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Pléiades: success story of a new birth

Following Pléiades 1 successful launch, Astrium GEO-Information Service is gearing up to provide 50 cm products to its customers

Back to origins

It all began back in 2001. The decision about the setting up of the Pléiades programme is the result of an in-depth study about the evolution of user needs. A cooperation programme was initiated between France and Italy, taking advantage of all the CNES Earth observation skills, to develop ORFEO, a dual Earth observation system with veryhigh resolution capacity, in which Pléiades (France) is the optical component and Cosmo-Skymed (Italy) is the radar component.

The French Space Agency, CNES, took over the responsibility of project manager for the Pléiades programme. Astrium was appointed prime contractor for the satellite manufacturing, interacting with Thales Alenia Space, who designed the optical instrument. In an agreement signed in 2008, the CNES appointed Astrium GEO-Information Services (formerly known as Spot Image) as the civilian operator and the exclusive worldwide distributor of Pléiades data.

Astrium GEO-Information Services is already exclusive distributor of the SPOT family data, and currently operates SPOT 4 and SPOT 5. The images taken from the SPOT 5 optical satellite have the benefit of combining a wide swath (60 kilometres) with a spatial resolution of 2.5 metres. This characteristic has made SPOT 5’s mission a huge success, providing users and customers with an excellent trade-off between coverage and resolution, for a right balance between the levelof information obtained and the cost to the user.

However, the needs of commercial and military users have progressively widened. They now also require images with increased resolution. The twin Pléiades satellites tie into this vision, adding local detail to the synoptic picture from SPOT. The system will deliver colour imagery products with a resolution of 50 centimetres combined with a 20-kilometre swath, the widest in their class of optical sub-metric satellites.

On December 17, 2011 UTC, Soyuz successfully launched the Pléiades 1 satellite from the Guiana Space Centre (CSG), marking a new success for ESA (European Space Agency), CNES (French Space Agency) and Arianespace, who jointly manage the CSG, after its first flight from the launch base on 21 October 2011. The launcher lifted off at 02:02:30 UTC and satellite separation occurred at 02:58 UTC over Perth, Australia. The satellite’s solar panels deployed 30 seconds later.

Only 3 days after the launch, Pléiades 1 returned its first images. The first image acquired by an Earth observation satellite is also the moment when, for the first time, the instruments on board and the ground segment are activated. The collection capability, which includes satellite tasking, image acquisition, data reception and pre–processing, is checked from end to end.

Athens, Greece (resampled at 1 m).Copyright: CNES 2012 © – Distribution Astrium Services / Spot Image

Mid-January, the satellite reached its final orbit. The tasking function was activated bythe civilian operator, Astrium GEO-Information Services. Pléiades is now well positioned to start releasing the first products. The commissioning phase will last until early March, when all parameters and processing elements have been fine-tuned and tested to deliver reliably high-quality images.

Very-high resolution and reactivity

Pléiades 1 is the first of a two-satellite constellation. It will later be joined by Pléiades 2 (around twelve months after the first), operating on the same orbit but phased 180° from its twin. Added to their oblique viewing capability and exceptional agility, this orbit phasing allows the satellites to revisit any point on the globe daily—ideal for anticipating risks and managing crises effectively.

The Pléiades satellites’ gyros enable them to tilt very quickly along and across track to image different areas of interest. Each satellite will be able to collect imagery anywhere within an 800-km-wide ground strip, covering 200 kilometres in 11 seconds or 800 kilometres in 25 seconds, including stabilization time. That kind of performance results in a reduced average acquisition window for the users, allowing more images to be collected during the same pass: collection opportunities are more numerous, conflicts between contiguous requests are minimized.

The agility will also make it possible to image multiple targets (typically 15 targets over 1,000 km within a corridor of +/-30 degrees), collect large mosaics in a single pass (up to 100 × 100 km in the same pass), conduct stereo and tri-stereo viewing for accurate 3D applications, and support coastal, border or corridor surveillance to closely match any user’s needs.

The ground operations component is also organized with maximum responsiveness in mind. Work plans are uploaded to the satellite three times a day by three stations around the globe, making it possible to task requests up to two hours before satellite pass. This reduces the lead time between tasking requests and image acquisition to a minimum. Customers with receiving stations configured for direct tasking will be able to refine tasking plans at the last moment (30 minutes prior to satellite arrival above the cone) according to the latest weather forecasts or emergency requests.

Dubai, UAE (resampled at 5 m).Copyright: CNES 2012 © – Distribution Astrium Services / Spot Image

A lot of work has gone into designing image production systems. The fully automatic orthorectification process is capable of generating a 20 km x 20 km colour image in less than 30 minutes and a single-pass mosaic of 60 km x 60 km in two to three hours.
On the user side, everything from ordering through to data delivery has been made as flexible and easy as possible. New acquisitions, catalogue data, subscription offers, online monitoring services and more mean that imagery is just a click away, ready to use.

Next steps

The first of a new generation of satellites operated by Astrium Services, Pléiades 1 will be followed between 2012 and 2014 by SPOT 6, its twin Pléiades 2 and finally SPOT 7. As the end of SPOT 5 is now scheduled for mid-2015, the question was raised about how to continue delivering the service SPOT 5’s users have come to expect. This was the brief underpinning the design of SPOT 6 and SPOT 7. An in-depth market survey and careful canvassing to ascertain users’ expectations were conducted. Conclusions led to keep the best features of SPOT 5, retaining a 60-kilometre swath, while improving agility and product resolution (1.5 meters).

Astrium Services CEO Eric Beranger officially announced funding for the SPOT 6 & 7 programme in June 2009. This is the first time in the remote-sensing industry that a satellite has been built with entirely private funds, proving Astrium GEO-Information Services’ confidence in this market.

The two satellites are currently under development: the SPOT 6 optical instrument is now coupled with the satellite platform. After a phase of mechanical and environmental testing, SPOT 6 launch is scheduled for September 2012. SPOT 7integration has also started and will be ready for a launch in the fourth quarter of 2013.

Built around a similar architecture and phased on the same orbit, this constellation of 4 satellites, composed of Pléiades 1, Pléiades 2, SPOT 6 and SPOT 7 will ensure even better responsiveness and availability of 50-centimetre-to-1.5-metre products through to 2023. 

Casablanca, Morocco (full resolution). Copyright: CNES 2012 © – Distribution Astrium Services / Spot Image

More information at
VHR product manager
GEO-Information Services
Astrium Services
5 rue des Satellites, BP 14359
F-31030 Toulouse Cedex 4 – France
Tel: +33 (0)5 62 19 40 40