Earth Resource Satellite SPOT (System Pour L ′ Observation De La Terre) : Introduction, History, and Details (Especially for GATE-Geospatial 2022)

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  • SPOT (System Pour l ‘Observation de la Terre) was designed by the Centre National d’ Etudes Spatiales (CNES) , France as a commercially oriented earth observation program. The first satellite of the mission, SPOT-1 was launched in February, 1986. This was the first earth observation satellite that used a linear array of sensors and the push broom scanning techniques.
  • Also these were the first system to have pointable/steerable optics, enabling sideto-side off-nadir viewing capabilities. SPOT 1,2 and 3 carried two identical High Resolution Visible (HRV) imaging systems. Each HRV were capable of operating either in the panchromatic mode or in the MSS mode. HRVs used along-track, push-broom scanning methods. Each HRV contained four CCD subarrays.
  • A 6000-element sub-array was used for recording in the panchromatic mode and the remaining 3 arrays, each with 3000 elements, were used for the MSS mode. Due to the off nadir viewing capability, HRV was also used for stereoscopic imaging.
  • Frequency with which the stereoscopic coverage can be obtained varies with the latitude; more frequent imaging is possible near the polar region compared to the equatorial region. SPOT 4 carried the High Resolution Visible and Infrared (HRVIR) sensor and the vegetation instrument (VI) . HRVIR also includes two identical sensors, both together capable of giving 120km swath width at nadir.
  • SPOT-5 carries two high resolution geometric (HRG) instruments, a single high resolution stereoscopic (HRS) instrument, and a vegetation instrument (VI) . SPOT-6 mission employs two New Astro Sat Optical Modular Instruments (NAOMI) .
  • The instrument operates in 5 spectral bands, including one panchromatic band. Pointable optics used in the program enables off-nadir viewing. This increases the frequency of viewing viz. , 7 additional viewings at equator and 11 additional viewings at 45deg latitude.
  • Due to the off-nadir viewing capabilities, stereo imaging is also possible. Stereo pairs, used for relief perception and elevation plotting (Digital Elevation Modelling) , are formed from two SPOT images.
SPOT, Satellite Program

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