April 23, 2024

NASA’s Laser Communications Relay Demonstration will be launched this summer. It will demonstrate the dynamic capabilities of laser communications technology. NASA’s increasing human and robotic presence in space can allow missions to benefit from a new “talking” method with Earth.

NASA has used radio frequency communications since the 1950s to transmit data to and from orbit. Missions will have unprecedented data capabilities thanks to laser communications, also called optical communications.

Why lasers?

Missions will require faster ways to send information to Earth as science instruments become more capable of capturing high-definition data such as 4K video. NASA can use laser communications to speed up data transfer and enable more discoveries significantly.

Laser communications will allow for 10 to 100 times greater data transmission back to Earth than the current radio frequency systems. It would take roughly nine weeks to transmit a complete map of ” data-gt-translate-attributes='[“attribute”: “data-cm tooltip,” “format”: “html”]’>Mars back to Earth with current radio frequency systems. It would take nine days if you used lasers.

Laser communications systems are also ideal for missions, requiring less power, volume, and weight. Laser communications systems are lighter and need less energy, so there is more space for science instruments. These are critical considerations for NASA in designing and developing mission concepts.

“LCRD will show all the benefits of laser systems and enable us to learn how they work best operationally,” stated Principal Investigator David Israel, NASA’s Goddard Space Flight Center Greenbelt. “With this capability further demonstrated, we can begin to implement laser communication on more missions making it a standard way to send and get data.”

How it works

Radio waves and infrared radiation are electromagnetic radiation that has wavelengths at different parts of the electromagnetic spectrum. Infrared light, similar to radio waves, is invisible to the human eyes but is present daily in things like TV remotes and heat lamps.

To traverse distances between ground stations on Earth and spacecraft, missions modulate their data onto electromagnetic signals. The waves propagate as the communication travels.

Laser communications use infrared lights that are different from radio waves. This is because infrared packs data into much smaller waves. Ground stations can therefore receive more data at once. Laser communications can transmit more data in one downlink, even though they are slower.

Space-based laser communications terminals use narrower beam widths than radio frequency systems. This allows for smaller footprints, which can reduce interference and improve security. A laser communications telescope that points to a ground station must be precise when broadcasting from distances of thousands or millions. Any deviation from the target can cause it to miss its mark completely. The quarterback must know the ball’s exact location, just like a quarterback throws a football to a receiver. The signal is sent to the receiver so they can catch it in stride. NASA’s laser communications engineers designed laser missions to ensure this connection is possible.

Laser Communications Relay Demonstration

LCRD is located in geosynchronous orbit at 22,000 miles above Earth. It will be able to support missions in the Near-Earth Region. LCRD will spend the first two years testing laser communication capabilities. Numerous experiments will be conducted to improve laser technology and increase our knowledge of future potential applications.

LCRD’s first experiment phase will use the ground stations in California, Hawaii, Optical Ground Stations 1 & 2, as simulated users. NASA can test atmospheric disturbances on lasers and practice switching support between users. After the experiment phase, LCRD will move to support space missions by sending and receiving data from satellites using infrared lasers. This will demonstrate the advantages of a laser communications relay network.

NASA’s Integrated LCRD low-earth orbit user modem and amplifier terminal (ILLUMA–T) will be the first to use LCRD in space. It is scheduled to launch on the International Space Station in 2020. This terminal will collect high-quality science data from instruments and experiments onboard the space station and then transmit this data to LCRD at 1.2 gigabits per Second. The data will be sent to ground stations by LCRD at the same speed.

ILLUMA-T and LCRD follow the 2013 Lunar Laser Communications Demonstration. This demonstration downlinked data at 622 megabits-per-second using a laser signal, proving the capability of laser systems on the Moon. NASA is currently developing many other laser communication missions. Each mission will expand our understanding of the advantages and challenges of laser communication and standardize the technology.

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