Earth Resources Satellites
These satellites are designed mainly for natural resource monitoring – land, water, vegetation, and environment.
1. LANDSAT (USA, since 1972)
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World's first dedicated Earth observation satellite series.
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Provides long-term continuous data for >50 years.
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Sensors: MSS (Multispectral Scanner), TM (Thematic Mapper), ETM+ (Enhanced TM), OLI (Operational Land Imager).
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Resolution: 15–30 m (optical).
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Applications: Land cover change, agriculture, forests, water resources.
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Fact: Landsat archive is the longest continuous Earth observation record.
2. SPOT (France, 1986 onwards)
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Name: Satellite Pour l'Observation de la Terre.
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Sensors: HRV (High Resolution Visible), HRVIR (with Infrared).
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Resolution: 1.5–20 m.
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Applications: Urban studies, vegetation monitoring, mapping.
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Fact: First civilian satellite to offer stereo imaging (3D views).
3. IRS (India, 1988 onwards)
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Name: Indian Remote Sensing Satellite Series.
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Sensors: LISS (Linear Imaging Self Scanner), PAN (Panchromatic), WiFS (Wide Field Sensor).
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Resolution: 5–180 m depending on sensor.
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Applications: Agriculture, water resources, forestry, disaster management.
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Fact: India's IRS program is one of the largest civilian remote sensing programs in the world.
4. IKONOS (USA, launched 1999)
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One of the first commercial high-resolution satellites.
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Resolution: 1 m (panchromatic), 4 m (multispectral).
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Applications: Urban planning, infrastructure mapping, defense, precision agriculture.
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Fact: Made high-resolution satellite imagery available for civilian use.
Meteorological Satellites
These satellites are designed for weather and climate monitoring.
1. INSAT (India)
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Name: Indian National Satellite System.
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Operates in Geostationary Orbit (GEO, ~36,000 km).
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Functions: Weather forecasting, cyclone tracking, rainfall estimation, communication.
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Fact: INSAT combines meteorology + telecommunications + broadcasting.
2. NOAA (USA)
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Name: National Oceanic and Atmospheric Administration Satellites.
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Operates in Polar Orbit (LEO ~850 km).
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Sensor: AVHRR (Advanced Very High Resolution Radiometer).
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Applications: Sea surface temperature, vegetation, snow cover, weather monitoring.
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Fact: Continuous data since 1970s, key for climate change studies.
3. GOES (USA)
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Name: Geostationary Operational Environmental Satellites.
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Orbit: Geostationary (36,000 km).
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Applications: Real-time weather monitoring, storm tracking, atmosphere studies.
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Fact: Provides continuous images of the same region every few minutes → crucial for cyclone and hurricane monitoring.
Optical Mechanical Scanners
These are instruments (sensors) that scan the Earth's surface in different wavelengths of the electromagnetic spectrum.
1. MSS (Multispectral Scanner) – Landsat
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Records data in 4 spectral bands (visible + near IR).
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Spatial resolution: ~80 m.
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Use: Early land cover studies.
2. TM (Thematic Mapper) – Landsat
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Improved sensor with 7 bands (visible, NIR, SWIR, thermal).
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Spatial resolution: 30 m (optical), 120 m (thermal).
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Use: Agriculture, geology, vegetation, water.
3. LISS (Linear Imaging Self Scanner) – IRS
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Variants: LISS-I, II, III, IV.
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Resolutions: 72 m (LISS-I) → 5.8 m (LISS-IV).
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Use: Agriculture, forestry, resources.
4. WiFS (Wide Field Sensor) – IRS
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Wide coverage, ~180 m resolution.
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Use: Vegetation and crop monitoring at regional scale.
5. PAN (Panchromatic) – IRS
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Records in single broad band (black & white).
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Very high spatial resolution: ~5–6 m.
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Use: Urban mapping, cartography, image fusion.
In short:
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Earth Resource Satellites (LANDSAT, SPOT, IRS, IKONOS) → monitor land, vegetation, water.
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Meteorological Satellites (INSAT, NOAA, GOES) → monitor atmosphere, weather, climate.
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Optical Scanners (MSS, TM, LISS, WiFS, PAN) → instruments onboard satellites that capture data in different resolutions and spectral ranges.
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