The United States Geological Survey (USGS) has complied a 35-year record of Landsat satellite images that have continuously recorded conditions on the Earth's surface. Imagery is valuable to scientists in many academic fields from climate change to emergency management. Many of the images are stunning views of the earth that don't need a scientific basis for their enjoyment.
USGS is part of the Department of Interior, Department Secretary Dirk Kempthorne has made development of a National Land Imaging Program one of his administration's priorities. Under this initiative, electronic access to the USGS Landsat image archive will be provided to the public at no charge. Implementation of the effort is scheduled for completion by February of 2009. Newly satellite imagery will be made available for public use in the archive three months after it is acquired.
In announcing this initiative at a meeting of the ESRI International User Conference in San Diego, Interior Secretary Dick Kempthorne said, "With the click of a mouse, scientists, government officials and land managers will be able to see the changes in the earth’s landscape at any point in the past three and a half decades. As Secretary of the Interior, I have made breaking down barriers and building bridges a high priority of the department. We are fully committed to this task."
The Landsat Satellite Program
The USGS and NASA joined forces in 1972 to operate a series of Earth observation satellites to remotely sense information about the Earth from space. Landsat satellites repetitively collect spectral information in moderate spatial-resolution from the Earth's surface that creates a significant historic archive for researchers. Beginning with Landsat 1, there has now been six different Landsat satellites launched with the lastest version being Landsat 7. Landsat 6 failed to reach a useful earth orbit.
The Landsat Satellite Image Archive
The USGS national archive of Landsat satellite images started with global scenes captured by Landsat 1, the first satellite launched in the series during 1972. Purchasing options for Landsat data will be discontinued by February 2009, after the entire archive is transitioned to free use. The following is a recap of the data rollout:
- Landsat 7 - Provides Enhanced Thematic Mapper Plus (ETM+) data covering North America and Africa - all new acquistions by July 2008 and all other data by September 2008
- Landsat 5 - Provides Thematic Mapper (TM) data and all data collected since the satellite launched in 1984 will be available in December 2008
- Landsat 4 - All TM data taken by Landsat 4 from 1982 to 1985 will come online in January 2009
- Landsats 1through 5 - Provided Multi-Spectral Scanner (MSS) data produced from 1972 to 1994 and will be available by the end of January 2009
Landsat scenes can be viewed online using the USGS Global Visualization Viewer. Users should select the archive labeled "L7 SLC-off (2003- >)" under the "Select Collection" menu option for the Landsat Archive.
Alan Sorum - Alan Sorum is the Maritime Operations Project Manager for the Prince William Sound Regional Citizens' Advisory Council (PWSRCAC). Alan is ...
