High-precision ephemerides not only support space missions,but can also be used to study the origin and future of celestial bodies.In this paper,a coupled orbit-rotation dynamics model that fully takes into account th...High-precision ephemerides not only support space missions,but can also be used to study the origin and future of celestial bodies.In this paper,a coupled orbit-rotation dynamics model that fully takes into account the rotation of the Martian moons is developed.Phobos and Deimos’rotations are first described by Eulerian rotational equations,and integrated simultaneously with the orbital motion equations.Orbital and orientational parameters of Mars satellites were simultaneously obtained by numerical integration for the first time.In order to compare the differences between our newly developed model and the one now used in the ephemerides,we first reproduced and simulated the current model using our own parameters,and then fit it to the Institut de Mécanique Céleste et de Calcul deséphémérides ephemerides using least-square procedures.The adjustment test simulations show Phobos and Deimos’orbital differences between the refined model and the current model are no more than 300 m and125 m,respectively.The orientation parameters are confirmed and the results are in good agreement with the International Astronomical Union results.Moreover,we simulated two perturbations(main asteroids and mutual torques)which were not included in our refined model,and find that their effects on the orbits are completely negligible.As for the effect on rotation,we propose to take care of the role of mutual attraction in future models.展开更多
Space debris poses a serious threat to human space activities and needs to be measured and cataloged. As a new technology for space target surveillance, the measurement accuracy of diffuse reflection laser ranging （D...Space debris poses a serious threat to human space activities and needs to be measured and cataloged. As a new technology for space target surveillance, the measurement accuracy of diffuse reflection laser ranging （DRLR） is much higher than that of microwave radar and optoelectronic measurement. Based on the laser ranging data of space debris from the DRLR system at Shanghai Astronomical Observatory acquired in March-April, 2013, the characteristics and precision of the laser ranging data are analyzed and their applications in orbit determination of space debris are discussed, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39 cm-228 cm. When the data are sufficient enough （four arcs measured over three days）, the orbital accuracy of space debris can be up to 50 m.展开更多
The CCD photometric observations of open star cluster M37(NGC 2099) were carried out up to a limiting magnitude of V ～ 20 in both B and V filters to search for variable stars using a 2k×4k CCD and the 1.3 m tele...The CCD photometric observations of open star cluster M37(NGC 2099) were carried out up to a limiting magnitude of V ～ 20 in both B and V filters to search for variable stars using a 2k×4k CCD and the 1.3 m telescope at the Vainu Bapu Observatory, Kavalur.A total of 314 stars were in the first observing run, out of which 60 were identified as variables.Eight out of the identified 60 variables are classified as W UMa binary stars.For model fitting, we used PHOEBE based on the W-D code to estimate the physical parameters of these newly detected W UMa binaries that theoretically best match the observed light curves.展开更多
对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=...对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.展开更多
采用遗传算法解决极短弧定轨问题时,由于遗传算法不同于经典方法的计算过程,野值剔除方法不再适用.在遗传算法中通过在适值函数中采用不同损失函数实现了稳健估计,解决了极短弧定轨中的野值处理问题.在遗传算法中不同损失函数的引入较...采用遗传算法解决极短弧定轨问题时,由于遗传算法不同于经典方法的计算过程,野值剔除方法不再适用.在遗传算法中通过在适值函数中采用不同损失函数实现了稳健估计,解决了极短弧定轨中的野值处理问题.在遗传算法中不同损失函数的引入较经典方法大大简化.通过对多种损失函数的计算比较,表明采用最小中值二乘(LMS,Least Median Square)和截尾最小二乘(LTS,Least Trimmed Square)估计可大幅度提高极短弧定轨的稳健性,具有极高的崩溃点.展开更多
基金supported by the National Key Research and Development Program of China(2021YFA0715101)the National Natural Science Foundation of China(NSFC,grant Nos.12033009 and 12103087)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0350300)the International Partnership Program of Chinese Academy of Sciences(020GJHZ2022034FN)the Yunnan Fundamental Research Projects(202201AU070225,202301AT070328,202401AT070141)the Young Talent Project of Yunnan Revitalization Talent Support Program。
文摘High-precision ephemerides not only support space missions,but can also be used to study the origin and future of celestial bodies.In this paper,a coupled orbit-rotation dynamics model that fully takes into account the rotation of the Martian moons is developed.Phobos and Deimos’rotations are first described by Eulerian rotational equations,and integrated simultaneously with the orbital motion equations.Orbital and orientational parameters of Mars satellites were simultaneously obtained by numerical integration for the first time.In order to compare the differences between our newly developed model and the one now used in the ephemerides,we first reproduced and simulated the current model using our own parameters,and then fit it to the Institut de Mécanique Céleste et de Calcul deséphémérides ephemerides using least-square procedures.The adjustment test simulations show Phobos and Deimos’orbital differences between the refined model and the current model are no more than 300 m and125 m,respectively.The orientation parameters are confirmed and the results are in good agreement with the International Astronomical Union results.Moreover,we simulated two perturbations(main asteroids and mutual torques)which were not included in our refined model,and find that their effects on the orbits are completely negligible.As for the effect on rotation,we propose to take care of the role of mutual attraction in future models.
基金Supported by the National Natural Science Foundation of China
文摘Space debris poses a serious threat to human space activities and needs to be measured and cataloged. As a new technology for space target surveillance, the measurement accuracy of diffuse reflection laser ranging （DRLR） is much higher than that of microwave radar and optoelectronic measurement. Based on the laser ranging data of space debris from the DRLR system at Shanghai Astronomical Observatory acquired in March-April, 2013, the characteristics and precision of the laser ranging data are analyzed and their applications in orbit determination of space debris are discussed, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39 cm-228 cm. When the data are sufficient enough （four arcs measured over three days）, the orbital accuracy of space debris can be up to 50 m.
文摘The CCD photometric observations of open star cluster M37(NGC 2099) were carried out up to a limiting magnitude of V ～ 20 in both B and V filters to search for variable stars using a 2k×4k CCD and the 1.3 m telescope at the Vainu Bapu Observatory, Kavalur.A total of 314 stars were in the first observing run, out of which 60 were identified as variables.Eight out of the identified 60 variables are classified as W UMa binary stars.For model fitting, we used PHOEBE based on the W-D code to estimate the physical parameters of these newly detected W UMa binaries that theoretically best match the observed light curves.
文摘对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.
文摘采用遗传算法解决极短弧定轨问题时,由于遗传算法不同于经典方法的计算过程,野值剔除方法不再适用.在遗传算法中通过在适值函数中采用不同损失函数实现了稳健估计,解决了极短弧定轨中的野值处理问题.在遗传算法中不同损失函数的引入较经典方法大大简化.通过对多种损失函数的计算比较,表明采用最小中值二乘(LMS,Least Median Square)和截尾最小二乘(LTS,Least Trimmed Square)估计可大幅度提高极短弧定轨的稳健性,具有极高的崩溃点.
