science

SDS-4

SDS-4 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 SDS-4 rather than just read about it. In short: SDS-4 (Small Demonstration Satellite 4) is a small satellite (50 cm cube with mass of 50 kg) developed by JAXA. It was launched as a secondary payload on the Shizuku mission on 17 May 2012 UTC.

Key takeaways

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

Reference excerpt

SDS-4 (Small Demonstration Satellite 4) is a small satellite (50 cm cube with mass of 50 kg) developed by JAXA. It was launched as a secondary payload on the Shizuku mission on 17 May 2012 UTC. In 2019, its ownership was transferred to the SKY Perfect JSAT Corporation (JSAT). Operation was terminated by the end of June 2021. There are four rather specialised systems on the satellite:

SPAISE (SPace-based Automatic Identification SystEm) - test on-orbit a receiver for picking up signals from Automatic Identification System transmitters on ships well out to sea, and determine how space-based reception is affected by interference between nearby transmitters and by environmental conditions. FOX (Flat heat-pipe on-orbit experiment) - to test whether flat heat pipes work in space in accordance with theoretical models and with tests on Earth IST (In-flight experiment of Solar absorption rate with THERME) - to acquire information about the effect of sunlight in space on thermal coatings, re-flying the THERME instrument developed by CNES for testing different thermal coatings QCM (Quartz Crystal Microbalance) - to test whether a Japanese-manufactured quartz microbalance works well in monitoring contamination of the satellite from assembly to on-orbit operation.

References

Worked examples

Example 1 — a first encounter with SDS-4

Start with the simplest possible case. Write down what SDS-4 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 SDS-4 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 SDS-4 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 SDS-4

In research: SDS-4 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 SDS-4 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: SDS-4 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Asian spacecraft stubs, Satellites of Japan, Secondary payloads, so understanding it makes those chapters shorter.
In everyday life: Look for SDS-4 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 SDS-4 in 20 minutes

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

Frequently asked questions

What is SDS-4 in simple terms?

SDS-4 (Small Demonstration Satellite 4) is a small satellite (50 cm cube with mass of 50 kg) developed by JAXA. It was launched as a secondary payload on the Shizuku mission on 17 May 2012 UTC.

Why does SDS-4 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 SDS-4?

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 SDS-4.