European Data Relay System developed by European Space Agency and Airbus Defense and Space (former Astrium) will start operating after launching Eutelsat-9B satellite with first part of the system as secondary payload.
It is trivial to say that communication is crucial in our world. In every aspect of our life communication became determinant of the efficiency of our operation. Information, even if is most accurate is nothing if it could not be forwarded. Today, when satellites became able to take a picture of a car on the street and we are considering Mars colonization, methods of most reliable and quick transmitting large amount of information became crucial, especially in terms of present and future space conquest.
Communication between Earth and spacecraft, like satellite, is full of limitations which do not exist in communication on Earth. For example satellites operating on LEO, due the relatively low altitude and movement, are not necessary always able to transmit data to ground stations. It results in delays during receiving information from satellite. It is not a big problem, when gathered data are used for example for urban planning. But when time is crucial – when images from satellite are necessary during rescue missions – time needed for receiving information decides about life. GEO satellites are not affected with this communication problem (for GEO satellites problem is delay in transmitting data which is result of great distance between satellite and Earth). Due the high altitude, around 36000 km, they are always able to cover ground station with range of onboard transmitters. It seems that simple solution could be resignation from LEO satellites and use only GEO satellites, but unfortunately for some objectives LEO satellites are necessary. For example imaging satellites and remote sensing satellites are able to gather more accurate data from LEO; satellites placed on LEO are in constant movement, so they are able to take detailed pictures or remote sensing images of Earth in reach of their orbit – it is another advantage. Different Earth observation and imaging programs are based mainly on LEO satellites. NASA Earth Observing System (EOS), main American Earth observation program, is utilizing LEO remote imaging satellites; Copernicus by ESA is also based on LEO satellites. But if EOS should be considered as substantially only observation program, Copernicus was designed to be in spite of observation role, to be utilized in crisis situations like natural disasters. It should not be surprising that ESA considered establishing new communication system with capability of near full time data transmitting from satellites as crucial for reaching by Copernicus full operational capability. That is how European Data Relay System became vital part of European space program.
European Data Relay System is European attempt to establish independent relay data system for satellites, spacecraft, UAVs (unmanned aerial vehicle), and ground stations. Developed, as part of long term ARTS (Advanced Research in Telecommunications Systems) program, by ESA and Airbus Defense and Space. System will serve for downlink data from observation satellites for military, security agencies, emergency services and for uplink commands and data to military satellites, UAV and aircraft in real time. It will provide highly efficient, secure and fast communication with utilization of laser beam between satellites and Ka band transmitters for communicating with ground stations. Potential speed of link with laser link, between LEO satellite and relay GEO satellite, will be at 1.8 Gbit/s on 45000 km range. First test was performed on 21 February 2008. For first transmission served German Terrasar-X satellite and American NFIRE satellite, both equipped with laser terminals made by German company TESAT. During test achieved speed for 5000 km distance was 5.6 Gbit/s. Second attempt for link between LEO and GEO satellites was performed on November 2014 when Sentinel-1A (Copernicus satellite) transmitted image for 36000 km with laser beam to Alphasat satellite equipped in Tesat laser terminal (Laser Communication Terminal (LCT) of second generation). Alphasat transmitted image to ground station with conventional Ka band radio transmitter. Laser emitting and receiving terminals were funded by ESA and DLR; designed and manufactured by German Company Tesat. After test on November 2014 advantages of system were confirmed. System was not requiring any regulations of frequency, there is no problem with jamming and based on latest technologies system has impressive resistance for Sun influence. EDRS will be fully operational around 2030 and will consist one payload and three additional spacecrafts. First, ERDS-A, will be launched as secondary payload on Eutelsat-9B satellite on 25th January 2016 (satellite will be placed on 9°E Eutelsat slot). It will be equipped with laser communication terminal and a Ka band inter-satellite link. It will serve as relay for Copernicus satellites: Sentinel-1A and Sentinel-2. Second payload, EDRS-C placed on designated spacecraft, is scheduled for 2017 and will be equipped with laser terminal; spacecraft will be manufactured by German company OHB and based on SGEO telecom satellite. Planned orbital position will be 31°E. For following years further two spacecrafts are planned. Ground segment of ERDS will consist Mission Operation Center placed in Germany (Ottobrunn) with backup in Redu, Belgium. MOC will process user’s requests and plan link details. Basing on orbital position of user’s satellite, MOC will designate which EDRS will be used: EDRS-A or EDRS-C. In case utilizing EDRS-A, commands will be prepared in Devolved Payload Control Center (DPCC) and will be sent to Eutelsat’s Satellite Control Center where are uplinked to Eutelsat-9B. Downlinked data will be received by following ground stations: RDGS, Weilheim, Germany and HDGS, Harwell, United Kingdom. If EDRS-C is going to be utilized, commands will be prepared and uplinked by two stations: FLGS, Weilheim, Germany and BFLGS, Redu, Belgium. Same stations will serve as receive centers for downlinked data. EDRS also provide capability of downlink directly to user ground station if necessary.
EDRS is an example of cooperation between public and commercial segments of space industry. Program was developed under Public Private Partnership with participation of ESA and Airbus Defense and Space. Necessary ground stations are funded by ESA; launch service provider and system integrator will be Airbus Defense and Space which will own EDRS after achieving by ERDS full operational capabilities. ESA will remain main customer and user of system which will be offered on market for commercial purposes.