Testing Gravity via Lunar Laser Ranging: APOLLO Analysis and Acquisition

最近建造的阿帕奇点天文台月球激光测距操作(Apollo)已经成为世界上首屈一指的月球激光测距(LLR)设备，在地球和月球之间提供1毫米的距离精度，作为测试广义相对论的一种方式。广义相对论对月球轨道的形状做出了具体的预测，这样我们就可以把月球用作实验室，这是阿波罗宇航员和苏联无人月球车在月球上留下的反射器实现的。这项工作的目标是将高质量的LLR观测延长三年，同时收集经过校准的当地重力测量结果，足以确定站点毫米级的位移。同时，将启动一项密集的努力，将太阳系模型推进到可以利用毫米级质量数据的状态。只有通过与完整和复杂的模型进行比较，才能探索与重力、地球物理和月球物理有关的问题。尽管不是主要关注点，但有关月球内部的知识将从阿波罗获得最大的收获，因为该实验通常在一次会议上获得4到5个反射器，提供对月球方向和变形的精确测量。但这种对月球的精细了解也将有助于理解月球在其轨道上的运动方式，因为这些信息对于确定月球在太空中的质心路径至关重要。LLR测试了引力的许多基本方面，如等效原理、重力不变性、引力磁学和平方反比定律。因此，提高我们对引力的认识可以为各种各样的宇宙学家、天体物理学家、粒子物理学家和弦理论家提供信息。这一努力还将有助于地球和行星科学，特别是通过纳入超导重力仪数据。该项目产生的开放源代码太阳系分析代码将为分析广泛的数据集提供一个有趣的平台，包括太阳系雷达测距、从多普勒雷达到太阳系周围的航天器、脉冲星计时实验等。此外，研究生和博士后培训是整个努力的重要组成部分。最后，阿波罗将继续其强大的公众宣传传统，包括在热门电视节目中亮相。

The recently built Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has become the premier lunar laser ranging (LLR) facility in the world, delivering one-millimeter range precision between Earth and Moon as a way to test General Relativity. General Relativity makes specific predictions about the shape of the lunar orbit, so that we may use the Moon as a laboratory, made possible by the reflectors left on the Moon by the Apollo astronauts and unmanned Soviet rovers. The goal of this work is to extend high-quality LLR observations over an additional three-year period, simultaneously collecting calibrated measurements of local gravity well enough to determine site displacements at the millimeter level. In tandem, an intensive effort will be initiated to advance the solar system model to a state that can take advantage of millimeter-quality data. It is by comparison to a complete and sophisticated model that questions relating to gravity, geophysics, and lunar physics can be explored. Though not the main focus, knowledge of the lunar interior stands to gain the most from APOLLO, as the experiment routinely acquires 4 to 5 reflectors in one session, providing exquisite measurements of the lunar orientation and distortion. But this refined knowledge of the moon will also facilitate understanding of how the moon moves in its orbit, as such information is crucial to determining the path of the Moon's center of mass through space.LLR tests many fundamental aspects of gravity, like the equivalence principle, the constancy of gravity, gravitomagnetism, and the inverse-square law. Improving our knowledge of gravity therefore informs a diverse range of cosmologists, astrophysicists, particle physicists, and string theorists. This effort will also contribute to Earth and planetary science, especially via the inclusion of the superconducting gravimeter data. The open-source solar-system analysis code emerging from the project will provide an interesting platform for analyzing a wide range of data sets, including radar ranging in the solar system, Doppler radar to spacecraft around the solar system, pulsar timing experiments, etc. The same platform can form the basis of covariant studies for future proposed space missions that aim to test fundamental physics. Additionally, graduate student and postdoctoral training is a valuable component of the total effort. Finally, APOLLO will continue its strong tradition of public outreach, including featured appearances on popular television shows.