Source: USGS Landsat Program

The U.S. Geological Survey’s Landsat group has announced that the six-millionth free Landsat scene has been downloaded from the USGS archive. USGS made Landsat data available for no cost starting in October 2008 (with free Landsat 7 data). Then, in January 2009 Landsat 1–5 data were also made available at no cost. Since then, USGS has experienced a 60-fold increase in daily data downloads. Free Landsat data together with today’s powerful computer processing capabilities have enabled large-scale land use studies that in the past were too costly to be conducted by all but a few institutions—what some are calling a “democratization of satellite mapping.”

Further Information:
USGS Landsat Website 
Within Reach: Easily Turning Landsat Data into Information
ESA To Follow Landsat’s Lead on Data Policy for its GMES Data 
Free Landsat Scenes Go Public by the Million