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.     

Specific features of motion of geosynchronous satellites in the neighborhood of unstable stationary points

A study of peculiarities of the motion of equatorial circular geosynchronous satellites is performed in the neighborhoods of unstable stationary points with longitudes of 165° and 345°. The maps of initial conditions are constructed on the phase plane “longitude of subsatellite point-semi-major axis of orbit” corresponding to various types of regular motions and to quasi-random solutions. The dimensions of zones of the quasi-random solutions are within the limits from decimal fractions of a degree to a few degrees (in longitude) and from hundreds of meters up to several kilometers (along the semi-major axis).     

空间碎片捕获过程动力学建模综述

文章分析了绳系捕获系统建模及精细化、捕获系统低阶鲁棒控制器和捕获过程半物理仿真的研究现状,并提出了有关空间碎片捕获过程动力学建模及仿真验证领域待解决的一些基本问题,为研制空间碎片回收系统奠定了理论基础。     

Space debris and the need for space traffic control

This report summarises the presentations which took place at the ‘Space Traffic Control – Is the Space Debris Problem Solvable?’ conference hosted by the Royal Aeronautical Society on the 2nd July 2013. The conference sought to promote discussion over methods to deal with the issue of space debris in particular and speakers included representatives from the European Space Agency, the United Kingdom Space Agency, practitioners and academia. Themes which emerged during the conference included the urgency of the problem of space debris, the need for short-term and long-term solutions, the necessity for the development and implementation of space debris remediation technologies to complement existing mitigation efforts and, last but not least, the wider applications of space traffic control. Regarding the sub-title of the conference, ‘is the space debris problem solvable?’, it would appear from the presentations that while there is the potential for future management of the issue through debris remediation and harmonised mitigation efforts, no comprehensive solutions exist at the time of writing.     

天基激光驱动空间碎片降轨效果仿真研究

在当前天基激光移除碎片方案设计中,通常采用kJ级高能激光器、100 m/s大速度增量和简单降轨模型计算移除系统参数,然而kJ级天基高能激光器尚未实现。文章基于目前实验室现有的J级激光器水平,参考现阶段碎片移除方案,针对特定区域的目标空间碎片,结合碎片轨道特性信息建立降轨模型,仿真研究目标碎片在低能量天基激光驱动下的运动过程和降轨效果,分析了影响目标碎片降轨效果的因素。对部署在500 km轨道高度的天基平台移除附近碎片的仿真结果表明,速度增量和降轨高度的变化具有累积效应,提高频率、增大有效作用距离等可延长激光烧蚀驱动时间,进而增强碎片降轨效果。分析表明,J级小能量激光器通过长时间的烧蚀,也可有效驱动和移除1～10 cm碎片。     

Strategy for capturing of a tumbling space debris

In general space debris objects do not possess much convenient features and are non-cooperative. In such cases, since the conditions for capture are not favorable, tracking errors will lead to loading, and momentum transfer will occur during the capture process.In most cases, detailed mass and inertial characteristics of the target are unknown, either because design details are unavailable or due to changes as a result of damage sustained when failure occurred or gradual degradation over the years, and this makes impedance matching of the capture arm force control system difficult.This led to us to devise a “joint virtual depth control” algorithm for robot arm control, which brakes the rotation of a target with unknown inertia. This paper deals with a removal work strategy and control method for capturing and braking a tumbling, non-cooperative target space debris.We propose a new brush type contactor as end-effecter of a robot arm for reducing the rotational rate of the target debris. As a means for relieving the loads generated during target tapping, in addition to joint compliance control we propose a new control method that controls the arm tip force according to a contact force profile.     

地基激光测距系统观测空间碎片进展

卫星激光测距作为地基光电望远镜系统重要技术应用,可直接精确测量空间碎片距离,提升碎片目标轨道监测精度。基于上海天文台60 cm口径激光测距望远镜,应用百赫兹重复率高功率激光器、高效率激光信号探测系统等,建立了空间碎片激光测距系统,实现了对距离500~2600 km、截面积0.3~20 m2的碎片目标观测,测距精度优于1 m,具备了碎片目标常规测量与应用能力。此外,开展了空间目标白天监视技术研究,实现了亮于6星等恒星的白天观测,并进行了望远镜局部指向误差模型分析,分析结果可应用于空间碎片白天激光观测的目标监视与引导。     

