来自BepiColombo无线电科学和照相机实验的水星的平动和倾角
Librations and Obliquity of Mercury from the BepiColombo radio-science and camera experiments
摘要：
BepiColombo水星任务的一个主要目标是确定水星内部的结构和状态。在这里，BepiColombo旋转实验进行了模拟，以评估实现任务目标的能力，并帮助制定一系列限制实验的可能进展。在旋转实验中，使用在不同时期拍摄的相同表面区域的图像对来检索水星旋转和方向的信息。这个想法是，从水星表面的同一块在水星的两个不同的太阳轨道上的观测可以确定水星的方向，因此也可以确定相对于均匀旋转的自转和自转变化。通过对观测到的表面标志进行模式匹配来估计天平动振幅和振幅是具有挑战性的。主要的问题是，由于水星的3：2自旋轨道共振，MPO极轨道平面没有漂移，以及需要结合来自不同仪器的数据和它们自己的测量限制，在MPO任务寿命期间很难重复观察行星表面上的同一地标。通过假设水星占据卡西尼状态和航天器名义上运行，我们表明，在最坏的情况下的假设下，每年的天平动振幅和振幅可以测量的精度分别为1.4弧秒（as）和1.0作为在标称BepiColombo MPO寿命与约25地标相当严格的照明限制。简单地放松观测约束或增加数据量并不能轻易改善实验结果。
英文摘要：
A major goal of the BepiColombo mission to Mercury is the determination of the structure and state of Mercury's interior. Here the BepiColombo rotation experiment has been simulated in order to assess the ability to attain the mission goals and to help lay out a series of constraints on the experiment's possible progress. In the rotation experiment pairs of images of identical surface regions taken at different epochs are used to retrieve information on Mercury's rotation and orientation. The idea is that from observations of the same patch of Mercury's surface at two different solar longitudes of Mercury the orientation of Mercury can be determined, and therefore also the obliquity and rotation variations with respect to the uniform rotation. The estimation of the libration amplitude and obliquity through pattern matching of observed surface landmarks is challenging. The main problem arises from the difficulty to observe the same landmark on the planetary surface repeatedly over the MPO mission lifetime, due to the combination of Mercury's 3:2 spin-orbit resonance, the absence of a drift of the MPO polar orbital plane and the need to combine data from different instruments with their own measurement restrictions. By assuming that Mercury occupies a Cassini state and that the spacecraft operates nominally we show that under worst case assumptions the annual libration amplitude and obliquity can be measured with a precision of respectively 1.4 arcseconds (as) and 1.0 as over the nominal BepiColombo MPO lifetime with about 25 landmarks for rather stringent illumination restrictions. The outcome of the experiment cannot be easily improved by simply relaxing the observational constraints, or increasing the data volume.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
