ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is one of the five state-of-the-art instrument sensor systems on-board Terra launched on December 18, 1999. He collected nearly 16 years of cartographic data to identify and monitor changes on the surface of the planet.
Until now, access to data collected by ASTER was fee required (with the exception of digital topographic data). Now, NASA and Japan’s Ministry of Economy, just made freely available the data collected by the satellite since its launch.
For more information on ASTER: https://lpdaac.usgs.gov/dataset_discovery/aster