The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program.
The instruments on the Landsat satellites have acquired millions of images. The images are a unique resource for global change research and applications in agriculture, cartography, geology, forestry, regional planning, surveillance and education.
Landsat data have contributed to our understanding of Earth in innumerable ways — from measuring the speed of Antarctic glaciers, to tracking water use in crop fields in the Western United States, to monitoring deforestation in the Amazon rainforest. The usefulness of the data stems from a variety of factors engineered into the satellite and the mission.
Each satellite repeats its orbital pattern every 16 days, with the two spacecraft offset so that each spot on Earth is measured by one or the other every eight days. As the Landsat satellites orbit, the instruments capture scenes across a swath of the planet that is 185 kilometers (115 miles) wide. Each pixel in these images is 30-meters across, which is about the size of a baseball infield, or — more important for resource management — an average crop field.
To get a sense of the power of the Landsat archive for tracking change, view this application produced by Google Earth.
Period of Record
Huete, A. R., Jackson, R. D., and Post, D. F. (1985), Spectral response of a plant canopy with different soil backgrounds, Remote Sens. Environ. 17:37-53.
Jackson, R. D., and Huete, A. R. (1991), Interpreting vegetation indices, J. Preventative Vet. Med. 11:185-200.
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