gnals. Once operational, Galileo will provide a highly accurate, guaranteed global positioning service under civilian control. It will be interoperable with other global satellite navigation systems, such as GPS, while providing greater accu- racy, down to two meters. Other applications for Galileo in the transport sector include vehicle location, taxi and truck fleet management, and monitoring levels of road use. 6.7 HELPING RANCHERS FROM SPACE Satellite technology can also be used to track things other than vehicles, includ- ing ocean currents, migratory animals, and crops. In fact, powerful new satellite imaging database software is coming to the aid of North American ranchers and other people who work on the land. SEEING INSIDE WALLS University of Arizona researchers have created a Web database that allows ranchers to compare land greenness from one year to the next, between years, against a 14-year average, and at two-week intervals. Such information can be invaluable for making long-term land management decisions. Ranchers, forest rangers, and other natural resource managers work directly on the land nearly every day to observe changes and decide how to handle them, whether grazing cattle, monitoring wildlife, or assessing fire danger. A new University of Arizona satellite image database, called Range View, offers users a bird's-eye view of broad terrain. "Range View provides frequent satel- lite images online to enhance the ability of natural resource managers, includ- ing ranchers, to manage the landscape," says Chuck Hutchinson, director of the Arizona Remote Sensing Center, part of the Office of Arid Lands Studies at the University of Arizona's College of Agriculture and Life Sciences. Stuart Marsh, professor of arid lands, and arids-lands researcher Barron Orr, and Hutchinson created the Web site to display NASA digital images in configurations that allow users to analyze the characteristics of the land. "This tool offers the ability to zoom in on your ranch, forest, or habitat and monitor changes in v