Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/01/2015 Terms of Use: http://spiedl.org/terms . #%'## #" "(/ (0 #-'( #))%"!!#"With a data rate of 5.6 Gbps the laser communication links reported here have been a milestone in the introduction of laser communication terminals to the space market. For the first time the major advantage of laser communication terminals compared to RF payloads -data rates larger than 1 Gbps -has been demonstrated on orbit. In terms of shortterm service realization the most imminent market applications are relay services (LEO-to-GEO-to-ground) to make the large data amount of LEO Earth observation satellites immediately available. DLR plans to utilize the laser communication capabilities for the TanDEM-X mission and took TESAT under contract to adapt the now successfully proven LEO-LEO laser communication terminals to LEO-to-GEO, GEO-GEO, and GEO-to-ground links. This GEOclass LCT is designed for up to 45,000 km distance at a maximum user data rate of 1.8 Gbps.The next figure (Fig. 8) shows the application for which TESAT has developed and currently builds laser communication terminals and a 600 Mbps Ka-band subsystem.

No abstract

No abstract

A summary of the currently running inter-satellite and satellite-to ground-laser communication experiments will be given. Furthermore, the European Data Relay System will be elucidated, using Tesat build Laser Communication Terminals as a data relay backbone between Earth observation spacecrafts in low Earth orbit and geostationary relay satellites I. Laser communication TICAL laser communication between spacecrafts and satellites have been evaluated and tested in the last 10 years. Optical laser communication is demonstrated between low Earth orbit (LEO) Earth observation spacecrafts 1 using homodyne binary phase shift keying (BPSK) at 5.6 Gbit/s at 1064nm laser wavelength, LEO to geostationary spacecrafts (GEO) 2 3 , GEO to airplane 4 , both using directly modulated laser light at 830 nm and 50 Mbit/sec, and spacecraft to ground (both LEO ( see reference 1 and 3 ) and GEO 5 . This paper briefly summarizes the results of the last 3 years of LEO -LEO and LEO to ground experiments performed with the 5.6 Gbit/sec Laser Communication Terminal (LCT, see Figure 1) developed and manufactured at Tesat-Spacecom in Backnang, Germany under contract by the German Space Administration (DLR). Afterwards, the system architecture for the planned European Data Relay System (EDRS) is shown, and the accommodation of the Tesat LCT on the different spacecraft is given. For the EDRS system, the LCT is serving as the front end of a Ka-band communication payload on the GEO data relay satellites. II. The LCTSX programSince 2008, two LCTs from Tesat are operational on two LEO spacecrafts. The US -owned NFIRE spacecraft, were the LCT is the secondary payload submitted under an inter governmental cooperation to the US side, and the German TerraSAR-X , an Earth observation satellite carrying a synthetic aperture radar as primary payload. The Figure 2 and Figure 3 show the locations of the Tesat LCT on the LEO spacecrafts. Mass and dimensions of the LEO-LEO terminal are 35 kg and 0.5m x 0.5m x 0.6 m, maximum transmit power is 1.5 W.