Earth Observation Satellite Programs

The Landsat program, jointly operated by the United States Geological Survey (USGS) and NASA, constitutes the longest continuous space-based record of the Earth's land surface. Landsat 1, originally launched on July 23, 1972 under the name Earth Resources Technology Satellite (ERTS-1), began an uninterrupted archive that now spans more than five decades. Successive satellites in the series, culminating in Landsat 8 (launched 2013) and Landsat 9 (launched 2021), carry the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments, delivering multispectral imagery at 30-meter resolution (15 meters in the panchromatic band) on a 16-day repeat cycle, with the two satellites phased to together provide an 8-day global revisit. USGS made the entire Landsat archive freely available to the public in 2008, a policy shift widely credited with driving a large increase in scientific use of the data, including the global forest-change mapping described later in this survey.