Astrium, the world's second ranking space company, has delivered the proto-flight model (PFM) of the microwave radiometer (MWR) (an instrument for the European Space Agency's (ESA) Sentinel-3A environmental monitoring satellite) to the prime contractor Thales Alenia Space for installation on the Sentinel-3A satellite.

The MWR works alongside the SRAL radar altimeter on the Sentinel-3 topography mission and determines the amount of humidity contained in the path of the radar pulses. This data can be used to compensate for interference caused by the level of humidity, therefore increasing the accuracy of the ocean height measurements.

Its data can also be used to characterise physical variables of the soil and the cryosphere, as well as to evaluate surface energy balances. The MWR is a noise-injection radiometer (NIR) that operates at two frequencies (23.8 and 36.5 GHz). It weighs approximately 25 kg, measures 1400 x 630 x 630 mm and has a power consumption of 34 watts.

The second flight model, to be integrated on the Sentinel 3B satellite, has reached a very advanced stage. Final integration of the electronic and thermal control units is scheduled for January 2014 and will be followed by a test campaign that will run from February to April 2014, with a final delivery around mid of 2014.

Antonio Cuadrado, Head of Astrium in Spain, said: "This contract is a further addition to the long list of Astrium contributions to the Sentinel satellites. We are playing a significant role in every one of them. Also, it helps to consolidate Astrium's role as prime contractor of instruments in Spain".

The instrument was developed by Astrium through its two subsidiaries in Spain, Astrium CASA Espacio as the prime contractor, and Astrium CRISA in charge of the radiometer processing electronics subsystem, while the Radiometer Front End Electronics was supplied by Thales Alenia Space

The Sentinels are a series of operational satellites designed to respond to European observation needs, as part of the European Union's Copernicus programme. The Sentinel-3 mission is specifically designed to ensure long-term collection and operational delivery of high-quality measurements for ocean, land and atmospheric services and it will be operated by EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites.

Through its centres in France, Germany, Spain and the UK, Astrium is making a major contribution to the Sentinel satellites in its capacity as the main contractor for the Sentinel-2 and Sentinel-5 precursor satellites and a number of instruments (the Sentinel-1 radar, Sentinel-3 MWR, spectrometers for Sentinel-4).