Remote sensing is the science of acquiring information from the Earth's surface, using the electromagnetic characteristics of radiations reflected or emitted from the objects.
The first remote sensing data were black & while or colored aerial photos obtained by airplane .The first experimental Earth Resources Technology satellite (ERTS-1), later called Landsat -1, was launched in 1972 providing a continuous coverage of Earth's surface. The Multi -Spectral Scanner (MSS), carried by Landsat.1 captured images in 4 visible and near infrared bands of electromagnetic spectrum. Later the Thematic Mapper (TM) Sensor was operated on Landsat -4 and with images in 7 bands and better spatial resolution made a great contribution to geological studies especially in identification of clay minerals and carbonates. Landsat-7 now carries Enhanced Thematic Mapper plus (ETM+) instrument which is an improved version of TM and provides an additional panchromatic image.
Recently ASTER (Advanced spaceborne Thermal Emission and Reflection Radiometer) Sensor, providing a broad spectral coverage in visible and near infrared, short-wave infrared and especially thermal infrared, has found a great application in identification of different kinds of alterations.
Radar (microwave) remote sensing uses relatively long wavelengths which allow these systems to see through clouds and some vegetation .Radar remote sensing can be operated day or night and is of significant application in structural and tectonic studies especially in areas covered by dense cloud or vegetation.
Recent advances in remote sensing have been led to development of hyperspectral sensors capable to imaging in more than 200 spectral bands and suitable spatial resolution. Hyperspectral remote sensing provides unique capabilities to discern different properties of the earth material and will open new horizons in many fields of science including geology and mineral exploration.
The remote sensing group of GSI was established in 1983 with the objective of utilizing modern remote sensing techniques in geological and mineral exploration applications. This group has been equipped with suitable hardwares; powerful image processing the softwares such as ERDAS, EASIPACE and ERMAPPER and satellite image data. The sets of TM, ETMT and Radar sat data, covering the entire country and some scattered scenes of SPOT, COSMOS, IRS and ASTER data are available for remote sensing studies. Presently, 15 experts are working in the group .The majority have postgraduate degree in different geosciences and remote sensing fields.