Airbus Defence and Space

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Tune into the weather channel

Airbus Defence and Space’s MetOp-B satellite is nearing the end of testing prior to launch from Baikonur in spring 2012. Equipped with numerous sophisticated instruments, it will double the capacity of the already highly effective European MetOp system. Weather forecasting and climate and environmental research will be given a major boost by the most powerful operational meteorology tool in the world.

For decades, meteorological satellite imagery has been part and parcel of TV weather reports governing whether the family spends a dreary Saturday playing board games or a sunny Sunday in the park, with the first meteorological satellites launched in the 1960s.

Around a decade ago, the need for polar-orbiting satellites was recognised in Europe to complement its existing geo-stationary satellites, located 36,000 kilometres above the Earth, when the continent assumed its role in an international system that had previously only been ‘staffed’ by satellites from the US’ National Oceanic and Atmospheric Administration (NOAA). With their low orbital altitude, these types of satellite can capture very accurate observations of numerous aspects of the atmosphere and achieve global coverage in a few days.

 METOP A, satellite undergoing final testing at Airbus Defence and Space's facilities in Toulouse © Airbus Defence and Space

Under the multi-billion euro MetOp (Meteorology-Operational) programme the first satellite was launched in 2006, with the second following next year and a third in 2017, to guarantee a minimum of 15 years of uninterrupted operational observations. “The continuity of data such as temperature, humidity, cloud cover and gas in the atmosphere is vital for meteorology and climate research,” explains Dieter Klaes, one of the MetOp project scientists at the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).

Airbus Defence and Space is managing a group of 40 companies for build of the three MetOps, whose design is based on the company’s product line for large polar orbit satellites. Very few adaptations are being made to MetOp-B and C; one exception is the new transistors on the ‘real-time’ data transmission channel to withstand cosmic radiation. “We began to build the three models simultaneously in 2002 and completed the first module before a storage phase for B and C between the MetOp-A launch and completion of the MetOp-B satellite,” notes Jean-Paul Gardelle, Head of the MetOp Programme at Airbus Defence and Space. The MetOps are operated by EUMETSAT, an organisation which represents 25 European countries from its site in Darmstadt, Germany. Each satellite is equipped with 12 instruments, including Airbus Defence and Space’s ASCAT and its MHS (Microwave Humidity Sounder) which is also used on the US NOAA 18 and 19 satellites.

At an altitude of 820 kilometres, MetOp overflies the poles 14 times each day and follows a sun-synchronous trajectory. It takes around 100 minutes to complete one orbit, during which time the Earth will have rotated around 25°, meaning observations will be made over a different section of the Earth in each orbit. MetOp thus scans the entire planet and probes swaths on the ground to take vertical measurements of physical and chemical characteristics of the atmosphere, as well as of the Earth’s surface.

It also produces 3D models of winds and greenhouse gases. “The information obtained with MetOp-A has achieved a record 99% availability of the data used to feed global numerical weather prediction models. A simple interruption of just a few minutes in the data packets of four to five hours would lead to rejection of the entire packet. In the abbreviation Met-Op, the second syllable ‘operational’ has become just as important as the first,” says Gardelle.

Atlantic alliance

The MetOp satellites form the space segment of EUMETSAT’s Polar System, the European contribution to the Initial Joint Polar Satellite System, a cooperative effort with NOAA. Within this setup, the European MetOp satellites monitor the crucial mid-morning orbit (9.30 a.m.), while the US satellites, supplied by the NOAA and the Pentagon, share the afternoon (1.30 p.m.) and very early morning (5.30 a.m.) polar orbits respectively. All the data from these weather satellites are constantly exchanged and redistributed to hundreds of users around the world within less than two hours of the measurements being taken. Both meteorologists and other scientists are delighted with the results. In addition to meteorological findings, in its first four years of service the two search and rescue instruments onboard MetOp-A delivered 2,635 distress signals to the global Cospas-Sarsat system, leading to the rescue of over 10,000 people.  

MetOp-A has now exceeded its planned five year service life and has a further 10 years of fuel reserves to maintain its orbit. As part of the meteorological products provided by MetOp, Airbus Defence and Space’s ASCAT instrument enables detailed ocean wind maps to be produced, helping fishermen and all sea-faring traffic, while the GOME instrument, through its ozone layer monitoring, assesses the level of harmful UV radiation passing through the atmosphere and reaching Earth. “For about 15 years we have been monitoring the ‘ozone hole’ at the two poles because we still have questions to answer and we don’t know how the story will end,” says Klaes. With MetOp-B doubling the amount of data delivered from next year, the scientific world hopes to close in on the final chapter.

Frédéric Castel



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