Sentinel-6 launched: the world’s oceans in view

Dhe fleet of European Sentinel series earth observation satellites has received reinforcements. On Saturday evening, at 6:17 p.m. German time, the sentinel-6 satellite was launched into space. The radar satellite lifted off from Vandenberg Air Force Base, California, aboard a private Falcon-9 launcher operated by space company SpaceX. Ten minutes after the second rocket stage with its precious cargo had separated from the first reusable stage, the latter landed safely not far from the launch site of the Falcon-9.

The second stage, meanwhile, stayed on course to release Sentinel-6 about an hour after launch in its intended orbit at an altitude of 1,300 kilometers. From there, the satellite sent the first signals to a ground station in Alaska half an hour later. Routine operations are to begin in six months. Then Sentinel-6 will measure and precisely map the rise in sea level for five years – for example as a result of climate change. In addition to the height of the sea level, the satellite also records the swell and the ocean currents in the oceans. To do this, Sentinel-6 scans 95 percent of the global ocean surface within ten days – with a resolution of a few millimeters. In 2025, a second identical satellite, Sentinel-6B, is to be sent into space, which will continue the measurements of its predecessor.


In this illustration, the earth observation satellite “Sentinel-6 Michael Freilich” is floating in orbit with extended solar panels.
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Image: dpa

“Sentinel 6 has a new radar on board, with a higher precision, which will be able to measure a rise in sea level even more precisely,” says Esa Director for Earth Observation Programs, Josef Aschbacher. The radar pulses from the satellite are transmitted, reflected by the sea surface and received again. Wave heights would have to be resolved and atmospheric influences would have to be calculated. This requires knowledge of the exact position of the satellite in Earth orbit. Two independent navigation systems on board take care of the location determination, and the satellite orbit is regularly measured with a laser.

Sentinel-6 is the eighth satellite in the European Copernicus program. The first sentinel satellite, Sentinel-1A, took off in April 2014. Like the other Sentinels, the new scout is controlled from a control center of Europe‘s meteorological satellite agency, Eumetsat, in Darmstadt. The realization of the radar scout in the form of an oversized doll’s house is a joint effort: The mission is a cooperation between Esa, the American space agency NASA, Eumetsat and the American weather and oceanography agency NOAA. The satellite is named after Michael Freilich, the recently deceased former director of NASA’s earth observation department.

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