Lunar Laser Ranging at the University of Texas at Austin

月球激光测距（LLR）实验精确地测量了从地球上的观测站发射的激光脉冲的往返旅行时间，该脉冲经过月球表面的反向反射器阵列反弹后返回。这样的观测已经在麦克唐纳天文台进行了30多年。这些数据提供了固体地球科学、大地测量学和地球动力学、太阳系星历表、地球和天体参照系、月球物理、广义相对论和引力物理等领域各种多学科和跨学科的科学成果。单独或结合其他观测技术的数据，LLR扩展了对地球岁差的理解。地球的自转轴，月球的章动，地球的方向，地球。S对黄道的倾角，天体赤道与黄道的交点，月球和太阳固体潮汐，月球潮汐减速，月球物理和自由振动，月球的结构和月球内部的能量耗散。LLR为月球表面制图和测量提供输入，并帮助确定地球站和月球表面反射器的位置和运动，地月系统的质量，月球和地球引力谐波和洛夫数，相对论测地线进动，以及广义相对论的等效原理。由于反射器的被动特性以及观测设备和数据分析能力的改进，LLR数据将继续提供改进的结果。收益是稳定的，随着数据库的扩展，我们正在努力通过应用更聪明的观察策略来学习更多。根据这一建议，我们在麦克唐纳激光测距站（MLRS）继续进行LLR观测工作。通过常规的单人操作和每天24小时，每周7天的时间表，随着我们与人造卫星激光测距（SLR）共同使用MLRS，月球覆盖范围将在未来几年大幅扩大。我们正在与世界各地的其他观测工作合作，特别是在法国南部的法国LLR/SLR站。除了观察之外，在奥斯汀的德克萨斯大学将进行一项具有世界范围交流、合作和协调的分析工作。我们与喷气推进实验室、麻省理工学院、巴黎天文台以及法兰克福和慕尼黑的BKG的分析工作合作。此外，德克萨斯大学麦克唐纳天文台，自1998年国际激光测距服务（ILRS）成立以来，拥有ILRS LLR操作和分析中心。LLR观测网络的规模较小，LLR分析中心的数量也相对较少，这决定了LLR运行/分析中心的独特性质和操作程序。LLR运营中心的职责已经演变为确保数据在LLR网络中的顺畅流动，其形式和格式有助于获得科学结果。该中心还协调观测和调度，以最大限度地提高科学成果。预测在每个LLR站点进行现场协调，数据自动从所有观测站点传输到ILRS数据中心。LLR数据分析师可以根据需要直接从数据中心保护他们的数据。这些分析人员的反馈通常直接传回各个观测站。在美国国家科学基金会的资助下，我们期待着更多成功的LLR观测和分析，从而实现科学成果的稳定和快速扩展。＊＊＊

AST-0204127ShelusThe Lunar Laser Ranging (LLR) experiment accurately measures the round-trip travel time for a laser pulse that is emitted from an observing station on the Earth and returns after bouncing off of a retroreflector array on the surface of the Moon. Such observations have been made at McDonald Observatory for more than 30 years. The data provide for varied, multi-disciplinary and inter-disciplinary science results in areas of solid Earth sciences, geodesy and geodynamics, solar system ephemerides, terrestrial and celestial reference frames, lunar physics, general relativity and gravitational physics. Standing alone or combined with data from other observing techniques, LLR expands the understanding of the precession of the Earth.s spin axis, the lunar nutation, Earth orientatation, the Earth.s obliquity to the ecliptic, the intersection of the celestial equator and the ecliptic, lunar and solar solid body tides, lunar tidal deceleration, lunar physical and free librations, the structure of the moon and energy dissipation in the lunar interior. LLR provides input into lunar surface cartography and surveying and helps determine Earth station and lunar surface retroreflector locations and motions, mass of the Earth-Moon system, lunar and terrestrial gravity harmonics and Love numbers, relativistic geodesic precession, and the equivalence principle of general relativity. Due to the passive nature of the reflectors and the improvement of observing equipment and data analysis capabilities with time, LLR data will continue to provide for improved results. Gains are steady and, as the data base expands, we are striving to learn even more by applying more clever observation strategies. Under this proposal, we continue the LLR observational effort at the McDonald Laser Ranging Station (MLRS). With routine single-person operation and a 24 hour/day, 7 day/week schedule, lunar coverage will be substantial in the years to come, as we share the use of the MLRS with artificial satellite laser ranging (SLR) efforts. We are cooperating with other observing efforts around the world, especially the French LLR/SLR station in the south of France. In addition to the observations, an analysis effort with world-wide communication, cooperation, and coordination will be ongoing here at the University of Texas at Austin. We cooperate with analysis efforts at the Jet Propulsion Laboratory, the Massachusetts Institute of Technology, the Paris Observatory, and the BKG in Frankfurt and Munich. Also, the University of Texas McDonald Observatory, since the inception of the International Laser Ranging Service (ILRS) in 1998, houses the ILRS LLR Operations and Analysis Center. The small size of the LLR observing network, and the relatively small number of LLR analysis centers, dictate the unique nature and operational procedures of this LLR Operations/Analysis Center. The responsibility of the LLR Operations Center has evolved to be one that assures the smooth flow of data through the LLR network, in a form and format that is useful for obtaining scientific results. The center also coordinates the observations and their scheduling in a manner to maximum the scientific gains. Predicts are coordinated on-site at each LLR station and the data are automatically transferred from all observing sites to the ILRS data centers. LLR data analysts can secure their data directly from the data centers as needed. Feed-back from these analysts often goes directly back to the individual observing stations. Under the auspices of this National Science Foundation Grant, we are looking forward to additional years of successful LLR observation and analysis, resulting in the steady and rapid expansion of scientific results. ***