Precision crystal oscillator for interplanetary radio science

This paper describes a 4.788194-MHz crystal oscillator developed for the radio science experiments aboard the Cassini spacecraft. The oscillator contains a bus voltage converter, stress-compensated resonator oscillator assembly, temperature controller, a single-stage oven, titanium vacuum flask, ×24 frequency multiplier, magnetic shielding, three-axis vibration isolators, and two well-isolated buffer amplifiers. Power consumption is less than 2.8 W at +20°C. The oscillator is housed in a 81-in³ package and has a mass of 1.78 kg. The design of this oscillator originated with Peter G. Sulzer in the late 1960s and was later translated for space flight by Jerry R. Norton and James M. Cloeren at The Johns Hopkins University Applied Physics Laboratory (JHU/APL). This work at JHU/APL has produced oscillators with outstanding performance for many spacecraft with widely diverse missions. Details of the Cassini radio science mission are presented to delineate the scientific needs that drove the design of the oscillator