卫星超高速撞击解体碎片特性的试验研究

为了研究超高速撞击下卫星解体碎片的分布特性,在弹道靶上开展了三次模拟卫星的超高速撞击试验。发射铝合金钝锥弹丸以3.2km/s~4.2km/s的速度撞击模拟卫星,对解体碎片进行回收、测量和统计分析,结果表明：碎片累积数量与碎片特征尺寸/特征质量在对数坐标系中基本呈直线关系,且碎片尺寸分布和质量分布在形式上和规律上具有高度相似性。通过数据拟合得到了碎片尺寸和质量分布的具体函数形式,分析了碎片质量分布与尺寸分布之间的内在关系。将试验结果与NASA标准解体模型进行了比较,讨论了两者的差别及其原因。
     

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k J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k J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。     

天基照相跟踪空间碎片批处理轨道确定研究

随着国内外天基观测空间碎片研究的展开,文章提出了利用跟踪卫星的CCD(Charge
Coupled Device)相机对空间碎片进行轨道探测的方法,首先建立了CCD照相观测模型和基于 照相观测 的空间碎片批处理轨道确定模型。通过对CCD相机底片归算方法的分析可知,利用
CCD相机所获得的观测数据与跟踪卫星的姿态无关,且其精度只与测量和坐标转换计算的精 度有关,在测量和计算中可获得较高的精度。分别对分布密度较高的低轨道和地球同步 轨道区域的空间碎片进行了定轨分析。仿真结果表明,定轨时采用两个跟踪弧段的照相数据 定轨精度大大高于一个弧段照相数据的定轨精度;跟踪卫星距离空间碎片越近,定轨精度越 高;低轨道空间碎片的定轨精度高于地球同步轨道上的空间碎片定轨精度。
     

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。     

航天器入轨段测轨数据误差特性及定轨结果分析

分析了航天器发射任务入轨段各类测轨数据的误差特性及入轨段各类测轨数据的常用定轨方法的定轨精度,提出了解决定轨结果一致性差、优选困难的方法,并用仿真计算结果和实战任务数据计算结果予以验证.     

激光移除空间碎片过程的三维仿真与建模

基于轨道力学和激光与物质相互作用理论建立激光移除空间碎片的三维变轨模型。该模型利用激光站/卫星与碎片位置和速度矢量作为初始数据,通过设定激光参数,实时计算和更新速度增量矢量,能够真实地反映碎片的移除过程。该模型包括地基和天基两种类型,根据激光作用临界条件与降轨效果计算碎片的降轨过程,能够实时输出碎片轨道信息,图形化输出使结果更加直观。考虑到速度增量分量对轨道倾角的影响,该模型增加了碎片逃逸情况的判断。最后,利用该模型计算了地基/天基系统移除多种空间碎片材料的过程和效果,发现钢材料碎片移除难度最大,而移除多层绝缘材料的效率最高。     

长征四号乙/丙运载火箭末级空间碎片减缓技术研究与应用

为有效减少空间碎片的产生,避免空间碎片危及空间活动和航天器安全,保护空间环境,对长征四号乙/丙(CZ-4B/4C)运载火箭末级空间碎片减缓技术及应用进行了研究。基于国际上对运载火箭末级空间碎片减缓的钝化和离轨等基本要求,确定了CZ-4B/4C运载火箭末级的钝化和离轨技术。给出了改进后的剩余推进剂排放方案。介绍了其中推进剂管理、排放程序优化设计、推进剂排放污染分析、全系统地面冷流试验、排放程序兼顾离轨,以及高压气体释放等关键技术。对CZ-4B/4C运载火箭28次LEO轨道发射任务事后的末级离轨效果统计表明:末级留轨近地点高度平均下降约200km,留轨寿命降低约70%,采取的末级钝化措施在LEO任务中的离轨效果明显。讨论了CZ-4B/4C运载火箭末级留轨时间控制中后续三级发动机二次点火离轨、三级发动机三次点火离轨和姿控正推推力器离轨等主动离轨方法发展及其关键技术。研究对推动我国运载火箭空间碎片减缓的发展有重要参考价值。     

美俄卫星碰撞事件验证及其对我国卫星的影响分析

北京时间2009年2月11日0时55分,美国铱星-33和俄罗斯宇宙-2251两颗卫星在太空相撞,在所在的高度产生了大量新增空间碎片,使得空间碎片环境更加严峻,低轨航天器运行遭受空间碎片撞击的风险大幅增加。文章通过碰撞前后轨道数据分析,确认并验证了此次碰撞事件;利用事前轨道数据进行碰撞预警分析,得出碰撞的相关的参数;通过分析此次事件产生的新增碎片的轨道数据,进一步验证确认碰撞事件;从空间碎片密度和通量角度分析其时当前空间碎片环境产生的影响;通过新增碎片寿命计算分析其对空间碎片环境的长期的影响;从碰撞概率出发分析对航天器运行安全的威胁。分析结果表明：我国低轨卫星在一定程度上增大了空间碎片碰撞风险,需要进行在轨空间碎片碰撞预警,以确保我国卫星的安全运行。     

