Remote Sensing

Introduction to SPOT

SPOT5
SPOT5

The SPOT (Systeme Provatoire d’Observation de la Terre), program, developed in France with the collaboration of Belgium and Sweden.

SPOT5 is the latest of the SPOT series of satellites continuing and complementing the mission assigned to its predecessors in the field of Earth Observation and Mapping. Launched on May 2002 the 3rd, its in-flight commissioning was led in two phases. The qualification phase permitted to hand over the satellite to Spot Image in july 2002 [Bouillon 2002,2003], [Breton 2002]. The second phase included fine tuning of its components and continued until early 2003 allowing to fully take advantage of the geometric improvements brought to SPOT5 compared to its elders :

star tracker and improved steering mirror on HRG instruments for the localization,

monolithic CCD array,

resolution,

along track stereoscopic instrument HRS.

Observations on the first SPOT 5 images showed imperfections in the CCD array and telescop alignments both on HRG and HRS instruments. An inner orientation of the instruments was therefore considered necessary, especially for

the HRS stereoscopic instrument with an optical distorsion of several pixels. Following is a non exhaustive list of the

outcomes expected from this inner orientation :

assessed and refined look angle models provided by the satellite constructor ;

optimized relative orientation between the forward and backward HRS stereoscopic instruments ;

optimized relative orientation between the panchromatic and multispectral bands within each HRG instrument.

On previous SPOT satellites the geometric performance of the detectors has been assessed with relative methods Valorge 2003] involving simultaneous acquisitions of the same scene with both instruments ; these methods never permitted to obtain an absolute measurement of the viewing direction [Gachet 1999]. The characteristics of SPOT5 instruments together with the objective of inner orientation made it necessary to implement another method based on absolute calibration using airborne images and elevation information from our « super site » in southeastern France. Since March 2003, ancillary data provided in the « METADATA.DIM » file associated with SPOT5 images [Spot Image 2002] include the instruments look angles for each detector with an estimated RMS accuracy of 0.03 pixel.

About the SPOT-5 Satellite Sensor

The SPOT-5 Earth observation satellite was successfully placed into orbit by an Ariane 4 from the Guiana Space Centre in Kourou during the night of 3 to 4 May 2002.

The VEGETATION 2 passenger instrument on SPOT-5 also provides continuity of environmental monitoring around the globe, like its predecessor on SPOT-4.

SPOT Image Corporation is composed of four subsidiaries, including an office in Germany and a dense global network of receiving stations, channel partners, and distributors. Satellite Imaging Corporation is an official distributor for SPOT Image Corporation.

Compared to its predecessors, SPOT-5 offers greatly enhanced capabilities, which provide additional cost-effective imaging solutions. Thanks to SPOT-5’s improved 5-metre and 2.5-metre resolution and wide imaging swath, which covers 60 x 60 km or 60 km x 120 km in twin-instrument mode, the SPOT-5 satellite provides an ideal balance between high resolution and wide-area coverage. The coverage offered by SPOT-5 is a key asset for applications such as medium-scale mapping (at 1:25 000 and 1:10 000 locally), urban and rural planning, oil and gas exploration, and natural disaster management. SPOT-5’s other key feature is the unprecedented acquisition capability of the on-board HRS stereo viewing instrument, which can cover vast areas in a single pass. Stereo pair imagery is vital for applications that call for 3D terrain modeling and computer environments, such as flight simulator databases, pipeline corridors, and mobile phone network planning.

Archived and New SPOT-5 Imagery

For many image requests, a matching image can already be located in the archives of SPOT-5 imagery from around the world. If no image data is available in the archives, new SPOT-5 satellite image data can be acquired through a satellite tasking process. Besides providing image data, Satellite Imaging Corporation also performs many tasks in the background to ensure that we meet customer specifications and time schedules. We:

  • Negotiate the attainment of archived or new images
  • Process imagery, including orthorectification, DSMs, DTMs, and culture and terrain extraction for GIS
  • Incorporate third-party United States and international GIS data
  • Consult on band combinations most appropriate to bring out the geographical and manmade features that are most relevant to your project
  • Perform spectral analysis for landcover use classifications and environmental changes

Source: SPOT Satellite Geometry Handbook

SPOT-5 Satellite Sensor Characteristics

Launch Date

May 3, 2002

Launch Vehicle

Ariane 4

Launch Location

Guiana Space Centre, Kourou, French Guyana

Orbital Altitude

822 kilometers

Orbital Inclination

98.7°, sun-synchronous

Speed

7.4 Km/second (26,640 Km/hour)

Equator Crossing Time

10:30 AM (descending node)

Orbit Time

101.4 minutes

Revisit Time

2-3 days, depending on latitude

Swath Width

60 Km x 60 Km to 80 Km at nadir

Metric Accuracy

< 50m horizontal position accuracy (CE90%)

Digitization

8 bits

Resolution

Pan: 2.5m from 2 x 5m scenes

Pan: 5m (nadir)

MS: 10m (nadir)

SWI: 20m (nadir)

Image Bands

Pan: 480-710 nm

Green: 500-590 nm

Red: 610-680 nm

Near IR: 780-890 nm

Shortwave IR: 1,580-1,750 nm

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