, also known as GPS IIR-9 and GPS SVN-45, is an American navigation satellite which forms part of the Global Positioning System. It was the ninth Block IIR GPS satellite to be launched, out of thirteen in the original configuration, and twenty one overall. It was built by Lockheed Martin, using the AS-4000 satellite bus. USA-168 was launched at 22:09:01 UTC on 31 March 2003, atop a Delta II carrier rocket, flight number D297, flying in the 7925-9.5 configuration. The launch took place from Space Launch Complex 17A at the Cape Canaveral Air Force Station, and placed USA-168 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37FM apogee motor. By 3 April 2003, USA-168 was in an orbit with a perigee of 20,063 kilometres (12,467 mi), an apogee of 20,433 kilometres (12,696 mi), a period of 720.64 minutes, and 54.9 degrees of inclination to the equator. It is used to broadcast the PRN 21 signal, and operates in slot 3 of plane D of the GPS constellation. The satellite has a mass of 2,032 kilograms (4,480 lb), and a design life of 10 years. USA-168 was decommissioned and removed from the GPS constellation on 27 January 2025.

References

Illustrations

USA-168 illustration

Worked examples

Example 1 — a first encounter with USA-168

Start with the simplest possible case. Write down what USA-168 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-168 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-168 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-168

In research
USA-168 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-168 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-168 is common in secondary-school and first-year university syllabi. It links to neighbouring topics American spacecraft stubs, GPS satellites, Spacecraft launched in 2003, so understanding it makes those chapters shorter.
In everyday life
Look for USA-168 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-168 in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what USA-168 means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain USA-168 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is USA-168 in simple terms?

USA-168, also known as GPS IIR-9 and GPS SVN-45, is an American navigation satellite which forms part of the Global Positioning System. It was the ninth Block IIR GPS satellite to be launched, out of thirteen in the original configuration, and twenty one overall.

Why does USA-168 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-168?

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-168.

Tags

  • American spacecraft stubs
  • GPS satellites
  • Spacecraft launched in 2003
  • USA satellites

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