轨控发动机羽流红外辐射的数值仿真

针对工作在高真空环境下的轨控发动机,数值模拟了其羽流红外特性。首先计算了考虑化学反应的轨控发动机喷管的内流场和外流场,得到了温度、压力、组分浓度等参数的分布。基于HITRAN 2008和HITEMP 2010数据库采用逐线积分法编程计算了气体光谱吸收系数。最后在此基础上用有限体积法建立的求解辐射传输方程的模型,计算得到羽流红外辐射强度在2~10μm范围内随波长变化的曲线。分析了羽流气体组分、波长、探测角度对羽流光谱辐射的影响,与同类文献中的计算结果进行了比较,结果表明：本文的计算模型和方法能较好地模拟轨控发动机羽流的红外辐射特性。     

球形气囊的超高速撞击损伤特性试验与仿真研究

低成本、可自主展开的气球卫星是未来卫星技术的应用方向之一,而日益增多的空间碎片是低轨航天器,包括气球卫星所面临的主要威胁之一.为满足气球卫星的生存力分析以及在轨被撞击产生空间碎片的评估需求,开展球形气囊超高速撞击试验与仿真研究,获得了不同材质气囊的撞击损伤特性,并初步揭示弹丸贯穿球形气囊过程的破坏细节以及碎片云团特性,...     

Debris area distribution of spacecraft under hypervelocity impact

Cross-sectional area is an important parameter for spacecraft breakup debris as it is the directly measured data in space observation. It is significant for observing and analysing the spacecraft breakup event to accurately modelling the area distribution of the breakup debris. In this paper, experimental study has been performed on debris area distribution characteristics of spacecraft under hypervelocity impact. The tests are carried out at the ballistic ranges of CARDC. Aluminium projectiles are launched to normally impact the simulated spacecrafts at about 3.0 km/s. The simulated spacecrafts are made up of aluminium plates, filled with some simulated electronics boxes, each of which was installed with a circuit board. “Soft-catch” devices are used to recover the breakup fragments. The test results show that: 1) the relationship between the cross-sectional area and the characteristic length of debris, which can be obtained in the logarithmic coordinates by linear fitting, represents the debris shape characteristic in a certain extent; 2) the area-to-mass ratios of fragments show normal distributions in the logarithmic coordinates; 3) debris made of different materials can be distinguished by different peaks on the distribution curves; 4) the area-to-mass ratio distributions can be expressed by a linear superimposition of several normal functions which represent the main materials of the spacecraft.     

数字全息测量超高速撞击碎片云实验研究

在中国空气动力研究与发展中心(CARDC)超高速碰撞中心(HIRC)7.6 mm超高速碰撞设备的基础上，搭建纳秒级脉冲激光数字全息系统。提出滤波片和衰减片组合布置，减弱超高速碰撞等离子体自发光、提高信噪比的方法。实验获得了2.25 mm铝球弹丸以4.0 km/s的速度撞击0.5 mm厚铝板形成碎片云的全息图。采用小波变换算法对碎片云全息图进行重建，得到超高速撞击碎片云的三维结构和碎片大小。碎片云的轮廓呈椭球型，分为碎片云的前端、核心和外壳，碎片主要分布在弹丸破碎形成的碎片云核心，存在大碎片，且分布较集中，对后板的损伤也严重     

空间碎片数据形式及轨道演化算法

根据建立空间碎片工程模型的需要,定义了一种描述单个空间碎片运行位置及其物理特性的数据形式。基于空间碎片运动规律给出了一种用于计算单个空间碎片运行时＂平均位置＂的演化算法。计算的演化结果与STK软件计算的标称轨道比较表明：该演化算法正确。     

Enhancement and Validation of the IDES Orbital Debris Environment Model

Orbital debris environment models are essential in predicting the characteristics of the entire debris environment, especially for altitude and size regimes where measurement data is sparse. Most models are also used to assess mission collision risk. The IDES (Integrated Debris Evolution Suite) simulation model has recently been upgraded by including a new sodium–potassium liquid coolant droplet source model and a new historical launch database. These and other features of IDES are described in detail. The accuracy of the IDES model is evaluated over a wide range of debris sizes by comparing model predictions to three major types of debris measurement data in low Earth orbit. For the large-size debris population, the model is compared with the spatial density distribution of the United States (US) Space Command Catalog. A radar simulation model is employed to predict the detection rates of mid-size debris in the field of view of the US Haystack radar. Finally, the small-size impact flux relative to a surface of the retrieved Long Duration Exposure Facility (LDEF) spacecraft is predicted. At sub-millimetre sizes, the model currently under-predicts the debris environment encountered at low altitudes by approximately an order of magnitude. This is because other small-size debris sources, such as paint flakes have not yet been characterised. Due to the model enhancements, IDES exhibits good accuracy when predicting the debris environment at decimetre and centimetre sizes. Therefore, the validated initial conditions and the high fidelity future traffic model enables IDES to make long-term debris environment projections with more confidence.     

