Archived Landsat imagery is unique to the European Space Agency (ESA) archive and many images have never before been accessible anywhere else by the scientific user community. In its archives, ESA holds around 2 million products that cover Europe and North Africa. The total amount of data available is worth about 450 terabytes—that's equivalent to about 900,000 hours of audio recorded at CD quality.
ESA has been acquiring Landsat data at European stations since the 1970s. "The missions were the main data source for many years during the 1980s when Earth observation started at ESA's ESRIN centre in Italy," said Gunther Kohlhammer, head of the Ground Segment Department.
ESA revised its Earth observation data policy in 2010 to adapt to the “Joint Principles
for a Sentinel Data Policy.” This policy was approved by ESA Member States participating in the GMES Space Component Programme and supports the concept of providing free and open access
to data. By revising the data policy, ESA followed the same path as the U.S. Geological Survey, which began making its Landsat data available free in 2009. The ESA archives opens access to all products from the Thematic Mapper and EnhancedThematic Mapper instruments aboard the Landsats. Data from the older Multispectral Scanner will be made available at a later stage.
To access the data, users can go to the Earth Observation Principal Investigator Portal to submit a brief project description and request data. ESA then assigns the project a quota based on the system's
current processing capacity. When the data are ready, the user will receive directions for online retrieval. To allow improved and faster access, ESA will soon begin gradually to process all data into an online archive for users to access independently. Owing to the vast amount of data, this process will take
about two years.
The Landsat series goes back to 1972, with Landsat 5 and Landsat 7 currently in orbit. Landsat 8 is due for launch by early 2013. The 40-year-old Landsat program is jointly managed by NASA and the U.S. Geological Survey. ESA supports the Landsat series as a Third Party Mission, meaning it uses its ground
infrastructure and expertise to acquire, process and distribute Landsat data to users.
"It is great finally to open the archives,” says Bianca Hoersch, Third Party Mission Manager. “We are keen to get the data to the users—especially in preparation for Sentinel-2, which is built on the heritage and knowledge of 40years of Landsat.”