BepiColombo's Mercury orbiter radio science experiment (MORE) was conceived to enable extremely accurate radio tracking measurements of the Mercury Planetary Orbiter to precisely determine the gravity field and the rotational state of Mercury, and to test theories of gravitation (e.g., Einstein's theory of general relativity). The design accuracy of the radio tracking data was 0.004 mm/s (at 1000 s integration time) for the range-rate measurements and 20 cm for the range (at a few seconds of the integration time). These accuracies are attained due to a combination of simultaneous two-way microwave links at X (7.2–8.4 GHz) and Ka-band (32–34 GHz) to calibrate the dispersive plasma noise component. In this letter, we present the first analysis of the range and range-rate data collected by ESA's deep-space antenna (DSA) during the initial cruise phase of BepiColombo. The novel 24 Mcps pseudonoise (PN) modulation of the Ka-band carrier, enabled by MORE's Ka-band transponder, built by Thales Alenia Space Italy, Rome, Italy, provided two-way range measurements to the centimeter-level accuracy, with an integration time of 4.2 s at 0.29 astronomical units. In tracking passes with favorable weather conditions, the range-rate measurements attained an average accuracy of 0.01 mm/s at 60 s integration time. Data from May 20–24, 2019 were combined in a multi-pass analysis to test the link stability on a longer timescale. The results confirm the noise level observed with the single-pass analysis and provide a preliminary indication that the MORE PN ranging system at 24 Mcps is compatible with the realization of an absolute measurement, where the need to introduce the range biases in the orbital fit is much more limited than in the past. We show that in the initial cruise test the BepiColombo radio link provided the range measurements of unprecedented accuracy for a planetary mission, and that, in general, all target accuracies for radio-metric measurements were exceeded.

中文翻译：

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BepiColombo 的水星轨道器无线电科学实验的首次飞行数据报告

BepiColombo 的水星轨道器无线电科学实验 (MORE) 旨在对水星行星轨道器进行极其精确的无线电跟踪测量，以精确确定水星的重力场和旋转状态，并测试引力理论（例如爱因斯坦的广义相对论） ）。射程速率测量的无线电跟踪数据的设计精度为 0.004 mm/s（积分时间为 1000 秒），距离测量精度为 20 cm（积分时间的几秒）。这些精度是通过在 X (7.2–8.4 GHz) 和 Ka 波段 (32–34 GHz) 上同时使用双向微波链路来校准色散等离子体噪声分量来实现的。在这封信中，我们对 ESA 收集的航程和航程率数据进行了首次分析 在 BepiColombo 的初始巡航阶段使用深空天线 (DSA)。Ka 波段载波的新型 24 Mcps 伪噪声 (PN) 调制由 MORE 的 Ka 波段转发器实现，由意大利罗马的 Thales Alenia Space Italy 制造，提供了厘米级精度的双向距离测量，具有0.29 天文单位下的积分时间为 4.2 秒。在天气条件良好的跟踪通道中，距离速率测量在 60 秒的积分时间内达到了 0.01 毫米/秒的平均精度。将 2019 年 5 月 20 日至 24 日的数据合并到多遍分析中，以在更长的时间范围内测试链路稳定性。结果证实了单程分析观察到的噪声水平，并初步表明 24 Mcps 的 MORE PN 测距系统与绝对测量的实现兼容，在轨道拟合中引入范围偏差的需要比过去更加有限。我们表明，在最初的巡航测试中，BepiColombo 无线电链路为行星任务提供了前所未有的准确度的范围测量，并且总的来说，无线电测量的所有目标准确度都被超过了。