CHANDLER, Ariz. -- Jerry Knoblach wants to bring wireless service to millions of rural Americans. His plan: Beam it down from balloons hovering at the edge of space.

This isn't just hot air. His company, Space Data Corp., already launches 10 balloons a day across the Southern U.S., providing specialized telecom services to truckers and oil companies. His balloons soar 20 miles into the stratosphere, each carrying a shoebox-size payload of electronics that acts like a mini cellphone "tower" covering thousands of square miles...