Pleiades satellites
The Pléiades constellation
Satellite constellation
A group of artificial satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and...

 is composed of two very-high-resolution optical Earth-imaging satellites. Pléiades 1 and Pléiades 2 will provide coverage of Earth’s surface with a repeat cycle of 26 days .
. Designed as a dual civil/military system, Pléiades will meet the space imagery requirements of Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an defence as well as civil and commercial needs.


The Pléiades system was designed under the French-Italian ORFEO
ORFEO is a German classical record label founded in 1979 and launched in 1982. It has released the archives of the Symphonieorchester des Bayerischen Rundfunks. The record label was used by its owner F. Axel Merhle as a tax shelter, which resulted in his prosecution for fraud in December 1985.-...

 program (Optical & Radar Federated Earth Observation) between 2001 and 2003. The Pléiades programme was launched in October 2003 with CNES
The is the French government space agency . Established under President Charles de Gaulle in 1961, its headquarters are located in central Paris and it is under the supervision of the French Ministries of Defence and Research...

 (the French space agency) as the overall system prime contractor and EADS Astrium
EADS Astrium
Astrium Satellites is one of the three business units of Astrium, a subsidiary of EADS. It is a European space manufacturer involved in the manufacture of spacecraft used for science, Earth observation and telecommunication, as well as the equipment and subsystems used therein and related ground...

 as the prime contractor for the space segment. Spot Image
Spot Image
Spot Image, a public limited company created in 1982 by the French Space Agency, Centre National d'Etudes Spatiales , the IGN, and Space Manufacturers is a subsidiary of EADS Astrium...

 is the official and exclusive worldwide distributor of Pléiades products and services under a delegated public service agreement. Pléiades 1 is scheduled to launch at the end of 2011, and will be followed by Pléiades 2 in mid 2012.


The two satellites will operate in the same phased orbit and will be offset at 180° to offer a daily revisit capability over any point on the globe.
  • Orbit: Sun-synchronous, phased, near-circular
  • Mean altitude: 694 km.


Equipped with innovative latest-generation space technologies like fibre-optic gyros and control moment gyros, Pléiades 1 and 2 will offer exceptional roll, pitch and yaw (slew) agility, enabling the system to maximize the number of acquisitions above a given area.

Agility for Responsive Tasking

This agility coupled with particularly dynamic image acquisition programming will make the Pléiades system very responsive to specific user requirements. Individual user requests will be answered in record time, thanks to multiple programming plans per day and a state-of-the-art image processing chain. Performance at a glance:
  • Image acquisition anywhere within an 800-km-wide ground strip with sub-meter resolution
  • Along-track stereo and tri-stereo image acquisition
  • Single-pass collection of mosaics (strip-mapping) with a footprint up to a square degree
  • Maximum theoretical acquisition capacity of 1,000,000 per day and per satellite
  • Optimized daily acquisition capacity (taking into account genuine order book, weather constraints, conflicts...) reaching 300,000 sq. km per day and per satellite.

Optical Instrument

Pléiades radiometer features
mode Channel Spectral band
multispectral 1 430 – 550 nm (blue)
2 490 – 610 nm (green)
3 600 – 720 nm (red)
4 750 – 950 nm (near-infrared)
panchromatic P 480 – 830 nm (black and white)


Resolution Panchromatic: 50 cm
Multispectral: 2 m
Pansharpened: 50 cm
Bundle: 50 cm PAN & 2 m MS
Footprint 20 km swath
Single pass mosaics up to 100 km x 100 km
Accuracy 4.5 m CE 90 with refined attitude data, without ground control points (GCPs)

Ground receiving stations

When satellite operations begin, four ground receiving stations will be deployed for the direct downlink and archiving of imagery data:
  • Two defence centres in France and Spain
  • Two civil stations: one in Toulouse (France) and a polar station in Kiruna (Sweden), which will receive most of the data.

Regional receiving stations (fixed or mobile) will subsequently be installed at the request of users.

Uplink Stations

The Pléiades tasking plan will be refreshed and uploaded three times per day, allowing for last minute requests and the ability to utilize up-to-the-minute weather forecasts.
  • The Kerguelen Island station uploads the morning pass, over Europe, Africa and the Middle East.
  • The Swedish station takes care of midday orbits, over North and South Americas.
  • The French station transmits the last tasking plan of the day over Asia and Oceania.

Applications of VHR imagery

The Pléiades system is designed for a range of very-high-resolution (VHR) remote sensing applications. These include:
  • Land planning: detection and identification of small features (e.g. vehicles, roads, bushes)
  • Agriculture: land management and crop yields, location of crop diseases, tree count (palm trees, vineyards...)
  • Defense: imagery-derived intelligence and tactical planning in urban/densely populated areas
  • Homeland Security: mitigation, assistance in crisis events and post-crisis assessment (particularly earthquakes)
  • Hydrology: topography and drainage basin gradient studies
  • Forestry: illicit deforestation and management of forestry yields; REDD data qualification (sampling)
  • Maritime and littoral surveillance: vessel reconnaissance and contamination (oil spill), harbor mapping
  • Civil Engineering/Asset Monitoring: planning of road, rail and oil pipeline corridors
  • 3D: flight simulators, high precision mapping, photovoltaic fields implantation...

External links

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