The Pleiades project is part of ORFEO, a joint Franco-Italian initiative by the countries' national space agencies CNES and ASI, marking a major technological advance in optical earth observation systems. The dual-technology program addresses both military and civil needs for European users, including mapping, volcano monitoring, geophysical and hydrology studies, urban planning, etc.

As prime contractor for the Pleiades system-in particular the ground segment-CNES selected Astrium as satellite prime contractor and Thales Alenia Space for the imaging instruments.

The Pleiades optical high-resolution imaging instruments offers enhanced resolution of 70 cm over a wide swath (20 km) in both the visible and near infrared bands.

This very high resolution instrument also introduces significant innovations such as the highly-integrated detection sub-assemblies (SEDHI), while also reducing volume three-fold compared to previous generations.

The instrument provides very high dimensional stability thanks to a concept combining a carbon/carbon structure (material insensitive to moisture and with a very low coefficient of thermal expansion) and Zerodur mirrors. To optimize in-flight performance, the instrument has an innovative thermal refocusing system, eliminating the need for a complex mechanism.

The absence of this mechanism plus the satellite's own enhanced performance (satellite pointing/tilting capabilities, downlink transmission rate of 450 Mbit/s) means a significant increase in mission performances.

The first flight-model instrument is now ready for delivery, after successfully passing its environmental tests. The performances of optical and radiometric tests, as measured in a Class 100 clean room in Cannes-the level required for this class of instrument-are excellent. The instrument will be integrated on the first satellite flight model, which will then undergo checks at Astrium's facility in Toulouse.

The two Pleiades observation satellites have a design life of five years and offer a high degree of in-orbit agility thanks to their maneuvering capability. They will be able to acquire a series of images both along the swath or across the swath to create a veritable mosaic of ground scenes. They are scheduled for launch in 2010 and 2011 respectively.

The Pleiades contract confirms Thales Alenia Space's position as the European leader in very-high performance, very-high resolution imaging instruments.

The new instrument leverages the broad array of competencies that Thales Alenia Space has developed during major programs, including payloads for Helios I and II for very high geometric resolution, the Vegetation instrument (on board Spot 4 and 5) and the MERIS instrument (on board Envisat) for high-resolution geometric and radiometric imaging of land and ocean surfaces.

Thales Alenia Space also built the IASI Infrared Atmospheric Sounding Instrument on board METOP, enabling French national weather service Meteo France to significantly improve weather forecasting accuracy.

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