NASA Moonshot Will Test Laser Communications
NASA launches a moon satellite this week that will test ultrafast optical data transmission.
A new communications technology slated for launch by NASA this Friday will provide a record-smashing 600 megabits-per-second downloads. The resulting probe will orbit the moon and send communications back to Earth via lasers.
The plan hints at how lasers could give a boost to terrestrial Internet coverage, too. Within a few years, commercial Internet satellite services are expected to use optical connections—instead of today’s radio links—providing far greater bandwidth. A Virginia startup, Laser Light Communications, is in the early stages of designing such a system and hopes to launch a fleet of 12 satellites in four years.
Already, some companies provide short-range through-the-air optical connections for tasks such as connecting campus or office buildings when an obstruction such as a river or road makes laying fiber infeasible. “There are a bunch of technologies that all come together for new applications and improved service, not just one,” says Heinz Willebrand, president and CEO of Lightpointe, a San Diego-based company whose technology provides up to 2.5 gigabits per second for a few hundred meters.
One new technology figuring in NASA’s moon probe: a superconducting nanowire detector, cooled to three kelvins. That gadget, developed at MIT and its Lincoln Laboratory, is designed to detect single photons sent nearly a quarter of a million miles from infrared lasers on an orbiting lunar probe, which is being launched Friday to measure dust in the lunar atmosphere.
The new communications system, dubbed Lunar Laser Communications Demonstration, will deliver six times greater download speeds compared to the fastest radio system used for moon communications. It will use telescopes that are just under one meter in diameter to pick up the signal. But it could be reëngineered to provide 2.5 gigabits per second, if the ground telescope designed to detect the signals were enlarged to three meters in diameter, says Don Boroson, the Lincoln Lab researcher who led the project. “This is demonstrating the first optical data transmission for a deep-ish space mission. If you resize it and partly reëngineer it, you could potentially do it to Mars,” he says.
Because clouds block photons, detectors are being installed at three spots: one each in California and New Mexico, and a third on the Canary Islands. On this mission, though, the system will merely be tested. Most operations will be handled by radio technologies—upgraded versions of the system that delivered Neil Armstrong’s “One small step for man” transmission in 1969. But if all goes well, optical systems will likely dominate space transmissions in the future, with radio systems serving as a backup.
In addition to the nanowire detector, the system depends on high-speed encoding and decoding of data, and a separate set of calculations and adjustments to keep the telescopes pointed at each other. “There are a bunch of technologies that are new and exciting,” Boroson says.
But what may be even more exciting for bandwidth-hungry Earthlings is the prospect of a satellite-based all-optical network to augment the ground-based one.
Laser Light Communications is putting together components for a commercial system that would provide all-optical satellite-to-ground and satellite-to-satellite communications. The company aims to supercharge Internet bandwidth around the world with a space-based optical network to complement the global fiber one (see “New Oceans of Data”).
The idea is that the system will often create shorter continent-spanning links than are available on the ground while bypassing any bottlenecks. What’s more, in the case of failures—such as the severed undersea fiber cable that blacked out much of the Middle East and parts of India in 2008 (see “Analyzing the Internet Collapse”)—it would offer alternative routes and greater resiliency.
The company is planning an initial 48 ground stations for its system. If clouds block downlinks or uplinks at one site, it can dump the data at a different receiver—perhaps just a few hundred miles away—achieving very high reliability, says Robert Brumley, CEO of Pegasus Global Holdings, which is launching the company based on federally funded defense research in the area of optical communications.
Many more could be installed: the detector units would be small enough to be fitted atop an office building or even a truck, such as to handle feeds for live television, Brumley adds.
Under the system, eight satellites whizzing around the planet at an altitude of about 12,000 kilometers would create a total system capacity of six terabits per second—and download speeds of 200 gigabits per second, about 100 times faster than today’s radio links. “We’re aiming for worldwide coverage at service levels and connectivity options previously unattainable by other satellite platforms,” says Brumley. But the company’s main aim is to become a wholesale supplier of bandwidth to other carriers–possibly even including other satellite services–and not to become a competitor, he added.
The recently launched satellite company O3B—which stands for “the other three billion”—provides between 150 megabits per second and two gigabits per second using radio frequencies. Other companies, Intelsat and Inmarsat, also deliver speeds in that ballpark.
Another Internet-boosting idea, Google’s “Project Loon,” envisions balloons circling the Earth in the stratosphere to provide coverage to underserved areas. But that would also use radio signals (see “African Entrepreneurs Deflate Google’s Internet Balloon Idea”), Google says.