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Spin-stabilized Transit satellites were developed by the US Navy into the first operational navigation satellite system, for use by ballistic missile submarines and surface vessels. Early Transits carried a variety of piggy-back payloads, many still classified. Transit was also known as the Navy Navigation Satellite (NNS). Transit provided continuous navigation satellite service from 1964, initially for Polaris submarines and later for civilian use. Transit receivers used the known characteristics of the satellites orbit, measured the Doppler shift of the satellite's radio signal, and thereby calculated the receivers position on the earth. Individual satellites operated for over 10 years. Technical breakthroughs during the program included gravity gradient stabilization, the use of radio-isotope thermoelectric generators (RTG), and navigation satellite technologies used in the later GPS series. The TRIAD satellite was launched in 1972 to test improvements. Transit was superseded by the Navstar global positioning system. The use of the satellites for navigation was discontinued at the end of 1996, but the satellites continued transmitting and became the Navy Ionospheric Monitoring System (NIMS). Major Events: .
Navy TRANSIT I-B launched into orbit by Thor-Able-Star with navigation payload experiment at Cape Canaveral. Flight demonstrated the first engine restart in space and the feasibility of using satellites as navigational aids.
Also returned geodetic data.
Destroyed by range safety; launched with Solrad 2. Thor shut down too early.
Dual launch; failed to separate from Transit 3B. Partial Failure.
Dual launch; failed to separate from Lofti 1. Partial Failure.
Carried SNAP-3A nuclear power source.
Carried SNAP 3 nuclear power source.
Operational prototype; failed first day.
The missions of Satellite 1963-038C were to measure omnidirectional flux of protons and electrons at various energy levels, radiation effects on transistors, and the effectiveness of thermal coatings. The satellite was launched together with a classified Department of Defense spacecraft on September 28, 1963. Its planned orbit was apogee 1120 kilometres, perigee 1070 kilometres, inclination 88.9 degrees. The satellite weighed 62 kg; its body was in the shape of an 0.46 m x 0.25 m octagonal prism. It was powered by four solar blades and transmited on 136, 162, and 324 mcs. The spacecraft was built for the Bureau of Naval Weapons. In 1967 it was still sending usable data from all systems.
Carried SNAP-9A nuclear power source.
Radiation monitoring.
Radiation monitoring.
Carried SNAP-9A nuclear power source.
Celestial UV, magnetic field data.
Named as part of Transit satellite series. Actually different spacecraft for auroral and ionospheric research and not part of the navigation system.
Named as part of Transit satellite series. Actually different spacecraft for auroral and ionospheric research and not part of the navigation system.
Prototype of improved Transit satellite.
Prototype of improved Transit satellite. Tested pulsed plasma engine.
Prototype of improved Transit satellite. Also tested pulsed plasma engine.
Improved Transit.
Improved Transit. Pulsed plasma engine.
Improved Transit. Pulsed plasma thruster