astronomy

Optus D3

Optus D3 is a astronomy 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 Optus D3 rather than just read about it. In short: Optus D3 is an Australian geostationary communications satellite, which is operated by Optus and provides communications services to Australasia. D3 was the third Optus-D satellite to be launched.

Key takeaways

Optus D3 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Optus D3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Optus D3 from memory before moving on to harder problems.

Reference excerpt

Optus D3 is an Australian geostationary communications satellite, which is operated by Optus and provides communications services to Australasia. D3 was the third Optus-D satellite to be launched. It is a 2,401-kilogram (5,293 lb) satellite, which was constructed by Orbital Sciences Corporation based on the Star-2.4 satellite bus, with the same configuration as the earlier Optus D2 satellite. It was launched, along with the Japanese JCSAT-12 satellite, by Arianespace. An Ariane 5ECA rocket was used for the launch, which occurred from ELA-3 at the Guiana Space Centre in Kourou, French Guiana. The launch took place at 22:09 GMT on 21 August 2009, at the start of a 60-minute launch window. Optus D3 separated from its carrier rocket into a geosynchronous transfer orbit, from which it raised itself to geostationary orbit using an IHI -500-N apogee motor. It has a design life of fifteen years, and carries thirty two J band transponders (US IEEE Ku band). Optus D3 will be visited by Mission Extension Vehicle-1, which will dock to Optus D3 and extend the mission of the satellite by 5-7 years.

Worked examples

Example 1 — a first encounter with Optus D3

Start with the simplest possible case. Write down what Optus D3 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 Optus D3 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 Optus D3 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 Optus D3

In research: Optus D3 appears in astronomy 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 Optus D3 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: Optus D3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Communications satellite constellations, Communications satellite stubs, Optus, so understanding it makes those chapters shorter.
In everyday life: Look for Optus D3 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 Optus D3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Optus D3 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 Optus D3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Optus D3 in simple terms?

Optus D3 is an Australian geostationary communications satellite, which is operated by Optus and provides communications services to Australasia. D3 was the third Optus-D satellite to be launched.

Why does Optus D3 matter?

Because it connects several astronomy 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 Optus D3?

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 Optus D3.