The world's largest solar power tower recently began operating outside Seville, Spain -- and it marks a historic moment in the saga of renewable energy. The solar tower PS20, next to its smaller sister PS10, produced even more power than expected over the course of its trial testing. It's been confirmed that the groundbreaking solar tower generates 20 megawatts of electricity: and it's now powering 10,000 homes with renewable energy. Here's how it works: PS20 consists of a solar field made up of 1255 mirrored heliostats, each with an area of 1291 square feet. They reflect the solar radiation they receive onto the top of a 531 feet-high tower, producing steam which is converted to electricity generation by a turbine. The image was acquired August 29, 2009, covers an area of 15 x 18 km, and is located at 37.5 degrees north latitude, 6.2 degrees west 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 December 18, 1999, on NASA's Terra satellite. 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 the 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 JPL, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

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