Debris dispersion effect in N-shape configuration

Spacecraft shields play an important role in shielding against the impact of space debris. Increasing the dispersion degree of the debris produced by the impact of the space debris on the bumper of configuration is able to lower the concentration of debris impacting on the rear plate and thus to reduce the risk of debris perforating the rear plate. In order to improve the dispersion degree, the N-shape configuration is proposed and studied by hypervelocity impact test with the velocity of 4.80 km/s and numerical simulation with the velocities ranging from 3.0 km/s to 7.0 km/s. As a comparison, the distribution of debris impacting on the rear plate is also investigated for the parallel triple-wall configuration with the same areal density. It is found that this degree is increased in the N-shape configuration due to the oblique plate, and therefore the risk of debris perforating the rear plate is reduced compared to the case of parallel triple-wall configuration.     

Density and mass distributions of orbital debris

Area-to-mass ratios for orbital debris tracked by the U.S. Space Command were calculated from observed changes in apogee and perigee altitude due to atmospheric drag. The area-to-masses observed for the orbital debris were similar to those found for debris from laboratory breakups, and suggest that much of the debris is composed of crumpled thin plates or of insulation material with low effective density. Areas for the debris objects were derived from radar cross-section data. Object masses were calculated from the ratio of the RCS-derived area to the area-to-mass ratio. Analysis of the distributions of fragment masses from the breakups suggests that in many cases, only a portion of the initial object breaks up into small fragments.     

夜气辉对天基光学碎片探测的影响分析

设计并完成了夜气辉背景下的天基碎片观测试验，获取了综合谱段的观测数据。基于观测数据进行夜气辉的辐射特性及其对天基碎片探测的影响分析。结果表明，夜气辉辐射随纬度和高度呈现一定的分布特点，这些特点均符合夜气辉的理论分布规律。在约90 km处辐射最强，亮度可达到单位积分时间每平方角秒近15星等，这对恒星及碎片提取概率影响较大，其中，13等星的提取概率仅为40.5%。     

Study on electrodynamic tether system for space debris removal

As a countermeasure for suppressing space debris growth (P. Eighler, A. Bade, Chain Reaction of Debris Generation by Collisions in Space—A Final Threat to Spaceflight? in: 40th Congress of the International Astronautical Federation, IAA-89-628, October 1989), the National Aerospace Laboratory of Japan is investigating a satellite capture, repair and removal system for non-cooperative satellites, part of which involves assessing the viability of electrodynamic tether (EDT) technology as an orbital transfer system. In this paper, some results concerning the time required to remove existing satellites, the behavior of flexible tethers during the debris separation phase, and orbital transfer strategies of EDT systems during space debris removal operations are described. From numerical simulations, it is found that EDT systems can transfer satellites from LEO to orbits with a short lifetime within a realistic timeframe. It is also found that the stability of EDT systems is compromised when debris separation occurs both while a tether current is running and when the ratio of the end mass to that of the service satellite is high. To ensure stability, the end mass should be selected from the target debris group with due regard for the maximum possible mass that can be maneuvered safely. Moreover, it is also found that orbital elements (a, e, i) can be changed independently with an adequate current control strategy.     

地球静止轨道卫星撞击解体的数值模拟

分析了地球静止轨道（GE0）环内的物体现状,引入美国家航空航天局（NASA）的标准解体模型,给出了卫星撞击解体算法,编写了数值仿真软件,仿真研究了GEO卫星撞击解体形成碎片的特征及其轨道分布。结果表明：撞击会产生大量碎片,对空间环境造成长期的严重危害。研究结果对分析卫星撞击解体特性、保护空间环境有一定的参考价值。     

超高速撞击中靶后碎片云的内外边界方程研究

研究超高速撞击防护靶形成的碎片云的形状模型对航天器防护结构设计具有重要意义。文章用数值仿真的方法研究靶后碎片云的内外边界模型:将碎片云根据其材料来源分为靶板碎片云和弹丸碎片云,分别根据各碎片云的分布特点建立碎片云形状的内外边界方程;在双纽线边界方程的基础上,修正为由双纽线方程和圆弧方程组成的边界方程。对比整体碎片云的适用率表明,由双纽线方程和圆弧方程组成的边界方程比单一的双纽线边界方程描述碎片云实际分布更为贴合。