Landsat satellite program

Space Technology moved on very fast with multipurpose satellites and manned spacecraft missions. Landsat satellite program by NASA is worth discussion in this field. Initial name for the satellites used in this program was Earth Resources Technology Satellites (ERTS). Six satellites were launched in this scheme. Since 6^th satellite suffered a launch failure, the successful 6 satellites were named later as Landsat 1,2,3,4,5 and 7. 5 different types of sensors namely return beam vidicon, multispectral scanner, thematic mapper, enhanced thematic mapper and enhanced thematic mapper plus were used in these satellites. Landsat 1, 2 and 3 were butterfly shaped systems and similar in their operation. Landsat 1, 2 and 3 images provided necessary data for the study of long term global changes. Landsat 4 and 5 satellites were launched into lower orbits. This lowering of orbit radius facilitated resolution of the different sensors mounted on the satellite. Enhanced thematic mapper plus was the earth observing sensor unit used in Landsat 7.