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First of Europe's Sentinel Earth Observing Satellites Reaches Orbit
KOUROU, French Guiana — A Europeanized Russian Soyuz rocket on April 3 successfully placed the first of a series of European Commission-owned environment-monitoring satellites into low Earth orbit.
All told, Europe’s multibillion-euro Copernicus Earth observation system, with optical and radar sensors of both high and medium ground resolution, will comprise some 15 satellite payloads and constitute what is probably the world’s most ambitious environmental surveillance program.
The launch, from Europe’s Guiana Space Center here on the northeast coast of South America, was the seventh Soyuz liftoff from the European spaceport. Three more Europeanized Soyuz launches are scheduled this year, a period of high demand on the rocket in its European configuration.
The April 3 launch placed the Sentinel-1A radar Earth observation satellite into a polar orbit of about 700 kilometers in altitude, inclined 98.2 degrees relative to the equator. Its orbit will permit it to refly any given area of the planet every 12 days, with a faster revisit time for regions farther from the equator.
European Space Agency managers confirmed that the satellite was in good health and sending signals in orbit. The satellite carried a small camera that produced images of the deployment of the 12-meter-long radar antenna and the 10-meter solar array.
An identical satellite, Sentinel-1B, is scheduled for launch in late 2015, halving the revisit time to six days. The principal observing instrument, a 12.3-meter-long C-band synthetic aperture radar, has multiple imaging modes with ground resolutions of between 5 meters and 20 meters.
“This really starts a new era for us, going from experimental and research satellites to the Sentinel era of providing operational services for European citizens and government agencies in maritime surveillance, land management and atmospheric monitoring,” Volker Liebig, director of ESA’s Earth observation division, said.
Thales Alenia Space is prime contractor for the Sentinel-1A and Sentinel-1B satellites, with Airbus Defence and Space providing the radar instrument.
In an example of what savings are possible when ordering two identical satellites at a time, the Sentinel-1A cost the 20-nation ESA 280 million euros ($384 million), while Sentinel-1B was 50 percent less.
Because Copernicus and the Sentinel satellites are never-ending programs, like Europe’s Galileo navigation constellation, currently being built, ESA had tried to persuade the European Commission to commit to financing a third Sentinel.
Commission rules did not permit that, which is why new competitions for the third and fourth Sentinel units will get underway this year.
ESA has spent some 1.7 billion euros developing the first models of the Sentinel satellites, which include free-flying spacecraft and payloads to be placed on meteorological spacecraft in geostationary and polar low Earth orbit operated by Europe’s Eumetsat meteorological satellite organization of Darmstadt, Germany.
The commission has spent, through the end of 2013, about 600 million euros on Copernicus, both for its share of the satellites’ financing and for development of a wide array of Copernicus services.
ESA has financed the first Sentinel models, which number eight satellites including identical Sentinels 1A/1B, 2A/2B and 3A/3B.
Liebig said ESA and the European Commission are still finalizing the legal procedure by which the entire Copernicus program is transferred to the commission. He said the follow-on Sentinels will be launched starting in 2015, with the goal of launching each model’s “B” unit about 18 months after the first.
The “C” and “D” units have been accounted for in the commission’s seven-year budget, recently adopted, for 2014-2020. The commission has set aside about 3.8 billion euros for the program, a budget that includes the launches of the follow-on Sentinels and the continued provision of services.
In addition to the dedicated Sentinel satellites and payloads, individual European governments have agreed to contribute time on their own satellites for Copernicus, although the terms of access are different.
Copernicus data will be distributed free of charge to users who identify themselves and agree to restrictions on redistribution. None of the Sentinel satellites carries high-resolution sensors and none is considered to be of special interest to Europe’s militaries.
But one aspect of the Copernicus program has elicited potential military interest — its laser-relay terminals placed on some of the low-orbiting Sentinel satellites, which will send large volumes of imagery via geostationary-orbiting satellites carrying similar terminals.
Europe’s AlphaSat satellite, whose main commercial L-band payload is owned by mobile satellite services operator Inmarsat of London, carries one of these laser communications terminals and will receive data from Sentinel-1A.
Under contract with ESA, Airbus Defence and Space is developing a commercial European Data Relay Service, with two terminals planned for launch as hosted payloads on commercial telecommunications satellites owned by Avanti of London and Eutelsat of Paris.
So far, only a couple of Sentinel satellites have been designed to carry laser terminals, and none of the higher-resolution, dual-use satellites operated by France, Germany, Italy or Spain has been fitted with them.
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