Lasers Enable Satellite-Data Tag Team

New laser data links could help satellites in disparate orbits communicate more effectively with one another, potentially benefitting disaster management here on Earth.

Last month the European Space Agency and partner organizations completed the first-ever gigabit transmission via laser between one satellite in low-Earth orbit and another in geostationary orbit.

An illustration of laser data transmission between satellites in low-Earth and geostationary orbits. Courtesy of Airbus Defence & Space.

The Laser Communication Terminal (LCT) technology was developed by Airbus Defence and Space subsidiary Tesat-Spacecom of Backnang, Germany, and the German Aerospace Center (DLR). The solid-state laser system is pumped by laser diode benches developed at the Ferdinand Braun Institute in Berlin.

During the demonstration, data transfer reached 0.6 Gbps out of a potential 1.8 Gbps over a distance of about 45,000 km, according to Airbus.

“You can visualize the link of today as an optical fiber in the sky that can connect the Sentinels back home to Europe, from wherever they are on their orbit around Earth,” said ESA Director of Telecommunications and Integrated Applications Magali Vaissiere. “The link is operated at 1.8 Gbps, with a design that could scale up to 7.2 Gbps in the future. Never has so much data traveled in space.”

A radar image of Berlin was one of the first images delivered using the LCT system. Courtesy of ESA.

Faster transmission between satellites could help get crucial data to the ground more quickly.

The Sentinel-1A performs radar observations of the Earth’s surface from an altitude of about 700 km. From this relatively shallow orbit, it can only transmit data when it passes over designated ground stations in Europe.

These ground stations are permanently visible, however, to Alphasat, Europe’s largest telecommunications satellite, which inhabits a geostationary orbiting at about 36,000 km. Thus images transmitted by laser from Sentinel-1A to Alphasat can reach the ground nearly in real time.

Airbus’ first operational LCT payload has been integrated on the EUTELSAT 9B satellite, to be launched in 2015. A second dedicated spacecraft will follow in 2016, providing an increased field of coverage and system redundancy.

Part of the system’s available data capacity is to be used for data communication on ESA’s Earth observation project, Copernicus, as well as security, disaster response, and antipiracy and antismuggling operations. The remaining bandwidth will be commercially available. The system can also provide beyond-line-of-sight control for unmanned aerial systems and can be used to control and reconfigure satellites in orbit.

For more information, visit www.esa.int, www.tesat.de and www.fbh-berlin.com.