Air and space were linked together in a recent flight test by General Atomics Electromagnetic Systems (GA-EMS) and Kepler Communications where a laser system was used to communicate between a standard aircraft and a low-Earth orbit satellite.
Radio has revolutionized the world by making it possible to communicate not just across miles but light years. It's so ubiquitous that we take it for granted, but it also has its limitations – not the least of which is that it only has limited bandwidth that can handle only so much data per second.
It's a problem that's already become acute in the field of space exploration, where reliance on antiquated radio systems means it can take days to download data that a deep space probe can collect in minutes. For years NASA and other space agencies have been experimenting with optical communication systems that use laser beams instead of radio beams, but the technology also has great potential when it comes to terrestrial applications.
Optical communications are of particular importance for defense applications. Where at one time soldiers and sailors made do with fluttering flags or flashes of light to send simple messages, the modern warfighter is part of a global digital network where data rushes about like water out of a firehose and satellites act as a vital link in that network.
While maintaining the sort of precise line-of-sight links required for lasers is relatively easy for ground stations, land vehicles, or warships, for aircraft in flight it definitely comes under the heading of tricky. It's one thing to link to a distant satellite using a deep space network radio telescope with a laser transceiver installed, it's another for an airplane banking across the sky to maintain communications with a satellite in low-Earth orbit arcing towards the horizon.
To overcome this bottleneck, General Atomics used its Optical Communication Terminal (OCT) system mounted on a De Havilland Canada DHC-6 Twin Otter aircraft to establish contact with a Space Development Agency (SDA) Tranche 0-compatible Kepler satellite in low Earth orbit.
Developed as part of SDA’s Proliferated Warfighter Space Architecture, the 12-inch (30-cm) OCT uses a 10-watt laser that can push data at a rate of 2.5 Gbps across a distance of 2,970 nautical miles (3,417 miles, 5,500 km) and can track its satellite target at 25° per second. However, during the test, the exchange rate appears to have peaked at about 1 Gbps.
"Our team achieved a proof-of-concept milestone," said Scott Forney, president of GA-EMS. "The airborne OCT completed pointing, acquisition, tracking, and lock with the Tranche 0-compatible satellite, then transferred data packets to validate uplink and downlink capability. Our OCT is designed to close a communications gap, enabling secure, robust data transfers to support tactical and operational missions."
“By pairing Kepler’s on-orbit optical capabilities with GA-EMS’ OCT, we’ve shown what’s possible when space and aviation systems work seamlessly together,” added Robert Conrad, president of Kepler US. “This achievement builds on our milestone of establishing bi-directional space-to-ground communications with Kepler’s SDA Tranche 0-compatible satellites and reinforces how commercial space operators will be partners in delivering secure, high-throughput connectivity for the defense community and the broader commercial sector.”
Source: General Atomics
