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Meet Sentinel-2A, the Guardian Satellite Now Orbiting Earth

The satellite is equipped with color and infrared cameras, and will carry out environmental surveillance missions as part of the agency’s mission, called "Copernicus."

by Pierre Longeray
Jun 23 2015, 7:56pm

Image via ESA/ATG medialab

The European Space Agency's Sentinel-2A satellite was put into orbit on Monday from the Guiana Space Center near Kourou, in French Guiana. This little satellite, weighing just one ton, is equipped with color and infrared cameras, and will carry out environmental surveillance missions as part of the agency's mission, called "Copernicus." Its job, quite simply, is to observe Earth as its climate changes, or as droughts, floods, and storms roll across its continents.

Liftoff of the Vegarocket with the Sentinel-2A on board this Monday from the Guiana Space Center near Kourou, French Guiana.

"The Sentinel-2A will allow us to observe the evolution of vegetation, coastlines, bodies of water (such as lakes and rivers), as well as glaciers — and all from space," Josef Aschbacher, ESA's head of program planning and coordinator for Earth observation missions, told VICE News. Among other projects, he's responsible for the Copernicus program.

Monday evening, at 10:51pm local time, the Vega rocket took off from Kourou to put Sentinel-2A, which had been developed by Airbus Defense and Space, into orbit. Some 54 minutes after liftoff, the satellite broke off from its booster rocket and deployed its solar panel. The mission will begin in earnest in three to four months, according to the ESA.

After breaking apart from the Vega AVUM module and stabilizing, Sentinel-2A deployed its solar panels. (image via ESA)

Thanks to its 13-band multispectral imaging system, allowing it to see 13 colors, it will play a vital role in monitoring the planet's evolution. For example, its infrared cameras will allow it to measure chlorophyll and water levels in forests, as Volker Leibig, ESA's Director of Earth Observation Programs, explained. As a result, it will be possible to see from space whether a particular area does or doesn't need a water supply, as François Spoto, ESA's Sentinel-2 Project Manager, told the AFP. This alone would be an invaluable service for agriculture.

Video explaining the Sentinel-2A's multispectral imaging system (via ESA)

As it carries out surveillance missions on environmental evolution over the long term — which will be essential to understanding and measuring climate change — the Sentinel-2A may be used for "natural catastrophes and humanitarian crises," Josef Aschbacher told VICE News. The satellite may help pinpoint refugee camps or even monitor such catastrophes as forest fires, floods, or landslides.

"It'll be very useful for assessing damage after a natural catastrophe," Aschbacher said.

A third potential use for the satellite may be to lead security operations and pinpoint various activities harmful to the environment, such as illegal pollution.

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According to the Airbus report, the satellite will orbit the Earth at an altitude of 786 kilometers and cover a 290-km-wide swath, which will allow it to obtain images of a 10-meter resolution. It will be able to circle the Earth in 100 minutes.

"The Sentinel-2A will send a complete image of the Earth every 10 days," Josef Aschbacher said. Repeatedly collecting these images is essential for ESA specialists. By reiterating these trips over the Earth, the new satellite will allow them to follow, almost in real time, the planet's evolution. Aschbacher says that American and French satellites already in use — named, respectively, Landsat and Spot — are also able to carry out such missions but would be less efficient and precise.

"For example, it would take 16 days for the Landsat satellite to deliver a complete image of the Earth [as compared to 10 for Sentinel] and it would have a 30-meter resolution, compared to 10 meters for the European satellite," Aschbacher said. "Spot, the French satellite, has four spectral bands. With 13 bands, the Sentinel-2A can capture far more detail in color, to the point that we'll be able to distinguish clouds of ice from those of snow."

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The Sentinel-2A is part of the European Earth-surveillance program developed by ESA, Copernicus. The program will ultimately encompass a set of satellites all named Sentinel. Sentinel-2A's little sibling — Sentinel-1A — was already launched in April 2014, and is collecting information about the Earth's surface with a radar instrument. The Sentinel-3 generation should be able to carry out surveillance missions over seas and oceans, while the Sentinel-4 and -5 generations will be focused on the atmosphere. Finally, the Sentinel-6 will be able to measure changes in the ocean's levels.

Each Sentinel satellite will work in pairs — an A version and a B version — so as to cut in half the time necessary to create their maps. Sentinel-1B and Sentinel-2B will be launched in 2016. As a result, in mid-2016, a new map of the Earth (including its forests, glaciers, and so on) will be available every five days.

The Copernicus program currently has a 4.3 billion-euro budget from the European Commission — for the 2014-2020 period. The ESA will make all the data collected from its Sentinel fleet freely available on a dedicated platform. Consequently, businesses and researchers will benefit from the open-data policies the ESA has advocated.

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Follow Pierre Longeray on Twitter: @PLongeray