Satellites Remote Sensing

Earth Resources Satellites

These satellites are designed mainly for natural resource monitoring – land, water, vegetation, and environment.

1. LANDSAT (USA, since 1972)

World's first dedicated Earth observation satellite series.
Provides long-term continuous data for >50 years.
Sensors: MSS (Multispectral Scanner), TM (Thematic Mapper), ETM+ (Enhanced TM), OLI (Operational Land Imager).
Resolution: 15–30 m (optical).
Applications: Land cover change, agriculture, forests, water resources.
Fact: Landsat archive is the longest continuous Earth observation record.

2. SPOT (France, 1986 onwards)

Name: Satellite Pour l'Observation de la Terre.
Sensors: HRV (High Resolution Visible), HRVIR (with Infrared).
Resolution: 1.5–20 m.
Applications: Urban studies, vegetation monitoring, mapping.
Fact: First civilian satellite to offer stereo imaging (3D views).

3. IRS (India, 1988 onwards)

Name: Indian Remote Sensing Satellite Series.
Sensors: LISS (Linear Imaging Self Scanner), PAN (Panchromatic), WiFS (Wide Field Sensor).
Resolution: 5–180 m depending on sensor.
Applications: Agriculture, water resources, forestry, disaster management.
Fact: India's IRS program is one of the largest civilian remote sensing programs in the world.

4. IKONOS (USA, launched 1999)

One of the first commercial high-resolution satellites.
Resolution: 1 m (panchromatic), 4 m (multispectral).
Applications: Urban planning, infrastructure mapping, defense, precision agriculture.
Fact: Made high-resolution satellite imagery available for civilian use.

Meteorological Satellites

These satellites are designed for weather and climate monitoring.

1. INSAT (India)

Name: Indian National Satellite System.
Operates in Geostationary Orbit (GEO, ~36,000 km).
Functions: Weather forecasting, cyclone tracking, rainfall estimation, communication.
Fact: INSAT combines meteorology + telecommunications + broadcasting.

2. NOAA (USA)

Name: National Oceanic and Atmospheric Administration Satellites.
Operates in Polar Orbit (LEO ~850 km).
Sensor: AVHRR (Advanced Very High Resolution Radiometer).
Applications: Sea surface temperature, vegetation, snow cover, weather monitoring.
Fact: Continuous data since 1970s, key for climate change studies.

3. GOES (USA)

Name: Geostationary Operational Environmental Satellites.
Orbit: Geostationary (36,000 km).
Applications: Real-time weather monitoring, storm tracking, atmosphere studies.
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

Records data in 4 spectral bands (visible + near IR).
Spatial resolution: ~80 m.
Use: Early land cover studies.

2. TM (Thematic Mapper) – Landsat

Improved sensor with 7 bands (visible, NIR, SWIR, thermal).
Spatial resolution: 30 m (optical), 120 m (thermal).
Use: Agriculture, geology, vegetation, water.

3. LISS (Linear Imaging Self Scanner) – IRS

Variants: LISS-I, II, III, IV.
Resolutions: 72 m (LISS-I) → 5.8 m (LISS-IV).
Use: Agriculture, forestry, resources.

4. WiFS (Wide Field Sensor) – IRS

Wide coverage, ~180 m resolution.
Use: Vegetation and crop monitoring at regional scale.

5. PAN (Panchromatic) – IRS

Records in single broad band (black & white).
Very high spatial resolution: ~5–6 m.
Use: Urban mapping, cartography, image fusion.

In short:

Earth Resource Satellites (LANDSAT, SPOT, IRS, IKONOS) → monitor land, vegetation, water.
Meteorological Satellites (INSAT, NOAA, GOES) → monitor atmosphere, weather, climate.
Optical Scanners (MSS, TM, LISS, WiFS, PAN) → instruments onboard satellites that capture data in different resolutions and spectral ranges.

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Natural Disasters

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Types of Remote Sensing

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geostationary and sun-synchronous

Orbital characteristics of Remote sensing satellite geostationary and sun-synchronous Orbits in Remote Sensing Orbit = the path a satellite follows around the Earth. The orbit determines what part of Earth the satellite can see , how often it revisits , and what applications it is good for . Remote sensing satellites mainly use two standard orbits : Geostationary Orbit (GEO) Sun-Synchronous Orbit (SSO) Geostationary Satellites (GEO) Characteristics Altitude : ~35,786 km above the equator. Period : 24 hours → same as Earth's rotation. Orbit type : Circular, directly above the equator . Appears "stationary" over one fixed point on Earth. Concepts & Terminologies Geosynchronous = orbit period matches Earth's rotation (24h). Geostationary = special type of geosynchronous orbit directly above equator → looks fixed. Continuous coverage : Can monitor the same area all the time. Applications Weather...

India remote sensing

1. Foundational Phase (Early 1970s – Early 1980s) Objective: To explore the potential of space-based observation for national development. 1972: The Space Applications Programme (SAP) was initiated by the Indian Space Research Organisation (ISRO), focusing on applying space technology for societal benefits. 1975: The Department of Space (DoS) was established, providing an institutional base for space applications, including remote sensing. 1977: India began aerial and balloon-borne experiments to study Earth resources and assess how remote sensing data could aid in agriculture, forestry, and hydrology. 1978 (June 7): Bhaskara-I launched by the Soviet Union — India's first experimental Earth Observation satellite . Payloads: TV cameras (for land and ocean surface observation) and a Microwave Radiometer. Significance: Proved that satellite-based Earth observation was feasible for India's needs. 1981 (November 20): Bhaskara-II launche...

Purvanchal Hills

The Purvanchal Hills are an eastern extension of the Himalayan system , bending southward from Arunachal Pradesh along the Indo-Myanmar border. They include a series of discontinuous hill ranges such as the Patkai Bum, Naga Hills, Manipur Hills, Mizo (Lushai) Hills, Barail Range, and the Meghalaya Plateau (Khasi, Jaintia, and Garo Hills) . They are geologically young fold mountains (Tertiary period) made of sedimentary rocks (sandstone, shale, siltstone) . Their structure is the result of the collision of the Indian and Eurasian Plates , which uplifted the Himalayan orogeny . Unlike the snow-clad Greater Himalayas, these hills are moderate in elevation (600–3000 m) , with dense forests, heavy rainfall, and humid climate . 1. Barail Range Location: Separates the Brahmaputra Valley (north) and Barak Valley (south) in Assam. Geomorphology: Tertiary folded ranges with elongated ridges and valleys. Drainage: Acts as a watershed between the Barak River and the Brahma...

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