A Population Dynamics Approach to the Distribution of Space Debris in Low Earth Orbit

The presence of the debris in the Earth’s orbit poses a significant risk to human activity in outer space.This debris population continues to grow due to ground launches,the loss of external parts from space ships,and uncontrollable collisions between objects.A computationally feasible continuum model for the growth of the debris population and its spatial distribution is therefore critical.Here we propose a diffusion-collision model for the evolution of the debris density in the low-Earth orbit and its dependence on the ground-launch policy.We parametrize this model and test it against data from publicly available object catalogs to examine timescales for the uncontrolled growth.Finally,we consider sensible launch policies and cleanup strategies and how they reduce the future risk of collisions with active satellites or space ships.

Meteoroid and Space Debris Risk Assessment for Satellites Orbiting the Earth/Moon

Interplanetary meteoroids and space debris can impact satellites orbiting the Earth or spacecraft traveling to the Moon.Targeting China Space Station(CSS),7 satellites selected from the constellation of Beidou Navigation Satellite System Phase III(BDS-3),and 3 spacecraft orbiting the Moon,we have adopted in the paper the Meteoroid Engineering Model 3,Divine-Staubach meteoroid environment model,and Jenniskens-McBride meteoroid steam model to analyze the meteoroid environment with the mass range of 10–6~10 g.Orbital Debris Engineering Model 3.1 space debris model is used to analyze the orbital debris environment faced by these satellites.The flux of space debris with a size larger than 100μm is compared with that of the meteoroids.The results show that the space debris flux encountered by China Space Station is much higher than that of the meteoroids with sizes in the above range.And quite the opposite,the meteoroids flux impacting the 7 satellites from the BDS-3 is higher.Upon adopting the double-layer Whipple protection measure,the catastrophic collision flux of these satellites encountering meteoroids is about 10–6 times of that without protection,or even less,implying that the Whipple protection effectively guarantees the safety of the satellites in orbit.Besides,it is also found that the flux of the high-density meteoroid population encountered by each satellite is greater than that of the low-density population,whereas the impact velocity is lower for each satellite.These results can aid the orbit selection and the protection design for satellites and spacecraft.

Survivability assessment of spacecraft impacted by orbit debris

To help optimize the spacecraft design and reduce the risk of spacecraft mission failure, a new approach to assess the survivability of spacecraft in orbit is presented here, including the following three steps: 1)Sensitivity Analysis of spacecraft. A new sensitivity analysis method, a ray method based on virtual outer wall, is presented here. Using rays to simulate the debris cloud can effectively address the component shadowing issues. 2) Component Vulnerability analysis of spacecraft. A function "Component functional reduction degree-Component physical damage degree" is provided here to clearly describe the component functional reduction. 3) System-level Survivability Assessment of spacecraft. A new method based on expert knowledge reasoning, instead of traditional artificial failure tree method, is presented here to greatly improve the efficiency and accuracy of calculation.

Influence of Solid Rocket Motor Slag on the Space Debris Environment

The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been also estimated via observations of sub-orbital tail-off events. We achieve slag initial data based on MASTER slag model and SRM historical launch data,and propagate slag long-term orbital evolution taking into account the zonal harmonics J2,atmospheric drag,solar radiation pressure and luni-solar attraction to discuss the slag size distribution and orbital characteristics. Finally,future slag debris environment is evaluated based on two different launch rate assumptions. The result shows that current launch frequency will make the slag population sustain growth and the population will not decrease at once even if there are no more launches in the future.

Research Progress in Laser Active Debris Removal of CAST

Based on the introduction to theresearch status and trend of international space-based laser debris re-moval technology, the existing problems of space-based laser debris removal technology are systematically analyzed.In view of the existing problems, the work and research progress of the Beijing Institute of Spacecraft EnvironmentEngineering in this field are introduced from several aspects, such as dynamic behavior of laser-driven debris, orbittransfer model, ground simulation system, space-based removal system scheme and target selection strategy. The mainresearch methods include laser-driven micro-impulse measurement experiment, surface triangulation three-dimension-al reconstruction calculation method based on laser-material interaction theory, simulation calculation based on orbitaldynamics, etc. It also looks forward to the future research direction in the field of this technology.

Investigation into debris cloud characterizations for oblique hypervelocity impact of projectiles on bumper

All long-duration spacecraft in low-earth-orbit are subject to high velocity impacts by meteoroids and space debris. Such impacts are expected to occur at non-normal incidence angles and can cause severe damage to the spacecraft and its external flight-critical systems and possibly lead to catastrophic failure of the spacecraft. In order to ensure crew safety and proper function of internal and external spacecraft systems, the characteristics of a debris cloud generated by such impacts must be known. An analytical model is therefore developed for the characterization of the penetration and ricochet debris clouds created by the hypervelocity impact of an aluminum spherical projectile on an aluminum plate. This model employs normal and oblique shock wave theory to characterize the penetration and ricochet processes. The prediction results of center-of-mass trajectory and leading velocity of penetration and ricochet debris clouds are obtained and compared with numerical and experimental results in figures.

