 Transit provided continuous navigation satellite service from 1964, initially for Polaris submarines and later for civilian use as well.The Transit satellite system, sponsored by the Navy and developed jointly by DARPA and the Johns Hopkins Applied Physics Laboratory, under the leadership of Dr. Richard Kershner at Johns Hopkins, was the first satellite-based geopositioning system.Just days after the Soviet launch of Sputnik 1, the first man-made earth-orbiting satellite on October 4, 1957, two physicists at APL, William Guier and George Weiffenbach, found themselves in discussion about the radio signals that would likely be emanating from the satellite.