激光角反射器:从月球激光测距到天体探测基础设施

Laser Retroreflectors:From Lunar Laser Ranging to Planet-exploration Key Payload

激光测距已成为太阳系内检验等效原理与洛仑兹破缺、测定后牛顿参数与引力常数时变等引力与相对论物理学研究的强大工具。为此,对激光角反射器在自然天体探测中的应用与发展进行了概述与分析。简单陈述激光角反射器的历史沿革后,首先介绍了数个有待或正在实施的包含激光角反射器部署的天体探测计划。其次,基于激光角反射器与激光测距资料的已有工程经验,描述了激光角反射器在天体探测中承担的科学任务与关键技术问题。最后,以本世纪新一代激光角反射器与收发光源革新为背景,预测了激光角反射器及其激光测距的发展趋势,并针对无人与载人月球探测,对激光角反射器在新阶段天体探测中的使用提出建议。

Laser retroreflectors are a crucial legacy of the Apollo program.Sites on the surface of the Earth have successfully provided lunar laser ranging(LLR) service to 5 corner cube retroreflectors(CCRs) on the surface of the Moon for half a century,generating more than 26,000 normal points.Upgraded systems have led to millimeter-level range accuracy.With appropriate modeling and data analysis,laser ranging is able to determine parameters associated with geophysics,geodesy,interior structure and reference frame of the target planet system.The same planet system is also a good test body for fundamental physics since laser ranging has become a powerful tool for gravitational and relativistic physics,capable of testing equivalence principle and Lorentz violation in the solar system,as well as solving for the postNewtonian parameters and the temporal variation of the gravitational constant.New types of CCRs,coupled by satellitebased laser transmitters,have been frequently seen in recent deep space exploration plans for Mars and asteroids,aiming to duplicate the success of LLR to other planet systems.This paper makes a brief review and analysis about the role and potential of laser retroreflectors in planet exploration.Following a short historical overview,several undergoing and ongoing planet exploration plans involving CCRs are introduced.The major scientific goals and requisite techniques are abstracted next according to past engineering experience of laser ranging projects.Considering the continuing revolution of next-generation CCRs and laser transmitters,future prospects on all fronts are described and advice is made for the use of CCRs in new deep space programs,especially in the next phase of Chang'e program and manned lunar exploration.