Risks Posed by Space Debris

With the rapid development of space technology, the dream of the exploration and peaceful use of outer space has been realized, which, meanwhile, brings great benefits to all mankind, promotes the development of people’s production and improves their social activities. Therefore, it is a common concern for people all over the world to make their great

基于光电阵列系统的空间碎片精密定轨应用研究

光电阵列系统具有视场大、单元众多、覆盖空域广、可靠性高、实时性好等优点,在空间碎片探测领域中具有重要的作用。首先,为了解决空间碎片关联匹配问题,采用TLE数据,配合SGP4/SDP4模型,实现了光电阵观测空间碎片的数据关联匹配。随后,研究了空间碎片弹道系数计算方法,为基于观测数据定轨结果的空间碎片平均弹道系数的计算奠定基础。最后,基于长春人卫站建设的光电阵列系统,验证其数据精度、定轨精度以及弹道系数计算精度,实验结果表明:空间碎片关联匹配成功率达到91.19%;观测精度可达7:65′′;对拥有高精度激光测距的空间合作目标Sentinel-6A和HY-2C进行基于激光测距数据的精密定轨,并以定轨结果为标准轨道,对光电阵列观测系统所得光学数据进行精密定轨和3 d预报的均方差做精度分析,三维位置精度分别为319.11 m、107.25 m,速度精度分别为0.26 m/s、0.09 m/s;计算所得目标36508弹道系数生成的新两行根数3 d预报均方根误差为746.84 m,比公开数据均方根误差748.68 m减小0.25%,两者精度相近。以上结果说明该系统基本满足常规任务需求。

Experimental and numerical study of hypervelocity impact damage on composite overwrapped pressure vessels

Ground-based tests are important for studying hypervelocity impact(HVI)damage to spacecraft pressure vessels in the orbital debris environment.We analyzed the damage to composite overwrapped pressure vessels(COPVs)in the HVI tests and classified the damage into non-catastrophic damage and catastrophic damage.We proposed a numerical simulation method to further study non-catastrophic damage and revealed the characteristics and mechanisms of non-catastrophic damage affected by impact conditions and internal pressures.The fragments of the catastrophically damaged COPVs were collected after the tests.The crack distribution and propagation process of the catastrophic ruptures of the COPVs were analyzed.Our findings contribute to understanding the damage characteristics and mechanisms of COPVs by HVIs.

Preliminary survivability analysis of manned spacecraft following orbital debris penetration

Meteoroid and orbital debris(M/OD) may cause severe damages or even catastrophic failures for long-term manned spacecrafts in orbit due to the hypervelocity impact(HVI) destruction.It is essential to quantitatively assess the M/OD risk of manned spacecraft.In this paper,the catastrophic failure as-sessment function is successfully integrated into the Meteoroid & Orbital Debris Assessment and Op-timization System Tools(MODAOST),which is the M/OD risk assessment system developed by China Academy of Space Technology.The survivability assessment for the US Lab by MODAOST was con-sistent with that of the Manned Spacecraft Crew Survivability computer code(MSCSurv).Meanwhile,the simulation process showed that this function was more effective than MSCSurv for the application of the standard methodology of M/OD risk assessment instead of the Monte Carlo model.This function expands the ability of MODAOST in predicting the survivability of the typical catastrophic failure modes such as crew hypoxia and the critical cracking.

The Space Infrastructure Vulnerability Cadastre:Orbital Debris Critical Loads

Orbital debris from over 50 years of human activity in space are threatening the operations of existing and future satellites and the sustainability of high-value satellite orbits. This technical memorandum calls for the development of a cadastre that depicts the vulnerability of critical satellite orbits to accumulating orbital debris. A space infrastructure vulnerability cadastre could serve as a governance tool for use by developers and operators of critical space infrastructures to better communicate the current and future vulnerability of high-value orbits to the accumulation of orbital debris. These high-value orbits are susceptible to 'loss' for decades or centuries if generation of orbital debris continues unabated. The concept of environmental critical loads is applied to heavily used orbits as a way to indicate acceptable debris density for satellite operations, and when debris density/risk thresholds approach unacceptable levels that reduce the probability of sustaining spacecraft operations in those orbits.

FY-2C De-orbited

It is announced recently that the FY-2C satellite was de-orbited by the Xi’an Satellite Control Center(XSCC).FY-2C was the first operational geostationary meteorological satellite in China with the capability of making continued and stable operation in orbit.It was launched in 2004 and stopped operation in 2009.Ever since then。

基于角度转化的空间碎片测角数据精密定轨方法

空间碎片对在轨卫星的影响日益增大,持续确定和更新空间碎片轨道日益受到重视。基于角度转化思想,提出了一种空间碎片测角数据精密定轨方法。基于常用的两行根数(TLE)数据应用需求,根据差分思想建立基于SGP4/SDP4预报模型的TLE精密定轨方法;以赤经-赤纬数据为典型场景,分析原始定义法、赤经投影法的优缺点;提出将常规双元素角度资料转化为三元素角度资料的角度转化法。仿真结果表明:当观测数据较多集中于测站天顶方向时,角度转化法能够将精密定轨收敛速度提高25%,轨道精度提高2~10倍。

