NASA launched its Laser Communication Relay Demonstration (LCRD) on December 7, 2021 from the Cape Canaveral Space Force Station in Florida.
The tech demo experiment embarked on a two-year series of experiments to test how optical communications links could help downlink large volumes of information faster than traditional radio-based communications systems. The test data will be sent through radio waves while the LCRD will reply using optical signals.
STPSat 6, the satellite hosting the LCRD payload, will be positioned in geosynchronous orbit, over 35,000 km above the Earth post launch. NASA has set up two ground sites in Hawaii and California to link up with the LCRD payload in space. The satellite will be controlled by the ground engineers at these stations.
LCRD is NASA’s first two-way optical communications relay satellite intended to demonstrate the benefits of optical technologies, such as higher data transmission and less size, weight, and power requirements. The LCRD will also validate the use of optical relays, which could be used for Mars one day, said NASA.
As missions generate and collect more data, higher bandwidth is needed to relay data back to the Earth. The LCRD will replace radio frequency to send data with an increased bandwidth that is 10 to 100 times higher than the radio waves. It will demonstrate how to use laser systems for space communications and soon will be able to implement lasers on more missions as a standard means of communications.
The LCRD payload consists of two optical communication terminals and a switching unit, allowing the instrument to receive a signal, transition the data to a transmitter, then beam the signal to its destination.
It works with infrared lasers, which are invisible to the human eye.
There are two optical terminals to receive and transmit data to user spacecrafts and ground stations respectively. With the modems, digital data will be translated to laser signals and transmitted via an encoded beam of lights.
Laser communications and radio waves use different wavelengths of light. Laser wavelengths are 10,000 times shorter than radio waves, meaning data can travel in narrower beams. Hence, more data will be transmitted in less time via laser mode. A laser would be able to send data in 9 days whereas radio waves would take 9 weeks to send the same data, said NASA. The laser terminals on the tech demo experiment will downlink data at a rate of 1.2 gigabits per second.
Optical communication requires a smaller set-up with units smaller in size, weight and require less power. Radio instruments on the hand are quite bulky and hence the former saves room for more science instruments and cost of the launch also decreases. The spacecraft batteries will drain less and missions will end up having unparalleled capabilities, the agency says.
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