Q. What is remote sensing? Describe the status of remote sensing in India. (42 BPSC/1999)

Q. What is remote sensing? Describe the status of remote sensing in India. (42 BPSC/1999)
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object. In current usage, the term “remote sensing” generally refers to the use of satellite or aircraft-based sensor technologies to detect and classify objects on Earth.It includes the surface and the atmosphere and oceans, based on propagated signals (e.g. electromagnetic radiation). It may be split into “active” remote sensing (when a signal is emitted by a satellite or aircraft to the object and its reflection detected by the sensor) and “passive” remote sensing (when the reflection of sunlight is detected by the sensor).Examples of passive remote sensors include film photography, infrared, charge-coupled devices, and radiometers. RADAR and LiDAR are examples of active remote sensing where the time delay between emission and return is measured, establishing the location, speed and direction of an object.
Some specific uses of remotely sensed images of the Earth include:

• Large forest fires can be mapped from space, allowing rangers to see a much larger area than from the ground.
• Tracking clouds to help predict the weather or watching erupting volcanoes, and help watching for dust storms.
• Tracking the growth of a city and changes in farmland or forests over several years or decades.
• Discovery and mapping of the rugged topography of the ocean floor (e.g., huge mountain ranges, deep canyons, and the “magnetic striping” on the ocean floor).
• in the areas of urban sprawl, infrastructure planning and other large scale applications for mapping.

The status of remote sensing in India

• India’s remote sensing program was developed with the idea of applying space technologies for the benefit of human kind and the development of the country.
• India demonstrated the ability of remote sensing for societal application by detecting coconut root-wilt disease from a helicopter mounted multispectral camera in 1970. This was followed by flying two experimental satellites, Bhaskara-1 in 1979 and Bhaskara-2 in 1981. These satellites carried optical and microwave payloads.
• India’s remote sensing programme under the Indian Space Research Organization (ISRO) started off in 1988 with the IRS-1A, the first of the series of indigenous state-of-art operating remote sensing satellites, which was successfully launched into a polar sun-synchronous orbit.
  • Following the successful demonstration flights of Bhaskara-1 and Bhaskara-2 satellites launched in 1979 and 1981, respectively, India began to develop the indigenous Indian Remote Sensing (IRS) satellite program to support the national economy in the areas of agriculture, water resources, forestry and ecology, geology, water sheds, marine fisheries and coastal management.
• India also established the National Natural Resources Management System (NNRMS) providing operational remote sensing data services.
• Data from the IRS satellites is received and disseminated by several countries all over the world.
• The IRS system is the largest constellation of remote sensing satellites for civilian use in operation today in the world, with 11 operational satellites. All these are placed in polar Sun-synchronous orbit and provide data in a variety of spatial, spectral and temporal resolutions.
• Various satellites are beings launched by ISRO to enrich the remote sensing data.
  • Cartosat-3: It is the third generation Earth observation satellite built by ISRO. It is one of the most advanced imaging satellites built by the organization so far. It includes Hyperspectral (Captures light from electromagnetic spectrum), Panchromatic (Captures all visible colors of light) and Multispectral (Captures light within specific ranges of the electromagnetic spectrum).
  • RISAT-2BR1 is a synthetic-aperture radar (SAR) imaging satellite for reconnaissance built by Indian Space Research Organisation (ISRO). They provide all-weather surveillance using synthetic aperture radars (SAR).
  • RESOURCESAT-2A
• Future IRS launches are Resourcesat-2, Oceansat-3 etc.

Data from IRS is available to its users through NRSC Data Centre and also through Bhuvan Geoportal of ISRO.Thus, India is seriously harnessing the remote sensing technology for enriching the data availability in diverse area which helps in evidence based decision making.