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astronautix.com SPOT-4


Other Designations: Satellite Probatoire d'Observation de la Terre. Class: Earth. Type: Landsat. Nation: France. Agency: CNES, SPOT-Image Corp. Manufacturer: Matra Marconi.

SPOT is the French government sponsored civil Earth observation program, with support from Belgium and Sweden. A single SPOT satellite provides complete coverage of the Earth every 26 days. Image products from SPOT are handled by a commercial entity, SPOT-Image Corp. Spacecraft: 3-Axis stabilised. Single 5-panel solar array, each panel is 2.6 x 1.9 m. Hydrazine propulsion system provides orbit maintenance. Payload: Two HRVIR (High Resolution Visible - Infrared) push-broom imaging instruments are carried. HRVIR is derived from the HRV instruments on SPOT 1-3. This system will provide 10 m resolution in the panchromatic band and 20 m resolution in the multispectral bands. HRVIR includes a new medium IR channel to support vegetation analysis and harvest forecasting. The HRVIRs are steerable to within 27 deg off-nadir. Each HRVIR has a swath width of 60 km. The Vegetation Monitoring instrument has 1 km resolution in the same bands as the HRVIR. PASTEL optical link terminal supports laser crosslink experiments. DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) precision orbit determination system.
Financial/Operational:
Uses $ 110 million Silex - semiconductor laser intersatellite link experiment. Provides data relay for Artemis.


Specification

Design Life: 5 years . Total Length: 5.4 m. Maximum Diameter: 2.0 m. Total Mass: 2,755 kg.


SPOT-4 Chronology


24 March 1998 SPOT 4 Program: SPOT. Launch Site: Kourou . Launch Vehicle: Ariane 4. Mass: 2,755 kg. Perigee: 824 km. Apogee: 826 km. Inclination: 98.7 deg.

Developed by Matra Marconi Space/Toulouse for CNES, the satellite provided 10-m resolution images with a wide field of view. SPOT 4 also carried a wide field 'vegetation' imager and a laser communications experiment. Launch was by an Arianespace Ariane 40 rocket, the base Ariane 4 model with no strap-on boosters. The liquid hydrogen fuelled third stage of the Ariane 40 entered an 800 km sun-synchronous orbit together with SPOT 4.



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Last update 12 March 2001.
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