A Transit receiver used the known characteristics of a satellite's orbit and measurements of the Doppler shift of the satellite's radio signal, to establish an accurate position on Earth. An operational system consisted of six satellites (three in service plus three on-orbit spares) in 1,100-km polar orbits, three ground control stations, and receivers. The constellation eventually consisted of two types of spacecraft, the 50-kg Oscar, with an average operating lifetime of 12 years, and the more advanced, 160-kg Nova, with an average lifetime of nine years. The last Transit satellite launch was in August 1988. Day-to-day operations, including telemetry, tracking, and control were conducted by the Naval Space Operations Center at Point Mugu, California, while the Applied Physics Laboratory at Johns Hopkins University devised and designed all aspects of the Transit satellites.
Related category SATELLITES AND SPACE PROBES
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