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Infrared Lasers Transmit Data at Record Speeds

Infrared Lasers Transmit Data at Record Speeds

NASA is developing an optical space communications system that will use infrared lasers to transmit data at speeds up to 260 megabits per second.
NASA is developing new communications technology that can transmit large amounts of data, including high-definition pictures and videos, to and from Earth via invisible beams of infrared (IR) light.  

Called optical space communications (OSC), the system involves communication links among satellites, spacecraft, and ground-based stations. IR lasers send data across space instead of radio frequencies (RF).  

Both RF and IR are electromagnetic radiation with wavelengths at different points on the electromagnetic spectrum. They also both carry data that is encoded into electromagnetic signals and transmitted to different stations. However, unlike RF, IR can store more data and transmit data at higher speeds, giving IR a big advantage over RF. IR light packs more data into much tighter waves, meaning ground stations can receive more data in a single downlink. 

With IR, data transfer rates are expected to be 10 to 100 times faster than current radio frequency systems. As an example, it takes roughly 60 days to transmit a complete map of Mars back to Earth using current RF systems; with lasers, it would only take about nine days.  

Benefits and challenges 

The ability to exploit higher data rates expands the engineering possibilities to create new high-definition instruments that collect larger volumes of data. OSC flight terminals are smaller, lighter, and require less power than standard RF transmission systems, saving energy. Smaller ground terminals could also be built for low-Earth missions at mission sites or data centers. In space, laser communications terminals use narrower beam widths than radio frequency systems, providing smaller footprints that can minimize interference or improve security. 

Perhaps the biggest challenge to OSC is maintaining exact positioning between a laser communications telescope in space pointing to a ground station that is thousands or millions of miles away. Misalignments result in less efficient data transfer; a deviation of even a fraction of a degree can result in the laser missing its target entirely. 

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Earth’s atmosphere is another complication. Weather conditions such as clouds and rain can impair or interrupt laser communications. A possible solution is having enough ground stations available so that if one station is cloudy, the data-enriched waves can be redirected to a different ground station where the weather is clear. 

Artemis II, the follow-up mission to the successful Artemis 1 mission, is scheduled for launch in November 2024. Artemis II will rely on an optical communication system that is still in development called the Orion Artemis II Optical Communications System (O2O). The development team for this system includes experts from the Massachusetts Institute of Technology, NASA’s Glenn Research Center, Jet Propulsion Laboratory, Peraton, and Northrop Grumman. 

The Artemis II mission will also mark the first time that a team of astronauts uses laser communications in space. O2O will allow the Artemis crew to send ultra-high-definition video feeds over laser links to Earth, transmitting data at a downlink rate of up to 260 megabits per second. Not only will O2O provide higher data rates, but it will be smaller, weigh less, and consume less power, making it more efficient than comparable radio systems.  

Deep space 

NASA continues to explore even more challenging laser communications in deep space. For example, the agency is working on a future terminal that could test laser communications over extreme distances in space and challenging pointing constraints.  

In April 2023, NASA’s tissue box-sized satellite, TeraByte InfraRed Delivery or TBIRD, set a new record for the fastest data transfer rate ever performed in space at 200 gigabits per second. TBIRD transferred 3.6 terabytes in six minutes from space to Earth, the rough equivalent of one million songs. 

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A truly long-distance effort involves NASA's Psyche spacecraft. Launched in October 2023, the spacecraft is headed for a metal-rich asteroid that orbits the sun between Mars and Jupiter. If all goes well, Psyche will start exploring the asteroid in 2029. During the mission, NASA scientists plan to test distant laser communication as the spacecraft travels hundreds of millions of miles toward its destination. 

Whether bringing laser communications to near-Earth missions, the Moon, or deep space, the infusion of optical systems will be integral for future NASA missions. 

“Laser communications’ higher data rates will enable exploration and science missions to send more data back to Earth and discover more about the universe,” according to NASA. The agency “will be able to use information from images, video, and experiments to explore not just the near-Earth region, but to also prepare for future missions to Mars and beyond.” 

Mark Crawford is a technology writer in Corrales, N.M. 

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