orbit the earth doing our bidding in ways that enrich the lives of almost all of us. Through electronic eyes from hundreds of miles overhead, they lead prospectors to mineral deposits invisble on earth's surface. Relaying communications at the speed of light, they shrink the planet until its most distant people are only a split second apart. They beam world weather to our living room TV and guide ships through storms. Swooping low over areas of possible hostility, spies in the sky maintain a surveillance that helps keep peace in a volatile w ....