EADS, FRIEDRICHSHAFEN, Germany: Astrium is writing another chapter in its space radar success story: Following the radar instruments for the ERS1/2, Envisat and Metop satellites, the company is to develop and build the latest imaging radar for an ESA satellite.
The development and delivery contract is to be signed in Friedrichshafen today by Massimo Di Lazzaro, 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 EUR 229 million, with the SAR instrument worth approximately EUR 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 environmental 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 kilometres 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 metres.
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.
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.
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 EUR 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 EUR 39.4 billion and employed a workforce of more than 116, 000.
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