Three Gorges Dam, China

The Three Gorges Dam spans the Yangtze River in east-central China, and is the world's largest power station in terms of installed capacity, with its vast reservoir stretching for 660 km. Since its completion in 2008, over 1.3 million people were relocated; 13 cities, 140 towns, and 1350 villages were submerged; and the cost of the project exceeded $40 billion. According to the BBC News, landslides and bank collapses upriver from the dam may force authorities to move another 100,000 people. The image was acquired June 24, 2009, and is located at 30.8 degrees north latitude, 111 degrees east longitude.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington, D.C.

More information about ASTER is available at http://asterweb.jpl.nasa.gov/.