Accessing the Landsat archive

The Landsat Earth observing satellites have assembled an essential record of moderate-resolution data sets of the planet’s surface features that can now be downloaded via the internet. The nearly four decades of data provide a valuable resource for scientists and decision makers concerned with changes to the land surface, as do the daily, current observations.

The Landsat series began in 1972. Each image in the archive covers an area of 185 by 185 km. Although technical changes have occurred over the 37-plus years of observation, the data in the archive are fully compatible with the current acquisitions. The series has maintained a consistent multispectral coverage using a range of instruments that were built specifically for the Landsat missions and that are upgraded regularly.

As of 31 December 2008, over 2.3 million individual scenes are available from the U.S. archive, and an estimated 4.7 million are available through a network of international ground stations.

Landsat data have recorded many of the natural and anthropogenic changes that have occurred in the global land surface. The effects of hurricanes, floods, tsunamis and wildfires, as well as urban growth, the Chernobyl incident and the clearing of tropical forests have been studied by scientists, resource managers, environmental planners and government agency representatives by using Landsat data.

As announced at the GEO-V plenary last November, all of the Landsat data in the U.S. archive are available at no cost over the Internet; images can be previewed and downloaded from http://glovis.usgs.gov or http://earthexplorer.usgs.gov.

Landsat images of the Aral Sea region of the former Soviet Union, now Uzbekistan and Kazakhstan.

Landsat images of the Aral Sea region of the former Soviet Union, now Uzbekistan and Kazakhstan. Processed by the US Geological Survey, these satellite images show the changes in the Aral Sea region in (from left to right) 1973, 1987 and 2000. Since the 1960s, water has been diverted from the Amu Darya and Syr Darya rivers feeding the Aral to irrigate millions of acres of land for cotton and rice production in Central Asia. In the past few decades, the Aral Sea's volume has decreased by 80 percent, and its surface area has decreased by 60 percent.

Landsat images showing over 30 years of rapid urban expansion in China's Shanghai region.

Landsat images showing over 30 years of rapid urban expansion in China's Shanghai region. Using Landsat data to monitor the expanded road network between cities helps planners to anticipate regional infrastructure needs and areas open to further growth. Urban planners use the Landsat data to measure the size and location of current roads and match that information with growth direction to help identify where new roads are needed. Additionally, the loss of cropland is evaluated and new farming areas are established to provide efficient food distribution to the growing population. The objective measurements possible from Landsat data are valuable tools for studying the impact of this growth on water supplies and coastal ecosystems, especially since growing cities have an enormous impact on ground water resources, including the locations of new well sites. Landsat imagery further allows the monitoring of drainage into fragile ecosystems.