Testing Gravity Using Millimeter Accuracy Data from APOLLO

引力是自然界最明显的力，但实际上是基本力中最弱的，因此也是最缺乏检验的。爱因斯坦的广义相对论是目前我们对引力的最好描述，它与量子力学根本不相容。 因此，我们必须对重力进行最严格的测试。月球激光测距（LLR），其中从望远镜发射的短激光脉冲被美国宇航员和苏联着陆器放置在月球上的反射器反射，几十年来通过绘制月球轨道的形状来产生了一些领先的重力测试。自2006年以来，一项名为APOLLO（阿帕奇点天文台月球激光测距行动）的实验一直在收集世界上最好的LLR数据，无论是在数据量还是精度方面。2016年，APOLLO进行了一次升级，使其能够保证毫米级的精度-这是第一次在任何地方都存在这种能力。 该项目将利用这一新能力。 除了对宇宙学的所有领域产生根本性的影响外，该项目在培训学生和向公众传达科学的兴奋方面也有很大的影响。该项目旨在使用APOLLO收集有史以来第一组毫米精度的LLR数据。 除了继续收集有史以来最准确的LLR数据外，这还涉及开发技术，以根据新安装的绝对校准系统校准APOLLO测距数据，并确定APOLLO性能和系统误差的特征。 此外，将由现场超导重力仪和附近的全球定位系统站收集现场大地测量数据，并将这些数据纳入LLR分析，以限制地面运动。

Gravity, the most evident force of nature, is in fact the weakest of the fundamental forces, and consequently the most poorly tested. Einstein's general relativity, which is currently our best description of gravity, is fundamentally incompatible with quantum mechanics. It is therefore imperative that we subject gravity to the most stringent tests available. Lunar laser ranging (LLR), in which short laser pulses launched from a telescope are bounced off reflectors placed on the moon by U.S. astronauts and Soviet landers, has for decades produced some of the leading tests of gravity by mapping the shape of the lunar orbit to high precision. Since 2006, an experiment called APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) has been collecting the best LLR data in the world, in terms of both data volume and precision. In 2016, an upgrade allowed APOLLO to guarantee accuracy at the millimeter level - the first time this capability has existed anywhere. This project will capitalize on this new capability. Besides its fundamental impact to all areas of cosmology, this project has a strong footprint in training students and in communicating the excitement of science to the public.This effort seeks to collect the first-ever set of millimeter-accurate LLR data using APOLLO. Besides continuing to collect the most accurate LLR data ever obtained, this involves developing techniques to calibrate APOLLO range data against the newly-installed absolute calibration system and to characterize APOLLO performance and systematic errors. Additionally, site geodetic measurements will be collected by an on-site superconducting gravimeter and a nearby global positioning system station, incorporating these data into the LLR analysis in order to constrain motion of the ground.