Using remote sensing and GIS analysis, NASA scientist Tom Sever is trying to answer questions about the past in order to protect the resources of the future. A thousand years ago, the ancient Mayans of northern Guatemala cut down most of the trees in their tropical forest. The loss of the natural resources contributed to the collapse of this great civilization. It took centuries for the forests of the Peten Region to recover. Today, satellite imagery is providing valuable data that may prevent deforestation and is being used to locate and preserve Mayan archeological sites still unexplored.