astronomy

Galaxy 4R

Galaxy 4R 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 Galaxy 4R rather than just read about it. In short: Galaxy 4R was a communications satellite operated by PanAmSat from 2000 to 2006, and by Intelsat from 2006 to 2009. It spent most of its operational life at an orbital location of 99° W, a slot once occupied by the Galaxy IV, which suffered a failure in 1998.

Key takeaways

Galaxy 4R belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Galaxy 4R to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Galaxy 4R from memory before moving on to harder problems.

Reference excerpt

Galaxy 4R was a communications satellite operated by PanAmSat from 2000 to 2006, and by Intelsat from 2006 to 2009. It spent most of its operational life at an orbital location of 99° W, a slot once occupied by the Galaxy IV, which suffered a failure in 1998. G4R was launched on April 18, 2000, with an Ariane launch vehicle, and covered North America with twenty-four transponders each on the C- and Ku bands. The satellite was stationed at 76.8°W, inclined. Users included Warner Brothers, National Public Radio, Public Radio International, Buena Vista Television Distribution, FOX, and Televisa. The satellite was also utilized for satellite internet services through DirecPC. Much of the Ku side was occupied by the HITS service, which re-distributes programming found on other satellites to cable providers. Designed for an operational lifespan of 15 years, Galaxy 4R suffered a propulsion system failure in 2003 and was replaced by Galaxy 16 on August 14, 2006. It was moved to 76.85 degrees west after being replaced and its orbit was allowed to become more inclined in order to save station-keeping propellant. The satellite was decommissioned in April 2009 and moved to a graveyard orbit.

References

External links

Galaxy 4R at the Wayback Machine (archived February 18, 2006)

Worked examples

Example 1 — a first encounter with Galaxy 4R

Start with the simplest possible case. Write down what Galaxy 4R 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 Galaxy 4R 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 Galaxy 4R 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 Galaxy 4R

In research: Galaxy 4R 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 Galaxy 4R 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: Galaxy 4R is common in secondary-school and first-year university syllabi. It links to neighbouring topics Communications satellite stubs, Communications satellites in geostationary orbit, Derelict satellites orbiting Earth, so understanding it makes those chapters shorter.
In everyday life: Look for Galaxy 4R 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Galaxy 4R in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Galaxy 4R 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 Galaxy 4R out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Galaxy 4R in simple terms?

Why does Galaxy 4R 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 Galaxy 4R?

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 Galaxy 4R.