SPOT and Other Moderate Resolution Satellites

SPOT
1. SPOT
        Le Systeme Pour l'Observation de la Terre
        (Earth Observation System)

        - a French satellite system
        - SPOT-1 was launched in Feb 21, 1986,
        - SPOT-2 in 1990
        - SPOT-3 in 1993
        - the first commercial system designed to provide high
            quality service and data for operational users worldwide

2. SPOT orbit
        - sun-synchronous
        - altitude 832km
        - inclination 98.70
        - 10:30am passes descending point
        - 26 days for vertical observation, 1-4 days for oblique obs.

3. SPOT sensor systems
   Components
        - two identical High Resolution Visible (HRV) imaging systems
        - a telemetry transmitter, and magnetic tape recorders

   The pushbroom technique
        - "pushbroom" scanning based on charge coupled devices (CCD)
          which allows imaging the entire data line along track
        - a linear array of CCDs each corresponding to a pixel
        - pushbroom allows longer lifetime, reduced geometric errors,
            and longer dwell time
        - a 6,000-detector subarray for the pan band
          3 3,000-detector subarrays for the 3 multispectral bands
        - the pointable mirror is controlled by the ground station to
            acquire oblique images

4. SPOT resolutions
   Panchromatic mode
        - spectral resolution: 0.51-0.73microm
        - radiometric resolution: 256 level of brightness
        - spatial resolution: 10x10m
        - temporal resolution: 2.5-26 days

   Multispectral configuration
        - spectral resolution:  band1: 0.50-0.59microm (green)
                                                band2: 0.61-0.68microm (red)
                                                band3: 0.79-0.89microm (near infrared)
        - radiometric resolution: 256 levels
        - spatial resolution: 20x20m
        - temporal resolution: 2.5-26 days

5. The stereoscopic pairs
        The nadir viewing
        - the 2 60km swath overlap 3km, the total swath is 117km

        The off-nadir viewing
        - can view in a maximum 27^o in 45 steps of 0.6^o each
        - can view an area of a maximum 950km, with each scene 60-80km
        - the same area can be viewed from different angles to acquire
            stereo coverage
        - the twin sensors can operate in different viewing angles

6. SPOT 4 and 5
     SPOT 4
        - launched on Mar 23,1998
        - High Resolution Visible and Infrared (HRVIR)
        - an additional mid-infrared 1.58-1.75microm for vegetation, mineral,
            and soil moisture monitoring
        - replace the pan band with a red band that produces both 10m black/white
            and 20m multispectral data
        - a wide IFOV Vegetation Monitoring Instrument
          1km resolution, 2250km swath, B, R, NIR, MIR bands

    SPOT 5
        - launched on May 3, 2002
        - replace HRVIR with two high resolution geometric instruments (HRG)
        - 5m pan band, 10m G, R, NIR, 20m MIR
        - high resolution stereoscopic (HRS) instrument, prepares 10m DEM global wide

7. SPOT data
        - direct transmission occurs within 2600km to the ground stations, otherwise tape recorders are used

        - SPOT Image Co. at Reston, VA distributes SPOT data in the US
             www.spot.com

Other Moderate Resolution Land Satellites

1. IRS (the Indian Remote Sensing)
        developed, launched, and operated by the Republic of India

    IRS-1A (1988) and IRS-1B (1991)
        - multispectral bands similar to TM bands 1-4
        - spatial resolutions 72.5 m and 36.5m
        - 140+ km swath

    IRS-1C (1995) and IRS-1D (1997)
        - multispectral bands 23m resolution, a MIR band 70m resolution
        - a pan band 5.8m resolution
        - Wide Field Sensor 188m resolution, 774km swath

2. RESURS-01
    the series was launched by Russia in 1985, 1988, 1994, 1998
    ESURS-01 3, 4 
       - 29-45m, 140-185m resolution for the green, red, and 2 NIR bands
       - 520-740m resolution for the thermal band
       - 600-710km swath
       - 4-day temporal resolution at the equator, daily at high latitudes
  
  3. ADEOS (ADvanced Earth Observing Satellite)
    launched by Japan in 1996
        the Advanced Visible and Near Infrared Radiometer
        - B, G, R, NIR bands, 16m resolution
        - a pan band 8m resolution
        - 80km swath

        Ocean Color and Temperature Sensor
        - 8 bands in visible and NIR, 4 bands in thermal region
        - 700m resolution, 3 day temporal resolution

4. JERS-1
        developed by Japan, 1992-1998

    Optical Scanner
        - uses pushbroom scanning in 7 visible, NIR, and MIR bands
        - stereoscopic observation
        - 18x24m resolution
        - 75km swath

  5. other satellites
        launched since 2000 by
        China-Brazil, European space agency, Algeria, Turkey, Nigeria, UK, India, Thailand, Russia, China
       
 

8. Reading: chpt 6
 
 
 
 
 
 
 

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