Remote sensing (RS) is the science of making inferences about material objects from
measurements, made at distance, without coming into physical contact with the objects
under study. A remote sensing system consists of a sensor to collect the radiation and a
platform – an aircraft, balloon, rocket, satellite or even a ground-based sensor-supporting
stand - on which a sensor can be mounted. Currently a number of aircraft and spacecraft
imaging systems are operating using remote sensing sensors. Some of the current image
systems from spacecraft platform include Indian Remote Sensing Satellites (IRS), French
National Earth Observation Satellite (SPOT), IKONOS etc.