In October 2013, a moon-orbiting NASA spacecraft aimed a laser beam at Earth, 239,000 miles away. Within seconds, the intended recipient—an observatory in New Mexico—locked onto the beam of infrared light, invisible to the naked eye. Encoded inside the light was a high-definition video of NASA administrator Charles Bolden delivering a short speech.
Bolden had, of course, recorded the video on Earth. NASA had first beamed the video up via laser link to the spacecraft, which beamed it right back down. “We’re making a leap in space communications ability that is unmatched in NASA’s history,” Bolden proclaimed in the video while flanked by US and NASA flags. It was—and still is—the furthest anyone has ever beamed an infrared laser message.
But engineers at NASA, the European Space Agency, and private companies like Airbus are preparing more ambitious laser communications projects in the next few years. They think that lasers—not radio—are the future of space data. If they have their way, the data that creates your snowstorm forecasts and Jupiter photos will rain down from the sky in the form of infrared light.
Right now, climate-monitoring satellites, the International Space Station, and space-faring probes like Juno all send and receive information in the form of radio signals. But these spacecraft can only use a limited range of government-controlled radio frequencies. For the amount of satellite and space imagery that scientists want, they need more data delivery options, says engineer Frank Heine of Airbus-owned company Tesat-Spacecom.
Heine is gunning for infrared lasers. He works on the European Data Relay System, a hybrid network of radio and infrared-delivering satellites operated jointly by ESA and Airbus. In the network, satellites in low Earth orbit—some 400 miles above Earth—ping infrared data up 22,000 miles to a geosynchronous satellite. The sat then converts that signal into conventional radio waves to beam down to Earth. The satellites deliver ocean, atmosphere, and other environmental data for Europe’s government-run Copernicus program.
They’ve been able to achieve 1.8 gigabits per second, about three times faster than a purely radio connection. Although they’ve demonstrated direct infrared links from space to their observatory in Spain, it’ll take them another five to 10 years before the downlinks to Earth are consistently in infrared, says Heine. They have to build more ground stations so that the satellite network is always within communication distance—but they still have to figure out how many they need and where to build them.
Infrared is faster than radio because you can cram a lot more data in it, says NASA engineer Don Cornwell, who managed the lunar laser demonstration. At its fastest, NASA’s moon-to-Earth laser connection delivered 622 megabits per second—the equivalent of streaming 30 HD movies on Netflix simultaneously.
It works like this: Both radio and infrared light are electromagnetic waves, but an infrared light wave oscillates thousands of times faster or more, depending on its frequency. Information gets encoded in each cycle of light, which means that faster cycles can encode more information per second, says Cornwell. An infrared light wave theoretically could encode thousands of times more data than a radio wave.