Satellites to measure sea-level under construction

May 24th, 2019, Published in Articles: PositionIT, Featured: PositionIT

Taking measurements of the height of the sea surface is essential to monitoring sea level rise – and the Copernicus Sentinel-6 mission is on the way to do just this. The mission will be a constellation of two identical satellites that are launched sequentially. Over the next decade, the Copernicus Sentinel-6A and then Sentinel-6B satellites will take the role as a reference missions, picking up the task of continuing the long-term record of sea-surface height measurements that have so far been supplied by the French–US Topex-Poseidon and Jason missions.

The radiometer being lowered into the satellite.

The Sentinel-6 satellites will each carry a radar altimeter, which works by measuring the time it takes for radar pulses to travel to Earth’s surface and back again to the satellite. Combined with precise satellite location data, altimetry measurements yield the height of the sea surface.

With Sentinel-6A scheduled for lift-off at the end of next year, the satellite is currently being equipped with its measuring instruments, which also include an advanced microwave radiometer. The radiometer accounts for the amount of water vapour in atmosphere, which affects the speed of the altimeter’s radar pulses.

While it is one of the European Union’s family of Copernicus satellite missions, this mission is also being realised due to cooperation between ESA, NASA, NOAA and Eumetsat. As part of this international cooperation, the radiometer has been supplied by NASA.

Both satellites are being built in parallel. The next step which will be to complete the satellite with the altimeter and the precise orbit determination instruments. The satellite will then be put through testing, which includes simulating the vibrations and temperature during lift-off and also the environment of space for its life in orbit.

Contact ESA, www.esa.int

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