Development of Asteroid Optical Determination Software and Data Processing Analysis
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摘要: 结合中国航天局2019年4月19日拟定的第一个小行星探测任务规划,本文针对任务目标之一的主带彗星133P/Elst-Pizarro(7968)自主研制了小行星光学定轨软件。使用1979年7月24日至2019年10月28日期间发布的133P/Elst-Pizarro地面光学观测数据进行精密定轨,与国际知名小行星光学定轨软件OrbFit对比分析。对比发现解算结果残差分布一致,两软件生成的残差差值的RMS小于0.01″,定轨的内符合精度相互吻合。这一结果初步表明自主研制的小行星光学定轨程序的可靠性。在此基础上,对133P/Elst-Pizarro开展光学数据仿真定轨分析,研究地面光学数据的定轨精度。结果表明:模拟云南站和智利站每月一次联测,在只考虑观测噪声影响的情况下,添加接近目前实际观测水平的高斯白噪声,使用20年光学观测资料定轨,小行星光学定轨精度在50 km量级。同时验证增加观测数据或降低观测噪声均可有效提高小行星光学定轨精度。
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关键词:
- 主带彗星133P/Elst-Pizarro /
- 光学定轨 /
- 仿真分析 /
- 精度分析
Abstract: Based on the first asteroid exploration plan announced by China Space Administration on April 19, 2019, we develop an optical orbit determination software for the main belt comet 133P/Elst-Pizarro (7968), which is one of the mission targets. The 133P/Elst-Pizarro's ground-based optical observation data from July 24, 1979 to October 28, 2019 are analyzed. Compared with the well-known OrbFit software system, it is found that the residual distribution is consistent, the measurement statistical residual RMS is less than 0.01″, and the internal coincidence accuracy of orbit determination is also consistent with each other. The results suggests the reliability of our software. Furthermore, we carry out a simulation orbit determination analysis aimed at 133P/Elst-Pizarro to discuss the orbit determination accuracy from ground-based optical data. When we use 20-year optical observation data measured once a mouth from Yunnan and Chile station and adding Gaussian white noise which is close to the current actual observation level, the results reflect that the optical orbit determination accuracy of the asteroid is at 50 km level. At the same time, it also shows that the optical orbit determination accuracy of the asteroid can be effectively improved by increasing the observation data or reducing the observation noise. -
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表 1 动力学模型和时空基准
Table 1 Dynamic Model and Space-Time Benchmark
表 2 自主软件参数解算结果
Table 2 Results of Parameters Solution Using Independent Software
参数 数值 与初轨偏差 RMS(1$ \mathit{\boldsymbol{\sigma }} $) X/km -291 090 530.559 13.986 43.489 Y/km −317 565 597.602 −22.477 39.189 Z/km 9 623 769.361 23.739 40.723 VX/(m⋅s-1) 15 055.7 3.631×10-3 0.001 1 VY/(m⋅s-1) −10 424.3 7.346×10-3 0.001 4 VZ/(m⋅s-1) 113.6 4.543×10-4 0.001 7 表 3 OrbFit参数解算结果
Table 3 Results of Parameters Solution Using OrbFit
参数 数值 与初轨偏差 RMS(1$ \mathit{\boldsymbol{\sigma }} $) X/km -291 090 532.667 16.093 44.477 Y/km -317 565 610.549 -9.530 39.289 Z/km 9 623 794.171 -1.071 39.574 VX/(m⋅s-1) 15 055.7 3.881×10-3 0.001 1 VY/(m⋅s-1) -10 424.3 6.951×10-3 0.001 5 VZ/(m⋅s-1) 113.6 2.290×10-4 0.001 6 表 4 初始轨道
Table 4 Equinoctial Orbital Elements
参数 数值 时间 2021-01-01 半长轴/AU 3.164 263 621 791 612 0 e$ \times $sin ($ \omega +\mathit{\Omega} $) -0.145 737 655 500 451 e×cos ($ \omega +\mathit{\Omega} $) 0.058 571 578 867 105 tan (i/2)×sin $ \mathit{\Omega} $ 0.004 122 980 432 246 tan (i/2)×cos $ \mathit{\Omega} $ -0.011 400 256 739 563 平均经度/(°) 77.633 785 095 603 7 表 5 不同情况标称轨道与重建轨道差值
Table 5 Difference Value Between Nominal Orbit and Reconstructed Orbit in Different Cases
方案 白噪声 数据 dX/m dY/m dZ/m 偏差值/m RMS(1$ \sigma $)/m 1 无 联测 -0.05 0.24 -0.01 0.24 云南站 -0.04 0.24 -0.01 0.24 2 赤经0.71″
赤纬0.53″联测 -30 519.91 18 815.50 15 651.02 39 120.86 81 714.93 云南站 34 435.95 18 911.55 10 867.80 40 762.61 129 212.05 3 赤经0.37″
赤纬0.37″联测 -18 289.31 10 679.24 9 769.22 23 323.44 46 610.53 云南站 19 144.14 10 929.88 8 315.42 23 560.70 73 702.88 4 赤经0.03″
赤纬0.03″联测 -1 486.84 868.06 792.09 1 895.16 3 779.23 云南站 1 548.28 888.39 674.21 1 908.14 5 975.91 -
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