太空环境飞行器交会对接设备精测工艺方法研究

交会对接设备是实现飞行器交会对接的重要部件。它的安装精度直接影响交会对接任务的成败。为了研究太空环境下飞行器舱体压差对交会对接设备安装姿态的影响,文章根据太空环境飞行器所受压差情况,设计了地面仿太空环境试验,对某型号飞行器的交会对接设备及舱体基准进行了姿态测量,分析了由于舱体内外压差的影响而造成的设备姿态变化,并根据试验结果分析研究出一种新的地面总装精测工艺方案。     

空间碎片的温度特性分析

对空间碎片温度特性的分析,是利用红外传感器探测空间碎片的基础,也是研究航天器在轨安全的重要内容。文章对空间碎片接收不同辐射进行全面分析,研究其在轨运行情况,建立热平衡方程,完成对不同时刻其温度变化的计算,并绘制出温度变化曲线。结果表明空间碎片在轨道上不同位置有不同的红外辐射特性。该研究对利用天基空间探测器进行空间碎片的检测、识别,以及航天器的规避有参考意义。     

空间碎片飞网捕获仿真研究

文章利用动力学建模的方法分析了采用柔性飞网进行空间碎片捕获的过程。以非合作性目标捕获系统为基础建立了柔性飞网X模型,利用EXCEL和MATLAB对飞网捕获碎片的全过程进行仿真,重点分析了抛射速度和抛射角度对飞网捕获能力的影响。结果表明,随着抛射角度的增大,飞网的捕获能力无明显变化;随着抛射速度的增大,飞网的捕获能力增强。     

Solution of the flyby problem for large space debris at sun-synchronous orbits

the paper considers the flyby problem related to large space debris (LSD) objects at low earth orbits. The data on the overall dimensions of known last and upper stages of launch vehicles makes it possible to single out five compact groups of such objects from the NORAD catalog in the 500–2000 km altitude interval. The orbits of objects of each group have approximately the same inclinations. The features of the mutual distribution of the orbital planes of LSD objects in the group are shown in a portrait of the evolution of deviations of the right ascension of ascending nodes (RAAN). In the case of the first three groups (inclinations of 71°, 74°, and 81°), the straight lines of relative RAAN deviations of object orbits barely intersect each other. The fourth (83°) and fifth (97°–100°) LSD groups include a considerable number of objects whose orbits are described by straight lines (diagonals), which intersect other lines many times. The use of diagonals makes it possible to significantly reduce the temporal and total characteristic velocity expenditures required for object flybys, but it complicates determination of the flyby sequence. Diagonal solutions can be obtained using elements of graph theory. A solution to the flyby problem is presented for the case of group 5, formed of LSD objects at sun-synchronous orbits.     

空间超高速撞击碎片云前端速度的预测模型

文章利用一组二级轻气炮发射2017-T4 铝质球形弹丸撞击6061-T6单层铝板的地面试验数据,通过选择适当的函数模型,采用多元函数拟合的方法,得到了碎片云前端速度与靶板厚度、弹丸直径和弹丸速度关系的三元二阶多项式模型。再用另外一组数据对该模型进行检验,验证了其对碎片云前端速度具有较好的预测效果。将以上两组数据同样用于建立“无量纲化”模型进行碎片云前端速度预测,并与前述多项式模型的预测结果进行比较发现,该多项式模型预测的方均根误差及平均相对误差均明显优于“无量纲化”模型。该多项式模型可用于预测空间碎片撞击航天器产生的碎片云的前端速度,有助于航天器的空间碎片防护设计。     

微小碎片对航天器舷窗玻璃损伤状况的跟踪研究

空间微小碎片环境比较复杂,其来源包括人为产生的碎片及微流星体。空间微小碎片不仅速度较高,而且数量庞大。它们频繁撞击航天器外表面,包括舷窗部位,特别是对航天飞机舷窗已造成巨大危害,使长期服役的国际空间站舷窗玻璃存在安全隐患。文章简要介绍了空间微小碎片对航天飞机和空间站舷窗玻璃的损伤状况,以及NASA对此做出的改进措施,这些跟踪研究成果可为我国长寿命、高可靠航天器舷窗结构设计提供参考依据。     

