The devel-opment and delivery contract is to be signed in Friedrichshafen today by Massimo Di Laz-zaro, Senior Vice President and General Manager of Thales Alenia Space BU Observation Systems & Radar, and Uwe Minne, Director of Earth observation and Science at Astrium Germany. The European Space Agency (ESA) awarded the main contact for the Sentinel-1 satellite in February to Thales Alenia Space.
Astrium is now to supply the C-band radar for the Sentinel-1 satellite. The contract value of the entire project is €229 million, with the SAR instrument worth approximately €85 million. Sentinel-1 is one element in the GMES (Global Monitoring for Environment and Security) programme, an initiative by the European Commission and ESA to set up a sustainable European network for recording and analysing envi-ronmental data. Sentinel-1 will help to monitor and analyse environmental events round the globe.
Weighing some 2.2 metric tons, the satellite will orbit the Earth at an altitude of 700 kilome-tres from 2011. Its orbital path will take it across the poles on each orbit, enabling the radar instrument to scan the Earth in “swaths” as it rotates beneath the satellite. Designed as a successor to the present satellites ERS and Envisat to assure continuity in radar-based Earth observation, Sentinel-1 will observe the Earth from orbit for at least seven years. In contrast to its predecessors ERS and Envisat, however, the radar instrument carried by Sentinel-1 will include improvements such as enhanced antenna performance, which in turn will ensure better data quality.
The Astrium-built C-band SAR (Synthetic Aperture Radar) instrument, which delivers radar images of the Earth’s surface, is the core element of the mission. By taking advantage of the satellite’s flight motion, SAR is able to simulate a considerably larger antenna than is in fact present, thus significantly increasing the image resolution. The radar on Sentinel-1 operates in the C band frequency range. The C-band radar beam, which has a wavelength of six cen-timetres, penetrates forests and scrub to reach the ground, and the C band radar registers any movements or changes on the Earth’s surface to within a centimetre.
Sentinel-1 will be equipped with an active antenna made of up 280 individual antennas, in-cluding electronic front ends (transmit/receive modules) provided by Thales Alenia Space Italy. The active antenna can be electronically directed towards a new observation terrain without having to be physically moved. Thanks to this technology, several adjacent swaths can be scanned on each overflight and later combined to form a larger overall picture.
The radar instrument can operated in four different observation modes which differ primarily in the width of the scanned corridor and the resolution of the radar images. This enables Sentinel-1 to respond to a wide range of varying requirements. In strip-map mode, strips of terrain 80 kilometres wide are scanned at a resolution of 5×5 metres. The interferometric wide-swath mode registers corridors 250 kilometres wide at a pixel size of 5×20 metres. The extra-wide swath mode provides a more extensive overview of larger expanses of terrain. In this mode, a corridor 400 kilometres wide is mapped at a resolution of 100×25 metres. The fourth mode, known as wave mode, scans 20×20 kilometre spots at a resolution of 20×5 me-tres.
Sentinel-1 has been specifically designed to cover a wide range of environmental and secu-rity tasks. Observing the melting ice masses in Greenland, for example, should provide im-portant data to help predict rises in sea levels. Sentinel-1 will also be used for the observa-tion of environmental events such as forest fires and for reconnaissance and support in criti-cal situations where up-to-the-minute data is needed at extremely short notice.
Accurate and up-to-date maps compiled from satellite data also better co-ordination of hu-manitarian relief projects and rebuilding activities after natural disasters. Sentinel-1’s sophis-ticated radar technology will be particularly useful during floods to help make reliable predic-tions of water levels and potential severity of the flooding in affected areas. To date, disaster relief organisations often rely on data from optical sensors. This can mean waiting a long time for the data, particularly when it is night or there is a lot of cloud. In situations like these, Sentinel-1’s radar technology makes it vastly superior to optical devices. Radar has numer-ous advantages over optical imagery: first, radar generates its own “illumination” which is precisely defined at all times. This is very different from optical satellite images, in which the position of the sun at any given time greatly affects the appearance of a landscape. Sec-ondly, radars operate day and night, and thirdly it is capable of delivering clearly focused images even in adverse weather conditions. This makes it possible to plan and co-ordinate protective measures much more efficiently and comprehensively.
A further application for the data from Sentinel-1 is in supporting agricultural projects. The satellite delivers information that is vital to monitoring crop growth with a view to harvesting.
Astrium has been the one of the leading provider of space radars for many years. As well as bearing the overall industrial responsibility for Envisat, ERS-1/ERS-2, TerraSAR-X and Tan-DEM-X, EADS Astrium also developed and built the SAR payloads AMI (ERS), ASAR (Envi-sat), and ASCAT (Metop).
GMES (Global Monitoring for Environment and Security) is a joint initiative by the EU and ESA for comprehensive Earth observation using ground- and space-based sensors, to pro-vide political decision-makers and experts with up-to-the-minute factual information on which to base all manner of decisions concerning environmental, economic, transport and security policy.
The objective of the programme is to integrate the different Earth observation and geo-science activities in Europe, on the one hand by using the existing satellite systems and the data they supply as efficiently as possible, and on other by setting up sustainable operational systems that are specifically adapted to this range of tasks. The Sentinel series of satellites is a response to the Earth observation needs of the GMES programme in Europe.
Astrium, a wholly owned subsidiary of EADS, is dedicated to providing civil and defence space systems and services. In 2006, Astrium had a turnover of €3.2 billion and 12,000 employees in France, Germany, the United Kingdom, Spain and the Netherlands. Its three main areas of activity are: Astrium Space Transportation for launchers and orbital infrastructure, Astrium Satellites for spacecraft and ground segment, and its wholly owned subsidiary Astrium Services for the development and delivery of satellite services. EADS is a global leader in aerospace, defence and related services. In 2006, EADS generated revenues of €39.4 billion and employed a workforce of more than 116, 000.
Rémi Roland (Astrium FR) – Phone: +33 (0) 1 77 75 80 37
Jeremy Close (Astrium UK) – Phone: +44 (0)1 438 77 3872
Mathias Pikelj (Astrium GER) – Phone: +49 (0) 7545 8 91 23
About Thales Alenia Space
European leader in satellite systems and at the forefront of orbital infrastructures, Thales Alenia Space is a joint venture between Thales (67%) and Finmeccanica (33%). Together with Telespazio, Thales Alenia Space forms a Space Alliance between the two groups. The company is a worldwide reference in telecoms, radar and optical Earth observation, defense and security, navigation and science. With 7200 employees and 11 industrial sites, Thales Alenia Space is located in France, Italy, Spain and Belgium.
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