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Satellite Systems

A Satellite system is composed of a scanner with sensors and a satellite platform. Sensors are made up of Detectors.

In a satellite system, the total width of the area on the ground covered by the scanner is called swath, or field of view (FOV).

Landsat and SPOT satellites are two important date acquisition satellites. Discuss Other important satellites in below.

Satellite System

Satellites

Landsat

Landsat 1-5 Satellite System

In 1972, National Aeronautics and Space Administration (NASA) initiated the first civilian program specializing in the acquisition of remotely sensed digital satellite data. The first system was called ERTS (Earth Resources Technology Satellites), and later renamed to Landsat. There have been several Landsat satellites launched in 1972. Landsats 1, 2, 3 and 4 are no longer operating. US Geological Survey Flight Operations Team completed decommission of Landsat 5 in June 2013.

Landsat 1, 2, and 3 gathered Multispectral Scanner (MSS) data and Landsats 4 and 5 collected MSS and Thematic Mapper (TM) data.

Landsat MSS

Multispectral Scanner from Landsats 4 and 5 had a swath width of approximately 185 × 170 km from a height of approximately 900 km for Landsats 1, 2, and 3, and 705 km for Landsats 4 and 5. MSS data are widely used for general geologic studies as well as vegetation inventories.

Spatial resolution of MSS data is 56 × 79 m, with a 79 × 79 m IFOV. A typical scene contains approximately 2340 rows and 3240 columns. Radiometric resolution is 6-bit, but it is stored as 8-bit.

Landsat MSS Band Composition
BandWavelength
(micrometres)
Uses
1, Green0.50 to 0.60Scans the region between blue and red
chlorophyll absorption bands.
Green reflectance of healthy vegetation.
Map water bodies.
2, Red0.60 to 0.70Red chlorophyll absorption band of healthy
green vegetation.
Identify vegetation types.
Determine soil boundary and geological
boundary delineations
Cultural features.
3, Red, NIR0.70 to 0.80dentify crops.
Identify soil and crop boundaries.
Identify land and water boundaries.
4, NIR0.80 to 1.10Vegetation surveys Penetrates atmospheric haze
Landsat TM

TM had a swath width of approximately 185 km from a height of approximately 705 km. It is useful for vegetation type and health determination, soil moisture snow and cloud differentiation, rock type discrimination, and so forth.

Spatial resolution of TM is 28.5 × 28.5 m for all bands except the thermal (band 6), which has a spatial resolution of 120 × 120 m. The larger pixel size of this band is necessary for adequate signal strength. However, the thermal band is resampled to 28.5 × 28.5 m to match the other bands. Radiometric resolution is 8-bit, meaning that each pixel has a possible range of data values from 0 to 255.

Landsat TM Band Composition
BandWavelength
(micrometres)
Uses
1, Blue0.45 to 0.52Coastal water area mapping.
Differentiate between soil and vegetation.
Forest type mapping.
Detect cultural features.
2, Green0.52 to 0.60Green reflectance of healthy vegetation.
Identify cultural features.
3, Red0.63 to 0.69Differentiate between many plant species.
Determine soil boundary and geological boundaries.
Identify cultural features.
4, NIR0.76 to 0.90Determine amount of vegetation biomass.
Identify crops.
Determine soil and crop boundaries.
Determine land and water boundaries.
5, MIR1.55 to 1.75Measure moisture content in plants for crop drought studies and plant health analysis.
Differentiate between clouds, snow, and ice.
6, TIR10.40 to 12.50Detect stress in vegetation and crops.
Measure heat intensity.
Determine insecticide applications.
Locate thermal pollution.
Locate geothermal activity.
7, MIR2.08 to 2.35Determine boundaries of geologic rock type and soil.
Measure soil and vegetation moisture content.
Landsat 7 Satellite System

Landsat 7 satellite, launched in 1999, uses Enhanced Thematic Mapper Plus
(ETM+) to observe the Earth. Capabilities new to Landsat 7 following:
• 15m spatial resolution panchromatic band
• 5% radiometric calibration with full aperture
• 60m spatial resolution thermal IR channel

Landsat 7 Band Composition
BandWavelength
(micrometres)
Resolution
(m)
10.45 to 0.5230
20.52 to 0.6030
30.63 to 0.6930
40.76 to 0.9030
51.55 to 1.7530
610.4 to 12.560
72.08 to 2.3530
8 (Panchromatic)0.50 to 0.9015

SPOT

SPOT 1 – 3 Satellite System

SPOT 1 satellite was developed by French Centre National d’Etudes Spatiales (CNES), launched in 1986, and deorbited in 2003. SPOT 2 satellite, launched in 1990 and deorbited in 2009, was the first in the series to carry the DORIS precision positioning instrument. SPOT 3, launched in 1993, also carried the DORIS instrument, plus the American passenger payload POAM II, used to measure atmospheric ozone at the poles. SPOT 3 was decommissioned in 1996.

SPOT Panchromatic

SPOT Panchromatic (meaning sensitive to all visible colors) has 10 × 10 m spatial resolution, contains 1 band—510 to 730 nm—and is similar to a black and white photograph. It has a radiometric resolution of 8 bits.

SPOT MSS/XS

SPOT XS, or multispectral, has 20 × 20 m spatial resolution, 8-bit radiometric resolution, and contains 3 bands.

SPOT MSS Band Composition
BandWavelength
(micrometres)
Uses
1, Green0.50 to 0.59Green reflectance of healthy vegetation.
2, Red0.61 to 0.68Discriminates between plant species.
Soil boundary and geological boundary
delineations.
3, Reflective IR0.79 to 0.89Measures amount of vegetation biomass present in a scene.
Crop identification.
Emphasizes contrasts between soil and crop, land and water.
SPOT 4 Satellite System

SPOT 4 satellite was launched in 1998. SPOT 4 carries High Resolution Visible Infrared (HR VIR) instruments that obtain information in the visible and near-infrared spectral bands.

