Radarsat are about 900 km above the earth. This is much higher than the international space station (about 200 km) but not as high as the communication satellites (in geostationary orbit) that are used for tv and telephone (about 32,000 km). How many remote sensing satellites are there?. Other satellites belong to different countries such as u. , europe, japan, france and india. Private companies are now launching remote sensing satellites too, because they have realized that this technology is very useful and profitable. How do the remote sensing satellites "cover" the earth?. The earth observation satellites move in a "near polar" orbit.
Radarsat are currently being used for studies of ecology, hydrology, oceanography, geology, ice sheets, glaciers, icebergs and for archaeological exploration. Ecological applications of SAR include land cover classification, above-ground woody plant biomass measurement, wetland inundation delineation, crop" identification and monitoring. SAR data have also been used for malaria risk mapping in tropical regions by providing imagery that shows the spatial and temporal distribution of flooding. Hydrology applications of SAR include measuring snow condition and snow pack thickness, which is used for estimating runoff and water supply. Oceanographers are using SAR data to study surface and internal waves, wave/current interactions, arctic sea-ice motions and for monitoring shipping lanes for icebergs. SAR data are also being used by geologists in studies of past climates and volcanic/earthquake hazards.