A View from David Talbot
A Successful Moon Shot for Laser Communications
A test of high-bandwidth optical communications from lunar orbiter to Earth stations succeeds.
There was no “Mr. Watson—come here—I want to see you” moment. But a pioneering space-based optical communications test has been a big success. And that means optical systems stand a higher chance not only dominating future space data transmissions (with radio systems serving as a backup) but of enabling new satellite networks that would boost the capacity of the terrestrial Internet.
A planned test of the Lunar Laser Communications Demonstration (see “NASA Moonshot Will Test Laser Communications”) aboard a probe in lunar orbit is working just as planned, delivering download speeds six times faster than the fastest radio system used for moon communications, Don Boroson, the researcher at MIT’s Lincoln Lab who led the project, says, “We have successfully hit all our marks—all the downlink rates up to 622 Mbps [and] our two uplink rates up to 20 Mbps.”
One of the toughest parts of the task: aligning ground telescopes to continually see the incoming infrared laser beam dispatched from a probe whizzing around the moon. This “signal acquisition” was “fast and reliable,” he added. His team even transmitted high-definition video of “shuttle launches, space station antics, and Earth images,” he said. “Also, some little videos we took of ourselves in the operations center.”
Ground-based detectors were set up in California, New Mexico, and one of the Canary Islands. The big difficulty with sending optical signals through the air is that they can be blocked by clouds. Still, in the future, networks of satellites could transmit data among each other and then to ground stations in various places, giving a bandwidth boost to the ground-based fiber network.