science

PROCYON

PROCYON 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 PROCYON rather than just read about it. In short: PROCYON (Proximate Object Close flyby with Optical Navigation) was an asteroid flyby space probe that was launched together with Hayabusa2 on 3 December 2014 13:22:04 (JST). It was developed by University of Tokyo and JAXA.

Key takeaways

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

Reference excerpt

PROCYON (Proximate Object Close flyby with Optical Navigation) was an asteroid flyby space probe that was launched together with Hayabusa2 on 3 December 2014 13:22:04 (JST). It was developed by University of Tokyo and JAXA. It was a small (70 kg, approx. 60 cm cube), low cost (¥500 million) spacecraft. It was intended to flyby the asteroid (185851) 2000 DP107 in 2016, but the plan was abandoned due to the malfunction of the ion thruster.

Mission overview PROCYON was launched as secondary payload together with the Hayabusa2 asteroid landing probe. After separation from the carrier rocket, PROCYON was left on a heliocentric orbit. On 22 February 2015, the ion engine was started, with the intention of adjusting the orbit so that an Earth flyby in December 2015 would direct the probe towards asteroid 2000 DP107. Initial results were favourable - the engine delivered 330 μN of thrust rather than the designed 250 μN - but the engine failed on 10 March and could not be restarted; PROCYON flew past Earth on 3 December 2015, but was unable to make a controlled orbit change. Shortly after the Earth flyby, contact with the spacecraft was lost. The 70 kg spacecraft had a specific impulse of 1000 seconds, for a delta-v budget of about 500 m/s; the intention was to use 20% of the xenon propellant for the initial orbit correction, and the rest of the propellant between the Earth flyby and the asteroid flyby to ensure a controlled flyby distance of 30 km. A novel subsystem tested by PROCYON involved feeding both the main ion engine and the eight attitude control cold-gas thrusters from the same tank (containing 2.5 kg of xenon at launch)

Instruments Small telescope for near-asteroid navigation and data acquisition. Lyman-alpha imaging camera to observe geocorona

Science results PROCYON observed the Lyman-alpha emission of comet 67P/Churyumov–Gerasimenko to determine its overall coma structure. PROCYON captured the first complete image of the geocorona, confirming for the first time that it has north–south symmetry.

Worked examples

Example 1 — a first encounter with PROCYON

Start with the simplest possible case. Write down what PROCYON 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 PROCYON 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 PROCYON 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 PROCYON

In research: PROCYON 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 PROCYON 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: PROCYON is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2014 in Japan, Earth flybys, Japanese inventions, so understanding it makes those chapters shorter.
In everyday life: Look for PROCYON 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 PROCYON in 20 minutes

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

Frequently asked questions

What is PROCYON in simple terms?

Why does PROCYON 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 PROCYON?

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 PROCYON.