SPOT 4 satellite orbits the Earth at 822 km at the Equator. It has 2 sensors on board: i) Multispectral sensor, and ii) Panchromatic sensor.
The multispectral scanner has a pixel size of 20 × 20 m, and a swath width of 60 km. The panchromatic scanner has a pixel size of 10 × 10 m, and a swath width of 60 km.

SPOT 4 Band Composition
BandWavelength
(nanometer)
1, Green500 to 590 nm
2, Red610 to 680 nm
3, (near-IR)780 to 890 nm
4, (mid-IR)1580 to 1750 nm
Panchromatic610 to 680 nm
SPOT 5 Satellite System

SPOT 5 satellite, launched in 2002, carries two new HRVIR viewing instruments which have a better resolution: 2.5 to 5 meters in panchromatic and infrared mode and 10 meters in multispectral mode.

IRS-1C, IRS-1D

IRS-1C satellite, developed by Indian Space Research Organisation, waslaunched in December 1995. ISRO announced mission complete in September 2007.

IRS-1D, launched in September 1997, was developed by Indian Space Research Organisation.(ISRO). ISRO announced mission complete in January 2010.

LISS-III

LISS-III had spatial resolution of 23 m, with the exception of the SW Infrared band, which was 70 m. Bands 2, 3, and 4 had swath width of 142 kilometers; band 5 had swath width of 148 km.

LISS-III Band Composition
BandWavelength
(micrometres)
1, Blue
2, Green0.52 to 0.59
3, Red0.62 to 0.68
4, NIR0.77 to 0.86
5, SWIR1.55 to 1.70
IRS Panchromatic Sensor

The panchromatic sensor had 5.8 m spatial resolution, as well as stereo capability. Its swath width is 70 m. Revisit time was every five days, with ± 26 off-nadir viewing.

Panchromatic Band Composition
BandWavelength
(micrometres)
Pan0.5 to 0.75
Wide Field Sensor (WiFS)

WiFS had 188 m spatial resolution, and repeat coverage every five days at the Equator. Swath width was 774 km.

WiFS Band Composition
BandWavelength
(micrometres)
1, Red0.62 to 0.68
2, NIR0.77 to 0.86
3, MIR1.55 to 1.75

ASTER

ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an instrument flying on Terra, a satellite launched in December 1999 as part of NASA’s Earth Observing System (EOS). Compared with Landsat Thematic Mapper and Japan’s JERS-1 OPS scanner, ASTER instrument is the next generation in remote sensing imaging.

ASTER captures high resolution data in the visible to thermal infrared wavelength spectrum and provides stereo viewing capability for DEM creation.

ASTER instrument consists of 3 subsystems:

  • Visible and Near Infrared(VNIR)
  • Shortwave Infrared (SWIR)
  • Thermal Infrared (TIR).
ASTER Sensor Characteristics
CharacterisicVNIRSWIRTIR
Spectral Range
Wavelengths in
micrometres
Band 1
0.52 – 0.60
Band 4
1.68 – 1.70
Band 10
8.125 – 8.475
Band 2
0.63 – 0.69
Band 5
2.145 – 2.185
Band 11
8.475 – 8.825
Band 3
0.76 – 0.86
Band 6
2.185 – 2.225
Band 12
8/925 – 9.275
Band 3
0.76 – 0.86
Band 7
2.235 – 2.285
Band 13
10.25 – 10.95
Band 8
2.295 – 2.365
Band 14
10.95 – 11.65
Band 9
2.360 – 2.430
Ground
Resolution
15 m30 m90 m
Swath Width60 km60 km60 km

IKONOS

IKONOS satellite was launched in September 1999. IKONOS panchromatic sensor resolution is 1 m, and multispectral scanner resolution is 4 m. The swath width is 13 km at nadir. Accuracy with out ground control is 12 m horizontally, and 10 m vertically; with ground control it is 2 m horizontally, and 3 m vertically.
IKONOS orbits at an altitude of 423 miles, or 681 kilometers. Revisit time is 2.9 days at 1 m resolution, and 1.5 days at 1.5 m resolution.

IKONOS Band Composition
BandWavelength
(micrometres)
1, Blue0.45 to 0.52
2, Green0.52 to 0.60
3, Red0.63 to 0.69
4, NIR0.76 to 0.90
Panchromatic0.45 to 0.90

QuickBird

QuickBird satellite was launched in 2001, by Digital Globe offering imagery for map publishing, land and asset management, change detection and insurance risk assessment.
QuickBird produces sub-meter resolution panchromatic and multispectral imagery. The data collection nominal swath width is 16.5 km at nadir, and areas of interest sizes are 16.5 km x 16.5 km for a single area and 16.5 km x 115 km for a strip.

QuickBird Satellite Characteristics
Geometry of orbitsun-synchronous
Orbit Altitude450 km
Orbit Inclination98 degrees
Swath Widthnormal – 16.5 km at nadir
accessible ground – 544 km
centered on the satellite ground
track
Sensor Resolution ground sample distance at nadirpanchromatic – 61 cm (2 feet)
multispectral – 2.4 m (8 feet)
Spectral Bandwidth Panchromatic445 to 900 nm
Spectral Bandwidth Multispectral450 – 520 nm (blue)
520 – 600 nm (green)
630 – 690 nm (red)
760 – 900 (near infrared)
Remotely Sensed Data
Remotely Sensed Data

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