Belli Alexandre, Exertier Pierre
IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Oct;65(10):1965-1976. doi: 10.1109/TUFFC.2018.2855085. Epub 2018 Jul 11.
This paper discusses the issues of radiation exposure that especially occur on the Doppler Orbitography and Radiopositioning Integrated on Satellite (DORIS) ultrastable oscillator (USO) that has been placed on the Jason-2 oceanography mission as the reference clock. We have studied the frequency response of the Jason-2 USO (launched in June 2008, at 66° of inclination and 1336 km of altitude) over 8.5 years. This is the only mission that provides different sources of data, internal and external, which permit a precise description of the oscillator behavior using several assumptions. While the ICARE-NG instrument provided continuous measurement of the electron and the proton fluxes, the Time Transfer by Laser Link (T2L2) experiment demonstrated its ability to monitor the "reading" of the oscillator at a level of a few parts in 10 with respect to a ground network of laser stations equipped with atomic clocks. From these inputs, and also environmental parameters such as the orbit, the attitude law of the platform, and the temperature of the oscillator, we have developed a complete physical model of the DORIS USO that fits the data at less than slightly below the threshold of 10 that limits the use of the DORIS data in current space geodesy analyses. In this way, the model also makes it possible to provide an assessment of the new Jason-3 USO to radiation effects after the satellite launch in January 2016.
本文讨论了辐射暴露问题，这些问题尤其出现在已被放置在Jason-2海洋学任务中作为参考时钟的多普勒轨道测绘与卫星无线电定位集成系统（DORIS）超稳振荡器（USO）上。我们研究了Jason-2 USO（于2008年6月发射，倾角66°，高度1336千米）在8.5年时间里的频率响应。这是唯一一项能提供内部和外部不同数据源的任务，这些数据源允许在采用多种假设的情况下精确描述振荡器的行为。ICARE-NG仪器持续测量电子和质子通量，而激光链路时间传递（T2L2）实验展示了其相对于配备原子钟的地面激光站网络，在10的若干分之一水平上监测振荡器“读数”的能力。基于这些输入数据，以及轨道、平台姿态规律和振荡器温度等环境参数，我们建立了一个完整的DORIS USO物理模型，该模型与数据的拟合程度略低于限制DORIS数据在当前空间大地测量分析中使用的10的阈值。通过这种方式，该模型还能够在2016年1月卫星发射后，对新型Jason-3 USO的辐射效应进行评估。
