Landsat, the world's longest-running Earth-observing satellite programme, has marked 40 years of recording the world's changing landscape.
The satellite programme, run by NASA and the United States Geological Survey, has captured the effect of large-scale human activities such as the building of cities and farming across the globe.
"The programme is a sustained effort by the United States to provide direct societal benefits across a wide range of human endeavours, including human and environmental health, energy and water management, urban planning, disaster recovery and agriculture," NASA said in a statement.
NASA has launched six of the seven Landsat satellites.
The first Landsat satellite was launched July 23, 1972, from Vandenberg Air Force Base in California. The next satellite in the programme, Landsat Data Continuity Mission, is to be launched in February next month.
LDCM will join Landsat 5 and Landsat 7 satellites in Earth orbit to continue the Landsat data record.
The remote-sensing satellites have helped scientists to observe the world beyond the power of human sight, to monitor changes and to detect critical trends in the conditions of natural resources.
"Over four decades, data from the Landsat series of satellites has become a vital reference worldwide for advancing our understanding of the science of the land," Interior Department Secretary Ken Salazar said.