太阳系二阶后牛顿光线传播及其测量

As standards of time and frequency are reaching the level of 1e-18, it is demanded to extend the theory of light propagation in the Solar System up to the second order post-Newtonian framework, which is one of the key elements for measurements on time and frequency in a curved spacetime. Such a framework has two potential scientific rewards: (1) being different from the way of traditionally dynamical fittings of planetary ephemerides, light propagation can be used to measure the dynamical factor of the Sun in a kinematic way; (2) being different from the classic tests of general relativity, the highly accurate standards of time and frequency can be used to measure the proper time advancement caused by the curved spacetime. The purpose of this proposal is to establish complete and self-consistent models for these two measurements, to analyse the effects of various sources and to solve two major problems: (1) in the solar superior conjunction, building a second order post-Newtonian model for light propagation, including the effects of the dynamical factor of the Sun, and analysing its potential accuracy for measuring the dynamical factor; and (2) establishing a model for gravitational proper time advancement, including the motions of the observer and the spacecraft, and analysing its optimal configuration for detection. These researches will be able to benefit the scientific application of the next-generation standards of time and frequency.

随着时间和频率标准正在稳步向1e-18精度水平推进，作为弯曲时空中时间和频率测量的要素之一，太阳系光线传播理论需要拓展到二阶后牛顿框架。该框架具有两个潜在的科学意义：（1）有别于传统行星历表动力学拟合方式，光传播可以运动学方式测量太阳的动力学形状因子；（2）不同于广义相对论经典实验，未来高精度的时频标准将可测量弯曲时空所导致的原时间隔提前。本课题旨在建立能够完备描述这两种测量的自恰模型，具体分析实测过程中不同因素的影响，解决两大核心问题：（1）在探测器上合实验中，建立包含太阳动力学形状因子的二阶后牛顿光信号测量模型并对其预期的测量精度进行分析；（2）建立包含观测者和探测器运动的原时间隔测量模型并找出最优的测量构形。有关的结果有望为未来高精度时频测量的科学应用提供理论基础和支撑。

随着时间和频率标准正在稳步向1e-18精度水平推进，作为弯曲时空中时间和频率测量的要素之一，太阳系光线传播理论需要拓展到二阶后牛顿框架。该框架具有两个潜在的科学意义：（1）有别于传统行星历表动力学拟合方式，光传播可以运动学方式测量太阳的动力学形状因子；（2）不同于广义相对论经典实验，未来高精度的时频标准将可测量弯曲时空所导致的原时间隔提前。本课题旨在建立能够完备描述这两种测量的自恰模型，具体分析实测过程中不同因素的影响，解决两大核心问题：（1）在探测器上合实验中，建立包含太阳动力学形状因子的二阶后牛顿光信号测量模型并对其预期的测量精度进行分析；（2）建立包含观测者和探测器运动的原时间隔测量模型并找出最优的测量构形。针对上述两大核心问题，本项目的主要研究结果包含了：（1）建立相应的光线传播天体测量模型；（2）解读测量模型中的物理信息；（3）研究引力时间提前最佳构型的特性。这些结果将为未来高精度时频测量的科学应用提供理论基础和支撑。