Updated release July 2, 2012.
Tapping into fossil ground water, Saudi Arabia has been steadily developing agricultural fields using center pivot irrigation. A remarkable example is in the Wadi As-Sirhan Basin in northwest Saudi Arabia. In the 1984 Landsat image (top), no fields are yet present. By 2000, ASTER showed extensive farming activity (middle); vegetation is bright red. And by 2011, the ASTER image shows several areas where wall-to-wall fields were developed, each about 1 km in diameter (bottom). The images cover an area of 19.5 x 33 km, and are located at 30.5 degrees north latitude, 38 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/.