The world followed the exploits of NASA's Artemis 2 moon mission in near real-time thanks to a high-tech laser link between the astronauts and Earth that enabled high-definition streaming video and images.
Transmitting data optically, in this case by infrared light, is referred to as 'lasercom', and was at the heart of what made Artemis 2 so successful in the eyes of the public. Thanks to the high-res imagery that was made available on a daily basis, it felt like we were all riding with Artemis 2 commander Reid Wiseman, pilot Victor Glover, and mission specialists Christina Koch and Jeremy Hansen every step of the way on their voyage around the moon.
This was made possible by a device called the Orion Artemis 2Optical Communications System (O2O), developed by researchers at MIT's Lincoln Laboratory. An infrared laser, it transmitted data to Earth at bit rates of up to 260 megabytes per second — faster than some home broadband internet. Infrared signals, rather than radio, were chosen for a variety of reasons. For one thing, near-infrared light can pass through thin clouds, so an obscured sky wouldn't prevent communication. And secondly, optical light operates at a higher frequency than radio, enabling more data to be packed in.
"Our goal was to demonstrate O2O's operational utility for human spaceflight, extending the high-bandwidth connections that Internet users enjoy on Earth to astronauts in deep space," said Farzana Khatri, who is the lead systems engineer in Lincoln Laboratory's Optical and Quantum Communications Group, in a statement. "We not only demonstrated the first use of a lasercom on a crewed mission beyond low Earth orbit, but also attracted massive public engagement as the astronauts shared multimedia from their journey in near real-time."
Imagery was very important on the Artemis 2 mission. The fantastic photos such as "Hello, World" and "Earthset" didn't happen by accident. The crew had been trained at NASA's Johnson Space Center in Houston to observe and photograph the moon and Earth, and the O2O system ensured that their best images could be beamed back to Earth and spread across news sites and social media within hours of taking them.
The O2O system has its origins in a similar project developed by the Lincoln Laboratory team called the Modular, Agile, and Scalable Optical Terminal (MAScOT). It flew to the International Space Station (ISS) and was tested for the first time in 2023, itself following on from earlier lasercom tests such as NASA's Optical Payload for Lasercom Science (OPALS) instrument that beamed a 165-megabit video from the ISS in 2014.
O2O is an evolution of MAScOT. It is composed of three modules. One is an optical module featuring a 4-inch telescope that focuses the laser and gimbals to help point it. A second module contained a modem that converted electronic data into optical data. Finally, the third module consisted of a controller that interfaced with the spacecraft to help point the telescope.
The laser targeted one of three ground stations, principally NASA's White Sands Test Facility in New Mexico and the Jet Propulsion Laboratory's Table Mountain Facility in California, with a third, experimental ground station at the Australian National University's Mount Stromlo Observatory.
Initially, the intention was to have an operating window of 1 hour per day, but because O2O proved so successful at transmitting data efficiently its use increased as the mission went on. NASA mission managed even decided to adjust the Artemis 2 Orion capsule's attitude (its orientation in space) at times in order to extend the period in which it was in line of sight of a ground station, allowing even more data to be downlinked. In total, O2O transmitted half a terabyte of data over the course of the 10 day flight.
"O2O was able to downlink all the data stored on multiple onboard cameras, allowing mission control to erase the memory cards and refill them with new photos and videos," said Khatri, who also emphasized how downlinking the data via O2O actually protected that data. "For any space mission, scientists and spacecraft engineers are concerned that data not sent down during the mission can become corrupted or get destroyed. And, when the spacecraft capsule returns, downloading the data can sometimes take months. The lasercom capability provided by O2O ensured the data were preserved and immediately available for analysis."
On Earth, we already use lasers to transmit data down optical fibers, and for decades lasers have been considered the future of space communications. Radio, while simpler, has a slower data rate thanks to its low frequency limiting its bandwidth — this is why even the search for extraterrestrial intelligence (SETI) is now looking for optical signals as well as radio. Lasers can transmit 10 to 100 times more data per second than radio waves, and Khatri reckons that O2O can even improve on this and increase the downlink rate by at least another factor of 10 over what was possible during Artemis 2.
This enhanced data rate will allow the world to follow future Artemis missions even more closely, and when a human finally does set foot on the moon for the first time since the Apollo era, thanks to O2O we will feel like we are right there with them.
