The Transit system, also known as NAVSAT or NNSS, was the first satellite navigation system to be used operationally. The radio navigation system was primarily used by the U.S. Navy to provide accurat

Explorer 22 was a small NASA ionospheric research satellite launched 9 October 1964, part of NASA's Explorers Program. It was instrumented with an electrostatic probe, four radio beacons for ionospher