Current status and future of the US Navy satellite navigation system

The status and future of the US Navy Transit satellite system for maritime navigation are reviewed in the light of its planned replacement by Navstar GPS. The Oscar, Nova, and SOOS satellites; their orbits and performance parameters; the Scout launcher; the tracking network; and the correction procedures for ionospheric refraction are characterized and illustrated with drawings, diagrams, and graphs. Current planning calls for maintenance of Transit with the 12 Oscar satellites in ground storage plus two or more of the drag-compensated Nova satellites throughout the transition to Navstar GPS, scheduled for completion in 1992; On-orbit storage of several Oscars (since Scouts will no longer be available after 1987) and/or extending Transit through 1994 are under consideration.