Sentinel-1 soon to make first laser link
The Sentinel-1 Earth observation satellite, set for launch on Thursday as the first space element of Europe’s Copernicus global monitoring programme, will be the anchor customer of another milestone ESA programme: the laser-equipped European Data Relay System.
This SpaceDataHighway will transmit information between satellites faster than ever, using laser links. The first EDRS element will be launched in 2015, and before then Sentinel will be able to connect through a precursor payload.
This precursor is a hosted package furnished by DLR on Europe’s biggest telecom satellite, Alphasat, launched in July 2013 and developed through a public–private partnership between ESA and Inmarsat. The Laser Communication Terminal is demonstrating the use of laser technology for collecting information from the congested low orbits and then transmitting it to Earth from its lofty position in geostationary orbit, 36 000 km up. The terminal was tested with ESA’s optical ground station in Tenerife in November 2013, proving all is working as it should and is ready for action.
Sentinel-1 is expected to start a series of successively more extensive link sessions with the terminal 6–8 weeks after launch.
Lasers can carry much more data at a much faster rate than traditional radio links, which addresses our ever-growing need for communication services delivered by satellite.
In particular, EDRS will be used by the Sentinels and other customers for environmental monitoring and disaster mitigation. These applications benefit greatly from rapid response times and the ability to receive large amounts of information at once.
It is estimated that Copernicus will require the SpaceDataHighway to transmit a large part of the six terabytes of data every day to the ground. Without laser communication, this would be difficult.
This new route also solves the problem of the limited ability of satellites in lower orbits to deliver time-critical information – they transmit data only when in sight of a ground station. The rest of the time, valuable information must be stored. Typically, this means only around 10 minutes of downlink per orbit, which is only a tenth of the total duration of each orbital journey. EDRS will boost the connection time by a factor of up to five.
The SpaceDataHighway will provide near-continuous availability of a link to the ground, thereby greatly improving the timely availability of data on the ground.
EDRS is a public–private partnership between ESA and Airbus Defence and Space. It will provide a fully commercial service to users all over the world following its launches in 2015 and 2016. Until then, the Sentinels will demonstrate the effectiveness of lasers in space.