Technical features and operation
Satellites in orbit
The SPOT satellites are impressive structures, standing about 4.5 metres high, weighing 2 to 3 tonnes each and capable of carrying all the necessary equipment for image collection.
The SPOT Earth observation satellite system comprises two identical telescopes with all the tools needed to record data and transmit them to ground.
The SPOT Earth observation satellite system comprises two identical telescopes with all the tools needed to record data and transmit them to ground.
Each telescope operates independently from the other, collecting light reflected from objects on the ground and concentrating it onto the arrays of detectors (photodiodes). Each detector converts the light energy into electrical impulses, which are processed and encoded and then transmitted as radio waves to the ground, where they are processed again to form the corresponding images.
Ground installations
CNES is responsible for satellite control and transmission of the payload work schedule via its network of telemetry, tracking and command stations. The main station is located in France at Issus-Aussaguel, near Toulouse.
Data are transmitted directly or from the satellite’s recorders to receiving stations in Toulouse and Kiruna, Sweden. In addition, a network of 21 direct receiving stations (DRS) receives SPOT data when the satellites are within their receiving footprint (2,500 km around the station).
The satellite's daily work schedule is established by the Spot Image Programming Centre (CPR), according to programming requests from clients and distributors, and taking into account technical and weather restrictions.
Data are transmitted directly or from the satellite’s recorders to receiving stations in Toulouse and Kiruna, Sweden. In addition, a network of 21 direct receiving stations (DRS) receives SPOT data when the satellites are within their receiving footprint (2,500 km around the station).
The satellite's daily work schedule is established by the Spot Image Programming Centre (CPR), according to programming requests from clients and distributors, and taking into account technical and weather restrictions.
Instruments
- HRG (High Resolution Geometric): Thanks to the Supermode process, the two HRG telescopes on SPOT 5 offer better resolution than their predecessors—2.5 metres to 5 metres in black and white (panchromatic mode) and 10 metres in colour (multispectral mode).
- HRS (High Resolution Stereoscopic): The HRS instrument is designed to acquire virtually simultaneous images from two different viewing angles. The result is a pair of images, which when combined, show the relief of the zone. This stereoscopic process is used to produce 3D models of the terrain.
- Vegetation 1 and 2: Passenger payloads on SPOT 4 and 5, these systems allow regular observation of crops and the continental biosphere.
- Doris (Doppler Orbitography and Radio-positioning Integrated by Satellite): Operational since the launch of SPOT 2, this system is used to determine the position of the satellite to within 10 cm, in real time, after ground processing.
