一种晨昏轨道卫星地球反照系数估计方法

针对地球反照对太阳同步轨道卫星太阳电池阵输出电流的影响,首先比较不同降交点地方时卫星的太阳电池阵输出电流,分析其变化规律,然后选定晨昏轨道卫星作为研究对象,建立太阳电池阵输出电流模型与地球反照系数估计模型,利用最小二乘法估计电流参数与地球反照系数,最后结合不同季节、不同轨道高度卫星的遥测数据进行在轨验证。结果表明,对于轨道高度在1200km以下的晨昏轨道卫星,地球反照系数在0.05以上;地球反照系数随轨道高度增加呈指数规律衰减,衰减系数约为0.002。     

利用连续推力的人工太阳同步轨道设计方法

针对人工太阳同步轨道的设计方法进行研究,通过施加法向连续推力调整升交点赤经（RAAN）变化率。首次推导了升交点赤经在变方向推力作用下的周期摄动平均值的精确计算公式,解决了已有近似方法对相关轨道参数的取值范围存在限制的问题,并给出了对应的轨道倾角周期摄动平均值计算公式。在分析J2项摄动对升交点赤经影响的基础上,给出了所需的法向连续推力幅值和一个轨道周期内对应的速度增量的计算方法。通过数值仿真,校验了计算公式的正确性,分析了实现人工太阳同步轨道的连续法向推力对轨道倾角的影响,给出了连续推力幅值随轨道参数的变化规律,并且提出了未来工程任务的应用建议。     

Orbit determination by genetic algorithm and application to GEO observation

This paper demonstrates an initial orbit determination method that solves the problem by a genetic algorithm using two well-known solutions for the Lambert’s problem: universal variable method and Battin method. This paper also suggests an intuitive error evaluation method in terms of rotational angle and orbit shape by separating orbit elements into two groups. As reference orbit, mean orbit elements (original two-lines elements) and osculating orbit elements considering the J2 effect are adopted and compared. Our proposed orbit determination method has been tested with actual optical observations of a geosynchronous spacecraft. It should be noted that this demonstration of the orbit determination is limited to one test case. This observation was conducted during approximately 70 min on 2013/05/15 UT. Our method was compared with the orbit elements propagated by SGP4 using the TLE of the spacecraft. The result indicates that our proposed method had a slightly better performance on estimating orbit shape than Gauss’s methods and Escobal’s method by 120 km. In addition, the result of the rotational angle is closer to the osculating orbit elements than the mean orbit elements by 0.02°, which supports that the estimated orbit is valid.     

The classical Laplace plane as a stable disposal orbit for geostationary satellites

The classical Laplace plane is a frozen orbit, or equilibrium solution for the averaged dynamics arising from Earth oblateness and lunisolar gravitational perturbations. The pole of the orbital plane of uncontrolled GEO satellites regress around the pole of the Laplace plane at nearly constant inclination and rate. In accordance with Friesen et al. (1993), we show how this stable plane can be used as a robust long-term disposal orbit. The current graveyard regions for end-of-life retirement of GEO payloads, which is several hundred kilometers above GEO depending on the spacecraft characteristics, cannot contain the newly discovered high area-to-mass ratio debris population. Such objects are highly susceptible to the effects of solar radiation pressure exhibiting dramatic variations in eccentricity and inclination over short periods of time. The Laplace plane graveyard, on the contrary, would trap this debris and would not allow these objects to rain down through GEO. Since placing a satellite in this inclined orbit can be expensive, we discuss some alternative disposal schemes that have acceptable cost-to-benefit ratios.     

