LandsatOriginally named ERTS-1 (Earth Resource Technology Satellite), NASA’s Landsat satellite, based on the Nimbus weather satellites, is launched to begin constant observations of Earth’s land, air and oceans. Landsat 1’s tour of duty lasts just under six years, during which it discovers a previously unknown island – never before spotted from land or sea – off the northeastern Canadian coast. Landsat 1 remains in service through 1978.