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Satellite constellation

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ESA / Applications / Observing the Earth / Copernicus / Sentinel-1

The Sentinel-1 mission is designed as a two-satellite constellation. The identical satellites orbit Earth 180° apart and at an altitude of almost 700 km. This configuration optimises coverage, offering a global revisit time of just six days. 

At the equator, however, the repeat frequency is just three days and less than one day over the Arctic. Europe, Canada and main shipping routes are covered in less than three days. 

Designed and built by a consortium of around 60 companies led by Thales Alenia Space and Airbus Defence and Space, the Sentinel satellites are an outstanding example of Europe’s technological excellence. 

Each satellite, weighing 2300 kg,  has been designed for a minimum lifetime of seven years in orbit. The design has benefited from experience gained with Canada’s Radarsat-2 and Italy’s Cosmo-SkyMed and uses the  Piattaforma Italiana Multi Applicativa, PRIMA, satellite platform with a mission-specific instrument, the C-band synthetic aperture radar in this case.

Sentinel-1 unfolds
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As well as the 12-m long radar, the satellites each carry two 10 m-long solar wings. During launch, the solar wings and radar are folded up for protection and to fit into the Soyuz rocket fairing.

After the satellite is released into space, the solar wings and radar deploy together, but in a specific sequence that takes around 10 hours to complete. The sequence is unique, choreographed to ensure that both deploy in the safest possible way. The sequence also allows power from the wings to be available as soon as possible so that the satellite is independent.

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