Labels:text | font | paper | document | letter OCR: POLAR-ORBITING SATELLITES gradually build up a picture as they move over the Earth between the North and South poles. Their instruments scan in an east-west direction, in a series of narrow strips that can be built up into one wide strip, running between the North and South poles. As the satellite begins its next orbit, the Earth will have turned slightly on its axis, so that the new strip lies next to the previous one. Eventually the whole surface is covered, usually about once every month. SOME EARTH-RESOURCES SATELLITES LANDSAT 1 COUNTRY USA MISSION DETAILS Ongoing series, first launched in 1972. In the 1990s, Landsats 4 and 5 will be replaced by Landsats 6 and 7. SPOT (SATELLITE POUR L'OBSERVATION DE LA TERRE) COUNTRY FRANCE MISSION DETAILS A series of three, with its first launch in 1 ...
