Two Laser Terminals of Tesat-Spacecom, Backnang (Germany) have been successfully tested in space in frame of a U.S.-German co-operation program. The date rate of 5.5 Gbit per second demonstrated during those tests sets a new worldwide milestone in space-borne communications.

Backnang: During the lasts weeks Laser Terminals have been tested for broadband data transmission in space between two satellites, the German TerraSAR-X and the U.S.-Satellite NFIRE. At a range of about 5'000 km optical inter-satellite links have been established and operated flawlessly at a data rate of 5.5 Gbit per second in both directions. This data rate would allow the transmission of about 200'000 DIN A4 pages or 400 DVD's per hour.

The U.S.-Satellite NFIRE and the German TerraSAR-X operate in low Earth orbit with several encounters per day. At those occasions laser links can be established for up to 20 minutes duration. In closing such link it is particularly challenging to aim the communication laser beam precisely onto the target satellite that passes
at a distance of up to 5'000 km and at a speed of about 25'000 km/h. This corresponds to the aiming at an individual window of an aircraft operating at high altitude and its tracking.

The Laser Terminals tested during this program have been developed and produced by Tesat-Spacecom, Backnang (Germany), an innovative, mediumsized enterprise.

The Tesat Laser Terminals have not only communication performance characteristics far superior to those of earlier developments of the European Space Agency ESA, they are also much smaller and more efficient. Based upon modern, highly sensitive coherent transmission technology the terminals are immune to sun interference, thus, the link quality does not degrade due to direct impact of sunlight.

With this successful demonstration Germany has taken the lead in a strategic field of technology; Laser Terminals will be important elements of the future high performance data relay satellite infrastructure that supports real-time data links from ground to Earth observation satellites, scientific missions or high flying
aircraft with global, ubiquitous coverage.