Recent efforts of tracking low Earth orbit and medium Earth orbit (MEO) satellites using geodetic very long baseline interferometry (VLBI) raise questions on the potential of this novel observation concept for space geodesy. Therefore, we carry out extensive Monte Carlo simulations in order to investigate the feasibility of geodetic VLBI for precise orbit determination (POD) of MEO satellites and assess the impact of quality and quantity of satellite observations on the derived geodetic parameters. The MEO satellites are represented in our study by LAGEOS-1/-2 and a set of Galileo satellites. The concept is studied on the basis of 3-day solutions in which satellite observations are included into real schedules of the continuous geodetic VLBI campaign 2017 (CONT17) as well as simulated schedules concerning the next-generation VLBI system, known as the VLBI Global Observing System (VGOS). Our results indicate that geodetic VLBI can perform on a comparable level as other space-geodetic techniques concerning POD of MEO satellites. For an assumed satellite observation precision better than 14.1 mm (47 ps), an average 3D orbit precision of 2.0 cm and 6.3 cm is found for schedules including LAGEOS-1/-2 and Galileo satellites, respectively. Moreover, geocenter offsets, which were so far out of scope for the geodetic VLBI analysis, are close to the detection limit for the simulations concerning VGOS observations of Galileo satellites, with the potential to further enhance the results. Concerning the estimated satellite orbits, VGOS leads to an average precision improvement of 80% with respect to legacy VLBI. In absolute terms and for satellite observation precision of 14.1 mm (47 ps), this corresponds to an average value of 17 mm and 7 mm concerning the 3D orbit scatter and precision of geocenter components, respectively. As shown in this study, a poor satellite geometry can degrade the derived Earth rotation parameters and VLBI station positions, compared to the quasar-only reference schedules. Therefore, careful scheduling of both quasar and satellite observations should be performed in order to fully benefit from this novel observation concept.

中文翻译：

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用于精确确定地球卫星轨道的大地测量 VLBI：模拟研究

最近使用大地测量甚长基线干涉测量法 (VLBI) 跟踪低地球轨道和中地球轨道 (MEO) 卫星的努力引发了对这种新颖的空间大地测量观测概念潜力的质疑。因此，我们进行了广泛的蒙特卡罗模拟，以研究大地测量 VLBI 用于 MEO 卫星精确轨道确定 (POD) 的可行性，并评估卫星观测质量和数量对派生大地测量参数的影响。MEO 卫星在我们的研究中由 LAGEOS-1/-2 和一组伽利略卫星代表。该概念是在 3 天解决方案的基础上进行研究的，其中卫星观测包含在 2017 年连续大地测量 VLBI 活动 (CONT17) 的实际时间表以及有关下一代 VLBI 系统的模拟时间表中，VLBI 全球观测系统 (VGOS)。我们的结果表明，大地测量 VLBI 可以在与 MEO 卫星 POD 相关的其他空间大地测量技术相当的水平上执行。对于优于 14.1 毫米（47 ps）的假设卫星观测精度，包括 LAGEOS-1/-2 和伽利略卫星在内的计划的平均 3D 轨道精度分别为 2.0 厘米和 6.3 厘米。此外，迄今为止超出大地测量 VLBI 分析范围的地心偏移接近有关伽利略卫星 VGOS 观测模拟的检测极限，具有进一步增强结果的潜力。关于估计的卫星轨道，相对于传统 VLBI，VGOS 导致平均精度提高 80%。就绝对值而言，卫星观测精度为 14.1 毫米（47 ps），这对应于 3D 轨道散射和地心分量精度的平均值分别为 17 毫米和 7 毫米。如本研究所示，与仅限类星体的参考时间表相比，较差的卫星几何结构会降低导出的地球旋转参数和 VLBI 站位置。因此，应仔细安排类星体和卫星观测，以便充分受益于这种新颖的观测概念。