science

International Designator

International Designator 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 International Designator rather than just read about it. In short: The International Designator is an international identifier assigned to artificial objects in space. It consists of the launch year, a three-digit incrementing launch number of that year and up to a three-letter code representing the sequential identifier of a piece in a launch.

Key takeaways

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

Reference excerpt

The International Designator is an international identifier assigned to artificial objects in space. It consists of the launch year, a three-digit incrementing launch number of that year and up to a three-letter code representing the sequential identifier of a piece in a launch. In TLE format the first two digits of the year and the dash are dropped. For example, 1990-037A is the Space Shuttle Discovery on mission STS-31, which carried the Hubble Space Telescope (1990-037B) into space. This launch was the 37th known successful launch worldwide in 1990.

Historical process The designator has been generally known as the COSPAR ID, named for the Committee on Space Research (COSPAR) of the International Council for Science. COSPAR subsumed the first designation system, devised at Harvard University. That system used letters of the Greek alphabet to designate artificial satellites. This was based on the scientific naming convention for natural satellites. For example, Sputnik 1 was designated 1957 Alpha 2. The launch vehicle, which was brighter in orbit, was designated 1957 Alpha 1. Brighter objects in the same launch were given the lower integer number, and Alpha was given since it was the first launch of the year. The Harvard designation system continued to be used for satellites launched up to the end of 1962, when it was replaced with the modern system. The first satellite to receive a new-format designator was Luna E-6 No.2, 1963-001B, although some sources, including the NSSDC website, retroactively apply the new-format designators to older satellites, even those no longer in orbit at the time of its introduction.

Assignment procedure

Designators are assigned to objects by the United States Space Command along with satellite catalog numbers as they are discovered in space. The United Nations Office for Outer Space Affairs (UNOOSA) and the National Space Science Data Center (NSSDC), part of NASA, maintain two catalogs that provide additional information on the launchers and payloads associated with the designators. While UNOOSA uses COSPAR ID, many NSSDC Master Catalog (NMC) entries are created before launches so they are not always bound to a COSPAR ID. Below are examples:

Spacecraft which do not complete an orbit of the Earth, for example launches which fail to achieve orbit, are not assigned IDs.

Assignment instructions Satellites launched from the International Space Station are assigned a COSPAR ID beginning with "1998-067", because the (first module of the) space station was launched in 1998. For example, the satellite GOMX-3, launched on an H-II Transfer Vehicle on August 19, 2015, from Tanegashima Space Center in Japan, is designated COSPAR ID 1998-067HA, because it first arrived on the International Space Station from where it was later launched.

Notes

Worked examples

Example 1 — a first encounter with International Designator

Start with the simplest possible case. Write down what International Designator 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 International Designator 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 International Designator 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 International Designator

In research: International Designator 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 International Designator 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: International Designator is common in secondary-school and first-year university syllabi. It links to neighbouring topics Identifiers, Satellites, so understanding it makes those chapters shorter.
In everyday life: Look for International Designator 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 International Designator in 20 minutes

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

Frequently asked questions

What is International Designator in simple terms?

Why does International Designator 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 International Designator?

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 International Designator.