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Research in Astronomy and Astrophysics 2024年第4期24卷 271-286页

作者： Yong-Xiong Zhang Wen-Xiu Guo Xiao-Ping Lu Hua Zheng Hai-Bin Zhao Jun Tian Wei-Lin Wang School of Engineering Guangzhou College of Technology and BusinessGuangzhou 510850China School of Computer Science and Engineering Macao University of Science and TechnologyTaipaMacao 999078China School of Mathematics and Statistics Shaoguan UniversityShaoguan 512099China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China Key Laboratory of Planetary Sciences Purple Mountain ObservatoryCASNanjing 210023China

Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally intensive.This paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution(PDE)algorithm to accelerate inversion.The PDE algorithm is more efficient than the Differential Evolution algorithm,achieving an extraordinary speedup of 37.983 with 64 workers on multicore CPUs.The PDE algorithm accurately derives period and pole values from simulated data.The analysis of real asteroid lightcurves validates the method’s reliability:in comparison with results published elsewhere,the PDE algorithm accurately recovers the rotational periods and,given adequate viewing geometries,closely matches the pole orientations.The PDE approach converges to solutions within 20,000 iterations and under one hour,demonstrating its potential for large-scale data analysis.This work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.

关键词： methods:numerical minor planets asteroids:general techniques:photometric astrom

Photometric Analysis for Asteroid (81) Terpsichore using Convex Inversion and Phase Function Fitting Methods

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Research in Astronomy and Astrophysics 2024年第6期24卷 203-210页

作者： Ao Wang Xiaobin Wang Xiaoyun Xu Longhua Qin Quangui Gao Huaizhen Li Yong Xiao Hairu Zhao Department of Physics Yuxi Normal University Yunnan Observatories Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences University of Chinese Academy of Sciences

The shapes and rotation states（periods and pole orientations） of main-belt asteroids are important for understanding their formation and evolution. In order to obtain sufficient photometric data covering different apparitions for asteroid （81） Terpsichore, ground-based photometric observations in 2020 and 2021 were carried out. By combining published and newly obtained photometric data, we calculated the shape and spin parameters for （81） Terpsichore using the convex inversion method. With this method, we have derived a best fitted pole orientation—(22.2±3.13.3°, 17.5±5.510.8°) with a spin period of 10.94 ±0.010.01h. Based on the derived convex shape of （81） Terpsichore, we have fitted the H, G+1, G2phase function using the calibrated TESS data and Gaia data after accounting for the lightcurve amplitude correction. As a result, we have derived its absolute magnitude H = 8.68 ±0.190.22mag with corresponding phase function parameters G1= 0.82 ±0.100.09and G2= 0.02±0.020.03.

关键词： asteroids: general asteroids: individual (Terpsichore) minor planets techniques: photometric

A Rendezvous Mission to the Second Earth Trojan Asteroid 2020 XL_5 with Low-Thrust Multi-Gravity Assist Techniques

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Research in Astronomy and Astrophysics 2024年第1期24卷 245-264页

作者： Shi-Hai Yang Bo Xu Xin Li School of Aeronautics and Astronautics Sun Yat-sen UniversityShenzhen 518107China

As the second of Earth's Trojan asteroids, 2020 XL_(5) is worthy of rendezvous and even sample return missions in many aspects. In this paper, a rendezvous mission to Earth's second Trojan asteroid 2020 XL_(5) is proposed.However, due to its high inclination and large eccentricity, direct impulsive transfer requires large amounts of fuel consumption. To address this challenge, we explore the benefits of electric propulsion and multi-gravity assist techniques for interplanetary missions. These two techniques are integrated in this mission design. The design of a low-thrust gravity-assist(LTGA) trajectory in multi-body dynamics is thoroughly investigated,which is a complex process. A comprehensive framework including three steps is presented here for optimization of LTGA trajectories in multi-body dynamics. The rendezvous mission to 2020 XL_(5) is designed with this three-step approach. The most effective transfer sequence among the outcomes involves Earth–Venus–Earth–Venus-2020 XL_(5). Numerical results indicate that the combination of electric propulsion and multi-gravity assists can greatly reduce the fuel consumption, with fuel consumption of 9.03%, making it a highly favorable choice for this rendezvous mission.

关键词： minor planets asteroids:general celestial mechanics Planetary Systems

Dynamics and control of a solar collector system for near Earth object deflection

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Research in Astronomy and Astrophysics 2011年第2期11卷 205-224页

作者： Shen-Ping Gong,Jun-Feng Li and Yun-Feng Gao School of Aerospace,Tsinghua University,Beijing 100084,China School of Aerospace Tsinghua University Beijing 100084 China

A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth objects.We investigate the dynamics and control of a solar collector system including a main collector （MC） and secondary collector （SC）.The MC is used to collect the sunlight to its focal point,where the SC is placed and directs the collected light to an asteroid.Both the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical path.First,the dynamical equation of the relative motion of the two collectors in the vicinity of the asteroid is modeled.Secondly,the nonlinear sliding-mode method is employed to design a control law to achieve the desired configuration of the two collectors.Finally,the deflection capability of this solar collector system is compared with those of the gravitational tractor and solar sail gravitational tractor.The results show that the solar collector is much more efficient with respect to deflection capability.

