science

Laser communication in space

Laser communication in space 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 Laser communication in space rather than just read about it. In short: Laser communication in space is the use of free-space optical communication in outer space. Communication may be fully in space (an inter-satellite laser link) or in a ground-to-satellite or satellite-to-ground application.

Key takeaways

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

Reference excerpt

Laser communication in space is the use of free-space optical communication in outer space. Communication may be fully in space (an inter-satellite laser link) or in a ground-to-satellite or satellite-to-ground application. The main advantage of using laser communications over radio waves is increased bandwidth, enabling the transfer of more data in less time. In outer space, the communication range of free-space optical communication is currently of the order of hundreds of thousands of kilometers. Laser-based optical communication has been demonstrated between the Earth and Moon and it has the potential to bridge interplanetary distances of millions of kilometers, using optical telescopes as beam expanders.

Demonstrations and tests

Before 1990 On 20 January 1968, the television camera of the Surveyor 7 lunar lander successfully detected two argon lasers from Kitt Peak National Observatory in Arizona and Table Mountain Observatory in Wrightwood, California.

1991–2000 In 1992, the Galileo probe proved successful one-way detection of laser light from Earth as two ground-based lasers were seen from 6,000,000 km (3,700,000 mi) by the out-bound probe. The first successful laser-communication link from space was carried out by Japan in 1995 between the NASDA's ETS-VI GEO satellite and the 1.5 m (4 ft 11 in) National Institute of Information and Communications Technology (NICT)'s optical ground station in Tokyo achieving 1 Mbit/s.

2001–2010 In November 2001, the world's first laser intersatellite link was achieved in space by the European Space Agency (ESA) satellite Artemis, providing an optical data transmission link with the CNES Earth observation satellite SPOT 4. Achieving 50 Mbps across 40,000 km (25,000 mi), the distance of a LEO-GEO link. Since 2005, ARTEMIS has been relaying two-way optical signals from Kirari, the Japanese Optical Inter-orbit Communications Engineering Test Satellite. In May 2005, a two-way distance record for communication was set by the Mercury laser altimeter instrument aboard the MESSENGER spacecraft. This diode-pumped infrared neodymium laser, designed as a laser altimeter for a Mercury orbit mission, was able to communicate across a distance of 24,000,000 km (15,000,000 mi), as the craft neared Earth on a fly-by. In 2006, Japan carried out the first LEO-to-ground laser-communication downlink from JAXA's OICETS LEO satellite and NICT's optical ground station. In 2008, the ESA used laser communication technology designed to transmit 1.8 Gbit/s across 40,000 km (25,000 mi), the distance of a LEO-GEO link. Such a terminal was successfully tested during an in-orbit verification using the German radar satellite TerraSAR-X and the American Near Field Infrared Experiment (NFire) satellite. The two Laser Communication Terminals (LCT) used during these tests were built by the German company Tesat-Spacecom, in cooperation with the German Aerospace Center (DLR).

2011–2020

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Illustrations

Worked examples

Example 1 — a first encounter with Laser communication in space

Start with the simplest possible case. Write down what Laser communication in space 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 Laser communication in space 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 Laser communication in space 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 Laser communication in space

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

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

Frequently asked questions

What is Laser communication in space in simple terms?

Why does Laser communication in space 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 Laser communication in space?

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 Laser communication in space.