What We Don't Know About Quartz Clocks in Space

摘要

An essential element of any space vehicle is the onboard clock. The proper operation of the entire payload is dependent on the performance of the onboard clock or master oscillator. However, there is a noticeable absence of crucial data in the space community regarding space environmental effects as well as circuitry contributions on the performance of quartz clocks. For example, the authors, in a previous paper, presented empirical data on dormant quartz oscillators (redundant/stand-by units that are activated in the event of an anomaly in the primary oscillator) to determine the long-term aging performance of oscillators in the non-operating mode. The aging rate data are extremely important for predicting the expected performance of these backup oscillators after 10 or 15 years in space. This paper is an extension of this previous publication, in which other phenomena that may affect the performance of clocks in space are addressed. Issues such as acceleration, spacecraft charging, discharges from floating metal, solar flares, single event upsets, operating temperature, magnetic fields, space debris, and meteorite impacts are addressed. Typically, the theoretical response of quartz clocks to stimuli such as these is fairly well understood; however, the magnitudes of the stimuli on particular spacecraft platforms are not. Analyses suggest that quartz clock performance in space may or may not be significantly degraded due to these phenomena, depending on their magnitudes. This paper is intended to explore ideas and stimulate thought in the space community with the goal of launching more robust clocks in the future.