天问一号是中国第一次实现地火转移行星际飞行的探测器，在长达202天的行星际转移飞行期间，共经历了4次中途修正及1次深空机动控制，在2021年2月10日成功进行了近火制动，被火星捕获而进入环火轨道。本文对探测器行星际转移期间的动力学模型进行了分析，制定了转移飞行期间定轨积分中心转换原则：在探测器飞出地球影响球后，定轨积分中心需要由地心更换为日心；对不同版本行星星历表的使用进行了分析，确定了使用DE436行星历表进行计算对定轨影响最小。根据探测器行星际转移飞行的特点，制定了一种基于逐日迭代定轨策略的精度评估方法。基于实测数据分析，验证了该方法的有效性，火星探测器行星际转移期间定轨位置误差优于2 km，速度误差优于20 mm·s–1 (1σ)。

针对嫦娥五号探测器(CE-5)开展基于深空网测量数据的定轨能力分析.首先从测量原理分析了深空网VLBI数据的误差源,然后利用CE-5的精密轨道评估了 VLBI数据的误差,最后基于实测数据与协方差分析理论,分析UXB与VLBI数据的定轨能力.结果表明:转移阶段,单独利用深空网测量数据可以获取优于1 km的转移轨道精度,标校VLBI系统偏差后可以实现优于500 m的轨道精度;环月阶段,轨道解算精度优于200 m,VLBI数据对轨道改进有限,系统偏差甚至会降低轨道精度;基于协方差分析表明,VLBI数据可以降低转移阶段的形式误差近1个量级,但对于环月阶段改进量小于10％.

针对大椭圆轨道在轨控期间使用传统Box规避阈值计算碰撞风险漏警率较高的问题,首先对大椭圆轨道预报偏差和控制偏差进行了分析,发现轨道偏差和轨控偏差随时间的传播规律可通过多项式拟合的方法模拟;然后提出将各种偏差导致的轨道预报偏差叠加,动态计算Box规避阈值的方法;最后与传统Box规避阈值确定方法进行比较.结果表明:使用动态Box规避阈值设置方法可以有效降低传统Box规避阈值计算碰撞风险漏警和虚警率.

The Chang'e-5 spacecraft has some new characteristics, such as direct entry into the Earth-Moon transfer orbit, lunar surface sampling, rendezvous and docking, high-speed re-entry and return, and after completing the main mission, the orbiter being able to fly to the first Lagrangian libration point of the Sun-Earth orbit. This paper evaluates the orbit determination and prediction accuracy and lunar surface-positioning accuracy of the mission key nodes. Results showed that the position error of the orbit determination prediction 6 h before midway correction and 6 h before lunar capture is 100 m. During rendezvous and docking, the position error is similar to 700 m from the forecast to the handover point after the fourth remote guidance and control. This is caused by the accumulation of the ascent's orbit and control error. Using 12-h data can effectively meet the task requirements. Besides, for the Chang'e-5 expansion mission, the overlapping arc analysis method is used, and the position error is similar to 500 m.

Solar radiation pressure（SRP）area is one of the key parameters of orbit determination and prediction in deep space detection，and directly affecting the prediction precision. The calculating method of SRP area based on target characteristics is used，and the sphere，cube，cylinder and cone are chosen to be analytical targets，assuming the materials are purely diffuse，purely specular and mixed surface separately. While the attitude angle changing from 0° to 360°，the influences of the surface materials，size and the shape of the target on the total SRP area of the target are analyzed，the general laws governing influential factors are described by comparing simulated results. These conclusions can provide reference for further research on SRP modeling solution and spacecraft design.

针对商业小卫星星座迅猛发展对航天器飞行安全造成潜在威胁的问题,以600 km高度星座和大型低轨航天器为研究对象,通过区域方法（BOX）和碰撞概率风险评估方法,分析了星座与大型低轨航天器的碰撞风险。根据星座轨道演化分析表明,整个星座卫星与大型低轨航天器可能发生碰撞的时间相对集中,持续时间约1～2年。BOX方法计算结果表明,每颗卫星与大型低轨航天器交会,并进入红色预警门限的交会次数约10次左右。碰撞概率计算结果表明,约有5%的卫星进入红色预警门限,星座如果在寿命末期采取无控再入将对大型低轨航天器在1～2年内产生较大的威胁。

Chang'E-4 relay satellite that flying on the mission orbit at the Earth-Moon L2 is the key for the probe to complete the landing and inspection on the farside of the moon,with the mission orbit of the southern clan Halo orbit with an average period of 14 days. Due to mission requirements, the + Z axis of the relay satellite will be in two states:orientation to the sun and orientation to the moon or the earth. In the non-directional orientation of the sun, the solar pressure will accelerate the angular momentum accumulation of satellites and increase the frequency of satellite jets. In this paper,under the existing TT&C conditions, the orbit determination accuracy of satellites in the two states is analyzed and evaluated by using overlapping arc method. The results show that the position error of overlapping arcs is 1.6 km and the velocity error is 8 mm/s for the relay satellite when the + Z axis is not pointing to the sun,while the position error of overlapping arcs is 0.6 km and the velocity error is 3 mm/s for the relay star when the + Z axis is pointing to the sun. This has important reference value for the long term operation of relay satellites.

Because of restricted earth-based tracking network, Tracking, Telemetry and Command (TT&C) for lunar orbit micro-satellite is depended on Unified S/X Band (USB) antennas in China Chang'E-4 lunar exploration. Based on analysis of the geometry between relay satellite, micro-satellite and earth-based antennas during earth-moon transfer orbit, an applicable method to acquire delay observable through Same-Beam Interferometry (SBI) tracking by China deep space network is discussed. Benefited from more kinds of tracking resources and high accuracy orbit of relay satellite, delay observable for angular position measurement of micro-satellite in the order of 1 ns is obtained, which improves the micro-satellite orbit determination accuracy from 2 km to less than 1 km and improves orbit prediction accuracy from 6 km to 2 km. SBI tracking plays an important role in short arc orbit determination of micro-satellite.

