Remote sensing from space

Abstract

Space-based remote sensing now has applications in pollution control, agriculture, resource assessment, climatology, land use, archaeology and oceanography. Several frequency bands in the visible and infrared spectrum are available, together with microwave frequencies. Using the visible and infrared spectrum depends upon the Earth's being a 'black-body' radiator. Two orbits permit the gathering of information from anywhere on the globe. From the geostationary orbit a sensor such as a camera can image a large amount of the Earth's sphere, which the satellite faces 24 hours a day. Changes across large areas of the Earth's surface can be followed and the extent and impact seen as fast as the data can be transmitted received and processed. This is particularly valuable for weather satellites. The near-polar orbit allows swaths to be scanned in far greater detail than is possible from the geostationary orbit. If the satellite is carrying passive sensors operating in the visible to near infrared portion of the spectrum then a sun-synchronous polar orbit is desired. The article describes the two types of sensors used in remote sensing as well as data transmission and image processing operations.