GEO- SYNCHRONOUS AND SUN-SYNCHRONOUS
STATIONARYSATELLITES: Geostationary satellites are the satellites which revolve round the earth above the equatoratthe height of about 36,000 to 41,000km., in the direction of earth's rotation. They make one revolution in 24hours, synchronous with the earth's rotation (Fig.2). As a result, it appears stationary with respect to earth.
These platforms always cover a specific area and give continuous coverage over the same area day and night. Their coverage is limited to 70 N and 70 S latitudes and one satellite can view one third globe. These are mainly used for communication and weather monitoring. Some of these satellites are INSAT, METSAT and ERS series.
SUN-SYNCHRONOUSSATELLITES:Sun-synchronoussatellitesarethesatelliteswhichrevolved round the earth in north-south direction (poleto pole) at the height of about 300to1000 km. (Fig.2.1) they pass over places on earth having the same latitude twice in each orbit at the same local sun-time, hence are called sun-synchronous satellites. Through these satellites, the entire globe is covered on regular basis and gives repetitive coverage on periodic basis. Alltheremotesensing resources satellites may be grouped in this category. Few of the sesatellites are: LANDSAT, IRS, SPOT series and NOAA, SKYLAB, SPACE SHUTTLE etc.