Transit Satellites


Transit satellites were not designed to provide accurate time. But they did carry ultra-precise quartz oscillators to control their radio frequencies. This unit containing two oscillators was designed at the Johns Hopkins University’s Applied Physics Laboratory in 1959. It is the same as those flown on Transit satellites 2A and 4B in the early 1960s.
Each Transit satellite contained quartz crystals. Set in an electrical circuit, a crystal resonator vibrates regularly and becomes an oscillator to control radio frequencies. Transmitting at a constant frequency was essential for Transit to work.