SPOT

## SPOT (Satellite Pour l'Observation de la Terre), France

Click on the image for detailed descriptions of the SPOT Satellite System

The SPOT program consists of a series of optical remote sensing satellites with the primary mission of obtaining Earth imagery for landuse, agriculture, forestry, geology, cartography, regional planning, water resources and GIS applications. it is committed to commercial remote sensing on an international scale and has established a global network of control centres, receiving stations, processing centres and data distributors. The SPOT satellites are operated by the French Space Agency, Centre National d'Etudes Spatiales (CNES). Worldwide commercial operations are anchored by SPOT IMAGE in France with the following subsidiaries: SPOT Image Corp. in the US, SPOT Imaging Services in Australia and SPOT Asia in Singapore.

SPOT 1 was launched on 22 February 1986, and withdrawn from active service on 31 December 1990. SPOT 2 was launched on 22 January 1990 and is still operational. SPOT 3 was launched on 26 September 1993. An incident occured on SPOT 3 on November 14, 1996. After 3 years in orbit the satellite has stopped functioning. SPOT 4 is scheduled for launching in early 1998. Engineering work for SPOT 5 has began so that the satellite can be launched late in 2002 to ensure service continuity. To meet the increasing demand for SPOT imagery, notably during the northern hemisphere growing season, SPOT 1 is reactivated in 1997 for routine operation.

The SPOT system provides global coverage between 87 degrees north latitude and 87 degrees south latitude.

## SPOT Orbit

:

Type | Sun-Synchronous
Altitude | 832 km
Inclination | 98.7 deg
Period | 101 min
Repeat Cycle | 26 days
Off-Nadir Revisit | 1 to 3 days

Sensors

HRV (High Resolution Visible)

SPOT Twin HRV Imaging System

Each SPOT satellite carries two HRV sensors, constructed with multilinear array detectors, operating in a cross-track direction. The position of each HRV entrance mirror can be commanded by ground control to observe a region of interest not necessarily vertically beneath the satellite. Thus, each HRV offers an oblique viewing capability, the viewing angle being adjustable through ±27º relative to the vertical. This off-nadir viewing enables the acquisition of stereoscopic imagery and provides a short revisit interval of 1 to 3 days.

Off-nadir viewing capability of SPOT HRV enables a short revisit interval of 1 to 3 days.

Two imaging modes are employed, panchromatic (P) and multispectral (XS). Both HRVs can operate in either mode, either simultaneously or individually.

Panchromatic (P) mode

Imaging is performed in a single spectral band, corresponding to the visible part of the electromagnetic spectrum without the blue. The band covers 0.51 to 0.73 µm. This single channel imaging mode supplies only black and white images with a pixel width of 10 m. This band is intended primarily for applications calling for fine geometrical detail.

Multispectral (XS) mode

Imaging is performed in three spectral bands. The bands used are band XS1 covering 0.50 to 0.59 µm (green), band XS2 covering 0.61 to 0.68 µ m (red) and band XS3 covering 0.79 to 0.89 µm (near infrared). By combining the data recorded in these channels, colour composite images can be produced with a pixel size of 20 meters.

## SPOT HRV Instrument Characteristics

| Multispectral Mode (XS) | Panchromatic Mode (P)
Instrument Field of View | 4.13 deg | 4.13 deg
Ground Sampling Interval (Nadir Viewing) | 20 m by 20 m | 10 m by 10 m
Pixel per Line | 3000 | 6000
Ground Swath (Nadir Viewing) | 60 km | 60 km

## SPOT HRV Spectral Bands

Mode | Band | Wavelength (µm) | Resolution (m)
--- | --- | --- | ---
Multispectral | XS1 | 0.50 - 0.59 (Green) | 20
Multispectral | XS2 | 0.61 - 0.68 (Red) | 20
multispectral | XS3 | 0.79 - 0.89 (Near IR) | 20
Panchromatic | P | 0.51 - 0.73 (Visible) | 10

Go to Main Index