remote sensing

1. Spot satellite
TITUS BUNNY CHAPUKIRA

2. Background
•SPOT stands for Satellite Pour l'Observation de la Terre
•The SPOT satellite Earth Observation System was designed by the
Centre National d'Etudes Spatiales (CNES), in France.
•There have been four SPOT satellites launched since 1986, providing
medium to high resolution of the Earth's surface. SPOT 1, 2 and 3
carried a multi-spectral (XS) and panchromatic (P) sensor on board.
SPOT 4 was successfully launched in March 1998.
•The SPOT Program supports commercial remote sensing on an
international scale, establishing a global network of control centers,
receiving stations, processing centres, and data distributors

3. Extent of coverage
 The SPOT satellites orbit at an altitude of 822km.
SPOT scene sizes are typically 60km by 60km
(vertical viewing) or 60km by 80km for oblique
viewing. The optical imaging instruments (HRVs) are
steerable to either side of the ground track - east to
west - by up to 30 degrees.
 The SPOT satellites orbit the same ground track
every 26 days with a nominal cycle of 369
revolutions.
 Its mean revolution period is equal to 101.4 minutes

4. Spectral modes of acquisition
 Imaging is performed in three spectral bands. The
bands used are band B1 covering 0.50 to 0.59 m
(green), band B2 covering 0.61 to 0.68 m (red)
and band B3 covering 0.79 to 0.89 m (near
infrared). By combining the data recorded in
these channels, color composite images can be
produced with a pixel size of 20 metres

5. Band 1(green)
 Wavelength range =0.50-0.59 micrometres
 Recommended for use in combination with other
bands because of low contrast and sensitivity to
haze
 Best for showing roads and bare soils.
 Resolution = 20meters

6. Band 2 (red)
 Wavelength range=0.61-0.68 micrometres
 This band heightens the contrast between
vegetated and non-vegetated areas

7. Band 3(near infra red)
 Wavelength range =0.79-0.89 micrometres
 This band is used to evaluate vegetation biomass
and separates water from vegetation.

8. HRV--High Resolution Visible Imaging Instrument
 The HRV instrument is a multispectral radiometer designed for
SPOT spacecraft. The HRV instrument provides for high-resolution
imaging in the visible and near-infrared portions of the
electromagnetic spectrum. The first three SPOT satellites carry
twin HRVs that operate in a number of viewing configurations and
in different spectral modes.

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 Some of those viewing configurations and spectral
modes include one HRV only operating in a dual
spectral mode (i.e. in both panchromatic mode
and multispectral mode); two HRVs operating in
the twin-viewing configuration (i.e. one HRV in
panchromatic mode and one HRV in multispectral
mode); and two HRVs operating independently of
each other (i.e. not in twin-viewing
configuration).

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 The position of each HRV entrance mirror can be
commanded by ground control to observe a region of
interest. Operating independently of each other, the
two HRVs acquire imagery in either multispectral (XS)
and/or panchromatic (P) modes at any viewing angle
within plus or minus 27 degrees. This off-nadir
viewing enables the acquisition of stereoscopic
imagery. To make sure the satellite covers every point
on the earth's surface, the HRV imaging instruments
offer a field of view that is wider than the greatest
distance between two adjacent tracks

11. Receiving Stations
 Two main stations are located at Toulouse
(France) and Kiruna (Sweden). These stations are
capable of receiving the telemetry recorded on
the on-board recorders or directly within their
visibility circle of approximately 2500 km radius
centered on the stations. 22 direct receiving
locations (DRS) can only receive telemetry within
their visibility circle.

12. The end