空间碎片多源数据融合定轨软件SPODFMD简介

空间碎片多源数据融合定轨软件SPODFMD(Spacedebris Precise Orbit Determination Fusing Multi-source Data)是由紫金山天文台卫星精密定轨团组自主研发的一款数值法编目定轨软件,目的是解决国内空间碎片监测网获取的多源数据融合问题.软件设计初期,充分调研了国内主流空间碎片监测设备。考虑到空间碎片轨道和物理特征的复杂性、大量碎片轨道更新对计算效率的要求以及工程应用对稳健性的要求等现实因素,在定轨算法中集成了具有自主知识产权的地球重力势及其偏导数无奇点快速算法、无奇点DTM94(Drag Temperature Model)大气密度模型及其偏导数的解析表达方法、大偏心率轨道密集星历精密快速计算算法以及稳健的自适应加权方法等结合软件工程设计理论,目前已实现了14种主流设备获取数据的任意融合,并取得了典型场景下的秒级定轨速度,适用于高、中、低轨和各种偏心率特点的全轨道碎片,且不存在计算奇点和极性奇点,经初步测试证实了SPODFMD软件的多源性、高效率、通用性和稳健性效果.

纤维织物超高速碰撞热-力学特性数值模拟

针对纤维织物防护结构在空间碎片超高速碰撞下发生的变形、破碎及温升、相变等热-力学问题,引入Johnson-Cook模型及Gruneisen状态方程,结合纤维织物纱线编织几何模型及FEM-SPH耦合算法,建立了纤维织物超高碰撞数值模型,并研究了纤维织物强度对超高速碰撞热-力学特性的影响规律。结果表明:随着纤维织物强度的增加,纤维织物防护结构对弹丸的动能吸收能力增强;纤维织物碰撞区域热效应显著,随着纤维织物强度的增加,碰撞区域中心的热效应先增强后减弱;当纤维织物强度在2000 MPa附近时,碰撞区域中心的热效应较为显著。

失效航天器非接触式消旋技术发展综述

对失效航天器非接触式消旋领域内的研究成果进行了综述,梳理了非接触式消旋的特点,并聚焦于系统动力学模型、消旋方法和关键技术等方面。首次将非接触式消旋方法按照其作用机理分为电磁式消旋和冲击式消旋两类,并分别总结了其技术特点和适用的任务场景。而后针对消旋任务的实践需求,系统阐释了非接触消旋中制导与控制、高性能星载计算等关键技术。最后,面向复杂空间任务和智能化消旋操控的需求,提出了非接触式消技术中4个值得研究的问题和方向。有望为未来失效航天器在轨维护和非接触式消旋技术的发展提供借鉴和参考。

低轨空间碎片捕获离轨方案设计与分析

针对低轨米级空间碎片清除任务需求,提出捕获离轨一体化载荷方案,采用飞网捕获和增阻帆离轨方案开展低轨空间碎片清除任务流程设计与效能分析,论证方案可行性。在考虑操控星悬停指向控制偏差和飞网发射偏差等因素后,采用16 m×16 m增程飞网,实现在100~200 m范围内对火箭末子级等米级空间碎片实施飞网捕获。在操控星对绳系组合体进行章动抑制和稳定后,释放5 m×5 m增阻帆,使初始轨道高度在600 km以内的火箭末子级5年内再入大气。

泡沫胶增阻空间碎片清除技术综述

空间碎片对人类开发利用外层空间资源造成了极大的阻碍。为了有效遏制地球近地轨道空间碎片数量日益增多、航天器与空间碎片碰撞风险日渐加剧的趋势,必须移除轨道上的空间碎片。介绍了泡沫胶增阻空间碎片清除技术的基本原理,总结了当前研究现状,可为今后空间碎片清除技术的研究和发展提供借鉴与参考。

“仰望一号”太空望远镜在轨综合应用

“仰望一号”作为中国首个发射升空的商业太空望远镜,近两年来在轨运行状态良好。在不同学科领域都取得了丰硕的成果,包括银河系巡天、夜光遥感、灾害监测、大气现象等。而在空间科学方面,由于空间碎片的持续增长,以及近地小天体的撞击风险成为当今亟待解决的问题,“仰望一号”也结合自身的硬件与特性,进行了一系列的在轨综合应用,包括在移动目标自动识别编目、人工目标的机动拍摄、近地小行星观测、目标定初轨以及地球同步轨道目标普查等一系列的尝试,积累了不少有用的成果,取得了一定的商业价值。

航天器微流星和空间碎片的防护方案

微流星和空间碎片是现在任何使命航天器的公认威胁．微流星和空间碎片的超高速撞击能导致航天器严重的损伤和灾难性的失效．因此，提高航天器的生存性是非常必要的．防护方案的确定是航天器设计的一个重要问题．防护方案的结构形式主要有局部防护、Whipple防护及其改型、各种多层防护屏防护方案。在综述国际上已采用和研究的航天器防护微流星和空间碎片防护方案的基础上，给出了不同防护材料和结构形式防护方案在超高速撞击下的行为特征。