摘要
为了研究激光天文动力学空间任务概念 ,我们建立了CGC 2星历框架及演算法。在此框架中 ,我们考虑了太阳、九大行星、月球等十一个主要天体和 492颗直径大于 65km的小行星。我们使用后牛顿运动方程式及Runge -Kutta四阶数值方法 ,取的演进间距为 0 .0 1天。鉴于个人计算机的进展 ,此星历之演算在个人计算机上即可进行 ,算法及程序公开 ,可供研究者方便使用。在和JPLDE 40 5之算法比较时 ,我们使用DE 40 5星历之参数及初始值演算并将其和DE40 5之差与DE 40 3和DE 40 5之差比较。比较结果 ,显示CGC 2星历与DE 40 5星历之演算结果相近。若要进一步成为独立的星历 ,则需重新拟合所有有效的观测数据。此公开的框架并可望在未来有新数据时供研究者改进。
Ephemeris is necessary for mission orbit design. For non-astrodynamical missions, an existing ephemeris like JPL DE 405 and 406 can be used for this purpose. For astrodynamical missions, one needs to have a working ephemeris flexible enough that one can do orbit simulation for mission design, and orbit determination and astrodynamical-parameter fitting during actual mission. In real-time with the astrodynamical mission, the working ephemeris is continuously improved. After the mission the working ephemeris would be better than all previously existing ephemeris at least for certain parts of the ephemeris. For the ASTROD orbit design and simulation, we have worked out CGC 1 and CGC 2 ephemeris framework. Here we describe how CGC 2 ephemeris framework is built (CGC: Center for Gravitation and Cosmology). In the CGC 2 framework, we include the Sun, nine planets, the Moon and 3 big asteroids in a mutually interacting evolution with the solar field to the post-Newtonian order. Solar quadrupole moment and Earth's quadrupole moment are also included. We include additional 489 asteroids with diameter larger than 65 km in the calculation of the perturbation of orbits of nine planets, the sun, the moon and the 3 big asteroids. To simplify calculation, the heliocentric orbits of these 489 asteroids are determined by the Kepler elements. At each calculation step, the Newtonian perturbation forces are calculated and added to the equations of motion of the 14 celestial bodies. For more accurate calculation of the positions and velocities of the Earth and the Moon, the quadrupole moment effect of Earth is added to the equations of motion of the Earth and the Moon. We use the Runge-Kutta 4 th order algorithm to solve the differential equations of essential celestial bodies with the stepsize 0.01 days. The initial time is 0:00 2005/06/10 (JD 2453531.5) with the initial positions and velocities of 11 celestial bodies taken from JPL DE405 ephemeris; those of the three big asteroids are calculated from MPO98 (1997). Thi
出处
《云南天文台台刊》
CSCD
北大核心
2002年第3期21-32,共12页
Publications of the Yunnan Observatoty