应用多项式混沌展开法(PCE)进行空间实验室轨道预报误差分析.通过构建PCE模型对轨道预报的不确定性传播过程进行近似,进而对轨道预报后航天器位置和速度的误差进行分析.分析了不同PCE模型阶数、预报时长以及样本点的数目对构建PCE模型的影响.综合考虑精度和计算效率,给出了适用于空间实验室轨道预报误差分析的PCE模型.将PCE方法与传统方法进行对比,结果表明PCE方法有较好的非线性近似能力,且计算效率高,验证了PCE方法应用于空间实验室轨道预报误差分析的有效性.

This paper analyzes the time differences between stations using least square method based on three-way tracking measurements of Chang'E 3probe,and achieves nanosecond level fitting accuracy on 5degree fitting.The precise ephemeris of the probe is used to calibrate the three-way measurements.Following the correction,the error of the ranging system decreases to 10 mlevel and the fitting noise level is improved to better than 1 m.Finally,three-way measurements are used in orbit determination,lunar landing positioning and powered descent trajectory calculation for the probe.As a result,the bias of the 100 km × 15 km lunar orbit compared to the precise orbit is100 mlevel,the bias of the 120 km ×70km lunar orbit is 10 mlevel compared to the precise orbit,and the bias of lunar position compared to the position calculated by two-way ranging and VLBI(Very Long Baseline Interferometry)delay is 10 mlevel.

大气阻力是影响低轨航天器众多空间操作的重要因素,尤其是经验密度模式,固有的至少15％的误差已经严重制约航天器轨道计算精度的提高.针对广泛应用的经验密度模式,选择物理背景简明的Jacchia71模式,以温度参数Tc和Tx为对象,建立密度相对于上述温度参数的条件方程,推导了密度相对于温度参数的解析偏导数,并给出其最小二乘解.利用CHAMP卫星数据对模式修正结果进行验证,模式平均误差从40％降低至3％左右.通过TG01飞行器的轨道预报比较,修正前后轨道预报误差从2 km降低至1.3 km.经过CHAMP卫星和TG01飞行器的实测数据检验,验证了修正算法的正确性和有效性.

热层大气的阻力效应是影响低轨航天器大量空间操作的重要因素, 尤其是经验密度模式, 其固有的至少15%的内符合误差已严重制约航天器轨道计算精度的提高. 针对广泛应用的经验密度模式, 选择物理背景简明、关联参数较少的JACCHIA71模式, 以地磁平静条件下的全球散逸层顶温度最小值Tc及125 km高度拐点温度Tx为对象, 建立密度相对于上述温度参数的条件方程, 推导密度相对于温度参数的解析偏导数, 并给出其最小二乘解. 同时, 利用CHAMP卫星数据对模式进行修正, 模式平均误差从40%降低至3%左右. 通过TG01飞行器的轨道预报比较, 修正前后轨道预报位置精度从2 km提升至1 km左右. 经过CHAMP卫星和TG01飞行器的实测数据检验, 验证了修正算法的正确性和有效性.

在我国自主实施的交会对接任务中,2个空间目标进行了数次对接试验,在近距离导引段使用星间测量数据进行自主导引.针对2个航天器对接过程中的星间测量数据建立观测模型,并设计了多目标定轨的算法,将单目标的绝对测量融合到两目标联合定轨的技术中,实现了对空间多个目标的精确定轨.最终分析表明,星间测量数据优于地面测量精度,多目标定轨达到了地面精确测控的水平,同时避免了由于多目标同时跟踪而导致的地面测控资源分配的问题,为后续载人航天任务的测控模式提供了借鉴.

针对交会对接任务目标飞行器与追踪器轨道运行特性,综合考虑规避策略计算方法与工程实际相结合的问题,提出高度规避、时间规避以及与正常轨控相结合的碰撞规避策略计算方法等三种空间目标碰撞规避策略计算方法.高度规避计算方法采用了Lambert飞行原理,用简化二体开普勒模型取代高精度轨道预报方法,迭代求解规避机动速度增量,实现了通过约束过交点与目标径向距离差得到速度增量的最优解;时间规避计算方法通过轨道周期与速度增量的关系,实现了通过约束过交点与目标的时间差得到速度增量的最优解;与正常轨控相结合的碰撞规避策略计算方法,在正常控制考虑冗余控制量的基础上,对控制策略的控制开始时间或沿迹方向的速度增量进行较小的修正,使两者通过碰撞点的时刻或径向距离错开,达到碰撞规避的目的,该方法不仅可以节省燃料、而且对任务的影响较小.通过对三种空间目标碰撞规避策略计算方法仿真分析结果表明,完全适用于交会对接任务,可为我国载人航天任务飞行安全提供技术保障.

New characteristics of orbit determination and prediction are presented in the background of the first rendezvous and docking mission of China.Factors affecting orbit prediction accuracy,including yaw steering mode,are analyzed quantitatively in order to solve the long term orbit prediction problem during the period of phasing maneuver of TG01(Tiangong-1).The optimal orbit prediction strategy is set up through results comparison using different strategies.Regarding the orbit determination with short arc of SZ08(Shenzhou-8) spaceship during the far range guided phase,orbit determination strategy adapted to the short arc condition is adopted.As a result,the position accuracy is better than 50m with 3 and 6 passes during orbit determination with ground-based S-band tracking data and tracking data of the TDRSS(Tracking and Data Relay Satellite System).