基于螺旋理论的航天器姿轨耦合分析

针对航天器运动姿轨耦合性问题,对基于螺旋理论得到的航天器运动模型,定性地分析了姿轨耦合特性。采用参数分析法,从模型所包含的耦合项出发,逐次改变各个参数,进而推导出对应的耦合表达式。为了检验耦合性对控制效果的影响,设计了PD 控制律并进行数值仿真。理论分析和仿真结果进一步证明,基于螺旋理论的航天器姿轨模型,其姿态和轨道运动之间是相互影响的,从控制角度而言,姿态运动对轨道运动影响相对更为严重,容易出现了大的振荡,而轨道运动对姿态运动的影响基本可以忽略,为工程实践提供参考。     

Local debris congestion in the geosynchronous environment with population augmentation

Forecasting of localized debris congestion in the geostationary (GEO) regime is performed to investigate how frequently near-miss events occur for each of the longitude slots in the GEO ring. The present-day resident space object (RSO) population at GEO is propagated forward in time to determine current debris congestion conditions, and new probability density functions that describe where GEO satellites are inserted into operational orbits are harnessed to assess longitude-dependent congestion in “business-as-usual” launch traffic, with and without re-orbiting at end-of-life. Congestion forecasting for a 50-year period is presented to illustrate the need for appropriately executed mitigation measures in the GEO ring. Results indicate that localized debris congestion will double within 50 years under current 80% re-orbiting success rates.     

CHANG'E-2 lunar escape maneuvers to the Sun–Earth L2 libration point mission

This paper addresses lunar escape maneuvers of the first Chinese Sun–Earth L2 libration point mission by the CHANG'E-2 satellite, which is also the world's first satellite to reach the L2 point from a lunar orbit. The lunar escape maneuvers are heavily constrained by the remaining propellant and the condition of telemetry, track and command, among others. First, these constraints are analyzed and summarized to design a target L2 Lissajous orbit and an initial transfer trajectory. Second, the maneuver mathematical models are studied. The multilevel maneuver schemes which consist of phasing maneuvers and a final lunar escape maneuver are designed for actual operations. Based on the scheme analysis and comparison, the 2-maneuver scheme with a 5.3-h-period phasing orbit is ultimately selected. Finally, the mission status based on the scheme is presented and the control operation results are discussed in detail. The methodology in this paper is especially beneficial and applicable to a future multi-mission instance in the deep space exploration.     

Cubature Kalman filtering for relative spacecraft attitude and position estimation

A novel relative spacecraft attitude and position estimation approach based on cubature Kalman filter is derived. The integrated sensor suit comprises the gyro sensors on each spacecraft and a vision-based navigation system on the deputy spacecraft. In the traditional algorithm, an assumption that the chief?s body frame coincides with its Local Vertical Local Horizontal (LVLH) frame is made to construct the line-of-sight observations for convenience. To solve this problem, two relative quaternions that map the chief?s LVLH frame to the deputy and chief body frames are involved. The general relative equations of motion for eccentric orbits are used to describe the positional dynamics. The implementation equations for the cubature Kalman filter are derived. Simulation results indicate that the proposed filter provides more accurate estimates of relative attitude and position over than the extended Kalman filter.     

月球轨道交会任务的远程导引变轨策略研究

对国内外月球轨道交会远程导引段变轨策略的2~5脉冲变轨方案进行了比较分析,在考虑月球轨道交会飞行任务测控资源有限和航天器所带燃料受限等特点的基础上,确定了我国月球轨道交会远程导引段的变轨策略为4脉冲方案;并介绍了在4脉冲基线轨道方案的基础上,进行标称轨道设计和月面上升窗口初步分析的结果。研究结果可为我国月球轨道交会对接任务提供参考。     

星载接收机通道时延实时校准方法

针对星间钟差测量及时间频率的精确传递的需求,通常情况都会在地面对卫星的收发通道时延进行准确标定,但在空间环境下设备老化和环境温度变化会导致收发通道时延逐渐偏离标定值。利用伪码相关测距的原理,结合时分早迟伪码相位交替调制技术和包络检波技术,提出了一种在轨通道时延自校准方法。通过3条闭合测量环路的建立,在不影响接收机正常收发通信的情况下,实时校准其收发通道时延。结果表明,该方法时延测量精度达到亚纳秒量级。