Space- and aircraft-based remote sensing technologies may enable the discovery of lost ruins of ancient civilizations, according to a study conducted by researchers at the University of New Hampshire in Durham and NASA’s Marshall Space Flight Center in Huntsville, Ala. By interpreting multispectral and visible images from satellites and synthetic aperture radar signals from an airborne laboratory, the scientists identified the effects on rain-forest vegetation caused by the limestone and lime used in the construction of Tikal, a Mayan city in what is now Guatemala that was inhabited from 900 B.C. to A.D. 900.As seen in the 30-m-resolution Landsat Thematic Mapper VIS/NIR image at left, the disintegrating building materials selectively discolor and kill some surrounding plant species, yielding a signature different from that of the surrounding forest. The 1-m-resolution Ikonos false-color visible image at right illustrates the correlation between the layout of the structures at Tikal and the variation in the floral signal.With the support of the Instituto de Antropologìa e Historia de Guatemala in Guatemala City, the researchers will visit the country annually through 2009. They hope to refine the approach to make possible the identification of promising sites for exploration that are concealed in the forests.