空间碎片国际机制发展趋势分析

文章通过对空间碎片国际机制(多边谈判机制)的分析,指出其发展趋势,从而为中国参加相关谈判工作提供参考。空间碎片国际机制的发展已呈现出明显的政策化、法律化和制度化的趋势。无论是从外空利益争夺、外空战略实现,还是从中国航天事业可持续发展、中国航天立法体系完善的角度来讲,积极参加空间碎片技术合作与规则制定的国际谈判都具有重要意义。从国内建设上来看,中国应尽快制定“技术—政策(战略)—法律”三位一体的解决思路和具体方案;从国际层面看,可以借鉴美国一直坚持和贯彻的“技术—政策—国内规则—国际软法—国际法”外空策略,来开展空间碎片减缓和清除等方面的技术与规则制定的合作。     

Numerical and experimental study on the shaped charge for space debris assessment

This paper proposes a numerical analysis method to simulate jet formation and penetration process by the ‘low-velocity’ (67 km/sec-class) inhibited shaped charge launcher, in order to assess the protection capability of the bumper structure against orbital space debris impacts on the spacecraft. The present simulations by a two-dimensional hydrocode (AUTODYN-2D), which was performed by an improved method on the basis of our former works, were compared with the test results based upon the experimental method that we had proposed in our another work. The both results were in fairly good agreement, and the feasibility was ascertained of the calibration between the inhibited CSC jet and solid spherical projectile by the numerical method. Consequently, the accuracy of the ballistic limit curve at 1015 km/sec is expected to be enhanced by making use of the present method hereafter.     

空间碎片软捕获姿轨控模型构建与仿真

为构建利用柔性机械臂捕获空间碎片的系统仿真模型,首先分析梳理空间碎片捕获典型任务流程,包括轨道转移、位置保持、路径规划、动量稳定控制等阶段;然后针对任务流程分别搭建基于Simu Link的路径规划、动量缓冲控制、姿态控制、动力学和轨道仿真等子系统;各个子系统之间以TCP/IP的方式进行数据交互,最终完成空间碎片软捕获任务姿轨控仿真系统的构建。     

Modeling the sodium potassium droplet interactions with the low earth orbit space debris environment

The NASA/JSC sodium potassium (NaK) RORSAT coolant source and propagation model has been extended to 1 mm in diameter via a size distribution, which is an inverse power law fit that has been modified to damp out in the large size regime. This function matches the observed Haystack NaK population down to diameters of about 6 mm. The extrapolated function takes the population to arbitrarily small sizes all the while retaining the mass dominance of the 1–3 cm droplets that is observed in the Haystack data. This result is physically satisfying since the mechanism of NaK ejection appears to be a nonviolent release at low relative velocities. We propose that any NaK particles smaller than about 1 mm that exist would not be due to that mechanism. Instead, we show that such a population could be the result of subsequent collisions of NaK droplets with larger resident space objects and the micrometeoroid population. Our preliminary analysis shows that collisions between these populations are likely in the time period of 1980 through present-day. Though the result of such collisions is generally unknown it is probable that some ejecta of NaK enter the low Earth orbit (LEO) environment as a result. It is these secondary NaK droplets/particles that we contend are the likely impactors noted on returned surfaces.     

航天材料紫外辐射效应地面模拟试验方法

空间紫外辐射环境可造成航天器材料的光学性能、电学性能或力学性能退化甚至失效。在地面模拟试验过程中较难真实模拟空间紫外辐射环境,因此,通常采用基于效应等效原理的加速模拟试验方法。文章首先对国内外紫外辐射效应试验方法和标准现状进行梳理,进而从紫外曝辐量的计算方法、紫外波长的选择、模拟光源选用、温度选择与控制以及总曝辐量和加速因子的选择等角度对紫外辐射效应地面模拟试验方法进行分析研究,并给出应进一步开展工作的建议。     

天基激光清除空间碎片方案与可行性研究

介绍了激光烧蚀驱动机理和空间碎片降轨清除原理,通过分析计算确立了空间碎片降轨清除判据和2 种降轨清除模式。理论计算给出了清除1200、800 和500 km 三个典型低地球轨道上空间碎片所必须的速度增量、激光器功率、单脉冲能量、激光发射镜直径等主要参数值。对比分析显示现有的硬件指标和条件能够满足清除低地球轨道上空间碎片的设计要求,因此,天基激光清除空间碎片方案从技术角度是可行的。