Long Term Behavior of Quartz Oscillators in Space

摘要

The generic, very long duration performance of quartz oscillators in space has implications ranging from deep-space missions to the outer planets to global-navigation satellite systems like Galileo and GPS. Here, using telemetry and frequency tuning data collected from spacecraft clocks that have been in operation continuously for anywhere from 2 to 17 years, we consider the performance and viability of quartz oscillators for very long duration space missions. The quartz oscillators considered in this study are actually modules within a family of Rb clocks. By studying the corrections made to the quartz oscillator by the rubidium frequency control loop, information on the underlying frequency variation of the quartz oscillator can be inferred. While the results that we present are general in nature, and in no way system specific, they are nonetheless important for space mission planners given the extremely limited availability of very long duration clock data. In particular, since the performance of quartz oscillators in the space environment can be significantly different from what is observed in the terrestrial environment, the data and analysis presented in this paper will be important for understanding the general capabilities and limitations of these clocks for long duration space missions. Our analysis will consider the long-term frequency aging of the oscillators, and also the effect of natural radiation on the oscillators' performance. Of special interest is the effect of solar flares on the frequency of quartz oscillators. By studying the response of multiple oscillators to the same solar flares, insight into the range of sensitivity to solar flare radiation is provided. Additionally, the analysis will examine the correlation between the oscillators' frequency stability and the devices' various operational parameters.