About ESA
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.
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Space in Member States
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Germany
Austria
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Denmark
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Science & Exploration
Exploring our Solar System and unlocking the secrets of the Universe
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Enabling & Support
Making space accessible and developing the technologies for the future
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MHS scanning principle
As MetOp orbits the Earth, the Microwave Humidity Sounder (MHS) instrument continuously scans down through the atmosphere across the track of the flight path. During each scan cycle the instrument provides data (for each of its five channels) for 90 individual Earth scenes, each with a footprint of about 16 kilometres in diameter at nadir. Each cycle takes 2.67 seconds, but the scan cycle is optimised to maximise the time available monitoring the Earth, which equates to more than 60% of the scan duration.
The MHS scanning reflector collects the upwelling radiation and focuses it into the receiver assembly. Here, the four target frequency bands are separated by a series of quasi-optical lenses, frequency-splitting plates and a polariser to provide the input signal to the four receiver assemblies.
Between consecutive scans of the Earth, the MHS also views and samples data from an area of deep space (used as a cold target), and an on board source (hot target), which provides reference for the self-calibration process.
