The USGS Landsat archive holds an unequaled 36-year record of the Earth's surface that is invaluable to climate change studies, forest and resource management activities, and emergency response operations.
An aggressive effort is taking place to provide all Landsat imagery [scenes currently held in the USGS Earth Resources Observation and Science (EROS) Center archive, as well as newly acquired scenes daily] free of charge to users with electronic access via the Web by the end of December 2008. The entire Landsat 7 Enhanced Thematic Mapper Plus (ETM+) archive acquired since 1999 and any newly acquired Landsat 7 ETM+ images that have less than 40 percent cloud cover are currently available for download.
When this endeavor is complete all Landsat 1-5 data will also be available for download. This includes Landsat 1-5 Multispectral Scanner (MSS) scenes, as well as Landsat 4 and 5 Thematic Mapper (TM) scenes.
Additional publication details
USGS Numbered Series
Opening the Landsat Archive
Version 1.1, Revised Oct 31, 2008
Geological Survey (U.S.)
Earth Resources Observation and Science (EROS) Center