Aboard the International Space Station (ISS), astronauts and cosmonauts from many nations are performing vital research that will allow humans to live and work in space. For more than 20 years, the ISS has been a unique platform for conducting microgravity, biology, agriculture, and communications experiments. This includes the ISS broadband internet service, which transmits information at a rate of 600 megabits per second (Mbps) – ten times the global average for internet speeds!
In 2021, NASA’s Space Communications and Navigation (SCaN) began integrating a technology demonstrator aboard the ISS that will test optical (laser) communications and data transfer. This system currently consists of Laser Communications Relay Demonstration (LCRD) and will soon be upgraded with the addition of the Integrated LCRD Low Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T). Once complete, this system will be the first two-way, end-to-end laser relay system, giving the ISS a gigabit internet connection!
The system relies on infrared light, which allows for information to be sent and received at higher data rates and will showcase the benefits a laser relay array could have for missions in low Earth orbit. This system will also allow missions beyond LEO to send more images and videos back to Earth in a single transmission. In addition to higher data rates, laser systems are lighter and use less power than conventional radio communications. The ILLUMA-T system measures only a few cubic meters and will be launched as part of SpaceX’s 29th Commercial Resupply Services (CRS) mission.
““Laser communications offer missions more flexibility and an expedited way to get data back from space,” said Badri Younes, the former deputy associate administrator for NASA’s SCaN program, NASA press release, “We are integrating this technology on demonstrations near Earth, at the Moon, and in deep space.” Once it reaches the ISS, the ILLUMA-T will be secured to an external module to conduct its demonstration with the LCRD. Recently, NASA concluded a year-long campaign, conducting experiments with the LCRD to refine NASA’s laser capabilities further.
These experiments have also demonstrated the benefits of laser relay communications in geosynchronous orbit (GSO) by beaming data between two ground stations: Optical Ground Station -1 (OGS-1) in California and OGS-2 in Haleakal?, Hawaii. Said Matt Magsamen, deputy project manager for ILLUMA-T:
“Once ILLUMA-T is on the space station, the terminal will send high-resolution data, including pictures and videos to LCRD at a rate of 1.2 gigabits-per-second. Then, the data will be sent from LCRD to ground stations in Hawaii and California. This demonstration will show how laser communications can benefit missions in low Earth orbit.”
ILLUMA-T will be installed on an external mount on the Japanese Experiment Module-Exposed Facility (JEM-EF), also known as “Kibo” (“hope” in Japanese). The ILLUMA-T team will then perform preliminary testing and in-orbit checkouts, followed by a first light test, where the mission will transmit its first beam of laser light through its optical telescope to the LCRD. These tests build on previous experiments, including the 2022 TeraByte InfraRed Delivery system (TBIRD), which is currently testing laser communications on small CubSat in LEO.
There were also experiments NASA conducted in 2014 as part of the Lunar Atmosphere and Dust Environment Explorer mission (LADEE), where the Lunar Laser Communications Demonstration (LLCD) transferred data between lunar orbit and Earth. The Optical Payload for Lasercomm Science in 2017 also demonstrated how laser communications can offer improved data transfer between Earth and space compared to radio signals. Once first light is achieved, experiments will commence and continue for the duration of the mission.
These tests will test the viability of laser communications in various scenarios and inform future missions to the Moon, Mars, and beyond. It is anticipated that robotic and crewed missions will rely on laser communications to supplement radio systems. These will allow for high-broadband communications between astronauts and their families back home, which is essential for long-duration missions. It will also allow robotic probes to send larger volumes of data back to Earth, greatly increasing the scientific returns of individual missions.
Further Reading: NASA