NASA’s Laser Communications Relay Demonstration (LCRD) will send data to and from ground stations and, eventually, in-space user missions over laser links.

While LCRD’s experimenter program will allow NASA and industry to test and refine techniques, both the agency and the commercial sector have been demonstrating and using laser communications for the past few decades.

LCRD is led by Goddard and in partnership with JPL and the MIT Lincoln Laboratory. LCRD is funded through NASA’s Technology Demonstration Missions program, part of the Space Technology Mission Directorate, and the Space Communications and Navigation (SCaN) program at NASA Headquarters in Washington, D.C.

While industry is focused on in-space optical communications to support terrestrial users, NASA is demonstrating direct-to-Earth capability from geosynchronous orbit to increase communications capabilities for future missions. With laser communications onboard, missions will be able to communicate more data in a single transmission than they could with traditional radio frequency communications.

NASA is committed to fostering the growing space economy and the commercial aerospace community to encourage technological innovation/ bring down costs for all users. This dedication extends to new technologies and capabilities like laser communications systems.

Generally, commercial efforts have been focused on developing space-to-space laser systems for use in low-Earth orbit. Companies are investing in satellite constellations which leverage laser communications to provide global broadband coverage. Proposed constellations have several hundred to thousands of satellites, creating an extensive in-space laser communications network. Commercial constellations still largely rely on radio frequency links to send data back to Earth. Whereas LCRD uses lasers for both in-space and direct-to-Earth communications.

Schlieren and shadowgraph techniques are basic and valuable tools in various scientific and engineering disciplines. They allow us to see the invisible: the optical inhomogeneities in transparent media like air, water, and glass that otherwise cause only ghostly distortions of our normal vision.

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Katherine Schauer is a writer for the Space Communications and Navigation (SCaN) program office and covers emerging technologies, commercialization efforts, exploration activities, and more.

"If you use or are interested in schlieren or shadowgraph research, you really need this text. … This book not only covers the theory behind the techniques, but it also shows what is needed to get started, by showing how to design and setup a system." (IEEE Electrical Insulation Magazine, Vol. 19 (6), 2003)

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Banner image: Illustration of STPSat-6 with the Laser Communications Relay Demonstration (LCRD) payload communicating data over infrared links. Credit: NASA’s Goddard Space Flight Center

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Topics: Engineering Fluid Dynamics, Fluid- and Aerodynamics, Engineering, general, Optics, Lasers, Photonics, Optical Devices, Thermodynamics, Industrial Chemistry/Chemical Engineering

“The Earth’s atmosphere distorts laser beams due to turbulence. Understanding these challenges are critical to enabling operational optical communications relay capability,” said Jason Mitchell, Director of the Advanced Communications and Navigation Technology division in the Space Communications and Navigation (SCaN) program at NASA Headquarters.

“Free-space” refers to the absence of the insulated, fiber optic cables that enable the terrestrial internet. Free-space laser communications flow freely through the vacuum of space, however atmosphere poses unique challenges to communications engineers.

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"The author begins with an interesting description of historical background, beginning with the ‘micrografia’ of Hooke (1665). … After explaining basic concepts like the light propagation through inhomogeneous media, the distinction between schlieren and shadowgraph methods are pointed out. … It is an extremely useful book for the users of these techniques." (W. Wuest, Zentralblatt MATH, Vol. 987 (12), 2002)

NASA and commercial aerospace companies are applying similar technologies to space communications, bringing optical speeds to the final frontier. Free-space optical communications leverages recent advancements in telecommunications to allow spacecraft to send high-resolution images and videos over laser links.

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These techniques are discussed briefly in many books and papers, but there is no up-to-date complete treatment of the subject before now. The book is intended as a practical guide for those who want to use these methods, as well as a resource for a broad range of disciplines where scientific visualization is important. The colorful 400-year history of these methods is covered in an extensive introductory chapter accessible to all readers.

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... This reviewer recommends Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transport Media to anyone interested in optical systems for flow visualization, and other studies benefiting from visualization of physical phenomena of transparent media. Even in the current period of competition for resources, an engineering librarian should carefully consider the customer's needs before deciding not to add this book to the library's collection. (from Applied Mechanics Reviews, 55, 4, B76, July 2002)

With these two different yet complementary goals, NASA also is partnering with industry to further refine laser communications hardware. In fact, LCRD includes commercially designed and built components alongside custom, NASA-developed systems. The optical module, which sends lasers to and from the payload, was designed by the Massachusetts Institute of Technology Lincoln Laboratory and built at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. However, multiple parts of LCRD came from companies like L3Harris Technologies, SEAKR Engineering, Moog Inc., and the Sierra Nevada Corporation. These include the telescope system, controller electronics system, and space switching unit – all critical to LCRD operations.

"Schlieren and shadowgraph techniques are basic and valuable tools in various scientific and engineering disciplines. They allow us to see the invisible: the optical inhomogeneities in transparent media like air, water and glass that otherwise cause only ghostly distortions of our normal vision. This book is intended as a practical guide for those who want to use these methods, as well as a resource for a broad range of disciplines where scientific visualization is important." (ETDE – Energy Database, April, 2002)

NASA explores the unknown in air and space, innovates for the benefit of humanity, and inspires the world through discovery.

LCRD’s mission will be spent proving out the technology by testing laser communications capabilities with experiments from NASA, other government agencies, academia, and – in particular – the commercial aerospace community. Industry-developed experiments will allow companies to test their own technologies, software, and capabilities. NASA is providing these opportunities to grow the body of knowledge surrounding laser communications and promote its operational use.

The U.S. Department of Defense’s Space Test Program Satellite-6 (STPSat-6), part of the Space Test Program 3 (STP-3) mission, will launch on a United Launch Alliance Atlas V 551 rocket from the Cape Canaveral Space Force Station in Florida no earlier than December 5, 2021. STP is managed by the United States Space Force’s Space Systems Command.

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Additionally, NASA’s Low-Cost Optical Terminal (LCOT) will use commercial off-the-shelf or slightly modified hardware to reduce expense and speed implementation. NASA depends on a robust domestic space industry and hopes these investments will allow the U.S. government to purchase future laser communications hardware and services. This will decrease costs while enabling more missions to use laser communications.

Our televisions and computer screens display news, movies, and shows in high-definition, allowing viewers a clear and vibrant experience. Fiber optic connections send laser light densely packed with data through cables to bring these experiences to users.