Time Transfer by Laser Link - T2L2: An Opportunity to Calibrate RF Links
Time Transfer by Laser Link - T2L2: An Opportunity to Calibrate RF Links
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发表时间：
2008-12
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通讯作者：
P. Guillemot
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作者：
P. Guillemot
摘要：由法国OCA （Observatoire de la C’te d’azur）和CNES （Centre National d’etudes Spatiales）研制的T2L2仪器，即“激光链路时间传递”实验T2L2，已于2008年6月20日随Jason-2航天器成功发射，并于5天后启动。除了验证激光链路时间转移方案外，Jason 2上的T2L2还有一整套科学目标，包括通过对GNSS和TWSTFT等现有系统的校准，对TAI等国际时间尺度的构建做出可能的贡献，与迄今为止进行的最佳校准相比，至少要提高一个数量级（约1ns精度）。它将进一步允许进行基本物理测试，例如通过比较Jason 2号任务寿命期间不同原子种类的时钟来测量精细结构常数的可能漂移。T2L2还将允许对杰森2号上的DORIS超稳定振荡器进行精确表征，并首次在轨道上演示单向激光测距。在简要介绍了T2L2实验的原理和可预见和可测量的性能之后，我们提出了第一个初步在轨结果，包括空间到地面和地对地时间转移。最后，我们对未来的开发活动进行了概述，例如比较了巴黎天文台不同的Cs喷泉，包括移动喷泉FOM和法国移动激光站。
Abstract : The T2L2 instrument, The "Time Transfer by Laser Link" experiment T2L2, under development at OCA (Observatoire de la C'te d'Azur) and CNES (Centre National d'Etudes Spatiales), France, has been successfully launched with the Jason-2 space vehicle on 20 June 2008 and switched on 5 days later. Besides the validation of the laser link time transfer scheme, T2L2 on Jason 2 has a whole panoply of science goals, including a possible contribution to the construction of international timescales such as TAI through the calibration of existing systems such as GNSS and TWSTFT, with an improvement of at least one order of magnitude as compared to the best calibrations performed so far (about 1 ns exactitude). It will further permit performing fundamental physics tests such as the measurement of a possible drift in the fine structure constant by comparing clocks of various atomic species over the Jason 2 mission lifetime. T2L2 will also permit precise characterization of the DORIS Ultra Stable Oscillator aboard Jason 2 and demonstrate for the first time in orbit one-way laser ranging. After a short reminder of principles and of foreseen and measured performances of the T2L2 experiment, we present the first preliminary in-orbit results, including space-to-ground and ground-to-ground time transfer. We then conclude with an overview of the future exploitation campaigns, such as the comparison of different Cs fountains of the Observatoire de Paris, including the mobile fountain FOM and the French transportable laser station.