astronomy

Palapa-D

Palapa-D 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 Palapa-D rather than just read about it. In short: Palapa-D was an Indonesian geostationary communications satellite which was operated by Indosat Ooredoo. It was built by Thales Alenia Space, based on the Spacebus-4000B3 satellite bus, and carries 35 C-band and 5 Ku-band transponders.

Key takeaways

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

Reference excerpt

Palapa-D was an Indonesian geostationary communications satellite which was operated by Indosat Ooredoo. It was built by Thales Alenia Space, based on the Spacebus-4000B3 satellite bus, and carries 35 C-band and 5 Ku-band transponders. It was positioned in geostationary orbit at a longitude of 113° East, where it replaced the Palapa-C2 satellite. Indosat ordered Palapa-D from Thales Alenia Space on 2 July 2007. The satellite was built without using American components, and was therefore not restricted by U.S. International Traffic in Arms Regulations (ITAR), which allowed the China Great Wall Industry Corporation to be selected as a launch service provider.

Launch A Long March 3B launch vehicle, flying from Launch Area-2 at the Xichang Satellite Launch Centre was used to launch Palapa-D. A problem with the third stage of its carrier rocket left it in an incorrect orbit, which was subsequently corrected using the spacecraft's onboard propulsion system. After launch, Palapa-D was to have separated from its launch vehicle into a geosynchronous transfer orbit (GTO), however one of its two identical upper-stage engines failed to deliver the necessary thrust, resulting in it reaching a lower orbit than planned. The S400 apogee motor of the satellite was subsequently used in for raise it into geostationary orbit.

Recovery and operations On 3 September 2009, the satellite's orbit was adjusted, placing it into a geostationary transfer orbit (GTO). It reached geostationary orbit on 9 September 2009. It underwent on-orbit testing, and arrived at its orbital slot of 113° East in mid-September 2009. After completing its testing, it is now being used to provide communications to Asia and Australia. Palapa-D was built with a design life of fifteen years, but due to the expenditure of fuel during maneuvers to correct its orbit, it was expected to have enough fuel for about ten years of operations, according to Reynald Seznec, President of Thales Alenia Space. Thales Alenia Space announced that the Palapa-D communications satellite is now positioned at its final location (113° East) and fully ready for operations for more than 10.5 years. On 31 August 2020, Palapa-D was officially declared inadequate for operation after it was close to running out of fuel for stationkeeping and all of its transponder services were officially moved to Telkom-4 (Merah Putih) and BRIsat satellites for broadcasting and data services respectively.

Replacement Palapa-D was planned to be replaced by the Nusantara Dua (Palapa-N1) satellite; the launch of Nusantara Dua on 9 April 2020 by Chinese Long March 3B/E launch vehicle was a failure, resulting in the loss of the satellite. A replacement satellite (Nusantara-2R or Palapa-N1R) to be built by the same manufacturer (China Academy of Space Technology/CAST) is being considered, albeit with possibly different specifications with the lost one. However, on 28 October 2021, Telkomsat awarded the replacement satellite (working designation HTS-113BT) contract to Thales Alenia Space instead of CAST using the Spacebus-4000B2 platform, with planned launch for 2024. The HTS-113BT is expected to have similar specifications to the lost one.

Worked examples

Example 1 — a first encounter with Palapa-D

Start with the simplest possible case. Write down what Palapa-D 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 Palapa-D 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 Palapa-D 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 Palapa-D

In research: Palapa-D 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 Palapa-D 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: Palapa-D is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2009 in Indonesia, Communications in Indonesia, Communications satellites in geostationary orbit, so understanding it makes those chapters shorter.
In everyday life: Look for Palapa-D 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 Palapa-D in 20 minutes

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

Frequently asked questions

What is Palapa-D in simple terms?

Why does Palapa-D 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 Palapa-D?

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 Palapa-D.