关键词： minor planets asteroids -- techniques： miscellaneous -- solar collector

The research objectives and observational possibilities for fast moving near-Earth asteroids

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Research in Astronomy and Astrophysics 2021年第7期21卷 199-208页

作者： Anton Pomazan Zheng-Hong Tang Nadiia Maigurova Kai Tang Yong Yu Yin-Dun Mao Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049China Research Institute“Mykolaiv Astronomical Observatory” Mykolaiv 54030Ukraine

The paper describes observations of fast-moving near-Earth asteroids(NEAs) made with the small ground-based telescopes of National Time Service Center of Chinese Academy of Science(NTSC of CAS) and Research Institute "Mykolaiv Astronomical Observatory"(RI MAO) by the rotating-drift-scan CCD(RDS CCD) technique. This technique is used to obtain the point images of both the studied objects and reference stars. The results of ongoing follow-up observations of NEAs are discussed. The residual differences(O-C) between the observed and calculated positions from JPL ephemeris were generally small for these asteroids. The standard deviations of these differences were typically ±(0.2′′-0.3′′) in both coordinates for objects with apparent velocity which substantially exceed FWHM for the given exposure time. The results of comparative statistics for such observations from the MPC database show that this is a good level of precision for NEAs. Moreover, the telescopes with the RDS CCD technique implemented can observe the NEAs that closely approach the Earth and with enough observations can improve the precision of determining their orbital elements and impact predictions.

关键词： astronomical databases:miscellaneous surveys methods:observational techniques:miscellaneous astrometry minor planets asteroids:general

Shape Model and Rotation Acceleration of(1685) Toro and(85989) 1999 JD6from Optical Observations

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Research in Astronomy and Astrophysics 2022年第12期22卷 166-182页

作者： Jun Tian Hai-Bin Zhao Bin Li Key Laboratory of Planetary Sciences Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHeifei 230026China

The Yarkovsky-O'Keefe-Radzievskii-Paddack(YORP) effect is a net torque caused by solar radiation directly reflected and thermally re-emitted from the surface of small asteroids and is considered to be crucial in their dynamical evolution. By long-term photometric observations of selected near-Earth asteroids, it is hoped to enlarge asteroid samples with a detected YORP effect to facilitate the development of a theoretical framework. Archived light-curve data are collected and photometric observations are made for(1685) Toro and(85989) 1999 JD6,which enables measurement of their YORP effect by inverting the light curve to fit observations from a convex shape model. For(1685) Toro, a YORP acceleration υ =(3.2 ± 0.3) × 10^(-9)rad · day^(-2)(1σ error) is updated,which is consistent with previous YORP detection based on different light-curve data;for(85989) 1999 JD6, it is determined that the sidereal period is 7.667 749 ± 0.000009 hr, the rotation pole direction is located atλ = 232° ± 2°, β =-59° ± 1°, the acceleration is detected to be υ =(2.4 ± 0.3) × 10^(-8)rad · day^(-2)(1σ error) and in addition to obtaining an excellent agreement between the observations and model. YORP should produce both spin-up and spin-down cases. However, including(85989) 1999 JD6, the dω/dt values of 11 near-Earth asteroids are positive totally, which suggests that there is either a bias in the sample of YORP detections or a real feature needs to be explained.

关键词： methods:data analysis methods:observational techniques:photometric minor planets asteroids:individual((1685)Toro (85989)1999 JD6)

Study of the Modified Gaussian Model on olivine diagnostic spectral features and its applications in space weathering experiments

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Research in Astronomy and Astrophysics 2020年第8期20卷 261-279页

作者：韩慧杰卢晓平杨亚洲张昊 Admire Muchimamui Mutelo State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyTaipa 999078MacaoChina State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Planetary Science Institute School of Earth SciencesChina University of GeosciencesWuhan 430074China CAS Center for Excellence in Comparative Planetology Hefei 230026China School of Earth Science and Resources China University of GeosciencesBeijing 100083China

The absorption features of olivine in visible and near-infrared(VNIR)reflectance spectra are the key spectral parameters in its mineralogical studies.Generally,these spectral parameters can be obtained by exploiting the Modified Gaussian Model(MGM)with a proper continuum removal.However,different continua may change the deconvolution results of these parameters.This paper investigates the diagnostic spectral features of olivine with diverse chemical compositions.Four different continuum removal methods with MGM for getting the deconvolution results are presented and the regression equations for predicting the Mg-number(Fo#)are introduced.The results show that different continua superimposed on the mineral absorption features will make the absorption center shift,as well as the obvious alterations in shape,width and strength of the absorption band.Additionally,it is also found that the logarithm of a second-order polynomial continuum can match the overall shape of the spectrum in logarithmic space,and the improved regression equations applied to estimate the chemical composition of olivine-dominated spectra also have a better performance.As an application example,the improved approach is applied to pulse laser irradiated olivine grains to simulate and study the space weathering effects on olivine diagnostic spectral features.The experiments confirm that space weathering can make the absorption band center shift toward longer wavelength.Therefore,the Fo#estimated from remote sensing spectra may be less than its actual chemical composition.These results may provide valuable information for revealing the difference between the spectra of olivine grains and olivine-dominated asteroids.

关键词： techniques:spectroscopic instrumentation:spectrographs methods:statistical minor planets asteroids:general