曹建峰

(中國(guó)科學(xué)院上海天文臺(tái)上海200030)

“嫦娥二號(hào)”平動(dòng)點(diǎn)和小行星探測(cè)試驗(yàn)中的軌道計(jì)算

曹建峰?

(中國(guó)科學(xué)院上海天文臺(tái)上海200030)

論文以CE-2(嫦娥二號(hào))平動(dòng)點(diǎn)飛行試驗(yàn)、小行星探測(cè)試驗(yàn)以及YH-1火星探測(cè)任務(wù)為背景,對(duì)深空探測(cè)測(cè)定軌技術(shù)開(kāi)展研究.相關(guān)研究成果直接為小行星圖塔蒂斯探測(cè)試驗(yàn)的拍照成像提供了高精度的軌道支持.針對(duì)YH-1火星探測(cè)開(kāi)展了先期的測(cè)定軌研究,研究成果雖未能直接應(yīng)用于火星探測(cè)任務(wù),但積累的理論知識(shí)可服務(wù)于我國(guó)后續(xù)深空探測(cè).論文的研究可以概括為以下幾個(gè)方面：

(1)回顧統(tǒng)計(jì)定軌理論,簡(jiǎn)單介紹了時(shí)空參考系、動(dòng)力學(xué)模型、估值方法及考察協(xié)方差理論.

(2)開(kāi)展深空探測(cè)的觀測(cè)建模研究.基于理論分析,推導(dǎo)建立測(cè)距、多普勒以及VLBI(Very Long Baseline Interferometry)等觀測(cè)類(lèi)型的測(cè)量模型.在觀測(cè)模型建立過(guò)程中對(duì)算法進(jìn)行優(yōu)化,在保證計(jì)算精度的同時(shí),提高了計(jì)算效率.此外,針對(duì)嫦娥衛(wèi)星巡航飛行階段自旋穩(wěn)定的特點(diǎn),建立了測(cè)量數(shù)據(jù)的自旋修正模型,既滿足了數(shù)據(jù)修正的需求,亦可實(shí)現(xiàn)天線安裝位置的估算.

(3)對(duì)CE-2平動(dòng)點(diǎn)飛行試驗(yàn)期間積分中心選取的問(wèn)題進(jìn)行了研究,基于理論推導(dǎo),得出選取地球作為積分中心開(kāi)展軌道計(jì)算更適合的結(jié)論.針對(duì)平動(dòng)點(diǎn)飛行試驗(yàn)期間的軌道計(jì)算,建立了真實(shí)力模型下空固坐標(biāo)系與會(huì)合坐標(biāo)系的轉(zhuǎn)換關(guān)系;構(gòu)建了對(duì)流層延遲修正的平均效應(yīng)模型,實(shí)現(xiàn)了CE-2在平動(dòng)點(diǎn)飛行階段全程2–10 km、在平穩(wěn)飛行階段優(yōu)于5 km的定軌精度,為CE-2平動(dòng)點(diǎn)飛行試驗(yàn)提供了精確軌道支持.

(4)對(duì)CE-2小行星探測(cè)試驗(yàn)的軌道計(jì)算開(kāi)展了研究,為探測(cè)試驗(yàn)小行星清晰成像提供精確軌道支持.交會(huì)前兩次軌道修正僅有13 d間隔,而小行星清晰成像要求軌道精度優(yōu)于15 km.針對(duì)控后弧段有限的特點(diǎn),建立了融合軌控前后測(cè)軌數(shù)據(jù)進(jìn)行軌道計(jì)算的策略,實(shí)現(xiàn)了控后12 d優(yōu)于10 km的定軌精度.

(5)針對(duì)早期YH-1火星探測(cè)任務(wù)開(kāi)展了仿真計(jì)算,分析了影響定軌精度的主要誤差源和當(dāng)前測(cè)控條件下YH-1可能的定軌計(jì)算能力,先期的研究工作可為后續(xù)的自主火星探測(cè)提供支持.對(duì)上海天文臺(tái)跟蹤的MEX(Mars Express)測(cè)軌數(shù)據(jù)進(jìn)行處理分析,解算的軌道與ESA(European Space Agency)精密軌道偏差百米量級(jí),驗(yàn)證了深空探測(cè)觀測(cè)模型、動(dòng)力學(xué)模型的準(zhǔn)確性以及定軌軟件的能力.

Setting within the context of the flight trial of CE-2(Chang’e 2)around the Sunterrestrial libration point,the asteroid exploration as well as the YH-1 Mars explorationmission,this paper conducted various related studies on orbit determination techniques for deep space exploration.The research results provided high-precision orbit support for the successful photographing of the Toutatis.This paper also carried out preliminary orbit determination studies on YH-1 mission.Although the study findings can not be used directly in the Mars exploration mission,they can still be useful for the future explorations.This thesis is composed of the following five aspects.

(1)Reviewed the statistical orbit determination theory,and gave a description of the spatiotemporal frame of reference,dynamical model issues,methods of estimation,perturbation analysis theory,as well as the algorithms for considering covariance analysis.

(2)Developed the observational model for the deep space exploration.Based on theoretical analysis,the models of ranging,ranging rate,and VLBI(Very Long Baseline Interferometry)are derived.During the modeling process,the algorithm is optimized to improve the computational efficiency without deteriorating the accuracy.In addition,with the spin-stabilized characteristic of CE-2 in its cruise phase taken into consideration,a spin stabilization correction model of the tracking data is constructed,which not only meets the requirement of data correction,but also can estimate the alignment of antenna.

(3)Carried out a study on the selection of integration center for CE-2 libration flight trial.The result shows that the Earth is most suitable for orbital prediction.A precise satellite ephemeris for CE-2’s flight trial is provided.The transformation relation between the spatial- fixed coordinate system and the rotation coordinate system is constructed.An orbital accuracy of 2–10 km in the whole flight process and 5 km for the stable flight phase are achieved based on an overlap comparison.

(4)Provided orbit support for CE-2’s asteroid exploration.Under the circumstances that only 13 days are left between the last two orbit maneuvers before the encounter,and an accuracy of better than 15 km is required for the target photographing,an orbit determination strategy incorporating pre-and post-maneuver tracking data is developed,which achieved an orbit determination accuracy of 10 km,and presented a calibration basis for velocity increment during the maneuver.

(5)Performed YH-1 Mars exploration simulation,and analyzed the major error sources a ff ecting the orbit determination accuracy.The YH-1’s possible orbit determination ability under the current tracking capacity is also studied.These researches can provide support for the subsequent Mars exploration.In addition,the Mars Express tracking data from Shanghai Astronomical Observatory are processed and calculated,and the position discrepancy between the orbit thus obtained and European Space Agency’s orbit is of the order of several hundred meters.This trial tested the accuracy of the observation model,dynamical model,and the ability of orbit determination software for deep space exploration.

Orbit Determination for CE-2 Libration Flight and Asteroid Exploration Trial

CAO Jian-feng
(Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030)

10.15940/j.cnki.0001-5245.2016.01.012 博士學(xué)位論文摘要選登

?2013-07-07獲得博士學(xué)位,導(dǎo)師:上海天文臺(tái)胡小工研究員;jfcao@foxmail.com