The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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Each arm of the GAS instrument contains numerous antennas. The signals received by these antennas are precisely correleated together through interferometry to build up a detailed picture, equivalent to 30km resolution at geostationary orbit. To further increase the detail deliverable by this 'sparse antenna', the Y-shaped antenna rotates. It only takes a half-rotation to compile a complete picture. The concept is similar to that used by ESA's SMOS, now in orbit, although SMOS does not rotate and uses longer-wavelength L-band instead.