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The Pléiades constellation is composed of two very-high-resolution optical Earth-imaging satellites. Pléiades-HR 1A and Pléiades-HR 1B provide the coverage of Earth's surface with a repeat cycle of 26 days.^[1] Designed as a dual civil/military system, Pléiades will meet the space imagery requirements of European defence as well as civil and commercial needs.

History

The Pléiades system was designed under the French-Italian ORFEO program (Optical & Radar Federated Earth Observation) between 2001 and 2003.^[2]

The Pléiades programme was launched in October 2003 with CNES (the French space agency) as the overall system prime contractor and EADS Astrium as the prime contractor for the space segment.

Spot Image is the official and exclusive worldwide distributor of Pléiades products and services under a delegated public service agreement.

Launches

• 
  Pléiades-HR 1A was launched via a Russian Soyuz STA rocket out of the Guiana Space Centre, Kourou, French Guiana, on December 17, 2011, 02:03 UTC.


• 
  Pléiades-HR 1B was launched via a Russian Soyuz STA rocket out of the Guiana Space Centre, Kourou, French Guiana, on December 2, 2012, 02:02 UTC.^[3][4]
  

Technologies

Orbit

The two satellites operate in the same phased orbit and will be offset at 180° to offer a daily revisit capability over any point on the globe. The Pléiades also share the same orbital plane as the SPOT 6 and 7, forming a larger constellation with 4 satellites, 90° apart from one another.^[5]

• Orbit: Sun-synchronous, phased, near-circular


• Mean altitude: 694 km.

Innovation

Equipped with innovative latest-generation space technologies like fibre-optic gyros and control moment gyros, Pléiades-HR 1A and 1B 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 70 cm of 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 km² per day and per satellite


• Optimized daily acquisition capacity (taking into account genuine order book, weather constraints, conflicts...) reaching 300,000 km² per day and per satellite.

Products

^[6]

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.^[7]

• 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...

See also

• GIS


• Remote sensing

References

External links

• Astrium Geo


• ASTRIUM


• CNES


• Gunter's Space Page


• eoportal.org