Europe launches second EDRS space laser satellite - 雅思论坛

Europe launches second EDRS space laser satellite

Europe has launched the second satellite in its space lasertelecommunications network.

It will use optical beams to pull pictures and data from otherspacecraft and then speed that information to the ground.

EDRS-C, as it is known, was sent into orbit on Tuesday by anAriane-5 rocket from the Kourou spaceport in French Guiana.

The new satellite will sit slightly to the east, where it willprovide additional capacity.

The European Data Relay System is a joint venture between theEuropean Space Agency and aerospace giant Airbus.

It is used predominantly by the European Union's Sentinel-1 andSentinel-2 Earth observation spacecraft. These platforms take images of theplanet's surface.

Ordinarily, such satelliteswould have to wait until they pass over a radio receiving dish on the groundbefore downloading their pictures, which could mean a delay of over an hour asthey circle the globe.

But the Sentinels were equipped to connect with the EDRSsatellites' 1.8-gigabit laser links.

The relay platforms orbit much higher in the sky - some 36,000kmin altitude - and always have visibility of a radio antenna on the ground.

The capability has particular relevance in the realm of naturaldisasters, such as major floods or big earthquakes.

Information about the scale of these emergencies can be put inthe hands of first responders much faster than would normally be the case.

"We have demonstrated that it's possible to get a Sentinelimage on the ground and ready to use after just 15 minutes of it beingacquired," Magali Vaissiere, the director of telecoms at Esa, told BBCNews.

"The launch of EDRS-C brings additional capacity to thenetwork, obviously, but it also provides redundancy, a back-up, which you needin an operational system."

Between a third and a half of all image data from Sentinels 1and 2 is now routed through EDRS, and usage is certain to expand with thesecond node now in orbit.

There are plans to use the relay system toregularly pull data to the ground from the European Columbus science laboratoryon the space station. Future Earth observation satellites are also activelybeing planned with EDRS in mind, including the EU's next batch of Sentinels andAirbus's Pléiades Neo satellites which will take Earth images at 30cmresolution. Airbus says airborne reconnaissance could make use of the laserlinks, too.

Telecoms satellites that rely solely on radio frequencytransmissions are being left behind by the performance of terrestrial fibrenetworks.

In time, this is going to put significant constraints onapplications that include TV broadcasting and the services carrying themessages of connected devices (the so-called Internet of Things).

It is why the space agency will propose to Europe's researchministers in November that they fund the R&D necessary to break the"bottleneck in the sky".

Esa's High Throughput Optical Network (HyDRON) project envisageslaser links, not just between satellites but between spacecraft and the ground.

This brings certain challenges, including the issue of how tomanage light transmissions through a turbulent - and often cloudy - atmosphere.

However, if the technologies can be mastered they should permitterabit-per-second connections.

"We have shown with EDRS that we have some leadership inEurope in these technologies, and one of the strategic lines we have definedfor [the ministerial meeting] will be dedicated to optical uses so that westrengthen that leadership," the Esa telecoms director said.

The Ka-band radio frequency payload on the 3-tonne EDRS-Csatellite was provided by the London-based Avanti telecommunications company.

Avanti calls the payload Hylas-3 and will be using it to deliverbroadband and other data services to markets in Europe, the Middle East andAfrica.