Landsat satellites provide repetitive coverage of continental Earth surfaces in the visible, near-infrared, short-wave, and thermal infrared regions of the electromagnetic spectrum.
A series of Landsat satellites has been continuously in orbit since 1972, collecting an invaluable time sequence of global imagery that records decades of land-use and land-cover changes. The recent decision by the U.S. Geological Survey (USGS) to provide Landsat imagery free of charge has led to an explosion in applications, enabling unprecedented study of global deforestation, changes in cropping systems and irrigation practices, and conversion of land from its natural state to managed or urban use.
Today, the continuity of this valuable historical record is under threat. At present, only Landsat 7 is still collecting data, but at degraded capacity due to a component failure in 2003. Landsat 8 is scheduled for launch by the National Aeronautics and Space Administration (NASA) no earlier than January 2013. Thus, much of the 2012 growing season will have limited coverage by Landsat imagery, a first since the early 1970s.
Landsat's thermal and optical sensors provide invaluable high-resolution (30 to 120 meters) information for monitoring global production of food and fiber, crop health, available soil moisture, and early warning of drought.