Since 1972, the Landsat Program, a joint effort between the U.S. Geological Survey and the National Aeronautics and Space Administration, has been used to acquire satellite imagery of the “Earth’s surface, coastal shallows and coral reefs,” according to the USGS website.

Starting with the Landsat 1 – originally named the Earth Resources Technology Satellite – the Landsat Program, according to the USGS website, has “provided worldwide science and resource-management communities with an archive of space-based land remotely sensed data.” The Landsat 1 also has the distinction of being the first civilian Earth observation satellite.

Since the first satellite launched on July 23, 1972, the Landsat Program has developed eight different satellites, the two most recent being the Landsat 7 in 1999 and Landsat 8 in 2013. Both are still operational. According to USGS, who assumes ownership and operation of the satellites once NASA launches and validates their performance, the four-decades-long program provides “a long-term record of natural and human-induced changes on the global landscape.”

According to USGS, their ground receiving stations have collected nearly 3.7 million Landsat scenes for the U.S. archives as of March 2013.