The two circular lakes in the upper right corner are believed to be craters formed by the impact of large meteorites. Five Landsats were launched between 1972 and 1984 to study the Earth in various spectral bands from the visible to the infrared with a resolution of about 30 metres. The Landsat programme is an ongoing one. Landsat 7, launched in 1999 is able to view the Earth's surface at a resolution of 15 metres, and the next satellite, Landsat 8, is scheduled to be launched into orbit in 2005. The satellites are used to provide information for map making, studies of land use, pollution monitoring and mineral prospecting.
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